CR 9: Neuromuscular I (Chapter 9)

69. A 10 yo F falls off a ledge and fractures the proximal humerus. After her cast is removed, she is noted to have weakness of the arm. On exam, she can abduct the arm to 30 degrees but not beyond this. Sensory exam reveals a small area of hypoesthesia on the lateral aspect of the upper arm, but is otherwise normal. Arm adduction, forearm pronation, forearm/wrist/finger extension are normal. What is the most likely diagnosis? A. Axillary neuropathy B. Radial neuropathy C. Posterior cord lesion D. C5 radiculopathy E. Middle trunk lesion

A. Axillary neuropathy can occur with a fracture at the surgical neck of the humerus. The axillary nerve is a continuation of the posterior cord and carries C5 and C6 fibers. It innervates the deltoid (main arm abductor between 30-90 degrees). It also provides sensory input to the upper lateral arm via upper lateral brachial cutaneous nerve.

12. Which of the following is correct regarding this condition (CIDP)? A. There may be prolongation of distal motor latencies B. There are specific sensory NCS findings required for the diagnosis C. Increased CSF white blood cells w/o elevated protein is typical of this disorder D. Sural nerve biopsy typically shows an acute inflammatory infiltrate without demyelination E. Conduction velocities are normal in this condition

A. CIDP presents with prolonged peak latency, reduced conduction velocity, and CMAP amplitude dispersion. All of this suggests demyelination. Conduction block is common in CIDP. Sensory NCS findings do not play a major role in diagnosis. Sural nerve biopsy should be considered if EMG/NCV or CSF studies are not supportive. It will typically show evidence of demyelination and remyelination in CIDP with an onion-bulb formation, sometimes with inflammation.

21. A 13 yo F is brought to the clinic by her mother for bilateral foot drop. As an infant and young child, she had always been clumsy and seemed to trip over her own feet and could not participate in ballet classes. More recently, her feet became noticeably weak. On exam, she has bilateral symmetric weakness of foot dorsiflexion and plantarflexion. She has hammertoes and high-arched feet. Ankle and knee reflexes are absent. Exam of the mother also reveals hammertoes and high-arched feet. Conduction velocities of approximately 30 cm/s are seen in all NCS of the legs (diffusely slow), with no identifiable conduction block. What is the most likely diagnosis in this patient? A. CMT 1 B. CMT 2 C. Muscular dystrophy D. CMT 3 E. CMT 4

A. CMT disorders are hereditary (AD) sensorimotor neuropathies or peroneal muscular atrophy. Typical EMG/NCV findings are uniformly slow conduction velocities without conduction block or temporal dispersion. CMT1 is the most common (duplication mutation of PMP22 in CMT1a, mutation of myelin protein 0 gene in CMT1b)--symptoms occur in the first two decades of life--progressive weakness, muscle atrophy, kyphosis, mild sensory loss with hammertoes, high-arched feet, palpably enlarged nerves 2/2 peripheral nerve hypertrophy, and pes cavus.

44. A 50 yo F is admitted for asthma exacerbation and suffers multiple complications during her hospitalization. She is bedridden > 4 weeks and develops R foot drop. On exam, she has weakness in dorsiflexion and eversion. NCS demonstrates reduced CMAP amplitude of the tibialis anterior and extensor digitorum brevis and well as reduced SNAP of the superficial peroneal nerve. EMG shows fibrillations in the tibialis anterior, extensor hallucis, extensor digitorum brevis, and peroneus longus. Short head of the biceps femoris is normal. Other muscles tested demonstrated no abnormalities. Which is the most likely site of her lesion? A. Common peroneal nerve B. Deep peroneal nerve C. L5 nerve root D. Sciatic nerve E. Tibial nerve

A. Common peroneal/fibular nerve, likely at the fibular head. Superficial peroneal/fibular nerve innervates the peroneus longus and brevis so the lesion can't just be the deep peroneal/fibular. The fact that the short head of the biceps is spared suggests that the lesion is distal to this level. The lack of tibial nerve involvement makes sciatic neuropathy, tibial neuropathy, or L5 radiculopathy less likely. In addition, SNAPs are generally not affected in radiculopathy.

18. A 40 yo M presents with BLE sharp, burning pains. Exam reveals bilateral symmetric loss of sensation to temp, pinprick, mild reduction in vibratory and fine touch. Normal proprioception. ROS reveals DOE, early satiety, erectile dysfunction, and constipation. Routine lab testing and monoclonal protein analysis are negative. His father had similar symptoms in middle age, and was in a wheelchair prior to his death at age 65 from heart and renal failure. What is the most likely diagnosis? A. Familial amyloid polyneuropathy type 1 B. Familial amyloid polyneuropathy type 2 C. Familial amyloid polyneuropathy type 3 D. Primary amyloidosis E. Secondary amyloidosis

A. FAP 1 is associated with polyneuropathy, autonomic features, and known family history. FAP2--family hx of carpal tunnel, mild predominance of sensory polyneuropathy, absence of autonomic features. Both FAP 1 and FAP2 are 2/2 transthyretin mutation. FAP 3 and 4 are rare and not related to abnormalities in transthyretin. FAP3 is similar to FAP1 in symptoms but with earlier renal involvement and more GI symptoms. FAP 4 presents in 20s with corneal dystrophy, later CN palsies, skin changes. Primary systemic amyloidosis is deposition of AL amyloid. Secondary amyloidosis is deposition of AA amyloid. Occurs with systemic disease.

86. A 60 yo F presents with 2 months of pain radiating from her buttock down to her R leg. She has foot drop on the R. There is sensory deficit in the R lateral leg and dorsum of the foot. NCS show reduced peroneal CMAP amplitudes recorded from the tibialis anterior and EDB muscles. Normal superficial peroneal SNAP amplitudes. Needle EMG shows fibrillations and reduced recruitment in the tibialis anterior, EDB, extensor hallucis, peroneus longus, tibialis posterior, and flexor digitorum longus. Which of the following is the most likely diagnosis? A. L5 radiculopathy B. S1 radiculopathy C. Common peroneal neuropathy D. Deep peroneal injury E. Sciatic nerve injury

A. Foot drop may be seen with L5 root lesions and common peroneal neuropathy but the two can be distinguished by NCS--superficial peroneal SNAPs are abnormal in common peroneal nerve lesions, but normal in L5 radiculopathies. Additionally, the peroneus longus is innervated by the tibial nerve but involves L5 so it would not be affected in a fibular injury but would be affected in an L5 radiculopathy as in this case.

75. A 20 yo F presents to the clinic with debilitating shooting pains in BLE. Exam shows loss of sensation to pinprick and temperature with decreased sensation to vibration, fine touch. Proprioception is intact. She is fearful that she is developing the condition that her father and paternal grandfather suffered from; they both are deceased, and she does not recall details, but remembers that they had problems with foot ulcerations and deformities in their toes and ankles, and her father had required a BKA. On directed questioning, she admits to heat intolerance and feels she does not sweat the way other people normally would. What is the most likely diagnosis in this patient? A. Hereditary sensory and autonomic neuropathy (HSAN) type 1 B. Charcot-Marie-Tooth 1A C. HSAN type 2 D. HSAN type 3 E. HSAN type 4

A. HSAN 1 is the most common HSAN and is autosomal dominant. Presents in young adulthood. Painful sensory symptoms such as lancinating pains are prominent. Pain and temperature are affected more than dorsal column modalities. The main autonomic manifestation is hypohidrosis. HSAN 1 results from a mutation in the gene coding for serine palmitoyltransferase which catalyzes the rate-limiting step of sphingolipid synthesis. HSAN2 begins in infancy wtih loss of sensation, insensitivity to pain, areflexia, and retinitis pigmentosa.

15. A 28 yo F presents with numbness and tingling in her feet. She had been seen in the ED, no neurologic abnormalities were found, and she was discharged home. The numbness now extends from the toes up to knees and involves the hands. Also found to have distal > proximal weakness in BLE and subtle weakness in the hands. Ankle, patellar reflexes are absent. Viral illness history a few weeks ago. What is the most likely diagnosis? A. GBS B. MS C. Stroke D. Myelopathy E. MG

A. History is consistent with GBS--post-viral distal > proximal weakness with some sensory symptoms.

53. A 32 yo M sustains a knife stab wound to the left antecubital fossa. He is brought to ED where he is treated for brachial artery hemorrhage and stabilized. On follow-up 8 weeks later, he denies pain. He has 2/5 strength on forearm pronation, thumb opposition/flexion/abduction, flexion at DIP joint of the 2nd digit, and flexion at the PIP joint of the 2nd-5th digits. Wrist flexion is 4/5, but the hand deviates in an ulnar direction during flexion. Flexion at the DIP joint of 4th, 5th digits is normal. Sensation is markedly reduced on the distal dorsal aspect of the first three digits and on the lateral aspect of the palm and entire first three digits, as well as the lateral aspect of the fourth digit. When asked to make a fist, the patient can barely flex the thumb, can partially flex the second digit, and has normal flexion of the fourth and fifth digits. What is the most likely diagnosis in this patient? A. Complete median nerve palsy at the antecubital fossa B. Ischemic monomelia C. Anterior interosseous nerve syndrome D. A medial cord lesion E. A C7 radiculopathy

A. Patient has a complete median nerve palsy at the antecubital fossa. Ischemic monomyelia is painful and causes circumferential sensory loss in multiple nerve distributions. Often occurs w/ AV shunt placement. Weakness of primarily C6- and C7-innervated muscles (pronators) and ulnar nerve muscles is evidence that this is not a medial cord lesion. Medial cord carries predominantly C8-T1 fibers. AOIN is a medial nerve branch and involves pure motor changes--weakness of flexor digitorum profundus of 2nd/3rd digits, FPL, PQ.

47. A 30 yo obese man who works as a mechanic comes for eval of pain and numbness in lateral thigh. No motor deficits. Which is the most likely structure involved? A. Lateral femoral cutaneous nerve B. Femoral nerve C. Saphenous nerve D. Obturator nerve E. Lumbosacral plexus

A. Patient has meralgia paresthetica--palsy of the lateral femoral cutaneous nerve typically seen in obese patients who wear a tight belt or tight-fitting waistband/pants.

49. A 50 yo F with a 10 year history of DM II presents with burning pain in both feet. Sensation to vibration and proprioception is preserved as are DTRs. Which most likely explains her symptoms? A. Small-fiber diabetic neuropathy B. Large-fiber diabetic neuropathy C. Diabetic polyradiculopathy D. Diabetic mononeuropathy E. Diabetic amyotrophy

A. Small-fiber diabetic neuropathy is characterized by painful paresthesias, burning sensations, and allodynia that typically affect both feet, but may affect other regions. It is often associated with autonomic neuropathy. Diabetic mononeuropathy can occur, often in CNs. Large-fiber involvement or amyotrophy is not suggested based on the history.

28. Which of the following is correct regarding lower extremity innervation? A. Gluteus medius and tensor fasciae latae receive innervation from the superior gluteal n. B. Gluteus minimus receives innervation from the inferior gluteal n. C. The long head of the biceps femoris is innervated by the peroneal division of sciatic n. D. Tibialis anterior is innervated by a branch of the tibial n. E. Inability to dorsiflex and evert the foot is seen with a lesion in deep peroneal n.

A. Superior gluteal nerve innervates the gluteus medius/minimus and tensor fasciae latae. Inferior gluteal nerve innervates the gluteus maximus. The sciatic nerve originates from L4-S3 roots and gives off two initial branches--superior and inferior gluteal nerves. Before the knee it branches into the tibial nerve medially and common peroneal (fibular) nerve laterally. The tibial nerve innervates the hamstrings except for the short head of biceps which is innervated by the common fibular nerve. A lesion in the deep fibular nerve produces foot drop with inability to dorsiflex the foot but intact eversion--the peroneus longus allows for eversion and is innervated by the tibial nerve with L5 input. **Testing eversion can differentiate L5 radiculopathy from peroneal neuropathy.**

29. A 42 yo F undergoes a very long and complicated hysterectomy. When she wakes up, she has numbness in the anterior and medial thigh and medial leg with knee extension weakness, and absent patellar reflex. Hip flexion seems to be strong. An EMG 3 weeks later demonstrates reduced saphenous SNAPs and fibrillations in the quadriceps femoris. Other muscles are spared, including the iliacus, thigh adductors, and the muscles distal to the knee. Which of the following is correct? A. Consistent with a femoral nerve injury distal to the inguinal ligament B. Consistent with a femoral nerve injury in the intrapelvic region C. Pt has a lumbar plexopathy D. Pt has an L2 + L3 radiculopathy E. Pt has involvement of the nerve arising from the anterior divisions of L2-L4 spinal roots

A. The femoral nerve originates from the posterior divisions of L2-L4. Femoral nerve injury will manifest as weakness in hip flexion and knee extension, loss of the patellar reflex, and sensory loss in the anteromedial thigh and medial leg. It's important to distinguish femoral nerve injury from L2-L4 radiculopathy and lumbar plexopathy. Impairment of other nerves suggest these diagnoses--adductor weakness with obturator nerve involvement or distal LE muscle weakness implying injury to other nerves. *Note also: Intrapelvic femoral neuropathy would involve the iliacus/iliopsoas which flexes the hip.

10. Regarding the types of skeletal muscle fibers, which of the following is correct? A. Type I fibers have low oxidative capacity and fast ATPase activity B. Type IIa fibers are fast with large glycolytic capacity C. Type I fibers are large in diameter D. Type IIb fibers are fast with high oxidative capacity E. Type IIb fibers are slow and resistant to fatigue

B. Type I muscle fibers are slow oxidative fibers with large oxidative capacity and large numbers of mitochondria. They are red and small in diameter. Type IIa fibers are fast oxidative or glycolytic fibers with moderate oxidative capacity. These fibers are fast and resistant to fatigue. They are red and large in diameter. Type IIb fibers are called fast oxidated glycolytic fibers with high glycolytic capacity but LOW oxidative capacity. These fibers are fast but fatigable. They are pale and large in diameter.

16. A patient with GBS is admitted to the hospital and continues to worsen. Which of the following should be obtained to ensure adequate care and may affect subsequent management? A. MRI of the lumbar spine B. Evaluation of respiratory parameters--including NIF, VC C. MRI of the brain D. CSF labs for various antibodies, oligoclonal bands, and myelin basic protein E. EMG/NCS as soon as possible

B. Concern for respiratory weakness should be high in GBS patients who are having worsening symptoms.

19. A 55 yo F presents with tingling and sensory loss over her R thumb, 2nd digit, and 3rd digit that wake her up at night. She has a history of L carpal tunnel syndrome, requiring surgery 3 years ago. Exam reveals bilateral symmetric distal loss of pinprick sensation in the feet, but it is otherwise normal. Family history significant only for bilateral carpal tunnel release in her mother and sister. ROS is otherwise negative. If a secondary etiology for carpal tunnel syndrome is being considered, which of the following is most likely? A. FAP type 1 B. FAP type 2 C. FAP type 3 D. Primary amyloidosis E. Secondary amyloidosis

B. FAP type 2 involves a transthyretin mutation. History shows carpal tunnel syndrome in 30s-40s with a family history of carpal tunnel syndrome as well. Manifests later than FAP type 1 (20s-30s). FAP3 is similar to FAP1 but with earlier renal involvement, more GI symptoms. Apolipoprotein A1 mutation. FAP4 presents in 20s with corneal dystrophy then CN palsies, peripheral sensorimotor neuropathy, and carpal tunnel syndrome without autonomic signs. Abnormal protein gelsolin. Primary amyloidosis = AL deposition. Secondary amyloidosis = AA deposition a/w systemic disease.

48. A 50 yo M undergoes coronary artery stenting through femoral artery puncture. After the procedure, he becomes hypotensive and requires admission to ICU. He later notices pain with hip flexion and numbness in the anterior and medial thigh. He also has difficulty flexing the hip and extending the knee. Patellar reflex is absent. Three weeks later, NCS shows a reduced saphenous nerve SNAP. On EMG, fibrillation potentials are seen in the iliacus and quads. Thigh adductors and muscles below the knee are normal. Which of the following is correct? A. Femoral nerve injury at inguinal region B. Femoral nerve injury in intrapelvic region C. Lumbar plexopathy D. Obturator nerve injury E. Pt has involvement of nerve arising from anterior L2, L3, L4 spinal roots

B. Femoral nerve injury in the intrapelvic region can be caused by pelvic surgery, pelvic masses, or retroperitoneal hematomas. Hx suggests a retroperitoneal hematoma, which can compress the femoral nerve in the intrapelvic region (presence of fibrillations in the iliacus and psoas muscles suggests intrapelvic injury rather than an inguinal injury, given that these muscles are innervated by the femoral nerve in the intrapelvic region before course through the inguinal region). Thigh adductor sparing suggests that this is not a plexopathy or radiculopathy as only the femoral nerve-innervated muscles are involved, not obturator muscles. Abnormal SNAPs point away from the diagnosis of a radiculopathy.

45. A 52 yo truck driver since his teenage years presents with tingling in 4th/5th digits of L hand presents to clinic. On exam, there is reduced sensation to all modalities on the dorsal and palmar aspect of the 4th/5th digits from wrist to fingertips with preserved strength. Which of the following is correct? A. He has carpal tunnel syndrome B. He has ulnar neuropathy at the elbow C. He should be referred to a surgeon D. EMG should show fibrillation potentials in C6 and C7 myotomes E. Conservative management frequently fails with this type of disorder.

B. History and exam are consistent with a mild ulnar neuropathy at the elbow. The ulnar nerve is most susceptible to entrapment at the postcondylar groove. This truck driver likely leans his arm against the window for prolonged periods while driving. C6 and C7 myotomes would not be affected and there are no other historical points suggestive of radiculopathy. Conservative management is very effective.

72. A 45 yo athlete who spends several hours a day weight-lifting presents with a deep, aching shoulder pain and arm weakness. On exam, he has weakness of shoulder abduction and external rotation with the forearm flexed while the elbow is stabilized against his side. Sensory exam is normal. Arm adduction is normal. No winging of the scapula. Biceps DTR is normal. This is most consistent with: A. Injury to the thoracodorsal nerve B. Suprascapular nerve entrapment C. Long thoracic nerve injury D. C5 radiculopathy E. An upper trunk lesion

B. History and exam are consistent with suprascapular nerve entrapment, as can occur in athletes, but also with trauma (shoulder dislocation or scapular fracture). The clinical picture is one of poorly localizable shoulder pain and weakness of the supraspinatus (abduction in first 30 degrees) and infraspinatus (external rotation). Thoracodorsal nerve injury would impair arm adduction 2/2 latissimus dorsi weakness. Long thoracic nerve injury would cause winged scapula 2/2 weakness of serratus anterior. C5 radiculopathy and an upper trunk lesion are ruled out due to normal forearm flexion (biceps are a largely C5-C6 innervated muscle) and intact biceps reflex.

70. A 39 yo M is admitted to the ICU with an acute pontine infarct. Work up shows a dolichoectatic basilar artery with a partially thrombosed aneurysm. Echo reveals a dilated cardiomyopathy. Per family, patient has a history of severe burning pains in hands and feet with heat or exercise. On exam, he has several dark purple punctate lesions on his trunk and scrotum. His father had burning hands and feet and in middle age and required dialysis for renal failure of unknown etiology. Which is correct regarding the disorder depicted in this case? A. It is due to deficiency of enzyme arylsulfatase A B. It is due to deficiency of enzyme alpha-galactosidase A C. It is autosomal dominant D. The stroke is likely unrelated E. It is a glycogen storage disease

B. History is consistent with Fabry's disease, an X-linked disorder that results from a deficiency in the enzyme alpha-galactosidase A (a lysosomal enzyme). This causes accumulation of globotriaosylceramide in kidneys, the heart, and the skin. Skin findings include angiokeratomas often found on the trunk and intertriginous areas such as the axilla and scrotum. Peripheral nerve system complications include small-fiber neuropathy and autonomic neuropathy. Strokes in Fabry's disease can be cardioembolic or due to vessel occlusion. Endothelial deposition of globotriaosylceramide can lead to dolichoectasia, increasing risk for thrombosis. Enzyme replacement for this disease is available.

80. A 22 yo M presents to the clinic with complaints of severe pain and redness of the limbs with exercise or whenever the weather is warm. When these episodes occur, he goes home and sits in a tub of ice water until he cools down. These episodes have become so severe that he minimizes physical exertion despite having a love for sports. He's otherwise healthy, physical exam is normal. Labs are normal. What is the most likely diagnosis? A. HSAN 1 B. Primary erythromelalgia C. Secondary erythromelalgia D. Fabry's disease E. Small-fiber neuropathy a/w glucose intolerance

B. History is consistent with primary erythromelalgia, a rare AD disorder characterized by severe burning and erythema of distal extremities. Precipitated by exposure to heat or cold. Due to mutation in the voltage-gated sodium channel SCN9A gene which results in hyperactivity of the dorsal root ganglia.

6. Which of the following is correct regarding the evaluation of a radiculopathy associated with an axon loss intraspinal canal lesion? a. Fibrillation potentials are typically seen within the corresponding segmental myotome immediately following onset of the lesion b. SNAP amplitudes in the segmental dermatome typically remain intact c. Reinnervation or collateral innervation occurs in a distal to proximal gradient d. The H-reflex tests the L3 reflex arc, and is helpful in the diagnosis of L3 radiculopathy e. Large polyphasic motor unit potentials are characteristic of acute radiculopathies

B. In a radiculopathy, there are normal SNAPs despite sensory symptoms, because SNAPs are recorded distal to the lesion, in the postganglionic projections from the dorsal root ganglion. A radiculopathy occurs from an intraspinal canal lesion resulting in damage of the preganglionic fibers. An axon loss radiculopathy will also injure motor fibers in the intraspinal canal region affecting the respective myotome. This leads to denervation, with fibrillation potentials seen 3 weeks after the onset of motor axon loss, decreased recruitment, and 3 to 6 mos later--large polyphasic MUPs. Presence of large polyphasic MUPs is dependent on reinnervation and collateral innervation, typically occurring in a proximal to distal fashion, with proximal muscles more successfully reinnervated than distal muscles. The H-reflex is the equivalent of the ankle reflex, which is an S1 reflex. This test is helpful in the evaluation of S1 radiculopathies.

61. A 34 yo F fractures her L tibia. Because of several complications, she requires the use of crutches over several months. She later presents with weakness in her R arm with forearm extension, wrist extension, and finger extension as well as sensory loss along the posterolateral arm, forearm, and dorsolateral hand. Triceps reflex is absent. Arm adduction/abduction, forearm pronation, wrist flexion are normal. What is the most likely diagnosis? A. Radial neuropathy at the spiral groove B. Radial neuropathy at axilla C. Radial neuropathy at elbow D. C7 radiculopathy E. Posterior cord lesion

B. Loss of sensation over the posterior arm (2/2 involvement of the posterior cutaneous nerve of the arm) as well as weakness of the triceps suggest that this lesion is proximal to the spiral groove. Proximal radial nerve lesions are not common, but can occur with repetitive pressure as seen in crutch use.

52. A 24 yo M undergoes minimally invasive valve repair. He does well with normal arm strength until 3 day post-op when he begins experiencing severe shoulder and arm pain. The pain resolves 7 day later, but his arm becomes weak over ensuing days. He has weakness of shoulder abductors, arm external rotators, forearm flexors, forearm pronators, and finger flexors. What is the most likely diagnosis? A. Cervical-brachial-pharyngeal GBS B. Acute brachial plexitis (Parsonage-Turner) C. Post-sternotomy brachial plexus lesion D. Infectious polyradiculitis E. Axillary neuropathy due to positioning during the operation

B. Parsonage-Turner syndrome can occur following surgery, vaccination, or systemic viral illness--can be idiopathic in some cases. This disorder can affect any parts of the brachial plexus. It can even be isolated to a single UE nerve. Luckily, it is most often monophasic with good recovery but recurrent episodes may occur. There is a familial form (hereditary neuralgic amyotrophy) which is AD in inheritance. Normal strength post-op suggests against compressive injury. Delayed weakness should also place brachial plexus hematoma on ddx. Infectious polyradiculitis is more common in immunocompromised patients.

59. A 19 yo M is hired as a packager on an assembly line. His main job is to take heavy objects off the belt and place them in a box that immediately follows. He repeats this hundreds of times a day with his RUE. Presents to clinic 3 months later with a deep aching pain in the proximal R forearm that worsens with forearm pronation against resistance. On exam, motor testing is limited due to pain but weakness of wrist flexion, thumb abduction, and flexion of the 2nd digit is apparent. Strength of forearm pronation appears normal. What is the most likely diagnosis? A. Complete median nerve palsy B. Pronator teres syndrome C. AION syndrome D. A medial cord lesion E. A C7 radiculopathy

B. Pronator teres syndrome results from compression of the median nerve as it passes through the two heads of the pronator teres. It is uncommon, but occurs in people who perform repetitive forceful pronation and may be associated with medial epicondylitis (golfer's elbow). Symptoms include gradual onset of a deep ache in the forearm that may worsen with pronation and weakness in median nerve-innervated muscles. Because branches of the median nerve that innervate the pronator teres arise proximal to this muscle, strength is otherwise intact. Normal strength in the pronator teres excludes a complete median nerve palsy at the elbow. Weakness of muscles not innervated by the AION rules out this syndrome. Weakness of the flexor carpi radialis, predominantly C6 and C7 in innervation, indicates that this is not a medial cord lesion (C8-T1).

51. A 38 yo M presents with pain, weakness, numbness in LLE. Pain and sensory deficits are localized to anterior thigh and medial leg. There is weakness on hip flexion, knee extension, and ankle dorsiflexion. Patellar reflex on L is depressed and ankle reflex is normal. Saphenous SNAP is normal. On EMG, fibrillation potentials are seen in the iliacus, vastus lateralis and medialis, rectus femoris, tibialis anterior muscles. Paraspinal fibrillations are also appreciated. Which is the most likely diagnosis? A. Lumbar plexopathy B. L2-L3-L4 radiculopathy C. L5 radiculopathy D. S1 radiculopathy E. Femoral neuropathy

B. Radiculopathies involving upper lumbar roots are more difficult to assess and less common than those in lower lumbosacral roots. L2-L3 radiculopathy manifests with pain in the hip and groin radiating down the anterior and medial thigh. L4 radiculopathy can cause pain down medial leg. In radiculopathy, SNAPs are normal BUT they are ABNORMAL in plexopathies. Another differentiating feature is that paraspinal fibrillations are seen in radiculopathies but NOT in plexopathies.

84. A 32 yo M is being evaluated by a company physician prior to employment. Physician notices arm weakness. Pt notes he has had weakness since birth. On exam, he holds his R arm close to his body, internally rotated, with wrist and fingers flexed. Abduction and flexion are weak. Biceps reflex is absent, triceps reflex is normal. Sensory loss along lateral half of the arm and forearm and thumb/index finger. EMG shows no evidence of denervation of rhomboids. What is the most likely diagnosis? A. An axillary neuropathy B. Upper trunk lesion C. C7 root lesion D. Middle trunk lesion E. C5 and C6 root lesion

B. The description is of Erb's palsy which is due to an upper trunk lesion, likely a birth injury. Arm adduction and internal rotation are 2/2 unopposed action of the pectoralis major (lateral pectoral nerve from lateral cord). Forearm extension is due to unopposed action of the pronator teres (C7-innervates the pecs and pronator teres). Normal rhomboids on EMG suggest that C5 and C6 nerve roots (origin of dorsal scapular nerves) are normal and point to an upper trunk lesion rather than injury at the nerve roots.

37. Regarding the ulnar nerve, which of the following is correct? A It innervates several muscles above the elbow B It is a continuation of the medial cord C It is most susceptible to injury at the lateral epicondyle D It passes through the carpal tunnel to reach the hand E It predominantly carries C5 and C6 fibers

B. The ulnar nerve is a continuation of the medial cord. The medial cord also gives rise to the medial brachial cutaneous nerve and medial antebrachial cutaneous nerve. The ulnar nerve is predominantly C8-T1 nerve roots and it does NOT pass through the carpal tunnel. It is most susceptible to injury in the cubital tunnel near the medial epicondyle.

85. A 39 yo F with DM I presents with numbness in glove-stocking distribution. No pain. Loss of sensation to vibration and proprioception. Hyporeflexic distally. Which most likely explains her symptoms? A. Small fiber diabetic neuropathy B. Large fiber diabetic neuropathy C. Diabetic polyradiculoneuropathy D. Diabetic mononeuropathy E. Diabetic amyotrophy

B. This is a length-dependent large-fiber diabetic neuropathy affecting the dorsal columns fibers. Small fiber diabetic neuropathy manifests with decreased temperature/pain sensation (spinothalamic tract fibers) and autonomic abnormalities.

11. A 55 yo M presents with weakness, initially in BLE. He undergoes an evaluation and treatment and is eventually admitted to rehab. He returns 9 weeks later with worsening of his weakness, affecting the upper extremities distally and lower extremities proximally and distally. He also has distal paresthesias, and his examination demonstrates diffuse areflexia. CSF shows 3 WBCs and protein of 100 mg/dL. An EMG/NCS is obtained and right median nerve NCS is shown in Figure 9.2 (prolonged peak latency, conduction velocity reduced). Which of the following is the most likely diagnosis? A. GBS B. CIDP C. MMN D. LEMS E. MG

B. This patient has CIDP. GBS is the acute form, when the time course is > 8 weeks the diagnosis becomes CIDP. Technically > 4 weeks is no longer acute, but diagnosis from 4-8 weeks is controversial. Studies in CIDP demonstrate features of a demyelinating polyneuropathy including prolonged distal motor latencies, reduced motor conduction velocities, prolonged or absent F waves, partial motor conduction block, and abnormal temporal dispersion.

39. Which of the following inherited neuropathies are NOT autosomal dominant? A. CMT 1 B. Hereditary sensory and autonomic neuropathy type 1 C. CMT 4 D. Familial amyloid polyneuropathies E. HNPP

C. Any recessive forms of CMT are classified as CMT4. This group consists of 8 sybtypes, which include both demyelinating and axonal forms. These disorders are rare and have an early age of onset with significant disability (features can include vision loss, severe scoliosis, and hearing loss). Hereditary sensory & autonomic neuropathies, HNPP, and FAP syndromes are all autosomal dominant in inheritance.

55. An LP is obtained on a patient with suspected GBS. Which of the following findings do you expect? A. Increased lymphocytes w/ normal protein B. Increased neutrophils w/ normal protein C. Increased protein w/ normal cell count D. Abnormal CSF production of Ig w/ oligoclonal bands and MBP E. Increased RBCs

C. Cytoalbuminologic dissociation is a hallmark finding of GBS. A and B may be seen with meningitis, encephalitis. D is seen w/ demyelinating disease. E is seen with hemorrhage.

Which of the following is incorrect regarding electrophysiologic studies of the peripheral nervous system? a. SNAP amplitude is a measure of the number of axons that conduct between the stimulation and recording sites b. Sensory distal latency is the time it takes for the action potential to travel between the nerve stimulation site and the recording site c. Axon loss lesions are invariably associated with reduced conduction velocities d. CMAP amplitude depends on the status of the motor axons, neuromuscular junctions, and muscle fibers e. The F-wave and H-reflex are late responses

C. Demyelinating disease is associated with conduction velocity decrease. Decrease in amplitude correlates with axon loss. Low amplitudes can result from demyelinating conduction block when the nerve stimulation is proximal to the block. Significant axon loss reduces action potential amplitudes with preserved or mildly reduced conduction velocities. Sensory NCS are obtained by stimulating a sensory nerve and recording at a different site along the nerve. You can measure SNAP amplitude, sensory latency (onset and peak), and conduction velocity. The SNAP amplitude is a measure of the number of axons conducting between the stimulation and the recording site. Sensory latency is the time it takes for the action potential to travel. Motor NCS are obtained by stimulating a motor nerve and recording at the belly of the muscle innervated. The CMAP is the resulting response, and depends on axons, the NM junction, and muscle fibers. CMAP amplitudes, motor onset latencies, and conduction velocities can be measured. The F-wave and the H-reflex are late responses. The F-wave involves supramaximal stimulation of a motor nerve while recording from a muscle. The impulse travels antidromically (opposite to the normal direction of impulses) along motor axons toward the motor neuron, backfiring and then traveling orthodromically (conduction in the normal direction) down the nerve to be recorded at the muscle. The H reflex is the electrophysiologic equivalent of the ankle reflex (S1 reflex arc) and is obtained by stimulating the tibial nerve at the popliteal fossa while recording at the soleus. The impulse travels orthodromically through a sensory afferent, enters the spinal cord, and synapses with the anterior horn cell, traveling down the motor nerve to be recorded at the muscle.

56. Which of the following findings does not occur in GBS? A. MRI showing contrast enhancement in the cauda equina B. Abnormal or prolonged F-waves on NCS C. Increased CMAP amplitude D. Conduction block E. Abnormal H reflex

C. Electrophysiologic studies should be performed early and repeated in 3 weeks if clinically indicated. Main findings are consistent with demyelination--prolonged or abnormal distal latencies, slow conduction velocities with abnormal late responses such as F waves and H reflex. A reduction in amplitude of muscle action potentials (as opposed to increased CMAPs) can be seen. There may also be evidence of motor conduction block (NR). EMG/NCS can help differentiate variants of AIDP/CIDP: AIDP--demyelination; AMSAN--no demyelination but reduced sensory and motor amplitudes; AMAN--no features of demyelination but reduced motor amplitudes.

78. Which of the following does not present as mononeuritis multiplex? A. Neuropathy associated with polyarteritis nodosa B. ANCA-associated vasculitis C. GBS D. Cryoglobulinemic vasculitis E. Neuropathy associated with HIV

C. GBS is a symmetric ascending sensorimotor neuropathy. Multiple mononeuropathies or MMN are typically associated with vasculitis (note that cryoglobulinemic vasculitis is often seen with HCV). Infection with Lyme and HIV can also cause MMN.

74. An 18 yo F presents to clinic complaining of R hand weakness. She reports that for many months while cheerleading, with her arms abducted and externally rotated w/ forearms flexed, she feels a dull ache and tingling in her hand at 4th/5th digits. Recently aching has become continuous and she has noted some numbness of the medial forearm. Exam shows weakness of thumb abduction and finger abduction/adduction w/ subtle atrophy of hand muscles. There is sensory loss over the medial aspect of the hand and forearm. What is the most likely diagnosis in this patient? A. Ulnar neuropathy at the elbow B. Carpal tunnel syndrome C. Neurogenic thoracic outlet syndrome D. T1 radiculopathy E. Median neuropathy at the elbow

C. History and exam are consistent with Neurogenic Thoracic Outlet Syndrome. Signs and symptoms result from compression of C8 and T1 nerve roots. The brachial plexus passes through the scalene triangle with the anterior scalene, middle scalene, and first rib bordering. Compression can result from an anomalous fibrous band between the scalenes, cervical rib, or an elongated C7 transverse process. There is weakness of intrinsic hand muscles and sensory loss in a C8 and T1 distribution. **Involvement of the medial antebrachial cutaneous nerve makes thoracic outlet syndrome more likely than ulnar neuropathy at the elbow.**

50. A 73 yo M with poorly-controlled diabetes presents with complaints of painless weakness of extension of fingers in L hand. On exam, forearm extension and wrist extension and abduction of wrist radially are normal in strength. Ulnar wrist extension is weak, forearm supination is weak (especially with forearm extended). Finger extension at MCP joint is also weak, as is thumb abduction in the plane of the palm, and thumb extension at the IP and MCP joints. Sensory exam is normal. On NCS, the superficial sensory radial nerve is normal. Triceps DTR is normal. What is the most likely diagnosis? A. Radial neuropathy at the spiral groove B. C7 radiculopathy C. Posterior interosseus nerve palsy D. Radial neuropathy at the elbow E. Supinator syndrome

C. History and exam are consistent with PION palsy (a pure motor branch of the radial nerve) which can occur as a diabetic mononeuropathy. Can also occur with compression from lipomas or nerve sheath tumors or with Parsonage-Turner syndrome. With a PION palsy, there is not an obvious wrist drop because the radial nerve branches to extensor carpi radialis longus/brevis originate proximal to the PION. Intact triceps reflex argues against a C7 radiculopathy. Strength of more proximal radial nerve-innervated muscles excludes a radial neuropathy at the spiral groove or elbow (intact sensory radial nerve responses further support this). Supinator syndrome causes a painful PION palsy due to compression or irritation of this nerve as it passes through the supinator muscle. Absence of pain on supination makes this uncommon disorder less likely.

14. A 62 yo retired secretary presents to the clinic complaining of painful tingling sensations and numbness in his left 1st-3rd fingers. On exam, movement is normal. Biceps, brachioradialis reflexes are normal. Median nerve sensory NCS is shown in Fig 9.3 (prolonged latency) and EMG is normal. What is the most likely diagnosis? A. C6 radiculopathy B. C7 radiculopathy C. Carpal tunnel syndrome D. Median neuropathy at elbow E. Brachial plexopathy

C. History is consistent with carpal tunnel syndrome. Figure 9.3 shows prolonged distal median nerve SNAP latency. Motor NCS/EMG amplitudes are normal and indicate mild carpal tunnel. Reflexes being normal makes cervical radiculopathy less likely. C6 radiculopathy would cause sensory loss over lateral forearm with weakness of flexion and supination. C7 radiculopathy would cause sensory loss over the 3rd digit. Both radiculopathies are less likely due to clear median nerve pathology. A brachial plexopathy would not usually lead to the limited distribution of sensory symptoms without motor symptoms.

25. Which of the following is incorrect regarding the lumbosacral plexus? A. The femoral nerve forms from posterior divisions of L2, L3, and L4 B. The obturator nerve forms from anterior divisions of L2, L3, and L4 C. The iliohypogastric and ilioinguinal nerves arise from the lumbosacral trunk D. The lumbosacral trunk joins the sacral plexus and gives off the sciatic nerve E. The lateral femoral cutaneous nerve arises from L2 and L3

C. Iliohypogastric, ilioinguinal, and genitofemoral nerves do not arise from the lumbosacral trunk, but rather from the lumbar plexus. The lumbar plexus is formed by contributions from T12-L4 and gives rise to 3 major and 3 minor nerves. The 3 minor nerves are the iliohypogastric, ilioinguinal, and genitofemoral nerves. The 3 major nerves are the femoral (L2-L4), obturator (L2-L4), and lateral femoral cutaneous (L2-L3) nerves.

8. A patient is referred for an EMG/NCS for a possible diagnosis of a NM junction disorder. Which of the following is correct? A. CMAP increment after high-frequency rep stim is a feature of MG B. CMAP increment after brief exercise is a feature of MG C. A decrease in CMAP during 2-3 Hz rep stim is consistent with MG D. Abnormal jitter on single-fiber EMG is a very specific finding for the diagnosis of MG E. Sensory NCS are typically abnormal in MG

C. Low frequency 2 Hz rep stim shows 10% decrease in CMAP consistent with MG. A and B are characteristic of LEMS (increment after exercise or higher frequency rep stim ~ 50 Hz). Jitter analysis by single-fiber EMG is performed by recording with a single-fiber needle electrode positioned to detect potentials from 2 muscle fibers of the same motor unit. The variation of interpotential interval between the two potentials is jitter and is abnormal in MG. Jitter is also abnormal in other NM junction blocking diseases. It is sensitive but NOT specific. Sensory NCS is typically normal in MG.

35. A 52 yo M presents with weakness without sensory symptoms. Initially he had L wrist drop about 1 month ago. 3 weeks ago he started complaining of R hand weakness. Last week, he developed R foot drop. Reflexes are absent in BUE, RLE. Anti-GM1 Abs are present. CSF shows protein level of 40, cell ct of 3. There is evidence of motor conduction block in many peripheral nerves. Which is the most likely diagnosis? A. CIDP B. AIDP C. MMN D. MADSAM E. Subacute IDP

C. MMN is also known as MMN with conduction block. This condition is purely motor that presents with asymmetric weakness. CSF is normal and anti-GM1 Abs are often detected but are not necessary for diagnosis. Electrophysiologic studies show conduction block with normal sensory NCS. MADSAM would have sensory involvement as well as demyelinating findings on EMG/NCS.

54. A 52 yo F presents with finger weakness in the R hand. She reports difficulty holding a teacup in the R hand using a pincer grasp. She denies any sensory symptoms. On exam of RUE, there is weakness of flexion at DIP joint of the 2nd and 3rd digits, weakness of thumb flexion, and weakness of forearm pronation when the forearm is fully flexed. Otherwise, all muscle groups are normal and there is no evidence of sensory loss. What is the most likely diagnosis? A. Complete median nerve palsy at the antecubital fossa B. Ischemic monomelia C. AION syndrome D. Medial cord lesion E. C7 radiculopathy

C. The anterior interosseus nerve is a pure motor branch of the median nerve and innervates the flexor digitorum profundus to the 2nd and 3rd digits, FPL, and PQ. Weakness without sensory loss suggests isolated involvement of the AION which can occur with trauma, fracture, or neuralgic amyotrophy (Parsonage-Turner). Patients complain of weakness with pincer grasp and cannot make an "okay" sign.

71. A 38 yo M sustains an injury while playing football. 8 weeks later, he presents with right arm weakness. He has 4/5 external rotation of the arm, forearm flexion, and shoulder abduction. There is sensory loss over the lateral aspect of the arm and forearm. The biceps deep tendon reflex is absent. On EMG, there are fibrillation potentials in the biceps, brachialis, deltoid, brachioradialis, supraspinatus, and rhomboid muscles. EMG examination of the triceps, pronator teres, brachioradialis, and intrinsic hand muscles is normal. Which best explains this patient's weakness? A. An upper brachial plexus trunk lesion B. An axillary nerve lesion C. A C5 and C6 root lesion D. A lesion to the musculocutaneous nerve E. A lesion to the lateral cord of the brachial plexus

C. The distribution of muscle weakness and sensory loss, combined with the EMG findings, suggests a proximal lesion at the C5 and C6 root level. The key clue to C5-C6 root lesion rather than upper trunk is the involvement of the rhomboids--supplied by the dorsal scapular nerve which arises directly from the C5 nerve root. Otherwise, this presentation of axillary and musculocutaneous nerve lesions would be consistent with an upper trunk lesion.

79. A 37 yo M presents with R wrist drop and L foot drop associated with painful paresthesias, rash, and arthralgias. A blood sample is sent and detects precipitation of protein when exposed to cold. Which of the following is correct regarding this condition? A. Manifestations are restricted to the peripheral nervous system B. Complement levels are typically increased C. It is commonly associated with HCV D. It is commonly associated with DM E. Immune stimulation therapies (such as granulocyte stimulating factor) can be helpful in treating this condition

C. This patient has cryoglobulinemia in which complement levels are reduced. Presents with constitutional symptoms, palpable purpura, arthralgias, lymphadenopathy, HSM, and peripheral neuropathy including MMN. CNS involvement may also occur in the form of ischemic stroke. Associated conditions--HCV, HIV, MGUS, multiple myeloma, connective tissue diseases. Treatment includes immunosuppressive therapies such as steroids, PLEX, and cyclophosphamide.

57. A 62 yo F presents with complaints of painless RUE weakness and sensory loss. She has a history of R breast cancer s/p surgery, chemo, and radiation 3 yrs ago. On exam, she has weakness in arm abduction and adduction, forearm flexion and extension, wrist flexion and extension, and sensory loss over the entire arm. EMG confirms involvement of all muscles examined, and myokymic discharges are evident on the EMG. Other extremities are normal. What is the most likely diagnosis in this patient? A. Carcinomatous invasion of the brachial plexus B. Chemotherapy-induced neuropathy C. Radiation-induced brachial plexopathy D. Paraneoplastic sensorimotor neuropathy E. Cervical spine stenosis

C. This patient's history and exam are consistent with radiation-induced brachial plexopathy. Exam suggests a pan-plexopathy. Radiation-induced plexopathy can occur months to years following exposure and is often seen with myokymia (help distinguish this from carcinomatous invasion). Also, unlike carcinomatous invasion, radiation-induced plexopathy is painless. A paraneoplastic neuropathy as well as chemo-induced neuropathy would affect other limbs as well. Similar to cervical spine stenosis, which would likely affect BUE.

26. Which of the following is incorrect regarding the lumbosacral plexus? A. The lumbosacral trunk originates from L4 and L5 B. The posterior femoral cutaneous nerve provides sensory innervation to the lower buttock, posterior thigh C. The pudendal nerve arises from S2-S4 and provides sensory innervation to the perineal region D. The tensor fasciae latae is a hip adductor E. The largest nerve of the lumbosacral plexus is the sciatic nerve.

D. Tensor fasciae latae is a hip abductor.

20. A patient with long-standing DM has autonomic dysfunction. Which of the following is least likely to occur with diabetic autonomic neuropathy? A. Impotence B. Silent MI C. Resting tachycardia, loss of respiratory influence on HR D. Malabsorption of fat-soluble vitamins E. Delayed gastric emptying

D. Autonomic dysfunction can account for GI changes, impotence, labile BP and HR, and increased risk of silent MI. Malabsorption of fat-soluble vitamins is not a typical manifestation of diabetic autonomic neuropathy.

27. A 22 yo F presents with painless R foot drop. NCS show a conduction block at the fibular head. She admits to frequently crossing her legs. She is prescribed an AFO, undergoes PT, and does well. Six years later, she presents with weakness of her intrinsic hand muscles, and NCS show conduction block of the ulnar nerve at the elbow. She does recall hitting her "funny bone" several times a few days prior to evaluation. Family history reveals that her father and brother have a history of similar episodes of weakness in the extremities since they were young adults. Which of the following is correct regarding the diagnosis of this patient? A. The radial nerve is most often affected B. AD in inheritance with 100% penetrance C. Pt has hereditary neuralgic amyotrophy D. Caused by a deletion in peripheral myelin protein 22 (PMP22) gene E. Neuropathologic analysis of a nerve biopsy from this patient would show lymphocytic inflammatory infiltrate

D. HNPP is an autosomal dominant condition with incomplete penetrance. It is caused by a deletion in PMP22. Patients present with recurrent compressive neuropathies. The radial nerve is less susceptible to compressive neuropathies than other UE nerves. Hereditary neuralgic amyotrophy can be distinguished from HNPP because it is typically painful whereas HNPP tends to present with painless motor symptoms.

76. The parents of a 1 yo boy bring him to clinic with multiple concerns. In the 1st month, they noted trouble swallowing and he had aspiration PNA requiring a PEG tube. During the admission, BP was labile. When he cries he doesn't produce tears but becomes flushed and sweats dramatically. What is the most likely diagnosis? A. HSAN type 1 B. CMT 1A C. HSAN type 2 D. HSAN type 3 E. HSAN type 4

D. HSAN 3, aka familial dysautonomia aka Riley-Day syndrome, is an autosomal recessive HSAN with prominent autonomic features. Symptom onset is in infancy with dysphagia, vomiting, recurrent infections, and BP lability. Prevalent among Ashkenazi Jews. With emotional stimulation, there is hyperhidrosis, skin flushing, and HTN. HSAN3 is due to a mutation in the IKAP gene, which results in abnormal mRNA splicing, leading to dysregulation of neural endocytosis.

63. A 52 yo M is diagnosed with a neck mass and undergoes excision with positive margins showing adenocarcinoma. Surgeon pursues radical neck dissection. During recovery, the patient has weakness raising his R arm above head. On exam, R shoulder is lower than L. R arm abduction to 90 degrees is normal, but there is weakness above that level. Shoulder shrug is 4/5. There is weakness turning head to the L. No sensory loss or other weakness. CN and gag reflex are otherwise normal. What is the most likely diagnosis? A. Lesser occipital nerve injury B. Jugular foramen syndrome C. Cervical plexus injury D. Spinal accessory nerve injury E. Greater occipital nerve injury

D. History and exam are consistent injury to the spinal accessory nerve, which is rare in isolation, but can be an iatrogenic complication of radical neck dissection. The spinal accessory nerve carries fibers from the lower medulla as well as C1 to C4. Cervical plexus injury would likely have a sensory component and additional findings.

30. A 32 yo M presents with sensory loss in his feet. He could not sense the water temperature with his toes and he had sustained abrasions to his feet several times not realizing it until he saw his feet bleeding. On exam, there is loss of sensation to pinprick and temperature on the distal lower extremities bilaterally. Exam also reveals an orange color to his tonsils. Which of the following is correct regarding the diagnosis of this patient? A. Patients with this disorder have low triglycerides and elevated LDL B. Typically involves anterior horn cells, peripheral nerves, and reticuloendothelial system C. Tonsils appear orange due to deposition of β-carotene D. Due to mutation in an ATP-binding cassette transporter protein E. AD in inheritance

D. History and exam are consistent with Tangier's disease. It is a rare AR disorder. Neurologic manifestations include a symmetric predominantly sensory neuropathy with loss of pain/temp and relative preservation of dorsal column vibration/proprioception. In other patients, relapsing MMN may occur. Tangier's disease is due to mutation in the ABCA1 gene that leads to low LDL and HDL with elevated TG levels. Deposition of TGs occurs in the RES and bone marrow biopsy may show fat-laden macrophages. Deposition of TGs in the tonsils accounts for their yellow-orange appearance.

82. A 36 yo M is standing on the ledge of a balcony putting up lights when he starts to fall and grabs on to the railing with his L hand and has to hang on until help comes. Over the next several days, he notices difficulty with fine motor movements in the L hand. On exam, he has weak finger flexion at PIPs and DIPs in 2nd-5th digits, weakness of finger abduction/adduction, weakness of thumb abduction, weakness of wrist flexion in an ulnar direction. There is sensory loss over the medial forearm and 4th/5th digits, but sensation is otherwise intact. Extensors are strong. What is the most likely diagnosis? A. Ulnar neuropathy at the wrist B. Median neuropathy at the elbow C. Radial neuropathy D. Lower trunk lesion E. Lateral cord lesion

D. History and exam are consistent with a lower trunk lesion due to stretching injury. Lower trunk lesions lead to weakness in ulnar and median nerve intrinsic hand muscles, sensory loss on the medial forearm/hand, and preserved sensation of the medial upper arm. A lateral cord lesion would lead to weakness of musculocutaneous-innervated muscles as well as C6 and C7 median nerve muscles which are not involved in this case.

62. A 37 yo M is involved in a MVC and fractures his R humerus. He later presents to clinic with complaints of weakness on wrist and finger extension. On exam, forearm extension is strong. Wrist extension in both the radial and ulnar direction and finger extension are weak, and there is loss of sensation on the lower lateral arm and posterior forearm. What is the most likely diagnosis in this patient? A. C7 radiculopathy B. Radial neuropathy at axilla C. Radial neuropathy at elbow D. Radial neuropathy at the spiral groove E. Posterior cord lesion

D. History and exam are consistent with a radial neuropathy at the spiral groove. Intact strength of the triceps and intact sensation on the posterior aspect of the arm support that the lesion is distal to origin of the posterior cutaneous nerve to the arm (past the axilla) and the branches to triceps, excluding a proximal radial nerve lesion or posterior cord lesion. Humeral fracture is a common mechanism of the injury to the spiral groove.

66. A 19 yo M is arrested during attempted robbery. While he is transported, he is agitated and pulling on the handcuffs. The prison doctor sees him for numbness of the R hand. On exam, he had decreased sensation over the dorsolateral aspect of the R hand, w/ normal motor strength and sensation in other areas. What is the most likely diagnosis? A. Acute ischemic stroke B. Carpal tunnel syndrome C. Malingering D. Superficial sensory radial neuropathy E. C8 radiculopathy

D. History and exam are consistent with a superficial sensory radial neuropathy. This is called Wartenberg's syndrome or cheiralgia paresthetica and results from compression or irritation of the nerve due to handcuffs or other compression/injury to the wrist including watches, venipuncture, or surgery. The nerve can also sometimes be pinched between the brachioradialis and ECRL tendons with repetitive pronation.

1. A 3 yo boy is seen by a peds neurologist for cognitive and motor developmental delay. The parents report that the patient seemed to walk on the insides of his feet. Exam shows nystagmus, BLE weakness, brisk reflexes with ankle clonus. One year later, he requires a PEG tube, has significant spasticity in all extremities, and has significant vision loss. He has significant language delay as well. 2 years later, he dies from complications of aspiration PNA. On autopsy, path reveals that patient has large focal axonal swellings filled with neurofilaments. What is the most likely diagnosis in this patient? a. Dejerine-Sottas syndrome b. CMT type 2A c. CMT type 4 d. Giant axonal neuropathy e. Metachromatic leukodystrophy

D. History and exam are consistent with giant axonal neuropathy. It is a rare AR disorder that appears in early childhood. Affects intermediate filaments of both central and peripheral nervous system leading to sensorimotor neuropathy plus corticospinal tract involvement with UMN signs & optic atrophy leading to vision loss. Patients walk on the inner edges of their feet. Skin is involved and patients often have tightly curled hair. Neuropathology reveals large focal axonal swelling with tightly packed disorganized neurofilaments. It is caused by mutation of the GAN gene that encodes for gigaxonin, involved in cross-linking of intermediate filaments. It is progressive and death typically occurs by adolescence. MCL is also a severe neurodegenerative disorder that manifests in early life with both central and peripheral nervous system manifestations. It is distinguished from GAN by neuropathologic and imaging features as well as studies showing elevated urine sulfatides in MCL.

36. Which of the following is correct regarding this condition (MMN with anti-GM1 antibodies)? A. Sensory NCS are usually abnormal B. Anti-GM1 Abs should be positive to make the diagnosis C. Anti-GM1 Ab titres predict response to treatment D. Presence of conduction block does not correlate with response to treatment E. This condition is very responsive to steroids

D. In MMN with conduction block, sensory NCS are normal. Anti-GM1 Abs do not need to be positive for a diagnosis and level does not predict response to treatment. MMN does not respond to steroids or PLEX and sometimes worsens with these therapies. IV Ig has shown benefit as well as rituximab and cyclophosphamide.

5. Regarding needle EMG, which of the following is incorrect? a. Insertional activity is increased in denervated muscles b. Fibrillation and fasciculation potentials are examples of spontaneous activity c. Short-duration motor unit potentials (MUPs) are seen more frequently in myopathic processes d. Large polyphasic MUPs are seen in acute neuropathic lesions e. Reduced recruitment is seen in axon loss lesions

D. Large polyphasic motor unit potentials (MUPs) are seen in chronic (not acute) neuropathic disease. Insertional activity is increased in denervated muscles and myotonic disorders, and decreased when the muscle is replaced by fat or connective tissue and during episodes of periodic paralysis. Spontaneous activity includes fibrillation potentials, fasciculation potentials, myokymia and myotonic potentials. All spontaneous activity at rest is abnormal. MUPs are obtained during voluntary contraction. Look at the recruitment pattern and MUP morphologic features--duration, amplitude, and configuration. Recruitment is a measure of the number of MUPs firing during voluntary muscle contraction. In axon loss lesions, reduced recruitment is seen. Early or rapid recruitment occurs in myopathic processes with loss of muscle fibers, in which an excessive number of short-duration and small-amplitude MUPs fire during contraction. With poor voluntary effort or CNS disorders causing weakness, recruitment is reduced with normal MUPs firing at slow-moderate rates, sometimes with variation. In neuropathic disorders with denervation and reinnervation, MUPs have increased duration and amplitude, and may be polyphasic. In myopathic disorders, MUPs have reduced duration and amplitude, and may be polyphasic.

40. A 40 yo M presents with pain in the right lower extremity radiating from the buttock down to his foot. He has pain and sensory deficit along the posterior thigh, leg, and lateral aspect of the foot. There is weakness on plantarflexion. Patellar reflex is normal, but the ankle reflex is depressed on the right side. Which of the following is the most likely diagnosis? A. L2 and L3 radiculopathy B. L4 radiculopathy C. L5 radiculopathy D. S1 radiculopathy E. Peroneal neuropathy

D. Lumbosacral radiculopathy is commonly caused by disc herniation or degenerative spine changes. S1 radiculopathy commonly manifests as pain radiating from the buttock down the posterior thigh, posterior leg, lateral foot, with sensory impairment in this dermatomal region. Most prominent weakness is plantarflexion & toe flexion, and ankle reflex will be reduced or absent. Muscles involved in S1 radiculopathies include the abductor hallucis, ADQP, soleus, medial and lateral gastrocnemius, EDB, biceps femoris (long & short head), and gluteus maximus. Although SNAPs should be normal in S1 radiculopathies, the H-reflex is commonly reduced or absent (surrogate for ankle reflex).

65. A 48 yo M presents with numbness/tingling and weakness. Initially experienced weakness in R hand and later in L hand and foot. DTRs are normal. CSF protein of 75, cell count of 3. There is evidence of conduction block in many peripheral nerves and abnormal sensory NCS. Which of the following is the most likely diagnosis? A. CIDP B. AIDP C. MMN D. MADSAM E. Subacute inflammatory demyelinating polyneuropathy

D. MADSAM is a demyelinating neuropathy with evidence of conduction block, presenting with asymmetric motor and sensory symptoms. Progression is gradual and slow, usually involving upper limbs initially and later the lower limbs. Unlike MMN, anti-GM1 Abs are not present and electrophysiologic studies show abnormalities in motor and sensory nerves rather than motor nerves alone. Patients with MADSAM may improve on steroids.

7. A patient presents for evaluation of weakness in the upper extremities that have been occurring for the past few months. NCS and EMG are relatively unremarkable. With high-frequency rep stim and evaluation after exercise, there is no increase in CMAP amplitude. Low-frequency rep stim is obtained, and is shown in Figure 9.1 (decreased response with each stimulation shown). Which of the following is the most likely diagnosis? a. A myopathy b. A demyelinating neuropathy c. An axon loss neuropathy d. Myasthenia gravis e. Botulism

D. Myasthenia gravis will show decreased response with each stimulation on low-frequency rep stim. LEMS is seen better with high-frequency rep stim (~ 50 Hz).

33. Which of the following treatment options is not used for treatment of chronic inflammatory demyelinating polyneuropathy? A. Prednisone daily B. Intravenous immunoglobulin C. Plasmapheresis D. Natalizumab E. Azathioprine

D. Natalizumab is Tysabri, an MS drug.

58. A 56 yo M with a history of diarrhea 2 weeks prior presents with 4 days of difficulty walking and diplopia. On exam, he is very unsteady, and cannot walk straight. The motor examination shows full strength; however, the ankle and patellar reflexes are absent. Which of the following antibodies may be involved? A. GM1 B. GD1a C. GD1b D. GQ1b E. GalNAc-GD1

D. Patient has diplopia (CN palsy) and sensory ataxia with absent reflexes which are all criteria for Miller-Fisher syndrome, which is associated with anti-GQ1b Ab. GM1, GM1b, and GD1a have been detected in AMAN and AMSAN. Abs to GalNAc-GD1a can be seen in AMAN. Abs to GD1b can be seen in acute sensory neuronopathy.

60. Which of the following is incorrect regarding the management of patients with carpal tunnel syndrome? A. In patients without known risk factors for carpal tunnel, and in the appropriate clinical setting, testing for hypothyroidism and DM is indicated B. Acromegaly can be a cause of carpal tunnel syndrome C. Amyloidosis can be a cause of carpal tunnel syndrome D. Surgical therapy is indicated in asymptomatic carpal tunnel syndrome E. Surgical release for carpal tunnel syndrome is indicated in severe cases

D. Patients with carpal tunnel syndrome often have a history of repetitive motions at the wrist. Conservative therapy and minimally invasive techniques are tried first. Some conditions predispose to carpal tunnel syndrome including DM, RA, chronic renal failure, amyloidosis, acromegaly, pregnancy, obesity, hypothyroidism so checking some labs is not unreasonable.

13. Which of the following is correct regarding an axon loss peripheral nerve injury? A. Fibrillation potentials appear immediately following the injury B. NCS 3 weeks after the injury are sufficient to localize a focal axon loss lesion C. A conduction block on NCS 3-4 weeks after injury invariably suggests complete axon transection with irreversible injury D. With severe axon loss, Wallerian degeneration occurs within 7 to 10 days E. In complete nerve transection, conduction distal to the lesion typically recovers 3 weeks after the injury

D. Peripheral nerve injury severity can range from focal demyelination to axonal injury to nerve transection. Focal nerve injury can cause segmental demyelination with conduction block, decrease in CMAP in proximal stimulation compared to distal stimulation without significant temporal dispersion. A conduction block is reversible, given that the lesion is demyelinating. In severe injury, axon loss may occur leading to Wallerian degeneration which is typically complete 7-10 days from the injury. Once denervation occurs, spontaneous muscle activity appears on EMG, manifested by fibrillation potentials, which usually appear after the 3rd week from injury.

22. Regarding the various manifestations of the different subtypes of Charcot-Marie-Tooth (CMT), which of the following statements is incorrect? A. Hammertoes and spine deformities are more prominent in CMT1 than CMT2 B. CMT2 typically has a later age of onset as compared to CMT1 C. CMT3, or Dejerine-Sottas syndrome, presents in infancy and typically leads to disabling weakness D. Respiratory muscle involvement is characteristic of the most common type of CMT E. Vision or hearing loss occurs in some subtypes of CMT

D. Respiratory weakness is not common to CMT. CMT1: first two decades of life, progressive weakness, muscle atrophy, kyphosis, mild sensory loss, hammertoes, high-arched feet, palpably enlarged nerves. CMT2: axonal neuropathy without demyelination. Symptoms appear later than type 1 with fewer foot/spine deformities. Optic atrophy, foot ulcerations, vocal cord paralysis, and intercostal/diaphragmatic weakness. CMT3: aka Dejerine-Sottas syndrome or hypertrophic neuropathy of infancy is severe and presents with proximal weakness, no DTRs, and hypertrophy of peripheral nerves. CMT4: Presents with vision loss, severe scoliosis, and hearing loss

32. A 70 yo F presents 3 mos after a R hip dislocation and fracture for eval of persistent R foot drop. EMG/NCS demonstrates reduced sural and superficial peroneal SNAP and reduced CMAPs in peroneal nerve-innervated muscles. There are fibrillations and reduced motor unit potential recruitment in the tibialis anterior, extensor hallucis, extensor digitorum brevis, peroneus longus, and peroneus brevis. Some fibrillations are noticed in the tibialis posterior and flexor digitorum longus, as well as the short head of the biceps femoris muscles. Where is the lesion? A. Common peroneal nerve B. Deep peroneal nerve C. L5 nerve root D. Sciatic nerve E. Tibial nerve

D. Sciatic nerve arises from L4-S3 nerve roots. It is composed of two nerves--the tibial nerve and common peroneal nerve. In this patient both the tibial and peroneal nerve-innervated muscles are affected including the short head of the biceps which suggests a sciatic nerve lesion rather than individual tibial or peroneal nerve involvement. The fact that the sural and superficial peroneal SNAPs are affected excludes the possibility of a radiculopathy (rules out C). The lack of involvement of gluteal nerve-innervated muscles also makes the diagnosis of lumbosacral plexopathy unlikely.

17. Regarding innervation of the upper extremity, which of the following is correct? A. The brachial plexus is formed from the posterior rami of the C2 to T1 nerve roots B. The lower (inferior) trunk is formed from the C3 and C4 roots C. The dorsal scapular nerve is the only nerve that branches directly off the nerve roots D. The middle trunk is formed from the C7 cord E. The cords of the brachial plexus are named according to their anatomic relationship to the subclavian vein

D. The brachial plexus extends from C5 to T1. Roots: Two nerves that innervate the upper extremity branch off the nerve roots themselves--dorsal scapular nerve (rhomboids, levator scapulae) and the long thoracic nerve (serratus anterior) from C5-C7. Trunks: Upper trunk is C5-C6 nerve roots with two branches (suprascapular n, n to subclavius). Middle trunk is C7 (no branches). Lower trunk is C8-T1 (no branches). Cords: Cords are named according to relationship to the axillary artery. Lateral--C5-C7. Posterior--C5-T1. Medial--continuation of lower trunk with 3 additional nerves (medial pectoral n, medial brachial cutaneous n, medial antebrachial cutaneous n.)

73. A 55 yo M with mild truncal obesity, HLD, and long-standing DM comes referred from gastroenterology. 4 months ago, he developed bulging in the right lower abdomen with a patch of numbness and a sensation of burning to touch in this area. You examine him and find that he has an absent superficial abdominal reflex in the right lower quadrant of the abdomen, as well as patchy reduction to pinprick and light touch on both sides of the abdominal wall at approximately T10 to T12. You feel his history is most consistent with the following: A. Spinal cord ischemia B. Stretch neuropathy due to obesity C. Femoral nerve injury D. Thoracoabdominal polyradiculopathy E. Malingering

D. This patient has a thoracoabdominal polyradiculopathy, seen in patients with diabetes. This syndrome presents with pain and dysesthesias, patchy sensory and motor changes in thoracic nerve root territories, usually unilateral but may be bilateral. It is often confused with intra-abdominal pathology. Etiology is thought to be related to ischemic radiculopathy (similar to CN III palsy caused by ischemic optic neuropathy in the setting of diabetes, vascular in origin). Recovery is protracted by may occur spontaneously or with treatment of DM.

38. A 49 yo M presents with 2 months of gradually progressive symmetric proximal and distal weakness, paresthesias, and areflexia. CIDP is considered and CSF shows WBCs 25 with protein level of 150. Which of the following tests is LEAST indicated for this patient? A. HIV testing B. Monoclonal protein analysis C. Hepatitis C antibody D. AChR Abs E. EMG/NCS

D. This patient is not suspected of having a NM junction disorder such as MG so AChR Abs are not indicated. In cases of CIDP where CSF shows a WBC count > 10, an underlying cause should be ruled out and tests should be obtained to look for other etiologies, including HIV, HCV, lymphoproliferative or myeloproliferative disorders, Lyme disease, and neurosarcoidosis. EMG/NCS will show features of demyelination with conduction block.

64. Which area of the peripheral nervous system is most commonly affected in diabetes? A. Cranial nerves B. Autonomic ganglia C. Small nerve fibers D. Nerve roots E. Large nerve fibers

E. A distal symmetric length-dependent polyneuropathy, due to large-fiber involvement, is the most common presentation. Small-fiber neuropathy is also seen. All of the other answers can be affected by diabetes, but not as commonly.

46. Which of the following complications is associated with diabetic neuropathy? A. Foot ulcers B. Arthropathy affecting the ankles C. Sensory ataxia D. Acute CN III palsy E. All of the above

E. Even though D is a more vascular process (typically caused by ischemia), it is most often seen in the setting of a diabetic patient.

77. A 2 yo girl is brought to the pediatric neurologist with recurrent fevers since childhood, but no ability to sweat. An infectious cause is not identified. They notice she did not cry with receiving vaccinations and since starting to walk she will not seem to feel pain with falling or bumping into things even when sustaining bruises and lacs. What is the most likely diagnosis? A. HSAN 1 B. CMT 1 A C. HSAN 2 D. HSAN 3 E. HSAN 4

E. HSAN 4 is associated with congenital insensitivity to pain. It is an AR disorder. Cognitive delay is also present as are significant behavioral problems including hyperactivity. Autonomic features include anhidrosis, leading to heat intolerance and frequent fevers. EMG/NCS are relatively normal. Diagnosis is made by demonstration of absent or markedly reduced number of unmyelinated axons and small myelinated fibers on skin biopsy. Also will show absence of sweating on QSAR test. HSAN 4 results from mutations in TyrK receptor for nerve growth factor NTRK1, which plays a role in development of unmyelinated nociceptive and sudomotor fibers.

67. A 32 yo M is involved in a motorcycle accident and sustains an anterior shoulder dislocation. 6 weeks later, he presents to the clinic complaining of weakness in flexing R forearm at the elbow. On exam, right forearm flexion strength is 2/5 and forearm extension is 5/5. The biceps reflex is absent. Arm adduction is normal. Forearm pronation and wrist flexion are normal. There is diminished sensation over the lateral aspect of the forearm, but sensation over the thumb and 2nd digit is normal. What is the most likely diagnosis? A. Biceps tendon rupture B. C6 radiculopathy C. Median neuropathy at the elbow D. Lateral cord lesion E. Musculocutaneous neuropathy

E. History and exam are consistent with a musculocutaneous neuropathy. It is rare but can occur with anterior shoulder dislocation. The musculocutaneous nerve is a continuation of the lateral cord and carries predominantly C5 and C6 fibers. The musculocutaneous nerve innervates the coracobrachialis muscle as well as brachialis and biceps. A lateral cord lesion would lead to weakness in other C5-C7 innervated muscles, such as the FCR and pronator teres. It would also cause sensory loss over the palm and 2nd/3rd digits.

83. A 14 yo F presents to the ED with severe abdominal pain and n/v. Routine lab testing includes liver enzymes is normal. She is admitted to the hospital and treated with IVFs. 2 days later, she has a generalized tonic-clonic seizure. Later has hallucinations and delusions. MRI brain with contrast and CSF analysis are both normal. 4 days after admission, she is noted to have mild weakness of wrist extension. 1 wk later, exam shows bilateral wrist drop. What is the most likely diagnosis? A. Wilson's disease B. SLE C. AIDP D. ADEM E. Acute intermittent porphyria

E. History is consistent with acute intermittent porphyria which is AD in inheritance. This results from enzymatic dysfunction in porphyrin metabolism with subsequent abnormalities in heme synthesis and metabolism. Common triggers for presentation of symptoms include medications, menstruation, and alcohol exposure. With these triggers, activity of the enzyme ALA synthase increases. In this case, an AED given for her witnessed seizure was likely was the trigger. Wilson's disease is on the ddx 2/2 neuropsych symptoms but does not typically lead to peripheral motor mononeuropathies or abdominal pain.

24. Which of the following treatment options has evidence to support its use for Guillain-Barre syndrome? A. Oral corticosteroids B. Intravenous corticosteroids C. PLEX with steroids D. Pyridostigmine E. IV Ig

E. IV Ig and PLEX are both used for the treatment of GBS. The use of steroids is not beneficial and is not recommended.

9. A patient with lung cancer is being evaluated for Lambert-Eaton myasthenic syndrome (LEMS). Which of the following is correct? A. Needle EMG is usually abnormal in LEMS B. Increased CMAP amplitude at rest is common in LEMS C. Slow rep stim (2 to 3 Hz) results in an incremental response of the CMAP amplitudes D. Voluntary single-fiber jitter analysis helps to distinguish myasthenia gravis from LEMS E. Rapid repetitive stimulation (20 to 50 Hz) results in an incremental response of the CMAP amplitudes

E. Patients with LEMS have a decreased response with slow rep stim (2-3 Hz) due to decrease in ACh release with each stimulus. It increases with rapid rep stim (20-50 Hz) due to increased calcium in the presynaptic terminal. Sensory NCS are normal in LEMS but CMAP amplitudes are usually low to borderline low normal. Jitter on single-fiber EMG shows NM junction disorder but is not specific for LEMS vs MG.

2. A 25 yo man is referred to the clinic by his ophthalmologist. In early childhood, he was noted to have a retinal disorder, and in his teenage years, he was denied a driver's license due to night blindness and VF deficits. In recent years, he has begun to complain of tingling in his legs as well as clumsiness and weakness. Exam reveals bilateral symmetric sensory loss and distal bilateral lower extremity weakness. A serum phytanic acid level is obtained and elevated. What is the most likely diagnosis? a. Myoneurogastrointestinal encephalopathy b. Kearns-Sayre syndrome c. Neurogenic muscle weakness, ataxia, and retinitis pigmentosa syndrome d. Abetalipoproteinemia e. Refsum's disease

E. Refsum's disease is an autosomal dominant peroxisomal disorder due to a defect in fatty acid metabolism leading to accumulation of an intermediate in the pathway, phytanic acid. Clinical manifestations include retinitis pigmentosa (night blindness and VF loss), cardiomyopathy, and skin changes. Neurologic manifestations include neuropathy, hearing loss, anosmia, ataxia, and cerebellar signs.

68. A 62 yo F presents for evaluation of pain and paresthesias in her feet. She also reports that stimuli that would normally not be painful (putting on socks) are painful. There is decrease in pinprick and temperature sensation. Motor function and reflexes are normal. A small fiber neuropathy is considered. Which of the following is correct regarding this condition? A. Lead poisoning is the most common cause B. EMG/NCS are usually abnormal C. Skin biopsy shows increased intraepidermal nerve fiber density, which accounts for allodynia D. Thermoregulatory sweat test shows reduced sweating on the trunk with intact distal sweating E. Quantitative sudomotor axon-reflex (QSAR) test is abnormal in this disorder and can aid in the diagnosis

E. Small fibers are myelinated A-delta and unmyelinated C fibers which are involved in autonomic, temperature, and pain neural transmission. Patients present with painful burning and dysesthesias distally (most often in feet). Some patients have autonomic signs such as sweating, vasomotor control issues, and GI/GU dysfunction. EMG/NCS is normal for these patients but thermoregulatory sweat test with small fiber neuropathy is abnormal with sweating in hands/feet but not in trunk. Similarly QSAR is abnormal.

4. Which of the following is incorrect regarding electrophysiologic studies of the peripheral nervous system? a. CMAP amplitudes may be reduced in axon loss lesions b. Prolonged distal latency is often seen in demyelinating lesions c. The H-reflex is the electrophysiologic equivalent of the ankle reflex d. The H-reflex is obtained by stimulating the tibial nerve e. The F-wave is obtained after submaximal stimulation of a motor nerve

E. The F wave is obtained after SUPRAmaximal stimulation of a motor nerve.

41. A 40 yo M presents to clinic with L hand weakness. Has significant loss of fine motor coordination. On exam, has atrophy of the intrinsic hand muscles, weakness of wrist flexion in ulnar direction, flexion at DIP joint of 4th and 5th digits, and abduction/adduction of all fingers. There is loss of sensation over hypothenar eminence and 4th/5th digits, but not more proximally. Proximal strength to the hand is normal. Thumb abduction is mildly weak. On attempt to make a fist there is hyperextension at the MCP joint of the 4th/5th digits and flexion at the proximal but not proximal DIP joints. Ulnar nerve CMAPs are shown in Fig 9.4 (amplitude drops significantly above the elbow). What is the most likely diagnosis in this patient? A. A C8 radiculopathy B. Ulnar neuropathy at wrist C. Medial cord lesion D. A C7 radiculopathy E. Ulnar neuropathy at or above the elbow

E. The history and exam are consistent with an ulnar neuropathy at or above the elbow. This can occur with trauma. There is significant loss of fine motor coordination 2/2 weakness of 3rd/4th lumbricals and palmar and dorsal interossei. Some thumb abduction can be achieved since it is innervated by both the median and ulnar nerves but it will be weak. The attempt to make a fist leads to ulnar claw with hyperextension at MCPs for 4th and 5th fingers but continued flexion at DIPs. Other signs of ulnar nerve palsy: Wartenberg's sign--5th digit abduction at rest 2/2 paralysis of 3rd palmar interossei with unopposed extensor digit minimi. Froment's sign--during attempted forceful adduction of the thumb (holding a piece of paper with thumb & index finger), thumb flexion occurs due to weak adductor pollicis and flexion compensating. **Ulnar compression at the list (Guyon's canal) can occur in bikers. Sensation over hypothenar eminence would be spared.** For C7 or C8 radiculopathy--the flexor digitorum profundus for index finger is of normal strength and forearm pronation is normal showing that this is not a radiculopathy. Intact strength of median nerve-innervated C8 and T1 muscles is also present--flexor pollicis brevis, APB, OP, and the lumbricals.

23. Which of the following is correct regarding the median nerve? A. Median nerve arises solely as a continuation of the medial cord B. Median nerve carries C2-T5 fibers C. Median nerve innervates all forearm extensors D. Median nerve innervates all intrinsic hand muscles E. Median nerve does not innervate any muscles above the elbow

E. The median nerve is derived from the lateral and medial cords. It innervates the pronator teres, FCR, flexor digitorum superficialis. It also gives off the AION that innervates the flexor digitorum profundus, FPL, PQ. The radial nerve innervates the forearm extensors. The ulnar nerve provides innervation to the intrinsic hand muscles in combination with the median nerve.

43. Which of the following is correct regarding the radial nerve? A. It carries C8 and T1 fibers B. It innervates strictly forearm extensors C. It contributes to triceps innervation, along with the median nerve D. It provides sensory innervation to the medial arm and forearm E. It is a continuation of the posterior cord

E. The radial nerve is a continuation of the posterior cord. It carries C5-C8 fibers. The first branch of the radial nerve is the posterior cutaneous nerve to the arm. It gives branches to the long, medial, and lateral heads of the triceps and is therefore the only innervator of the triceps. Distal to the spiral groove, it gives off the lateral cutaneous nerve to the arm. It also innervates brachioradialis (forearm flexor), extensor carpi radialis longus & brevis.

34. Which of the following is correct regarding the tibial nerve? A. A lesion at the tarsal tunnel presents with plantarflexion weakness B. Calcaneal branch innervates the abductor hallucis and flexor digitorum brevis C. Sural nerve arises from the tibial nerve after it passes through the tarsal tunnel D. The tibialis anterior is an L5 and tibial nerve-innervated muscle E. Innervates semimembranosus, semitendinosus, and long head of the biceps femoris

E. The tibial nerve is a division of the sciatic nerve and provides innervation to the semimembranosis, semitendinosus, and long head of the biceps femoris. At the medial ankle, the tibial nerve passes through the tarsal tunnel and gives off 3 terminal branches--1) calcaneal (sensory to the heel), 2) medial plantar (adductor hallucis, flexor digitorum brevis, flexor hallucis brevis, skin of medial sole), and 3) lateral plantar (ADQP, FDQP, adductor hallucis, interossei, skin of lateral sole).

31. A 62 yo M presents with sensory ataxia, painful paresthesias, and sensory deficits in his hands and feet. He is found to have a lung mass and biopsy shows a small cell neoplasm. Which of the following antibodies will most likely be positive? A. Anti-voltage-gated calcium channel B. Anti-Yo C. Anti-Ri D. Anti-MAG E. Anti-Hu

E. This patient has a sensory neuronopathy (dorsal root ganglionopathy) and possibly a peripheral neuropathy in the setting of small cell lung cancer. Anti-Hu (aka ANNA-1) is typically associated with peripheral neuropathy and sensory neuronopathy in the setting of SCLC. A (P/Q type calcium channel Abs) would be associated with LEMS. B (anti-Yo) is present with ovarian carcinoma--cerebellar degeneration. C (Anti-Ri) is seen with opsoclonus-myoclonus +/- ataxia with lung and breast cancer. Anti-MAG Ab are associated with demyelinating neuropathy in the setting of MGUS.

81. A 57 yo M presents with 3 months of gradually progressive symptoms that began with numbness and dysesthesias in his hands and feet, which have worsened. More recently, he has been having difficulty walking, especially in the dark, and is unsteady with closing his eyes. On exam, he has ataxia in all limbs, patchy sensory deficits in various parts of his body without a distal to proximal gradient, and areflexia. Strength is normal. NCS shows bilateral asymmetric reduction of SNAPs in various sensory nerves, more in BUE than BLE. Normal CMAPs. Which of the following is NOT an appropriate part of this patient's management? A. SSA and SSB Abs B. Anti-Hu Abs C. Malignancy work up D. HIV testing E. B6 should be administered at high doses

E. This patient has a sensory neuronopathy (ganglionopathy) in which the DRG are involved, presenting as progressive sensory deficits that are usually non-length dependent, patchy, asymmetric, and lead to global sensory loss. Pyridoxine intoxication is one of the causes of sensory neuronopathy and should NOT be supplemented.

42. A 65 yo M with DM II presents with RLE pain/weakness. He reports that symptoms began with severe LBP radiating down R hip and thigh. Then had difficulty flexing hip and extending knee. On exam, he has atrophy of the R thigh muscles and severe weakness of the hip flexors, adductors, quadriceps, and hamstrings on the R side. There are sensory deficits in the anteromedial thigh. Patellar reflex is absent on the R as well. He has lost ~ 30 lbs over the past year unintentionally. Which of the following is the most likely diagnosis? A. Small-fiber diabetic neuropathy B. Large-fiber diabetic neuropathy C. Diabetic autonomic neuropathy D. Diabetic mononeuropathy E. Diabetic amyotrophy

E. This patient has diabetic amyotrophy, which is a polyradiculoneuropathy. These are usually older people with diabetes (may be undiagnosed, so you should check if you have a suspicion). Symptom onset in known diabetics typically occurs during a period of transition, such as initiation or adjustment of insulin or with episodes of hyper- or hypo- glycemia. Presentation begins with pain starting in the low back and radiating down the hip and lower limb. Deep pain with superimposed lancinating pain is described, usually worse at night. Sensory deficits may involve L2-L4 distribution. Days-weeks later the patients develop weakness and atrophy with the pelvic girdle and thigh muscles most affected. EMG will show evidence of denervation in involved myotomes. Progression is gradual, may continue for months. Pain often resolves spontaneously and there may be recovery of strength but it can take months-years. CL involvement can occur later in some cases.