Regional Question Pool

A 75-year-old woman with a history of pulmonary embolism is scheduled for a right lower lobectomy for lung cancer. She is receiving dalteparin (Fragmin) for deep vein thrombosis (DVT) prophylaxis. How long after her last dose should one wait prior to placement of a thoracic epidural? a. 12 hours b. 24 hours c. 30 hours d. 72 hours e. No waiting necessary

*a. 12 hours In patients taking low-molecular weight heparin, or LMWH (e.g., enoxaparin, dalteparin, tinzaparin), caution should be exercised before proceeding with an epidural or spinal anesthetic because of the risk of producing an epidural or spinal hematoma. The amount of time between the last dose of the LMWH and the relative safety of starting a central neuraxial block depends on the dose of the LMWH. At the lower doses, used for thromboprophylaxis, the LMWH should be held at least 10 to 12 hours prior to the block. At the higher doses, used to treat an established DVT, one should wait at least 24 hours after the last dose of LMWH prior to the block

Discharge criteria from the post-anesthesia care unit (PACU) would be reached fastest after a 20 to 30 mL volume of which of the following epidurally administered local anesthetics? a. 3% 2-chloroprocaine b. 2% lidocaine c. 1% etidocaine d. 0.75% ropivacaine e. 0.5% levobupivacaine

*a. 3% 2-chloroprocaine Procaine and 2-chloroprocaine have a short duration of action; lidocaine, mepivacaine and prilocaine have an intermediate duration of action; etidocaine, bupivacaine, levobupivacaine, tetracaine and ropivacaine have a long duration of action. For similar sensory anesthesia, a higher concentration of local anesthetic is needed for the short duration of local anesthetics compared with both the intermediate and long duration agents, because they are less potent

The brachial plexus nerve roots form ____ trunks, ____ divisions, & ____ cords. a. 3,2,3 b. 4,1,4 c. 2,2,1 d. 3,3,2

*a. 3,2,3 Three distinct trunks are formed between the middle and anterior scalene muscles. As the trunks pass over the lateral border of the first rib and under the clavicle, each trunk divides into anterior and posterior divisions. As the brachial plexus emerges below the clavicle, the fibers combine again to form three cords.

Which nerves must be blocked separately to prevent pain from an arm tourniquet? (Choose 2) a. Medial brachial cutaneous nerve b. Axillary nerve c. Ulnar nerve d. Intercostobrachial nerve

*a. Medial brachial cutaneous nerve *d. Intercostobrachial nerve

The most common complication associated with a supraclavicular brachial plexus block is: a. Blockade of the phrenic nerve b. Intravascular injection into the vertebral artery c. Spinal blockade d. Blockade of the recurrent laryngeal nerve e. Pneumothorax

*a. Blockade of the phrenic nerve The most serious complication associated with a supraclavicular brachial plexus block is pneumothorax. The most common complication is a phrenic nerve block which is usually mild and relatively common (40%-60% of blocks). Bilateral supraclavicular blocks however, are not recommended due to the possibility of bilateral phrenic nerve paralysis or pneumothoraces. Other potential complications include Horner's syndrome, nerve damage or neuritis, or intravascular injection

Which local anesthetic undergoes the LEAST hepatic clearance? a. Chloroprocaine b. Bupivacaine c. Etidocaine d. Prilocaine e. Lidocaine

*a. Chloroprocaine Commonly injected local anesthetics are divided chemically into two groups: the aminoesters (esters) and the aminoamides (amides). The esters include procaine, chloroprocaine and tetracaine (all have one letter i in the name). The amides are lidocaine, mepivacaine, prilocaine, bupivacaine, levobupivacaine, etidocaine and ropivacaine (all have two i's in the name). The esters undergo plasma clearance by cholinesterases and have relatively short half-lives, whereas the amides undergo hepatic clearance and have longer half-lives

Severe hypotension associated with high spinal anesthesia is caused primarily by: a. Decreased cardiac output secondary to decreased preload b. Decreased systemic vascular resistance c. Decreased cardiac output secondary to bradycardia d. Decreased cardiac output secondary to decreased myocardial contractility e. Increased shunting through metarterioles

*a. Decreased cardiac output secondary to decreased preload Hypotension with a high spinal anesthesia is related to sympathetic blockade; venodilation (decreases preload), arterial dilation (decreases afterload) and a decrease in heart rate (cardioaccelerator fibers T1-T4 blockade and a fall in right atrial filling that affects the intrinsic chronotropic stretch receptors). With a high spinal, the decrease in venous dilation is the predominant cause of hypotension

Four days after a left total hip arthroplasty, an obese 62-year-old woman complains of severe back pain in the region where the epidural was placed. Over the ensuing 72 hours, the back pain gradually worsens and a severe aching pain that radiates down the left leg to the knee develops. The most likely diagnosis is: a. Epidural abscess b. Epidural hematoma c. Anterior spinal artery syndrome d. Arachnoiditis e. Meralgia paresthetica

*a. Epidural abscess Development of an epidural abscess is fortunately an exceedingly rare complication of spinal and epidural anesthesia. Most anesthetic related epidural abscesses are associated with epidural catheters. When an epidural abscess is developing, prompt recognition and treatment are essential if permanent sequelae are to be avoided. Symptoms from an epidural abscess may not become apparent until several days (mean 5 days) after placement of the block. There are four clinical stages of epidural abscess symptom progression. Initially, localized back pain develops. Second stage includes nerve root or radicular pain. The third stage involves motor and sensory deficits followed by the last stage of paraplegia. Unlike an epidural hematoma, in which severe back pain is the key feature, patients with epidural abscesses will complain of radicular pain approximately 3 days after development of the back pain. Anterior spinal artery syndrome is characterized predominantly by motor weakness or paralysis of the lower extremities. Meralgia paresthetica is related to entrapment of the lateral femoral cutaneous nerve as it courses below the inguinal ligament and is associated with burning pain over the lateral aspect of the thigh. It is not a complication of epidural anesthesia

Complex regional pain syndrome type I (reflex sympathetic dystrophy) is differentiated from complex regional pain syndrome type II (causalgia) by knowledge of its: a. Etiology b. Chronicity c. Affected body region d. Type of symptoms e. Rapidity of onset

*a. Etiology Complex regional pain syndrome type I or CRPS type I also called reflex sympathetic dystrophy (RSD) is a clinical syndrome of continuous burning pain, usually occurring after minor trauma. Patients present with variable sensory, motor, autonomic, and trophic changes. Complex regional pain syndrome type II or CRPS type II (causalgia) exhibits the same features of reflex sympathetic dystrophy, but the etiology is usually major traumatic damage to large nerves (e.g., median nerve of the upper extremity or tibial division of the sciatic nerve in the lower extremity)

Five days after knee arthroscopy under spinal anesthesia, a 55 year old complains of double vision and difficulty hearing. The other likely finding would be: a. Headache b. Fever c. Weakness in legs d. Mental status changes e. Backache

*a. Headache Post dural puncture headaches (spinal headaches) usually develop within 12 to 48 hours after a dural puncture, but may develop immediately or take months to develop. The most characteristic symptom is a postural component where the headache occurs in the upright position and is usually completely gone when the patient is in the supine position. The headache is typically frontal and/or occipital in location. Other symptoms include nausea, vomiting, anorexia, visual disturbances (blurred vision, double vision, photophobia) and occasionally hearing loss (routinely found with auditory testing)

The most common complication of a celiac plexus block is: a. Hypotension b. Seizure c. Subarachnoid injection d. Retroperitoneal hematoma e. Constipation

*a. Hypotension The sympathectomy produced by a celiac plexus block causes hypotension by decreasing preload to the heart. This complication can be avoided by volume loading the patient with lactated Ringer's solution. Subarachnoid injection is the most serious complication of celiac plexus block. Seizure is possible with an intravascular injection. Retroperitoneal hematoma is also possible, but extremely rare. This block frequently relieves constipation by interrupting the sympathetic fibers and leaving the parasympathetic fibers unopposed

Which of the following types of regional anesthesia is associated with the greatest serum concentration of lidocaine? a. Intercostal b. Caudal c. Epidural d. Brachial plexus e. Femoral nerve block

*a. Intercostal The site of injection of the local anesthetic is one of the most important factors influencing systemic local anesthetic absorption and toxicity. The degree of absorption from the site of injection depends on the blood supply to that site. Areas that have the greatest blood supply have the greatest systemic absorption. For this reason, the greatest plasma concentration of local anesthetic occurs after an intercostal block, followed by caudal epidural, lumbar epidural, brachial plexus, sciatic/femoral nerve block, and subcutaneous

If a needle is introduced 1.5 cm inferior and 1.5 cm lateral to the pubic tubercle, to which nerve will it lie in close proximity? a. Obturator nerve b. Femoral nerve c. Lateral femoral cutaneous nerve d. Sciatic nerve e. Ilioinguinal nerve

*a. Obturator nerve The obturator nerve provides variable cutaneous innervation of the thigh. An obturator nerve block is achieved by placement of the needle 1 to 2 cm lateral to and 1 to 2 cm below the pubic tubercle. After contact with the pubic bone, the needle is withdrawn and walked cephalad to identify the obturator canal. Between 10 and 15 mL of local anesthetic should be placed in the canal. If a nerve stimulator is used, contraction of the adductor muscles with nerve stimulation indicates proximity to the nerve

Each of the following items describes pain in the abdominal viscera EXCEPT: *a. Pain is transmitted via the vagus nerve b. The nerve fibers are type C c. Pain is not in a dermatomal distribution d. Pain is characterized by a dull aching or burning sensation e. Distention of the transverse colon causes more pain than surgical transection

*a. Pain is transmitted via the vagus nerve Virtually all pain arising in the thoracic or abdominal viscera is transmitted via the sympathetic nervous system in unmyelinated type C fibers. Visceral pain is dull, aching, burning, and nonspecific. Visceral pain is caused by any stimulus that excites nociceptive nerve endings in diffuse areas. In this regard, distention of a hollow viscus causes a greater sensation of pain than does the highly localized damage produced by transecting the gut

Which portion of the upper extremity is not innervated by the brachial plexus? a. Posterior medial portion of the arm b. Elbow c. Lateral portion of the forearm d. Medial portion of the forearm e. Anterolateral portion of the arm

*a. Posterior medial portion of the arm The arm receives sensory innervation from the brachial plexus except for the shoulder, which is innervated by the cervical plexus, and the posterior medial aspect of the arm, which is supplied by the intercostobrachial nerve

Which of the following nerves can be electrically stimulated at the ankle to produce flexion of the toes? a. Posterior tibial nerve b. Saphenous nerve c. Deep peroneal nerve d. Superficial peroneal nerve e. Sural nerve

*a. Posterior tibial nerve Five nerves are blocked when performing an ankle block. The saphenous, superficial peroneal, and sural nerves are all sensory below the ankle and electrical stimulation would have no effect. Stimulation of the posterior tibial nerve causes flexion of the toes by stimulating the flexor digitorum brevis muscles and abduction of the first toe by stimulating the abductor hallucis muscles. The posterior tibial nerve also is sensory to most of the plantar part of the foot. Stimulation of the deep peroneal nerve causes extension of the toes by stimulating the extensor digitorum brevis muscles. The deep peroneal nerve has a small sensory branch for the first interdigital cleft. From the practical standpoint, many anesthesiologists perform a purely infiltration block of these nerves. If a nerve stimulator is used, it is mainly used to find the posterior tibial nerve, which can be hard to anesthetize if small volumes of local anesthetic are administered. The posterior tibial nerve can be difficult to stimulate in diabetics with diabetic neuropathy

The primary mechanism by which the action of tetracaine is terminated when used for spinal anesthesia is: a. Systemic absorption b. Uptake into neurons c. Hydrolysis by pseudocholinesterase d. Hydrolysis by nonspecific esterases e. Spontaneous degradation at 37° C

*a. Systemic absorption Ester local anesthetics are hydrolyzed by cholinesterase enzymes that are present mainly in plasma and, in a smaller amount, in the liver. Because there are no cholinesterase enzymes present in cerebrospinal fluid (CSF), the anesthetic effect of tetracaine will persist until it is absorbed into systemic circulation. The rate of hydrolysis varies, with chloroprocaine being fastest, procaine intermediate, and tetracaine the slowest. Toxicity is inversely related to the rate of hydrolysis; tetracaine is, therefore, the most toxic

A celiac-plexus block would NOT effectively treat pain resulting from a malignancy involving which of the following organs? a. Uterus b. Adrenal gland c. Stomach d. Pancreas e. Gallbladder

*a. Uterus The celiac plexus innervates most of the abdominal viscera, including the lower esophagus, stomach, all of the small intestine and the large intestine up to the splenic flexure as well as the pancreas, liver, biliary tract, spleen, kidneys, adrenal glands and omentum. The pelvic organs

An analgesic effect similar to the epidural administration of 10 mg of morphine could be achieved by which dose of intrathecal morphine? a. 0.1 mg b. 1 mg c. 5 mg d. 10 mg e. There is no correlation

*b. 1 mg The site of action of spinally administered opiates is the substantia gelatinosa of the spinal cord. Epidural administration is complicated by factors related to dural penetration, absorption in fat, and systemic uptake; therefore, the quantity of intrathecally administered opioid required to achieve effective analgesia is typically much smaller. The ratio of epidural to intrathecal dose of morphine is approximately 10:1. Morphine is typically given in doses of 3 to 10 mg in the lumbar epidural space. Intrathecal morphine dosage is 0.2 to 1.0 mg. Onset time for epidural administration is 30 to 60 minutes with a peak effect in 90 to 120 minutes. Onset time for intrathecal administration is shorter than epidural administration. Duration of 12 to 24 hours of analgesic effect can be expected by either route

Which of the following concentrations of epinephrine corresponds to a 1:200,000 mixture? a. 0.5 μg/mL b. 5 μg/mL c. 50 μg/mL d. 0.5 mg/mL

*b. 5 μg/mL 1:200,000 means 1 g = 1000 mg = 1,000,000 μg per 200,000 mL 1,000,000 μg/200,000 mL = 5 μg/mL

Which nerve block is most optimal for procedures from the elbow to the hand? a. Interscalene b. Axillary c. Median d. Radial

*b. Axillary In contrast, the axillary approach to the brachial plexus is most optimal for procedures from the elbow to the hand

A caudal block with 0.25% bupivacaine and 1:200,000 epinephrine is planned for postoperative analgesia after bilateral inguinal hernia repair in a 5 month old. Each of the following would be consistent with an intravascular injection EXCEPT: a. Systolic blood pressure increase by 15 mm Hg b. Heart rate decrease by 10 bpm c. Ventricular extrasystoles d. Seizure e. T-wave amplitude of 25 percent over baseline

*b. Heart rate decrease by 10 bpm A change in the T-wave amplitude of 25 percent, an increase in heart rate of 10 beats per minutes, or systolic blood pressure greater than 15 mm Hg is considered a positive response to an epinephrine containing local anesthetic solution. A slight drop in heart rate may result if the block is properly performed and no intravascular injection occurs

Which of the following local anesthetics is inappropriately paired with a clinical application because of its properties or toxicity? a. Tetracaine, topical anesthesia b. Bupivacaine, intravenous anesthesia c. Prilocaine, infiltrative anesthesia d. Chloroprocaine, epidural anesthesia e. Ropivacaine, epidural anesthesia

*b. Bupivacaine, intravenous anesthesia For topical anesthesia, lidocaine, tetracaine, dibucaine and benzocaine are effective, as well as the combination of lidocaine and prilocaine or EMLA cream. For intravenous regional anesthesia or Bier blocks, many drugs have been used. Ester local anesthetics are not used for IV regional blocks because they can be broken down in the blood stream (by plasma ester hydrolysis) which can shorten the drug's duration of action and can also cause thrombophlebitis of the vein (reported with chloroprocaine). Because cardiovascular collapse has been reported with bupivacaine, and would likely also occur with etidocaine and ropivacaine, if the tourniquet unintentionally is released while the block is setting up, they are not used for intravenous regional anesthesia. Lidocaine and prilocaine are used for Bier blocks because of their relative safety. For infiltrative anesthesia, all local anesthetics can be used. All local anesthetics can be used in the epidural space, although procaine and tetracaine are rarely used (procaine has a slow onset and tetracaine has marked motor block)

The correct arrangement of local anesthetics in order of their ability to produce cardiotoxicity from most to least is: a. Bupivacaine, lidocaine, ropivacaine b. Bupivacaine, ropivacaine, lidocaine c. Lidocaine, bupivacaine, ropivacaine d. Ropivacaine, bupivacaine, lidocaine e. Lidocaine, ropivacaine, bupivacaine

*b. Bupivacaine, ropivacaine, lidocaine Central nervous system (CNS) toxicity from local anesthetics generally parallels anesthetic potency (e.g., bupivacaine is four times as potent as lidocaine, ropivacaine is three times as potent as lidocaine). Cardiovascular (CV) toxicity occurs at a higher blood level than CNS toxicity. For bupivacaine and ropivacaine, CV toxicity occurs at two times the CNS dose, whereas for lidocaine the CV toxicity occurs at seven times the CNS toxicity levels, making lidocaine the least cardiotoxic, and bupivacaine the most cardiotoxic of the listed local anesthetics

Interscalene blocks tend to produce a most intense block at what level? a. C2-C3 b. C5-C7 c. T1-T2 d. T4-T6

*b. C5-C7 Injection at the interscalene level tends to produce a block that is most intense at the C5-C7 dermatomes & least intense in the C8-T1 dermatomes.

A 49-year-old type I diabetic patient with a long history of burning pain in the right lower extremity receives a spinal anesthetic with 100 mg of procaine with 5% dextrose. The patient reports no relief in symptoms but has complete bilateral motor blockade. What diagnosis is consistent with this differential blockade examination? a. Diabetic neuropathy b. Central pain c. Myofascial pain d. Meralgia paresthetica e. Complex regional pain syndrome I (reflex sympathetic dystrophy)

*b. Central pain Somatic pain in the extremities is relieved with spinal anesthesia. If a patient fails to obtain pain relief despite complete sympathetic, sensory, and motor blockade, a "central" mechanism for the pain is likely or the lesion causing the pain is higher in the CNS than the level of blockade achieved by the spinal. Central pain states may include encephalization, psychogenic pain, or malingering. Persistence of pain in the lower extremities after successful spinal blockade suggests a central source or psychological source of pain

Which of the following techniques is LEAST effective in a treatment of pruritus from administration of neuraxial opiates? a. Nalbuphine 5 mg IV b. Dexmedetomidine 30 μg IV c. Diphenhydramine 50 mg IV d. Hydroxyzine 20 mg IM e. Propofol 10 mg IV

*b. Dexmedetomidine 30 μg IV The treatment of pruritus, the most common side effect of neuraxial opiates, is primarily with opioid antagonists, mixed opioid agonist-antagonist, and antihistamine drugs (by their sedating effects). Nalbuphine is a mixed opioid agonist-antagonist; diphenhydramine and hydroxyzine have antihistamine properties. Propofol at very low doses (e.g., 10 mg) has been useful to treat pruritus not only induced by neuraxial opiates but also the pruritus associated with cholestatic liver disease. Propofol does not affect analgesia, whereas opioid antagonists and mixed agonist-antagonist may reverse some or all of the analgesia, depending upon dose. Dexmedetomidine is a highly selective α2-receptor agonist that has a faster onset and shorter duration of action compared with clonidine. Dexmedetomidine has analgesic properties, can potentiate neuraxial analgesia when injected spinally, and can perhaps decrease the incidence of pruritus by reducing the narcotic dose is used. It does not treat pruritus

Tachyphylaxis to local anesthetics is most closely related to which of the following? a. Speed of injection b. Dosing interval c. Temperature of local anesthetic d. Volume of local anesthetic e. pH of solution

*b. Dosing interval Tachyphylaxis is a well-known phenomenon associated with repeated injections of local anesthetics leading to decreased effectiveness. Interestingly, the dosing interval seems most important in the development of tachyphylaxis. If the dosing interval is short (and no pain between injections) tachyphylaxis does not develop. However, with longer dosing intervals (and pain between injections) tachyphylaxis develops

According to the 2004 American Society of Regional Anesthesia and Pain Medicine (ASRA) practice advisory on infectious complications of regional anesthesia and pain medicine, the most important action to maintain aseptic technique and prevent cross-contamination during regional anesthesia techniques is: a. Wearing surgical gown b. Hand washing c. Using soap and water instead of alcohol-based antiseptics d. Keeping fingernails short e. Using povidone iodine (e.g., Betadine) instead of alcohol-based chlorhexidine to scrub

*b. Hand washing Hand washing is one of the most important techniques to prevent infections especially when alcohol-based antiseptic solutions are used with sterile gloves. Although soap and water remove bacteria, they do not effectively kill organisms. Antiseptic solutions with alcohol appear better than nonalcoholic antiseptics (e.g., povidone iodine). Nail length does not appear to be a risk factor for infections, because the majority of bacterial growth occurs along the proximal 1 mm of nail adjacent to the subungual skin. Universal use of gowns and gloves does not appear to be better than gloves alone in preventing infections in ICUs and presumably is less important than adequate hand washing and use of sterile gloves

The artery of Adamkiewicz most frequently arises from the aorta at which spinal level? a. T1-T4 b. T5-T8 c. T9-T12 d. L1-L4 e. L5-S3

*c. T9-T12 The artery of Adamkiewicz is also called the arteria radicularis magna and is one of the "feeder" arteries for the anterior spinal artery. Damage to this artery can lead to ischemia in the thoracolumbar region and may result in paraplegia. The origin of this artery is variable (e.g., T9-T12 in 75% of cases, L1-L2 in 10% of cases)

The common element thought to be present in every case of cauda equina syndrome after continuous spinal anesthesia is: a. Use of microcatheter b. Maldistribution of local anesthetic c. Administration of lidocaine d. Addition of epinephrine e. Hyperbaricity

*b. Maldistribution of local anesthetic The symptoms of cauda equina syndrome include low back pain, bilateral lower extremity weakness, saddle anesthesia and loss of bowel and bladder control. Pooling of local anesthetics in dependent areas of the spine within the subarachnoid space has been identified as the causative factor in cases of cauda equina syndrome. Microlumen catheters may enhance the nonuniform distribution of solutions within the intrathecal space, but cauda equina syndrome has been associated with the use of larger catheters, 5% lidocaine with dextrose, and 2% lidocaine, as well as 0.5% tetracaine

Which of the following observations, after nerve injury, is correctly paired with the appropriate nerve? a. Inability to flex the forearm—ulnar nerve b. Numbness in the thumb—radial nerve c. Inability to extend the forearm—musculocutaneous nerve d. Numbness in the little finger—median nerve

*b. Numbness in the thumb—radial nerve The motor responses include: arm flexion at the elbow (musculocutaneous nerve), arm extension at the elbow (radial nerve), forearm pronation, wrist flexion and thumb opposition (median nerve), ulnar deviation of the wrist, little finger flexion, thumb adduction and flaring of the fingers (ulnar nerve), wrist and finger extension (radial nerve). The sensory response (includes some variations) is: back of the arm, forearm and radial side dorsal side of the hand (radial nerve), skin of the lateral forearm (musculocutaneous nerve), ulnar side of the hand and both surfaces of the ulnar one and one-half fingers (ulnar nerve), the radial side of the palm of the hand as well as the dorsal aspect of the radial three and one-half fingers (median nerve). To evaluate the setup of a brachial plexus block, a common technique is to perform the four P's (Push, Pull, Pinch, Pinch). Have the patient push or extend the forearm (radial), pull or flex the forearm (musculocutaneous nerve), pinch the index or second finger (median nerve), pinch the little finger (ulnar nerve)

A 95-year-old woman has persistent and prolonged thoracic pain after a herpes zoster infection. Which of the treatments below would be the LEAST efficacious in the treatment of her pain? a. Oral amitriptyline b. Oral clonidine c. Topical capsaicin ointment d. Transcutaneous electrical nerve stimulation (TENS) e. Topical lidocaine patch

*b. Oral clonidine Acute herpes zoster is due to the reactivation of the varicella-zoster virus. Acute treatment includes symptomatic pain treatment and antiviral drugs (e.g., acyclovir). It is typically a benign and self-limiting disease in patients younger than 50 years of age. As one gets older, the incidence of postherpetic neuralgia (PHN) defined as pain persisting beyond the healing of the herpes zoster lesions increases. The incidence of PHN is about 50% in patients older than 50 years. Treatment of established PHN has been shown to be resistant to interventions and, thus, can be difficult. However, proven therapies include tricyclic antidepressants, anticonvulsants, topical local anesthetics (e.g., 5% lidocaine patch), topical capsaicin and TENS. Sympathetic blocks can provide excellent analgesia but are most useful during the more acute stages of the disease rather than during the late chronic stages. Sympathetic blocks in the acute stages may decrease the incidence of PHN. Oral clonidine, which is used to treat hypertension and opioid withdrawal, has not been shown to be an effective treatment for postherpetic neuralgia

A 69-year-old man with a history of diabetes mellitus and chronic renal failure is to undergo placement of a dialysis fistula under regional anesthesia. During needle manipulation for a supraclavicular brachial plexus block, the patient begins to cough and complain of chest pain and shortness of breath. The most likely diagnosis is: a. Angina b. Pneumothorax c. Phrenic nerve irritation d. Intravascular injection of local anesthetic e. Intrathecal injection of local anesthetic

*b. Pneumothorax The risk of pneumothorax is a significant limitation for supraclavicular brachial plexus blocks (incidence 0.5%-6% depending upon experience). Furthermore, the technique is difficult to teach and describe. For these reasons, this block should not be performed in patients in whom a pneumothorax or phrenic nerve block (40%-60% of patients) would result in significant dyspnea or respiratory distress. A pneumothorax should be considered if the patient begins to complain of chest pain or shortness of breath or begins to cough during placement of supraclavicular brachial plexus

Cutaneous innervation of the plantar surface of the foot is provided by the: a. Sural nerve b. Posterior tibial nerve c. Saphenous nerve d. Deep peroneal nerve e. Superficial peroneal nerve

*b. Posterior tibial nerve There are five nerves that supply the ankle and foot: the posterior tibial, sural, superficial and deep peroneal, and saphenous nerves. These nerves are superficial at the level of the ankle and are easy to block. The posterior branch of the tibial nerve gives rise to the medial and lateral plantar nerves, which supply the plantar surface of the foot

The addition of epinephrine to epidural bupivacaine will: a. Prolong motor blockade only b. Prolong sensory blockade only c. Prolong motor and sensory blockade d. Shorten duration of sensory blockade e. Have no effect on either duration of motor or sensory blockade

*b. Prolong sensory blockade only Epinephrine's effect on the duration of anesthesia depends on the local anesthetic and the site. Infiltration and peripheral block duration with most agents will be prolonged with epinephrine. The addition of epinephrine to epidural 0.5% or 0.75% bupivacaine has not been shown to increase the duration of the motor blockade but does extend the duration of the sensory block. The effect of epinephrine is greater for the intermediate duration local anesthetics lidocaine and mepivacaine

Which of the following nerves is located immediately lateral to the trachea? a. Vagus b. Recurrent laryngeal c. Phrenic d. Long thoracic e. Spinal accessory

*b. Recurrent laryngeal The structures in the neck from medial to lateral are the recurrent laryngeal nerve, carotid artery, vagus nerve, internal jugular vein, and phrenic nerve

Which of the following choices is NOT consistent with a limb affected by complex regional pain syndrome? a. Osteoporosis b. Allodynia c. Dermatomal distribution of pain d. Atrophy of the involved extremity e. Hyperesthesia

*c. Dermatomal distribution of pain Complex regional pain syndromes are associated with trauma. The main feature is burning and continuous pain that is exacerbated by normal movement, cutaneous stimulation, or stress, usually weeks after the injury. The pain is not anatomically distributed. Other associated features include cool, red, clammy skin and hair loss in the involved extremity. Chronic cases may be associated with atrophy and osteoporosis

A sciatic nerve block is performed in a healthy 26-year-old male patient for bunion surgery. Fifteen mL of 1.5% mepivacaine is slowly injected after the landmarks are identified and a paresthesia is elicited in the great toe. In what order would the following nerve fibers be blocked? a. Sympathetic, proprioception, pain, motor b. Sympathetic, pain, proprioception, motor c. Motor, pain, proprioception, sympathetic d. Pain, proprioception, sympathetic, motor e. Pain, proprioception, motor, sympathetic

*b. Sympathetic, pain, proprioception, motor Differential nerve blockade is a complex process where anatomic and chemical factors determine the susceptibility of fibers to blockade by local anesthetics. Diameter, myelinization, and location within the nerve trunk affect the onset and regression time. In general, the small unmyelinated sympathetic fibers are blocked first, followed by unmyelinated C fibers (pain and temp), then small myelinated fibers (proprioception, touch, pressure), and finally the large myelinated fibers (motor)

Which section of the brachial plexus is blocked with a supraclavicular block? a. Roots b. Trunks c. Divisions d. Cords e. Branches

*b. Trunks The brachial plexus starts out at the root level from the ventral rami of C5-T1 with a small amount from C4 and T2. These roots at the level of the scalene muscle become the 3 trunks: superior, middle and inferior. The trunks then divide into the dorsal and ventral divisions at the lateral edge of the first rib. When the divisions enter the axilla, they become the cords: posterior, lateral and medial. At the lateral border of the pectoralis muscle they become the five peripheral nerves: radial, musculocutaneous, median, ulnar and axillary. The plexus is blocked at the distal level of the trunks just before they become divisions. Here a small volume of anesthetic is required and no part of the plexus is spared, as with axillary or interscalene block. The block can be performed with the arm in any position

How much local anesthetic should be administered per spinal segment to patients between 20 and 40 years of age receiving a lumbar epidural anesthetic? a. 0.25 to 0.5 mL b. 0.5 to 1.0 mL c. 1 to 2 mL d. 2 to 3 mL e. 3 to 5 mL

*c. 1 to 2 mL In general, each 1-2 mL of local anesthetic will anesthetize about one spinal segment in the 20 to 40-year-old patient. Because of the negative intrathoracic pressure transmitted to the epidural space with breathing, about two thirds of the segments are blocked above the level of the lumbar placement and one third of segments are blocked below the injection. For example, to achieve a T4 block when an epidural is placed at the L2-L3 space about 10 segments above and 5 segments below the epidural would be needed (15 segments) or about 20-25 mL. As one gets older, the dose of local anesthetic mL/segment decreases (e.g., 80 year old may need 0.75-1.5 mL/segment). Also, pregnant patients are more sensitive to local anesthetics and reduced doses are needed

How long should a patient be off clopidogrel (Plavix) before performing a central neuraxial block? a. 1 day b. 2 days c. 7 days d. 14 days e. No waiting necessary

*c. 7 days Patients taking nonsteroidal anti-inflammatory drugs (NSAIDs), ticlopidine and clopidogrel, exert effects on platelet function. Nonsteroidal anti-inflammatory drugs (NSAIDs) are not a problem if given alone before epidural or spinal anesthesia. But patients taking ticlopidine should wait 14 days and patients taking clopidogrel should wait 7 days before having a neuraxial block placed, because of the increased risk of spinal hematoma formation. Keep in mind that caution is always needed and the ASRA statement of "Careful preoperative assessment of the patient to identify alterations of health that might contribute to bleeding is crucial" is important

If the recurrent laryngeal nerve were transected bilaterally, the vocal cords would: a. Be in the open position b. Be in the closed position c. Be in the intermediate position (i.e., 2-3 mm apart) d. Not be affected unless the superior laryngeal nerve were also injured e. Appear exactly the same as if an intubating dose of succinylcholine were given

*c. Be in the intermediate position (i.e., 2-3 mm apart) The recurrent laryngeal nerve innervates all the muscles of the larynx except the cricothyroid muscle, which tenses the vocal cords and is innervated by the external branch of the superior laryngeal nerve. With bilateral transections of the recurrent laryngeal nerve, the vocal cords lie within 2 to 3 mm of the midline. The airway maybe inadequate and a tracheostomy may be needed

A 68-year-old woman is to undergo foot surgery under spinal anesthesia. Which of the following statements concerning the immediate physiologic response to the surgical incision is true? a. The cardiovascular response to stress will be blocked, but the adrenergic response will not b. The adrenergic response to stress will be blocked, but the cardiovascular response will not c. Both the adrenergic and cardiovascular responses will be blocked d. Neither the adrenergic or cardiovascular response will be blocked e. The cardiovascular response will be blocked but the adrenergic response will be augmented

*c. Both the adrenergic and cardiovascular responses will be blocked Surgical trauma includes a wide variety of physiologic responses. General anesthesia has no or only a slight inhibitory effect on endocrine and metabolic responses to surgery. Regional anesthesia inhibits the nociceptive signal from reaching the CNS and, therefore, has a significant inhibitory effect on the stress response, including adrenergic, cardiovascular, metabolic, immunologic, and pituitary. This effect is most pronounced with procedures on the lower part of the body and less with major abdominal and thoracic procedures. The variable effect is probably due to unblocked afferents, i.e., vagal, phrenic, or sympathetic

Which of the following local anesthetics has the lowest ratio of dosage required for cardiovascular collapse to dosage required for central nervous system toxicity? a. Lidocaine b. Etidocaine c. Bupivacaine d. Prilocaine e. Chloroprocaine

*c. Bupivacaine In general, in both in vivo and in vitro studies there is an overall direct correlation between anesthetic's potency and its direct depressant effect on myocardial contractility. The ratio of dosage required for cardiovascular collapse in animal models compared with that required to produce neurologic symptoms is the lowest for bupivacaine, levo-bupivacaine and ropivacaine (2.0). Ratios for other local anesthetics are as follows: prilocaine, 3.1; procaine and chloroprocaine, 3.7; etidocaine, 4.4; lidocaine and mepivacaine

A 21-year-old patient reports tingling in her thumb during cesarean section under epidural anesthesia. To which dermatomal level would this correspond? a. C4 b. C5 c. C6 d. C7 e. C8

*c. C6 The thumb corresponds to dermatome C6, the second and middle fingers correspond to dermatome C7, and the fourth and little fingers correspond to dermatome C8

Each of the following is associated with an increased incidence postdural puncture headaches (PDPH) EXCEPT: a. Young age b. Female gender c. Early ambulation d. Pregnancy e. Large needle size

*c. Early ambulation Younger adults have a higher incidence of PDPH than older adults. Women have a slightly higher incidence than men. Pregnant women have a higher incidence than nonpregnant women. Since the incidence and severity of PDPH relates to the amount of CSF leakage through the dural hole, it makes sense that the larger the needle and the more holes in the dura the greater incidence of PDPH. In addition, the shape of the tip of the needle is important; a cutting needle (e.g.. Quincke) has a greater incidence of PDPH than noncutting needles (e.g., Whitacre, Sprotte). The incidence of headache has been shown to be less when the dural fibers are split longitudinally rather than when they are cut while the needle is held in a transverse direction. The timing of ambulation relative to dural puncture has not been shown to affect the incidence of postspinal headache. The block should wear off before ambulation is attempted

Which of the following is the most important disadvantage of interscalene brachial plexus block compared with other approaches? a. Not suitable for operations on the shoulder b. Large volumes of local anesthetics required c. Frequent sparing of the ulnar nerve d. Frequent sparing of the musculocutaneous nerve e. High incidence of pneumothorax

*c. Frequent sparing of the ulnar nerve The major disadvantage of the interscalene block for hand and forearm surgery is that blockade of the inferior trunk (C8-T1) is often incomplete. Supplementation of the ulnar nerve often is required. The risk of pneumothorax is quite low, but blockade of the ipsilateral phrenic nerve occurs in up to 100% of blocks. This can cause respiratory compromise in patients with significant lung disease

The femoral nerve is always ___________ to the femoral artery. a. Posterior b. Superior c. Lateral d. Medial

*c. Lateral The femoral nerve is always lateral to the artery

The "snap" felt just before entering the epidural space represents passage through which ligament? a. Anterior longitudinal ligaments b. Posterior longitudinal ligaments c. Ligamentum flavum d. Supraspinous ligament e. Interspinous ligament

*c. Ligamentum flavum The structures that are traversed by a needle placed in the midline prior to the epidural space are as follows: skin, subcutaneous tissue, supraspinous ligament, interspinous ligament, and ligamentum flavum. The ligamentum flavum is tough and dense and a change in the resistance to advancing the needle is often perceived and to many feels like a "snap." The anterior and posterior longitudinal ligaments bind the vertebral bodies together

Which of the following is the earliest sign of lidocaine toxicity? a. Shivering b. Nystagmus c. Lightheadedness and dizziness d. Tonic-clonic seizures e. Nausea and vomiting

*c. Lightheadedness and dizziness Toxic reactions to local anesthetics are usually due to intravascular or intrathecal injection or to an excessive dosage. The initial symptoms of local anesthetic toxicity are lightheadedness and dizziness. Patients also may note perioral numbness and tinnitus. Progressive central nervous system (CNS) excitatory effects include visual and auditory disturbances, shivering, muscular twitching, and ultimately, generalized tonic-clonic seizures. CNS depression can ensue, leading to respiratory depression or arrest

The primary determinant of local anesthetic potency is: a. pKa b. Molecular weight c. Lipid solubility d. Concentration e. Protein binding

*c. Lipid solubility The potency of local anesthetics is directly related to their lipid solubility. In general, the speed or onset of action of local anesthetics is related to the pKa of the drug. Drugs with lower pKa values have a higher amount of non-ionized molecules at physiologic pH and penetrate the lipid portion of nerves faster (an exception is chloroprocaine, which has a fast onset of action that may be related to the higher concentration of drug used). The amount of protein binding seems related to the duration of action of local anesthetics (more protein binding has longer duration of action)

Epidural use of which of the following opioids would result in the greatest incidence of delayed respiratory depression? a. Sufentanil b. Fentanyl c. Morphine sulfate d. Hydromorphone e. Methadone

*c. Morphine sulfate Although the more hydrophilic drugs such as morphine have a longer duration of action of analgesia, they also have a higher potential for inducing delayed respiratory depression through cephalad migration in the CNS, as compared with the more lipid-soluble drugs listed in this question

Select the one true statement concerning phantom limb pain. a. Most phantom limb pain becomes more severe with time b. Most amputees do not experience phantom limb pain c. Nerve blocks may be used to treat phantom limb pain d. Trauma amputees have a higher incidence of phantom limb pain than nontrauma amputees e. The incidence of phantom limb pain increases with more distal amputations

*c. Nerve blocks may be used to treat phantom limb pain The incidence of phantom limb pain is estimated to be 60% to 85%. The incidence of phantom limb pain does not differ between traumatic and nontraumatic amputees. The incidence of phantom pain increases with more proximal amputation. Although very difficult to treat, nerve blocks are commonly used in an attempt to treat phantom pain. These include trigger point injections, peripheral and central nerve blocks, and sympathetic blocks

A 42-year-old woman with a morbid fear of general anesthesia receives an interscalene block for shoulder arthroscopy consisting of 20 mL 0.5% ropivacaine. Much of her arm, shoulder and hand are numb, but the patient complains of pain as the incision is made at the upper portion of the shoulder. The most appropriate next step is: a. Repeat block b. Perform intercostobrachial block c. Perform superficial cervical plexus block d. Perform a deep cervical plexus block e. Induce general anesthesia

*c. Perform superficial cervical plexus block The needle insertion site for an interscalene block is C6. Local anesthetics usually spread to C5, C6 and C7 which supply much, but not all, of the cutaneous innervation to the shoulder. With low-to-moderate volume blocks there will be sparing of the (C3-C4) nerve roots, which supply some of the innervation to the anterior shoulder. Of note, C8 and T1 may also be spared, often resulting in the need for ulnar nerve supplementation if this block were used for a hand operation. Complete anesthesia for shoulder arthroscopy may require a supplemental superficial cervical plexus with use of low to moderate volumes of a local anesthetic

What is the correct order of structures (from cephalad to caudad) in the intercostal space? a. Nerve, artery, vein b. Vein, nerve, artery c. Vein, artery, nerve d. Artery, nerve, vein e. Artery, vein, nerve

*c. Vein, artery, nerve VAN (Vein, Artery, Nerve) describes the anatomical relationship of the intercostal structures deep to the lower border of the ribs from cephalad to caudal direction. The block is performed by walking off the inferior edge of the rib typically about 5 to 7 cm from midline. The two principle risks are pneumothorax and intravascular injection of local anesthetics. Because of the close proximity of the vein and artery to the nerve, intercostal blocks have relatively high blood levels as compared to other blocks (e.g., epidural, brachial plexus, infiltration) and caution with dose is needed if many levels are blocked

The stellate ganglion lies in closest proximity to which of the following vascular structures? a. Common carotid artery b. Internal carotid artery c. Vertebral artery d. Axillary artery e. Aorta

*c. Vertebral artery The stellate ganglion usually lies in front of the neck of the first rib. The vertebral artery lies anterior to the ganglion as it has just originated from the subclavian artery. After passing over the ganglion, it enters the vertebral foramen and lies posterior to the anterior tubercle of C6

The deep peroneal nerve innervates the: a. Lateral aspect of the dorsum of the foot b. Entire dorsum of the foot c. Web space between the great toe and the second toe d. Web space between the third and fourth toes e. Medial aspect of the dorsum of the foot

*c. Web space between the great toe and the second toe The deep peroneal nerve innervates the short extensors of the toes and the skin of the web space between the great and second toe. The deep peroneal nerve is blocked at the ankle by infiltration between the tendons of the anterior tibial and extensor hallucis longus muscle

What epidural dose of bupivacaine will give similar sensory analgesia as 10 mL of 2% lidocaine? a. 5 mL of 0.25% b. 10 mL of 0.25% c. 5 mL of 0.5% d. 10 mL of 0.5% e. 5 mL of 0.75%

*d. 10 mL of 0.5% In the epidural space, bupivacaine is four times more potent than lidocaine, so 0.5% bupivacaine is similar to 2% lidocaine. The duration of the bupivacaine block will be longer because bupivacaine has a long duration of action and lidocaine has an intermediate duration of action

An axillary block utilizing the transarterial approach with 0.5% bupivacaine and epinephrine (1:200,000) is performed in a 70-kg patient. Thirty mL is injected posterior to the axillary artery and 30 mL anterior to it. How many mg have been injected and was the maximum recommended dose exceeded? a. 150 mg bupivacaine, 150 μg epinephrine did not exceed maximum dose b. 150 mg bupivacaine, 150 μg epinephrine exceeded maximum dose c. 300 mg bupivacaine, 300 μg epinephrine did not exceed maximum dose d. 300 mg bupivacaine, 300 μg epinephrine exceeded maximum dose e. Transarterial blocks should never contain epinephrine and the block should not be done

*d. 300 mg bupivacaine, 300 μg epinephrine exceeded maximum dose A total of 60 mL of 0.5% bupivacaine with epinephrine (1:200,000) was used. A 0.5% solution = 0.5 g in 100 mL of fluid = 500 mg/100 mL = 5 mg/mL. A 1:200,000 solution means 1 gram in 200,000 mL = 1000 mg/200,000 mL = 1 mg/200 mL = 1000 μg/200 mL = 5 μg/mL. Therefore 60 mL of 0.5% bupivacaine with 1:200,000 epinephrine contains 60 mL × 5 mg/mL or 300 mg bupivacaine and 60 mL × 5 μg/mL or 300 μg of epinephrine. For a major nerve block the maximum recommended dose with epinephrine (1:200,000) is 500 mg for lidocaine and mepivacaine, 600 mg with prilocaine, and 225 mg with bupivacaine. Epinephrine is used in the local anesthetic to check for intravascular injection of the incremental doses and is not contraindicated but should be used for this block

The maximum dose of lidocaine containing 1:200,000 epinephrine that can be administered to a 70-kg patient for regional anesthesia (other than spinal anesthesia) is: a. 50 mg b. 100 mg c. 200 mg d. 500 mg e. 1000 mg

*d. 500 mg The maximum dose of local anesthetics containing 1:200,000 epinephrine that can be used for major nerve blocks is lidocaine, 500 mg; mepivacaine, 500 mg; prilocaine, 600 mg; bupivacaine, 225 mg; etidocaine, 400 mg; and tetracaine, 200 mg

Which of the following patients would be LEAST likely to develop a decrease in heart rate with a high (C8) level spinal anesthesia? a. A 15-year-old female patient with history of Wolff-Parkinson-White syndrome b. A 73-year-old patient with glaucoma treated with pilocarpine eye drops c. A 33 year old with a T6 paraplegia d. A 45-year-old diabetic man with a history orthostatic hypotension e. A 47-year-old patient who had a myocardial infarction 1 month ago, now taking procainamide

*d. A 45-year-old diabetic man with a history orthostatic hypotension The cardiac accelerator fibers originate in the T1-T4 segments. A high spinal, above T1, can cause bradycardia by anesthetizing these fibers. Diabetic patients who display orthostatic hypotension have an autonomic neuropathy. The cardiac accelerator fibers are essentially ablated in these patients and therefore, the slowing of heart rate does not ordinarily develop with high spinals. Pilocarpine, a parasympathomimetic agent, will not prevent bradycardia with spinal anesthesia. Patients with Wolff-Parkinson-White syndrome will become bradycardic when the autonomic accelerator fibers are interrupted, as will patients with a spinal cord transection below T4. Recent myocardial infarction does not eliminate susceptibility to bradycardia with sympatholysis unless the patient has a complete heart block

The mechanism of the TENS unit in relieving pain is: a. Direct electrical inhibition of type A-delta and C fibers b. Depletion of neurotransmitter in nociceptors c. Hyperpolarization of spinothalamic tract neurons d. Activation of inhibitory neurons e. Distortion of nociceptors

*d. Activation of inhibitory neurons Transcutaneous electrical nerve stimulation (TENS) is low-intensity electrical stimuli (2 and 100 Hz,) that produces a tingling or vibratory sensation. It is thought that TENS units produce analgesia by releasing endogenous endorphins. These endorphins have an inhibitory effect at the spinal cord level and augment descending inhibitory pathways

A 36-year-old female patient is undergoing thyroidectomy under a deep cervical plexus nerve block. Which of the following complications would be LEAST likely with this block? a. Horner's syndrome b. Subarachnoid injection c. Blockade of the recurrent laryngeal nerve d. Blockade of the spinal accessory nerve e. Vertebral artery injection

*d. Blockade of the spinal accessory nerve Complications of deep cervical plexus block include injection of the local anesthetic into the vertebral artery, subarachnoid space, or epidural space. Other nerves that may be anesthetized include the phrenic nerve (which is why bilateral deep cervical plexus blocks should be performed with caution, if at all), and the recurrent laryngeal nerve

Which of the following local anesthetics would produce the lowest concentration in the fetus relative to the maternal serum concentration during a continuous lumbar epidural? a. Etidocaine b. Bupivacaine c. Lidocaine d. Chloroprocaine e. Mepivacaine

*d. Chloroprocaine Chloroprocaine is an ester local anesthetic that is rapidly metabolized by pseudocholinesterase. With the epidural injection of chloroprocaine, very little drug is available to cross the placenta, because the half-life is about 45 seconds (and that which crosses is also rapidly metabolized making fetal effects essentially non-significant). The amide local anesthetics undergo liver metabolism and have relatively long half-lives, but with prolonged epidural administration may accumulate in the fetus

Differences in which of the following local anesthetic properties account for the fact that the onset of an epidural block with 3% 2-chloroprocaine is more rapid than 2% lidocaine? a. Protein binding b. pKa c. Lipid solubility d. Concentration e. Ester versus amide structure

*d. Concentration Local anesthetics are weak bases. The neutral (non-ionized) form of the molecule is able to pass through the lipid nerve cell membrane, whereas the ionized (protonated) form actually produces anesthesia. Chloroprocaine has the highest pKa of local anesthetics, meaning that a greater percentage of it will exist in the ionized form at any given pH than any of the other local anesthetics. Despite this fact, 3% chloroprocaine has a more rapid onset than 2% lidocaine, presumably because of the greater number of molecules (concentration). If one compares onset time for 1.5% lidocaine against 1.5% chloroprocaine, the former will have a more rapid onset

After placement of an epidural catheter in a 55-year-old patient for total hip arthroplasty, an entire epidural dose is administered into the subarachnoid space. Physiologic effects consistent with subarachnoid injection of large volumes of local anesthetic include all of the following EXCEPT: a. Hypotension b. Bradycardia c. Respiratory depression d. Constricted pupils e. Possible cauda equina syndrome

*d. Constricted pupils With the unintentional injection of an epidural dose of local anesthetic into the subarachnoid space, spinal anesthesia develops rapidly. Blockade of the sympathetic fibers (T1-L2) produces hypotension, particularly if the patient is hypovolemic. Bradycardia is produced by blocking the cardiac accelerator fibers (T1-T4). Respiratory arrest is due to hypoperfusion of the respiratory centers as well as paralysis of the phrenic nerve (C3-C5). The pupils become dilated after intrathecal injection of large quantities of local anesthetics; they will return to normal size after the block recedes. Cauda equina syndrome has occasionally developed when the epidural dose was unintentionally administered into the subarachnoid space (most commonly with chloroprocaine). If one suspects an unintentional placement of the epidural dose subarachnoid, supportive methods are initially done (the basic ABC's of resuscitation). One can also aspirate CSF from the epidural catheter (if it was inserted) to help remove some of the drug as well as reducing the pressure in the subarachnoid space, which might help better perfuse the spinal cord and decrease the chance of cauda equina syndrome developing

A healthy 27-year-old female stepped on a nail and is to undergo débridement of a wound on her right great toe. She is anxious about general anesthesia but agrees to an ankle block with mild sedation. Which nerves must be adequately blocked in order to perform the surgery? a. Deep peroneal, posterior tibial, saphenous, sural b. Deep peroneal, saphenous, superficial peroneal, sural c. Deep peroneal, posterior tibial, superficial peroneal, sural d. Deep peroneal, posterior tibial, saphenous, superficial peroneal e. Deep peroneal, posterior tibial, saphenous

*d. Deep peroneal, posterior tibial, saphenous, superficial peroneal The great toe is innervated by the deep peroneal, posterior tibial, superficial peroneal, and occasionally the saphenous nerve. All four of these nerves should be blocked for surgery on the great toe

Administration of an interscalene block is associated virtually 100% of the time with: a. Hoarseness b. Ulnar nerve blockade c. Ipsilateral Horner's syndrome d. Diaphragmatic hemiparalysis e. Bradycardia

*d. Diaphragmatic hemiparalysis Ipsilateral phrenic nerve block with diaphragmatic paralysis occurs is virtually 100% of patients receiving an interscalene block. This produces a 25% reduction in pulmonary function, making this block a contraindication in patients with borderline pulmonary function. Blockage of the recurrent laryngeal nerve can occur but is rare; however, if the patient has contralateral vocal cord palsy and develops a recurrent laryngeal nerve block, complete airway obstruction can occur. With this block, the inferior trunk of the brachial plexus where the ulnar nerve is derived may be spared

A 54-year-old man is administered morphine via patient-controlled analgesia (PCA) pump after a left total hip arthroplasty. The pump is programmed to deliver a maximum dose of 2 mg every 15 minutes (lockout time) as needed for patient comfort. The total maximum dose that can be delivered in 4 hours is 30 mg. On the first day the patient receives 15 doses every 4 hours by pressing the delivery button every 15 to 18 minutes. How should his pain control be further managed? a. Discontinue the PCA pump and administer intramuscular morphine b. Increase the lockout time from 15 to 25 minutes c. Change the analgesic from morphine to fentanyl d. Increase the dose to 3 mg every 15 minutes as needed up to a total maximum dose of 40 mg every 4 hours e. Make no changes

*d. Increase the dose to 3 mg every 15 minutes as needed up to a total maximum dose of 40 mg every 4 hours. Frequent dosing by a patient receiving postoperative analgesia through a PCA pump suggests the need to increase the magnitude of the dose. It is important to keep in mind that a patient should be given a sufficient loading dose of narcotic before initiative therapy with a PCA pump. Otherwise, the patient will be playing the frustrating game of "catch up"

Which of the following would hasten the onset and increase the clinical duration of action of a local anesthetic, and provide the greatest depth of motor and sensory blockade when used for epidural anesthesia? a. Addition to 1:200,000 epinephrine b. Increasing the volume of local anesthetic c. Increasing the concentration of local anesthetic d. Increasing the dose e. Placing the patient in the head-down position

*d. Increasing the dose Increasing the total dose (mass) of local anesthetic is more efficacious in hastening the onset and increasing the duration of an epidural anesthetic than increasing the volume or increasing the concentration

Which of the following structures in the antecubital fossa is the most medial? a. Brachial artery b. Radial nerve c. Tendon of the biceps *d. Median nerve e. Musculocutaneous nerve

*d. Median nerve The median nerve is the most medial structure in the antecubital fossa. To block this nerve, first the brachial artery is palpated at the level of the intercondylar line between the medial and lateral epicondyles, and then a needle is inserted just medial to the artery and directed perpendicularly to the skin

List the order of structures from lateral to medial in the femoral canal. a. Artery, nerve, empty space, vein, lymphatics b. Lymphatics, empty space, vein, artery, nerve c. Vein, artery, nerve, empty space, lymphatics d. Nerve, artery, vein, empty space, lymphatics

*d. Nerve, artery, vein, empty space, lymphatics The femoral nerve is always lateral to the artery; from lateral to medial the order is nerve, artery, vein, empty space, and lymphatics (NAVEL).

Select the FALSE statement concerning neurolytic nerve blocks. a. There is little difference in the efficacy between alcohol and phenol b. Destruction of peripheral nerves can be followed by a denervation hypersensitivity that is worse than the original pain c. Neurolytic blocks should be reserved for patients with short life expectancies d. Neurolytic blockade with phenol is permanent e. Intrathecal neurolysis may be an effective management for certain pain conditions

*d. Neurolytic blockade with phenol is permanent Alcohol and phenol are similar in their ability to cause nonselective damage to neural tissues. Alcohol causes pain when injected and sometimes is mixed with bupivacaine, whereas phenol is relatively painless. Neural tissue will regenerate; therefore, neurolytic blocks are never "permanent" and neurolysis can lead to a denervation hypersensitivity, which can be extremely painful

Through which of the following would a spinal needle NOT pass during a midline placement of a subarachnoid block in the L3-L4 lumbar space? a. Supraspinous ligament b. Interspinous ligament c. Ligamentum flavum d. Posterior longitudinal ligament e. Dura mater

*d. Posterior longitudinal ligament The structures include the skin, subcutaneous tissue, supraspinous ligament, interspinous ligament, the ligamentum flavum, and finally the dura (posterior). If you were to continue to advance the spinal needle, you would encounter the dura (anteriorly) while exiting the subarachnoid space, the posterior longitudinal ligament, the periosteum of the vertebral body, and finally, bone

Important landmarks for performing a sciatic nerve block (classic approach of Labat) include: a. Iliac crest, sacral hiatus, greater trochanter b. Iliac crest, coccyx, and greater trochanter c. Posterior superior iliac spine, coccyx, and greater trochanter d. Posterior superior iliac spine, greater trochanter and sacral hiatus e. Posterior superior iliac spine and greater trochanter

*d. Posterior superior iliac spine, greater trochanter and sacral hiatus To perform a sciatic nerve block, first draw a line from the posterior superior iliac spine to the greater trochanter, then draw a 5-cm line perpendicular from the midpoint of this line caudally and a second line from the sacral hiatus to the greater trochanter. The intersection of the second line with the perpendicular line marks the point of entry

Which of the following local anesthetics used for intravenous regional anesthesia (Bier block) is most rapidly metabolized and thus, least toxic? a. Lidocaine b. Ropivacaine c. Mepivacaine d. Prilocaine e. Etidocaine

*d. Prilocaine Prilocaine is the most rapidly metabolized of the amide local anesthetics and therefore least toxic. 2-Chloroprocaine is hydrolyzed rapidly in the blood and, therefore, would appear to be ideal, but it has been associated with a high incidence of thrombophlebitis and is therefore not recommended. To avoid toxicity, maximum doses are as follows: prilocaine, 3 to 4 mg/kg; lidocaine, 1.5 to 3 mg/kg; ropivacaine, 1.2 to 1.8 mg/kg. Bupivacaine is not recommended for Bier blocks because of reports of cardiovascular toxicity and death that have occurred

Para-aminobenzoic acid is a metabolite of: a. Mepivacaine b. Ropivacaine c. Bupivacaine d. Procaine e. Prilocaine

*d. Procaine Para-aminobenzoic acid is a metabolite of the ester-type local anesthetics. Local anesthetics may be placed into two distinct categories based on their chemical structure: ester or amide. The amides, which are ropivacaine lidocaine, etidocaine, prilocaine, mepivacaine and bupivacaine, are metabolized in the liver. The ester local anesthetics are cocaine, procaine, chloroprocaine, tetracaine, and benzocaine. These drugs are metabolized by the enzyme pseudocholinesterase found in the blood. Para-aminobenzoic acid is a metabolic breakdown product of ester anesthetic and is responsible for allergic reactions in some individuals

Each of the following is a potential complication of lumbar sympathetic blocks EXCEPT: a. Puncture of the renal pelvis b. Intravascular injection (aorta) c. Seizure d. S1 nerve block e. Accidental subarachnoid injection

*d. S1 nerve block Potential complications from lumbar sympathetic block include subarachnoid injection, puncture of a major vessel (e.g., aorta) or renal pelvis, neuralgia, somatic nerve damage, perforation of a disk, infection, ejaculatory failure, and chronic back pain. Blockade of nerves arising from the lumbar plexus is possible, but given the anatomic location of the sacral plexus, blockade of an S1 nerve would be extremely unlikely if not impossible

A 35-year-old woman receives a popliteal block for ankle and foot surgery. Which other nerve must be blocked in order to have complete anesthesia of the foot? a. Deep peroneal nerve b. Superficial peroneal nerve c. Sural nerve d. Saphenous nerve e. Posterior tibial nerve

*d. Saphenous nerve All of the nerves of the foot with the exception of the saphenous are derived from the sciatic nerve. The sciatic nerve distally becomes the tibial and peroneal nerves which can be blocked at the popliteal fossa for surgery below the knee. The saphenous nerve is a branch of the femoral nerve and provides sensory innervation along the medial aspect of the lower leg between the knee and the medial malleolus and must also be blocked for surgery below the knee

The main advantage of neurolytic nerve blockade with phenol versus alcohol is: a. Denser blockade b. Blockade is permanent c. The effects of the block can be evaluated immediately d. The block is less painful e. Phenol is selective for sympathetic fibers

*d. The block is less painful Neurolytic blockade with phenol (6% to 10% in glycerine) is painless because phenol has a dual action as both a local anesthetic and a neurolytic agent. The initial block wears off over a 24-hour period, during which time neurolysis occurs. For this reason you must wait a day to determine effectiveness of the neurolytic block. Alcohol (100% ethanol) is painful on injection and should be preceded by local anesthetic injection. Unfortunately, there is no neurolytic agent that affects only sympathetic fibers

The occipital portion of the skull receives sensory innervation from: a. Spinal accessory nerve (nerve XI) b. Facial nerve (nerve VII) c. Ophthalmic branch of trigeminal nerve (nerve V) d. Maxillary branch of trigeminal nerve (nerve V) e. Greater and lesser occipital nerves

*e. Greater and lesser occipital nerves The occiput receives sensory innervation from the greater and lesser occipital nerves, which are terminal branches of the cervical plexus. Blockade of these nerves is usually carried out as a diagnostic step in the evaluation of head and neck pain

Select the FALSE statement regarding spinal anatomy and spinal anesthesia in adults. a. The addition of phenylephrine to lidocaine will prolong spinal anesthesia b. A high thoracic sensory block will result in total sympathetic blockade c. The largest vertebral interspace is L5-S1 d. The dural sac extends to the S4-S5 interspace e. Tetracaine provides longer anesthesia than does procaine

*d. The dural sac extends to the S4-S5 interspace Both phenylephrine and epinephrine will prolong a spinal anesthetic when administering lidocaine. The Taylor approach for spinal anesthesia uses a paramedian approach to the L5-S1 interspace—the largest interspace of the vertebral column. The sympathetic nervous system originates in the thoracic and lumbar spinal cord T1-L3; therefore, a high thoracic sensory level can cause a complete sympathetic block. The dural sac extends to S2-S3, not S4-S5. The spinal cord extends to L3 in the infant and L1-L2 in adults

During placement of an epidural in a 78-year-old patient scheduled for a total knee arthroplasty, the patient complains of a sharp sustained pain radiating down his left leg as the catheter is inserted to 2 cm. The most appropriate action at this time would be: a. Leave the catheter at 2 cm, give test dose b. Give small dose to relieve pain then advance 1 cm c. Withdraw the catheter 1 cm, give test dose d. Withdraw needle and catheter, reinsert in a new position e. Abandon epidural technique, place long-acting spinal anesthetic

*d. Withdraw needle and catheter, reinsert in a new position When an epidural catheter is placed without fluoroscopic guidance, the exact location of the needle tip relative to the anatomic structures of the back can only be surmised. If malposition of either the needle or the catheter is suspected, it is prudent to withdraw the entire apparatus and reinsert a second time. In this case, it is possible that the catheter tip has found its way into a nerve root. Under these circumstances, injection of a local anesthetic or narcotic could produce pressure that would lead to ischemia and possible neurologic damage. During placement or injection of an epidural catheter, a paresthesia is always a warning sign that should be heeded

All the following agents are acceptable for use in a Bier block EXCEPT: a. 0.5% Lidocaine b. 0.5% Mepivacaine c. 0.5% Procaine d. 0.5% Prilocaine e. 0.25% Bupivacaine

*e. 0.25% Bupivacaine Because of the potential for cardiotoxicity and because bupivacaine has no advantages over other local anesthetics in this setting, it is no longer recommended for use in intravenous regional anesthesia

The epidural administration of a mixture of chloroprocaine and bupivacaine would have: a. A latency similar to chloroprocaine with a duration of action similar to bupivacaine b. A latency shorter than chloroprocaine with a duration of action longer than bupivacaine c. A latency shorter than chloroprocaine with a duration of action similar to bupivacaine d. A latency longer than chloroprocaine with a duration of action similar to chloroprocaine e. A latency longer than chloroprocaine with a duration of action shorter than bupivacaine

*e. A latency longer than chloroprocaine with a duration of action shorter than bupivacaine Mixtures of local anesthetics have been used to take advantage of the short latency of certain agents (chloroprocaine) and the long duration of other agents (bupivacaine). Duration of epidural anesthesia by mixtures of chloroprocaine and bupivacaine has been shown to be shorter than bupivacaine alone and onset time longer than chloroprocaine alone

Each of the following additives to a spinal anesthetic possesses analgesic properties EXCEPT: a. Clonidine b. Neostigmine c. Epinephrine d. Fentanyl e. All of the drugs listed possess analgesic activity

*e. All of the drugs listed possess analgesic activity Drugs with α-agonist activity (phenylephrine/epinephrine) possess some analgesic activity but less than narcotics and local anesthetics. In addition, intrathecal epinephrine will reduce systemic/vascular uptake of local anesthetics, thereby enhancing their effects, including hypotension. Clonidine alone, when administered neuraxially, is an effective analgesic. Neostigmine has some mild analgesia properties but experience is limited. Opioids added to the spinal solution enhance surgical anesthesia and provide postoperative pain. Fentanyl 25 μg is commonly added for short surgical procedures (outpatient) whereas morphine can be used when longer postoperative analgesia is desired for inpatients

Which of the following muscles of the larynx is innervated by the external branch of the superior laryngeal nerve? a. Vocalis muscle b. Thyroarytenoid muscles c. Posterior cricoarytenoid muscle d. Oblique arytenoid muscles e. Cricothyroid muscle

*e. Cricothyroid muscle The vagus nerve innervates the airway by two branches: the superior laryngeal nerves and the recurrent laryngeal nerves. All the muscles of the larynx are innervated by the recurrent laryngeal nerve except for the cricothyroid muscle. The superior laryngeal nerve divides into the internal and external laryngeal branches. The external laryngeal branch innervates the cricothyroid muscle. The internal laryngeal branch provides sensory fibers to the cords, epiglottis and the arytenoids

A 57-year-old patient is scheduled for hemorrhoidectomy. The patient has a history of mild chronic obstructive pulmonary disease, hypertension, and traumatic foot amputation from a tractor accident. His only hospitalizations were for two suicide attempts related to phantom limb sensations 10 years ago. He takes phenelzine (Nardil), thiazide, and potassium. Which of the following anesthetic techniques would be most appropriate for this patient? a. Spinal anesthetic with 0.5% hyperbaric bupivacaine b. Epidural anesthetic with 0.5% bupivacaine c. Local infiltration with lidocaine and epinephrine, sedation with propofol and meperidine d. General anesthesia with thiopental sodium (Pentothal), succinylcholine, nitrous oxide, isoflurane, meperidine e. General anesthesia with propofol, succinylcholine, nitrous oxide, fentanyl

*e. General anesthesia with propofol, succinylcholine, nitrous oxide, fentanyl. Reactivation of phantom limb sensations has been reported in patients who have received both spinal and epidural anesthetics (90% in some series). In the majority of these cases (80%), phantom limb sensation persisted until the block receded. With a history of a phantom limb sensations that drove this patient to attempt suicide, it is probably wise to avoid spinal and epidural anesthetics. Phenelzine (Nardil) is a monoamine oxidase (MAO) inhibitor that is occasionally used for the treatment of depression. Any anesthetic or combination of techniques that involves meperidine is contraindicated in patients receiving MAO inhibitors. The combination of meperidine and MAO inhibitors has been associated with hyperthermia, hypotension, hypertension, ventilatory depression, skeletal muscle rigidity, seizures, and coma. Because of this unfavorable drug interaction, meperidine should be avoided in patients receiving MAO inhibitors. Accordingly, the only acceptable choice in this question would be general anesthesia with propofol, succinylcholine, nitrous oxide, and fentanyl. As an interesting side point, the drug phenelzine prolongs the duration of action of succinylcholine by decreasing plasma cholinesterase activity

An 18-year-old man has a seizure during placement of an interscalene brachial plexus block with 2% lidocaine. The anesthesiologist begins to hyperventilate the patient's lungs with 100% O2 using an anesthesia bag and mask. The rationale for this therapy includes all of the following EXCEPT: a. Helps to prevent and treat hypoxia b. Hyperventilation decreases blood flow and delivery of lidocaine to the brain c. Hyperventilation induces hypokalemia which elevates the seizure threshold d. Hyperventilation induces alkalosis which elevates the seizure threshold e. Hyperventilation induces alkalosis which converts lidocaine to the protonated (ionized) form

*e. Hyperventilation induces alkalosis which converts lidocaine to the protonated (ionized) form During a seizure, administration of 100% O2 helps to prevent and treat hypoxia in a patient who otherwise might not be breathing. Hyperventilation also causes cerebral vasoconstriction and decreased delivery of local anesthetic to the brain. Hyperventilation induces hypokalemia and respiratory alkalosis, both of which result in hyperpolarization of nerve membranes and elevation of the seizure threshold. Hyperventilation also raises the patient's pH (respiratory alkalosis) and converts lidocaine into the non-ionized (nonprotonated) form, which crosses the membrane more easily than the ionized form, which is detrimental

Which is NOT a potential complication of a stellate ganglion block? a. Recurrent laryngeal nerve paralysis b. Subarachnoid block c. Brachial plexus block d. Pneumothorax e. Increased heart rate

*e. Increased heart rate All of the choices listed are potential complications of stellate ganglion blockade except an increase in heart rate. The stellate ganglion supplies sympathetic fibers to the upper extremity and head and some to the heart. Loss of the cardiac acceleratory fibers may slow the heart rate, not speed it up. Other potential complications of stellate ganglion blockade include accidental injection of the local anesthetic into a vertebral artery resulting in seizure and inadvertent cervical epidural

A retrobulbar block anesthetizes each of the following nerves EXCEPT: a. Ciliary nerves b. Cranial nerve IV (trochlear nerve) c. Cranial nerve III (oculomotor nerve) d. Cranial nerve VI (abducens nerve) e. Maxillary branch of the trigeminal nerve

*e. Maxillary branch of the trigeminal nerve A retrobulbar block anesthetizes the three cranial nerves responsible for movement of the eye. The ciliary nerves are also blocked, providing anesthesia to the conjunctiva, cornea, and uvea. The ophthalmic branch of the trigeminal nerve provides sensory innervation to the skin of the forehead, cornea, and eyelid. This branch of the trigeminal nerve may be blocked, but the maxillary branch would be spared

Which statement concerning peripheral nerve structure and function is FALSE? a. Both nonmyelinated and myelinated nerves are surrounded by Schwann cells b. The speed of propagation of an action potential along a nerve axon is greatly enhanced by myelin c. Generation of an action potential is an "all-or-nothing" phenomenon d. Propagation of an action potential along myelinated nerve axons occurs by saltatory conduction via the nodes of Ranvier e. Myelination renders nerves less sensitive to local anesthetic blockade

*e. Myelination renders nerves less sensitive to local anesthetic blockade. Peripheral nerve axons are always enveloped by a Schwann cell. The myelinated nerves may be enveloped many times by the same Schwann cell. Transmission of nerve impulses (i.e., action potentials) along nonmyelinated nerves occurs in a continuous fashion, whereas transmission along myelinated nerves occurs by saltatory conduction from one node of Ranvier to the next. Myelination speeds transmission of neurological impulses; it also renders nerves more susceptible to local anesthetic blockade. An action potential is associated with an inward flux of sodium that occurs after a certain membrane threshold has been exceeded

An anesthesia pain service consult is sought for a 78-year-old patient with a complaint of pain in the distribution of the trigeminal nerve. The patient has no other medical problems except a history of congestive heart failure for which he takes digoxin and thiazide. In addition to his chief complaint, the patient over the last 72 hours has complained of dysesthesia in the feet, difficulty with vision, and emesis times three. The most appropriate step at this time would be: a. Trigeminal nerve block with bupivacaine b. Obtain neurologic workup for multiple sclerosis c. Administration of fentanyl and ondansetron d. Initiate therapy with carbamazepine e. Obtain a digoxin level

*e. Obtain a digoxin level The early signs of digitalis toxicity include loss of appetite and nausea and vomiting. In some patients there may be pain that is similar to trigeminal neuralgia. Pain or discomfort in the feet and pain and discomfort in the extremities may be a feature of digitalis toxicity. Transient visual disturbances (e.g., amblyopia, scotomata) have been reported in patients with digitalis toxicity. In this patient, it would be prudent to obtain a digoxin level as an early part of the workup for these complaints. He may also have true trigeminal neuralgia, and workup for this condition can be undertaken after digitalis toxicity has been ruled out

Allodynia is defined as: a. Spontaneous pain in an area or region that is anesthetic b. Pain initiated or caused by a primary lesion or dysfunction in the nervous system c. An unpleasant abnormal sensation, whether spontaneous or evoked d. An increased response to a stimulus that is normally painful e. Pain caused by a stimulus that does not normally provoke pain

*e. Pain caused by a stimulus that does not normally provoke pain The International Association for the Study of Pain (IASP) has defined several pain terms. Anesthesia dolorosa refers to spontaneous pain in an area or region that is anesthetic. Neuropathic pain is pain initiated or caused by a primary lesion or dysfunction in the nervous system. Dysesthesia is an unpleasant abnormal sensation, whether spontaneous or evoked. Hyperalgesia is an increased response to a stimulus that is normally painful. Allodynia is pain caused by a stimulus that does not normally provoke pain

Which of the following would have the greatest effect on the level of sensory blockade after a subarachnoid injection of hyperbaric 0.75% bupivacaine? a. Coughing during placement of the block b. Addition of epinephrine to the local anesthetic solution c. Barbotage d. Patient weight e. Patient position

*e. Patient position Many factors have an effect on the sensory level after a subarachnoid injection. The baricity of the solution and the patient position are the most important determinants of sensory level. The other listed options have little to no effect on sensory level. Patient height also has little effect on sensory level

A 63-year-old woman undergoes total knee arthroplasty under spinal anesthesia. Two days later she complains of a severe headache on the left side of her head. Pain intensity is not related to posture. The LEAST likely cause of this headache is: a. Caffeine withdrawal b. Malingering c. Viral illness d. Migraine e. Postdural puncture headache

*e. Postdural puncture headache Postdural puncture headache (PDPH) will have a postural component. When supine, the headache is usually gone but may be mild in some cases. When the head is elevated the headache may be severe, is bilateral and may be associated with diplopia, nausea and vomiting. The headache pain is typically frontal and/or occipital in location

Addition of bicarbonate to local anesthetics results in: a. Delayed onset of action b. Reduced toxicity c. Increased duration of action d. Increased anesthetic potency e. Reduced pain with skin infiltration

*e. Reduced pain with skin infiltration Adding sodium bicarbonate to local anesthetic solutions hastens the onset of action of the local anesthetics, especially when the local anesthetic solution contains epinephrine (which is produced at a lower pH). By raising the pH, more of the local anesthetic is in the non-ionized, more lipid-soluble state. Raising the pH too much (i.e., >6.05-8) would cause precipitation of the local anesthetic. It also seems to decrease pain with skin infiltration. Pain on injection can also be decreased by a slow injection of the local anesthetic

A 24-year-old man undergoes repair of a right anterior shoulder dislocation under interscalene brachial plexus block. Anesthesia is produced with 30 mL of 0.5% bupivacaine with 5 μg/mL of epinephrine. The next morning, the patient complains of numbness in his right arm and hand. The most likely cause of these complaints is: a. Excessive retraction by the surgeon b. Prolonged pressure on the brachial plexus from malpositioning c. Pressure on the right medial epicondyle from malpositioning d. Pressure on the right posterior humerus from malpositioning e. Residual anesthesia

*e. Residual anesthesia The brachial plexus is not normally retracted during repair of an anterior shoulder dislocation. Prolonged pressure on the brachial plexus will result in hand or arm numbness. This may occur if this structure becomes pinched between the clavicle and the head of the humerus, as seen in patients placed in steep Trendelenburg position with the shoulders resting against shoulder braces. Prolonged pressure on the medial epicondyle may produce an ulnar neuropathy, whereas prolonged pressure against the posterior surface of the humerus may produce a radial neuropathy. Bupivacaine is a long-acting local anesthetic and may cause numbness for 8 to 12 hours

The anterior and posterior spinal arteries originate from the: a. Common carotid and vertebral arteries, respectively b. Internal carotid and vertebral arteries, respectively c. Internal carotid and posterior cerebral arteries, respectively d. Vertebral and anterior cerebellar arteries, respectively e. Vertebral, radicular arteries and the posterior inferior cerebellar arteries, respectively

*e. Vertebral, radicular arteries and the posterior inferior cerebellar arteries, respectively. The one anterior spinal artery supplies about 75% of the blood flow to the spinal cord (motor tracts) and arises from the vertebral arteries and radicular arteries from the aorta. It descends in front of the anterior longitudinal sulcus of the spinal cord. The two posterior spinal arteries supply about 25% of the blood flow to the spinal cord (sensory tracts) and arise from the posterior and inferior cerebellar arteries, the vertebral arteries, and the radicular arteries