1-Peripheral Nerves

nerves that are most likely to be iatrogenic injury

- accessory nerve from lymph node biopsy from posterior triangle of neck - median nerve from carpal tunnel repair

PE klumpke's palsy

- arm is supinated - wrist in extreme extension d/t unopposed wrist extensors - hyperextension of MCP d/t loss of intrinsic hand muscles - flexion of IP d/t loss of intrinsic hand muscles - ipsilateral horner's syndrome

why is CNS regeneration limited?

- astrocytes form myelin in CNS (not schwann cells)

guillian barre PE

- asymmetric ascending weakness - autonomic dysregulation - respiration - facial paralysis

grade II classification of nerve injury

- axonotmesis - intact endometrium - damaged axons

grade III classification of nerve injuury

- axonotmesis - intact perineurium - damage axons and endoneurium

grade IV classification of nerve injury

- axonotmetsis - intact epineurium - damaged axons, endoneurium, and perineurium

how is glutamate level held in check

- by conversion to GABA (inhibitory NT)

lasegue sign

- clinical test to determine lumbosacral nerve root compression - pt supine, lifting left up <45degrees elicits pain = positive

cauda equina syndrome technically involves nerve roots of PNS injury....

- damage may be irreversible - is a surgical emergency

glutamic acid decarboxylase

- enz that converts glutamate to GABA - keeps glutamate from becoming too hight, and GABA from too low

lower brachial cord injury

- excessive upward pull of limb - klumpke's palsy (claw hands) - C8-T1

glutamte

- excitatory NT founds in small concentrations - related to ability to learn, attend, and cognitively function

multiple sclerosis PE

- hemisensory loss - diplopia - optic neuritis --> eye pain/loss of vision - hemiparesis and ophthalmoplegia (weak eye muscle) - bladder/bowel incontinence

LP CSF findings in multiple sclerosis

- high protein (IgG) and oligoclonal bands

upper brachial cord injury

- increase in angle bw neck and shoulder - erb-duchenne palsy (tipper's hands) - C5-6

grade VI classification of nerve injury

- multifocal mixed injury of the nerve - most common type of injury

neurapraxia brachial plexus injury

- nerve is stretched, but not torn - usually heals w/o surgery

avulsion brachial plexus injury

- nerve is torn from its attachment to the spinal cord - surgical repair is impossible

Grade I classification of nerve injury

- neuropraxia - histological changes leading to focal segmental demyelination

grade V classification of nerve injury

- neurotmesis - complete nerve transection

describe IV disc herniation

- nucleus pulposus (found between each vertebrae) confined by anulus fibrosus --> herniates into the area of spinal cord --> compresses spinal nerve root

charcot's triad for MS

- nystagmus - intentional tremor - ataxic dysarthria (trouble speaking)

cauda equina syndrome

- pattern of neuromuscular and urogenital sx d/t simultaneous compression of lumbosacral nerve roots below conus medullaris

nerve involved in stabbing/penetrating injury

- posterior triangle of neck - CN 11 (spinal accessory)

wallerian degeneration

- repair of damaged nerves in PNS by schwann cells (however, fails to restore full function) - limited capacity

multiple sclerosis tx

- symptomatic and immunsuppressive tx (methylpredisolone) - B-interferon

why are lumbosacral nerve roots particularly susceptible to injury?

- they have poorly developed epineurium --> not protected against compressive/tensile stresses (tumors/space occupying lesions)

cauda equina syndrome PE?

- urinary retention - urinary fecal incontinence - saddle anesthesia (sensory disturbance around anus, genital, buttock) - weakness/paralysis of usually more than one root --> affect lower extrem - sciatica - sexual dysfunction

procedures w/ high risk of iatrogenic surgical injuries

- varicose vein procedures - inguinal hernia repair - baker cyst removal - carpal tunnel release - posterior cervical triangle bx - arthrodesis - osteosynthesis

Steps of Wallerian Degeneration

1. distal to injury site, axon and myelin degenerate and fragment 2. - schwann cells do not degenerate, instead proliferate along path of original axon - marcopahge move into the area and remove degenerating debris distal to injury site 3. - as neuron recovery, axon grows into the site of injury and along path created by schwann cell - neurilemma and endoneurium grow together - new schwann cell grows within this tunnel 4. - as axon elongates, schwann cells wrap around it - if axon reestablishes normal synapse, normal function may be established - if axon stops growing or in new direction, normal functions will not return - cell body must reorganize its ribosomes - several growth sprouts - muscle atrophy occurs d/t denervation

LP CSF findings of guillian barre

Albuminocytologic dissociation (normal WBC, high protein)

is cauda equina LMN or UMN

LMN lesion

guillian barre syndrome

acute inflammatory demyelinating polyradiculopathy involving peripheral motor fiber nerves d/t infection/autoimmune stress

multiple sclerosis

autoimmune inflammation and demyelination of CNS

nerve involved in shoulder disolocation

axillary nerve

is recovery possible w/ neuropraxia?

complete recovery is expected w/ spontaneous remyelination

progressive multifocal leukoencephalopathy

destruction of oligodendrocytes

what happens during neuropraxia

focal segmental demyelination at the sight of injury W/O disruption of axon/connective tissue --> results in blockage of nerve conduction and transient weakness/paresthesia

Charcot-Marie-Tooth disease

heredity motor and sensory neuropathy (abnormal protein formation, including MBP)

iatrogenic surgical injuries

high tension, compression, and/or transection of the involved nerve

acute disseminated encephalomyelitis

inflammation and demyelination

nerve involved in elbow dislocation

median nerve

rupture brachial plexus injury

nerve is torn, but not at the spinal cord

mildest form of traumatic peripheral nerve injury

neuropraxia

neurotmesis

occurs after sharp, traction, avulsion, and toxic damage to nerve

nerve involved in knee dislocation/fibular fx

peroneal nerve

nerve involved in humeral fx

radial nerve

neurapraxia

result of compression or entrapment

axonotmesis

result of crush and stretch injuries

neuroma brachial plexus injury

scar tissue formation puts pressure on the nerve

nerve involved in pelvic fx/hip dislocation

sciatic nerve

causes of neuropraxia

sports, accidents, improper positioning

nerve involved in seat belt injury

upper trunk of brachial plexus