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