Peripheral neuropathy Flashcards
Peripheral neuropathy
- disturbance in function of one or more peripheral nerves
- motor, sensory, autonomic nerves or mixture of any of above can be affected
- clinically see mixed deficits
- sensory nerves are the first ones to be affected
Classification of peripheral nerve lesions
- bases on number and pattern of nerves involved
- mononeuropathy simplex
- mononeuritis multiplex
- polyneuropathy (axonal and myelinopathies)
Mononeuropathy simplex
- focal involvement of a single nerve
- due to trauma, compression, or entrapment
- most often entrapment (soft tissue around it trap it )
- usually unilateral
Common entrapment neuropathies
- media
- ulnar
- facial (Bell palsy)
- Radial
- Peroneal
- Posterior tibial
- Femoral
- Lateral femoral cutaneous nerve
Median neuropathy
- AKA: carpal tunnel syndrome
- most common mononeuropathy
- compression of the median nerve as it passes through the carpal tunnel
Median neuropathy symptoms
- pain and parasthesias in distribution median nerve-thumb, middle and 1/2 ring finger
- more at night
- weakness later symptoms
- parasethsias: numbness, tingling, but also can be pain and burning
Median neuropathy exam, testing, tx
exam: decreased sensation in thumb, index, middle, and 1/2 ring finger, weakness & wasting abductor pollicis brevis & opponens pollicis
- testing: slowed nerve conduction tests
- tx: splint (at night), injection (steroids - only last 6 months), surgery
- if they can shake their hand and it makes the numbness better it will most likely be carpal tunnel.
Ulnar neuropathy
- most often trapped at below: pain & parasthesias along ulnar border hand and 5th finger, worse with elbow flexion, weak adductor pollicis, often due to external compression
- tx: can split, but if bad need to surgically transpose nerve
Radial neuropathy
- from pressure from crutches in axilla, or falling alseep on arm
- motor deficit: wrist drop and lack of supination (waiter’s tip palsy, Erb’s palsy)
Peroneal nerve neuropathy
- from trauma or pressure at knee over head of fibula
- too tight LE cast is most common cause
- clinically can’t extend foot or evert foot
- brace foot and support until gets better
Posterior tibial neuropathy
- AKA tarsal tunnel
- analogous to carpal tunnel, but trapped behind medial malleolus
Lateral femoral cutaneous neve
- AKA: meralgia paresthetica
- supplies sensation to outer part of thigh
- from compression of nerve as it passes through inguinal canal
- common in pregnancy or obesity
Mononeuritis multiplex
- simultaneous or sequential loss of non contiguous nerve trunks
- noncontinguous important b/c means systemic process as opposed to local/mechanical process
- clinically get deficit attributable to involvement of one or more isolated nerves (a bunch of mononeuropathies put together)
- more than one compression = systemic process
Mononeuritis multiplex causes
- infarction of multiple nerve
- DM
- hypothyroidism
Mononeuritis multiplex pathology
- cell mediated immunity and immune complex deposition are most common and serious cause
- diabetes can also cause b/c underlying nerve dysfunction makes susceptible to multiple compression neuropathies
Mononeuritis multiplex history/presentation
- step wise loss in discrete nerve distribution
- weakness is a major feature (along w/ sensory sx)
- often presents with foot drop (peroneal nerve) or wrist drop (radial nerve)
Mononeuritis multiplex evaluation
- Think systemic
- nerve bx tends to be more helpful here than in polyneuropathy
Mononeuritis multiplex tx
- underlying disease: if immune bases process need to suppress immune system, if DM, control sugar
- relieve compression, if caused by compression
- sx: meds for neuropathic pain (i.e. gabapentin)
- can also use Topamax
Polyneuropathy
- multiple nerves affected at the same time (all nerves)
- subclassification: axonal and myelinopathies
Axonal polyneuropathy
- lesion in the nerve itself
- generalized, homogenous
- affects all nerve fiber types (sensory, motor, autonomic), but manifests more in certain types
- sensory fibers show sx first and more b/c smaller caliber axons
- fibers that innervate distally are longest and manifest abnormalities first
- classic example is diabetic axonal neuropathy
Myelinopathies polyneuropathy
- lesion in myelin sheath
- classic example: Guillain-Barre
Axonal Polyneuropathy epidemiology
- mild cases fairly common
- severe manifestations less common
Axonal Polyneuropathy pathophysiology
- most often toxin based or other systemic problem
- balance between damage and repair
Axonal Polyneuropathy etiologies
- DM
- EtOH: chronic
- B12 deficiency
- Syphillis
- HIV
- Lyme
- Uremia
- Chemo: Taxol
- Paraneoplastic
- Amylidosis
Axonal Polyneuropathy clinical presentation
- can be fast or slow depending on cause
- decreased sensation in feet first, longest, and most profoundly affected nerve fibers
- vibration and proprioception first to go
- stocking glove distribution (hands not involved until at knees)
- sensory loss more common than weakness
- if get autonomic dysfunction see: postural hypotension, erectile dysfunction and diarrhea
Axonal Polyneuropathy PE
- skin: can see loss of hair, shiny skin, if severe can get painless ulcers
- autonomic: orthostatic hypotension
Axonal Polyneuropathy neuro exam
- sensory: decreased sensation, posterior columns first then spinothalamic tract
- lose proprioception and vibration first
- worst in toes and works way up
- weakness if present tends to not be profound
- maybe can’t walk on heels/toes
- hyporeflexic often lose ankle jerks
- if severe neuropathy can see atrophy and fasciculations
- If you find sensory in the toes you can stop as the rest of the body will be intact it toes are
Axonal Polyneuropathy diagnostic eval
- EMG / nerve conduction can tell..
- muscle vs. nerve
- polyneuropathy vs. monoeuropathy vs. radiculopathy
- axonal vs. demyelinating
- Nerve bx
Axonal Polyneuropathy labs
- CBC: for anemia and B12 deficiency
- Vitamin B12 levels
- blood glucose, urinalysis, A1C for DM
- TSH for hypothyroidism
- ESR: increased in amyloid and connective tissue disease
- ANA: CTD (rheumatologic cause)
- Serum protein electrophoresis: multiple myeloma
Axonal Polyneuropathy tx
- tx underlying cause
- physical therapy to prevent contractions and splint to maintain limbs in useful position
- simple analgesics (acetaminophen and NSAIDs)
- episodic stabbing pains: tricyclic antidepressants, carbamazepine, gaapentin, pregabalin, phenytoin, topiramate
- Narcotics if nothing else works (Tramadol)
Axonal Polyneuropathy pt education
- more susceptible to other nerve trauma so no crossing legs or resting elbows
- guard against burns if insensate: test hot water first, or lower temp use hot water heater
- examine shoes and feet daily for pressure ulcers
Demyelinating Polyneuropathy
- classic ex: Guillian-Barrre syndrome
- affects myelin sheath, tends to be more acute and tends to have more motor than sensory sx
- “ascending paralysis”
Diabetic peripheral neuropathy
- many presentations
- Axonal
- mononeuropahty
- autonomic neuropathy
Diabetic peripheral neuropathy epidemiology
- common in DM
- can be presenting sx in occult DM
Diabetic peripheral neuropathy pathophysicology
- nerve infarction or vascular insufficiency
- longer axons first (feet first - hands only after it reaches knees)
- sensory before motor sx
Diabetic peripheral neuropathy clinical presnetation
- stocking glove distribution of numbness and paresthesias
- start: mild weakness of lower legs
- slowly progressive, more in legs than arms
- next: numb feet going up legs, when it reaches knees, hands start
- severe cases reach intercostal nerves and numb over sternum
Diabetic peripheral neuropathy PE
- may see decreased DTRs and impaired vibration before any sx
- found on good lower extremity PE
- mild gait abnormalities (sensory ataxia)
- loss of proprioception and vibration then pinpick and fine touch
- reflexes ab sent starting at ankles
- distal hair loss
- wasting of intrinsic muscles of legs
Diabetic peripheral neuropathy tx
- CONTROL BLOOD SUGAR
- nerve growth factor possibly
Diabetic peripheral neuropathy symptomatic tx
- neuropathic pain sx: tricyclic antidepressants, SSRs, SNRIs, gabapentin or pregabalin
- physical therapy: for splints and assistance devices
Diabetic autonomic neuropathy
- signs of autonomic dysfunction involving cholinergic system
- sx: resting tachycardia, orthostatic hypotension, gastroparesis, erectile dysfunction
