Peripheral Neuropathies Flashcards
Examples of pain/temp small fiber pathologies
DM
Leprosy
amyloidosis
Examples of proprioception/vibration fiber pathologies
Vit B12 deficiency
DM
Hereditable
Examples of motor fiber pathologies
Immune-related (Guillan-Barre)
Lead toxicity
Acute intermittent porphyria
Inherited disorders
Examples of autonomic fiber pathologies
Amyloid DM Sjogren's Botulism Amiodarone
Sx and PE of pain/temp fiber damage
pain, burning, shock-like, stabbing, dysesthesias, allodynia, paresthesias
PE: decreased response to painful stimuli (pin prick), decreased temp sensation (light touch)
Sx and PE of proprioception/vibration fiber damage
numbness, pins & needles, poor balance
PE: decreased proprioception and vibration (joint position sense); diminished DTRs
Sx and PE of motor fiber damage
cramps, weak grip, foot drop, fasciculations
PE: weakness, diminished DTRs
Autonomic nerve damage sx and PE
lightheaded, dry eyes/mouth, abnormal sweating, erectile dysfxn
PE: orthostasis, anisocoria (unequal pupils)
Location of peripheral neuropathies
outside brain and spinal cord
Which cranial nerves are involved in peripheral neuropathy?
all cranial nerves except I and II
Most common causes in U.S.? worldwide?
US: DM and alcohol
worldwide: leprosy
Most common presentation of peripheral neuropathy?
distal symmetric sensorimotor dysfxn
How are PN categorized by pattern of involvement?
- mononeuropathy = single nerve and its innervation
- Multiple mononeuropathy = multiple indiv peripheral nerves
- Polyneuropathy = widespread distribution
symmetric vs asymmetric, distal vs proximal
Likely cause of mononeuropathy
compression, trauma, vascular cause
common distribution of polyneuropathies
“stocking-glove distribution”
How are PN categorized by time course?
acute: toxic or inflamm
subacute: chemo, lead
chronic: DM, Charcott-Marie-Tooth
recurrent: Guillan-Barre, HIV
How are PN categorized?
Location
Time course
Fiber type
Axonal or Demyelinating
Common example of demyelinating disease
MS
axonal neuropathy
neuropathy with axonal and myelin sheath degeneration DISTAL to injury (Wallerian degeneration)
Common mononeuropathies
median neuritis, radial neuritis, ulnar neuritis, peroneal neuritis
Hypothesis for why so many diabetics get neuropathy?
direct axonal loss and demyelination secondary to hyperglycemia OR insufficient blood flow in vaso nervorium
Most common diabetic neuropathy
diabetic sensorimotor polyneuropathy (DSPN)
Complications of diabetic neuropathy
foot ulcers, Charcot joint
Where nerve fibers affected in DSPN?
mixed with small and large fibers, sensory, motor, and autonomic
sensory and autonomic»_space; motor
symptoms of DSPN
initially distal: numbness/tingling, burning of toes/feet
progresses to proximal: up leg and to hands (“stocking-glove”)
later: gait disturbances, distal motor weakness
PE of diabetic neuropathy
Distal sensory loss of pain, temp, touch, vibration
Reduced DTRs at ankle
What are signs of autonomic fiber involvement?
impotence, nocturnal diarrhea, difficulty voiding, abnormal sweating, orthostatic hypotension
Asymmetric Diabetic Neuropathy
- occurs in older puts who already have DSPN
- involves CN VI, III, and sometimes IV (abrupt onset d/t acute ischemia)
- radiculopathies, limb mononeuropathies
CN VI palsy affects on vision
painless double vision (diplopia)
Tx of diabetic neuropathy
- Strict glycemic control
- Tricyclics or gabapentin for pain
- Most recover over months
“length dependent” neuropathy
longest nerves affected first
How is asymmetric diabetic neuropathy different from typical DSPN?
Asymmetric
Acute
Cranial nerves affected
Cause of asymmetric diabetic neuropathy
acute ischemia
signs/sx and tx of uremic neuropathy
- Distal symmetric sensoriomotor polyneuropathy
- stocking-glove distributions, distal motor weakness, restless leg syndrome
- tx: dialysis, renal transplant
Examples of infection related neuropathies
Bell's Palsy Lyme Disease Herpes Zoster (shingles) Cytomegalic Virus (CMV) in HIV Symmetric Distal Polyneuropathy associated with AIDS
Bell’s Palsy is paresis of _____ nerve and associated with _____ infection.
CN VII (facial) herpes simplex virus
How would Bell’s Palsy be classified?
acute mononeuropathy
How do you differentiate Bell’s Palsy from stroke?
Stroke patient can still wrinkle forehead, only lower face affected
Bell’s Palsy affects upper and lower face
Signs/Sx of Bell’s Palsy
UNILATERAL paresis
corner of mouth droops, no nasolabial fold, forehead unfurrowed, can’t close eyelids
SENSORY INTACT
Bell’s Palsy management
80% recover within weeks to months w/ or w/o treatment
May give steroids or Acyclovir
Ramsay Hunt Syndrome
may present as Bell’s Palsy; so must rule Ramsay out!!!
shingles of CN VII with vesicular rash in external canal/pharynx
shingles caused by what virus?
Herpes Zoster in adults
signs of shingles?
vesicular painful rash in dermatomal distribution
Postherpetic neuralgia
persistent pain following shingles that can last years
Shingles treatment
Tricyclics
Gabapentin
Pain meds
Lyme disease caused by what organism?
Borrelia burgdoferi in ticks
CMV infections often associated with ______.
HIV/AIDS
All dying from AIDS with have what neuropathy?
symmetric distal polyneuropathy
Different causes of toxic neuropathies
drugs (chemo), heavy metals (lead), industrial compounds, alcohol
Chelation therapy
used to treat heavy metal toxic neuropathy
______ to prevent and treat isoniazid (INH) neurotoxicity.
pyridoxine (B6)
Vitamin deficiencies that result in neuropathies?
Thiamine B1, Pyridoxine B6, Vit B12, Vit E
Most common inherited neuromuscular disease that is also an inherited neuropathy
Charcot Marie-Tooth
Categorization of Charcot Marie-Tooth
Chronic distal sensory and motor neuropathy which develops over years
Signs/Sx of Charcot Marie-Tooth
long standing gait difficulties, h/o being “unathletic” child; mostly LE but progresses hands
PE: wasted leg muscles, weakness, hammer toes, distal sensory loss and loss of DTRs
Autoimmune acute inflammatory demyelinating polyneuropathy
Guillan-Barre Syndrome
Clinical signs of Guillan-Barre Syndrome
- Rapidly evolving motor paralysis with areflexia
- Ascending paralysis over hrs to days
- C/O “rubbery legs”
- DTRs disappear in days
- Autonomic instability
CSF findings of Guillan-Barre Syndrome
typically normal at disease presentation; after 7-14 days- elevated protein, normal glucose, no pleocytosis
Guillan-Barre Syndrome management
85% achieve full recovery within several months to a year; treat ASAP
tx: plasmapheresis or IV immune globulins
supportive: 30% need intubation, trach, or mechanical ventilation
Symptoms of trigeminal neuralgia
- episodes of electric (lancinating) shock pain in CN V innervation
- pain so intense they wince (“tic”)
- single jabs or cluster of pain in “trigger zone”
- no sensory loss
Who is most likely to be affected by trigeminal neuralgia?
F > M
middle aged/elderly
Trigeminal neuralgia treatment
Carbamazepine or phenytoin
Surgery if fail med therapy
