The Peripheral Nervous System Flashcards
What are the signs/symptoms of a peripheral neuropathy affecting the SMALL nerve fibers?
neuropathic pain
disturbed temperature sensation
autonomic dysfunction (arrhythmias, othostatic hypotension, impotence, incontinence, constipation)
What are the signs/symptoms of a peripheral neuropathy affecting the LARGE nerve fibers?
loss of vibration and proprioception
weakness
fasciculations
loss of DTRs
What are some of the common causes of peripheral neuropathies? Mnemonic: VITAMINS
Vitamin deficiency/Vasculitis
Infections (TB, Leprosy)
Toxic (amiodarone, lead, vincristine, chemo)
Amyloid
Metabolic (alcohol, diabetes, porphyria, hyperthyroidism, liver and renal failure)
Idiopathic/Inherited
Neoplasm
Systemic (SLE, polyarteritis nodosa, multiple myeloma)
What are the 4 most common causes of peripheral neuropathy in order?
Diabetes
Alcohol
Non-alcoholic liver disease
Malignancy
What’s the term for a neuropathy that involves several individual nerves in a multifocal distribution?
mononeuropathy multiplex
What is the mortality rate for GBS (Acute inflammatory demyelinating polyneuropathy)?
only 5%
20% of GBS cases in the US are preceded by infection with what?
c. jejuni
others include HSV, CMV, EBV
What are some of the antibodies found in GBS?
most against gangliosides:
anti-GM1 (poor prognostic indicator)
anti-GD1a
anti-GQ1b
anti-GD1b
How does GBS present?
rapidly evolving, ascending areflexic motor paralysis with or without sensory disturbances
often starts with tingling in the feet or with lower back pain
How long does GBS usually take to reach its nadir?
usually 2 weeks, but can be up to a month
There is a variant of GBS associated with fait ataxia, areflexia and external opthalmoplegia, usually without limb weakness. What’s this one called?
Miller-Fisher syndrome
What antibody is positive in 90% of Miller-Fisher cases?
anti-GQ1b
What will you see on CSF analysis in GBS?
albuminocytologic dissociation (high protein but few or no cells)
What will early EMG/NCS studies show in GBS?
prolonged distal latencies
variably prolonged or absent F waves
possible conduction block
decreased motor unit recruitment
Because of the potential for diaphragm involvement, patients are tracked with FVCs. An FVC below what would make you plan to intubate?
less than 15 mL/kg