The Peripheral Nervous System Flashcards

1
Q

What are the signs/symptoms of a peripheral neuropathy affecting the SMALL nerve fibers?

A

neuropathic pain
disturbed temperature sensation
autonomic dysfunction (arrhythmias, othostatic hypotension, impotence, incontinence, constipation)

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2
Q

What are the signs/symptoms of a peripheral neuropathy affecting the LARGE nerve fibers?

A

loss of vibration and proprioception
weakness
fasciculations
loss of DTRs

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3
Q

What are some of the common causes of peripheral neuropathies? Mnemonic: VITAMINS

A

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)

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4
Q

What are the 4 most common causes of peripheral neuropathy in order?

A

Diabetes
Alcohol
Non-alcoholic liver disease
Malignancy

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5
Q

What’s the term for a neuropathy that involves several individual nerves in a multifocal distribution?

A

mononeuropathy multiplex

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6
Q

What is the mortality rate for GBS (Acute inflammatory demyelinating polyneuropathy)?

A

only 5%

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7
Q

20% of GBS cases in the US are preceded by infection with what?

A

c. jejuni

others include HSV, CMV, EBV

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8
Q

What are some of the antibodies found in GBS?

A

most against gangliosides:

anti-GM1 (poor prognostic indicator)
anti-GD1a
anti-GQ1b
anti-GD1b

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9
Q

How does GBS present?

A

rapidly evolving, ascending areflexic motor paralysis with or without sensory disturbances

often starts with tingling in the feet or with lower back pain

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10
Q

How long does GBS usually take to reach its nadir?

A

usually 2 weeks, but can be up to a month

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11
Q

There is a variant of GBS associated with fait ataxia, areflexia and external opthalmoplegia, usually without limb weakness. What’s this one called?

A

Miller-Fisher syndrome

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12
Q

What antibody is positive in 90% of Miller-Fisher cases?

A

anti-GQ1b

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13
Q

What will you see on CSF analysis in GBS?

A

albuminocytologic dissociation (high protein but few or no cells)

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14
Q

What will early EMG/NCS studies show in GBS?

A

prolonged distal latencies
variably prolonged or absent F waves
possible conduction block
decreased motor unit recruitment

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15
Q

Because of the potential for diaphragm involvement, patients are tracked with FVCs. An FVC below what would make you plan to intubate?

A

less than 15 mL/kg

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16
Q

What is the treatment for GBS?

A

IVIg or plasmapheresis are equally effective

IV steroids are not beneficial

17
Q

Describe a typical presentation of chronic inflammatory demyelinating polyneuropathy.

A

It’s basically chronic GBS

it’s a slowly evolving weakness beginning in the legs with widespread areflexia and loss o vibratory sense (so a large fiber issue)
weakness of neck flexors often present
can have painful paresthesias

they tend to have a chronic course with many relapses

18
Q

About 90% of CIDP will respond to what?

A

steroids, but 50% will relapse afterwards

can also do periodic IVIG with weekly or monthly treatments

19
Q

Describe the typical presentation of multifocal motor neuropathy.

A

it’s pure-motor multiple mononeuropathy; usually presents with a slowly progressive, asymmetric, predominantly distal limb weakness usually beginning in the arms

you get weakness developing in the distribution of individual nerves instead of following a spinal myotome

20
Q

What antibody is often found in multifocal motor neuropathy?

A

IgM anti-GM1

21
Q

It’s important to distinguish multifocal motor neuropathy from typical motor neuron diseases because MMN will respond will to what treatment regimen?

A

IVIg, rituximab and immunosuppressants

22
Q

Is the neuropathy associated with monoclonal gammopathies (multiple myeloma, amyloid, macroglobulinemia, lymphoma, etc) primarily demyelinating or axonal?

A

demyelinating

23
Q

Describe the peripheral neuropathy seen in diabetes.

A

Usually a distal, symmetric, slowly progressive sensory loss in the legs (stocking distribution beginning in the toes and feet before the hands)

autonomic insufficiency is an important feature

weakness is a late feature

24
Q

Is uremic neuropathy more sensory or motor-predominant?

A

More motor predominant - foot drop and leg weakness are common features

25
Q

What is the diagnosis if someone has an acute or subacute sensorimotor peripheral neuropathy that mimicks GBS with abdominal pain?

A

the neuropathy associated with acute intermittent porphyria

26
Q

What is the most common inherited peripheral neuropathy?

A

Charcot-Marie-Tooth

27
Q

Describe the typical progression of CMT.

A

Usually adolescents with symmetric, slowly progressive distal muscular atrophy of the legs and feet, eventually involging the hands

hammer toes and pes cavus are common

28
Q

Most of the CMTs are primarily demyelinating, except which one?

A

CMT-2 is an axonal motor neuropathy

29
Q

What’s the diagnosis in an HIV patient with a CMV infection who presents with rapidly progressive flaccid paraperesis, sphincter dysfunction, perineal sensory loss, and lower limb areflexia?

A

lumbosacral polyradiculoneuropathy

30
Q

Leprosy is one of the most common causes of neuropathy world-wide. What are the clinical features of the neuropathy?

A

usually mononeuropathy multiplex with a predilection for cooler areas of the body like the nose, ears or distal limbs

DTRs usually preserved

NERVE HYPERTROPHY that can be palpated

31
Q

What are some features of autonomic neuropathy?

A

orthostatic hypotension, diarrhea, constipation, early satiety, tachycardia or palpitations, blurred vision, urinary retention, and erectile dysfunction

32
Q

What is Pandysautonomia?

A

it’s an acquired autonomic neuropathy, usually immune in nature following a viral illness in which both the sympathetic and parasympathetic nervous systems are affected