The Peripheral Nervous System

Question 1

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

Answer 1

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

Question 2

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

Answer 2

loss of vibration and proprioception
weakness
fasciculations
loss of DTRs

Question 3

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

Answer 3

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)

Question 4

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

Answer 4

Diabetes
Alcohol
Non-alcoholic liver disease
Malignancy

Question 5

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

Answer 5

mononeuropathy multiplex

Question 6

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

Answer 6

only 5%

Question 7

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

Answer 7

c. jejuni

others include HSV, CMV, EBV

Question 8

What are some of the antibodies found in GBS?

Answer 8

most against gangliosides:

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

Question 9

How does GBS present?

Answer 9

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

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

Question 10

How long does GBS usually take to reach its nadir?

Answer 10

usually 2 weeks, but can be up to a month

Question 11

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

Answer 11

Miller-Fisher syndrome

Question 12

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

Answer 12

anti-GQ1b

Question 13

What will you see on CSF analysis in GBS?

Answer 13

albuminocytologic dissociation (high protein but few or no cells)

Question 14

What will early EMG/NCS studies show in GBS?

Answer 14

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

Question 15

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

Answer 15

less than 15 mL/kg

Question 16

What is the treatment for GBS?

Answer 16

IVIg or plasmapheresis are equally effective

IV steroids are not beneficial

Question 17

Describe a typical presentation of chronic inflammatory demyelinating polyneuropathy.

Answer 17

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

Question 18

About 90% of CIDP will respond to what?

Answer 18

steroids, but 50% will relapse afterwards

can also do periodic IVIG with weekly or monthly treatments

Question 19

Describe the typical presentation of multifocal motor neuropathy.

Answer 19

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

Question 20

What antibody is often found in multifocal motor neuropathy?

Answer 20

IgM anti-GM1

Question 21

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

Answer 21

IVIg, rituximab and immunosuppressants

Question 22

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

Answer 22

demyelinating

Question 23

Describe the peripheral neuropathy seen in diabetes.

Answer 23

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

Question 24

Is uremic neuropathy more sensory or motor-predominant?

Answer 24

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

Question 25

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

Answer 25

the neuropathy associated with acute intermittent porphyria

Question 26

What is the most common inherited peripheral neuropathy?

Answer 26

Charcot-Marie-Tooth

Question 27

Describe the typical progression of CMT.

Answer 27

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

Question 28

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

Answer 28

CMT-2 is an axonal motor neuropathy

Question 29

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?

Answer 29

lumbosacral polyradiculoneuropathy

Question 30

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

Answer 30

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

Question 31

What are some features of autonomic neuropathy?

Answer 31

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

Question 32

What is Pandysautonomia?

Answer 32

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