Peripheral neuropathy

Question 1

Negative sensory symptoms

Answer 1

numbness, hypoesthesia

Question 2

positive sensory problems

Answer 2

spontaneous pain: parasthesias, burning pain, shock-like pain
Evoked pain: allodynia (normally non-painful), hyperalgesia (normally painful stimuli)
often worse at night

Question 3

motor neuron lesion pattern

Answer 3

Distal weakness (axonal)
UMN: increased reflexes and tone
LMN: decreased reflexes and tone, atrophy

Question 4

Patterns of peripheral nerve damage

Answer 4

Stocking/glove distribution
Dermatomal
Peripheral nerve pattern

Question 5

Loss of reflexes

Answer 5

axonal: absent ankle jerks, usually most indolent
Demyelinating: all reduced or absent

Question 6

Axonal peripheral neuropathy

Answer 6

length dependent - longest/thinnest nerves die first (stocking and glove distribution)
Slowly progressive
Sensory > motor unless severehhyy
loss of ankle jerks
e.g. Diabetic neuropat

Question 7

Demyelinating peripheral neuropat

Answer 7

arms and legs
Rapid (if acquired, usually autoimmune and rapid)
Motor and sensory
Areflexia
e.g. GBS

Question 8

Peripheral neuropathy diagnostic studies

Answer 8

Hx/PE
Blood: glucose, TSH, CBC, renal/liver, B12, VDRL, HIV, Lyme, Connective tissue screen, serum immunoelectrophoresis
EMG/NCS
Lumbar puncture: less common, unless demyelinating
Heavy metal analysis
Nerve biopsy (vasculitis/amyloidosis) - avoid if possible, 1% risk of nerve pain

Question 9

Metabolic peripheral neuropathy characteristics

Answer 9

Sensory> motor (PNSS common)
Distal, symmetric
Gradual onset
Risk factors/diseases/exposure
DDx: diabetes, uremic neuropathy, alcoholism, B12/B1 deficiency, meds

Question 10

Immune peripheral neuropathy characteristics

Answer 10

Most often sensorimotor (PNSS common)
not distal, symmetric
not insidious (definite date of onset)
symptoms of vasculitis/systemic 
DDx: non-vasculitic: GBS, CIDP, sarcoidosis; vasculitic

Question 11

Neoplastic peripheral neuropathy characteristics

Answer 11

Most often sensorimotor (PNSS common)
Not distal, symmetric
not insidious
Symptoms of cancer/paraprotenemia
DDx: Paraneoplastic, paraproteinemic

Question 12

Infectious peripheral neuropathy characteristics

Answer 12

Most often sensorimotor (PNSS common)
Not distal, symmetric
Not insidious
Symptoms/risks for infection?
DDx: Hep C, Lyme, HIV, Sarcoidosis, West Nile, Syphilis

Question 13

Ulnar neuropathy risk factors

Answer 13

Renal disease: uremic neuropathy

pressure on arm rest at ulnar groove

Question 14

GBS etiology

Answer 14

acute rapidly evolving polyneuropathy
often starts in distal lower limbs and ascends
AI attack and damage to peripheral nerve myelin
Sometimes preceded by bacterial/viral infections (most commonly C. jejuni)

Question 15

GBS signs and symptoms

Answer 15

Sensory: distal and symmetric paresthesias, loss of proprioception and vibration sense, neuropathic pain
Motor: Weakness starting distally in legs, areflexia
Autonomic: BP dysregulation, arrythmias, bladder dysfunction

Question 16

GBS Investigations

Answer 16

CSF: albuminocytological dissociation (high protein, normal WBC)
EMG/NCS: conduction block, differential or focal (motor> sensory) slowing, decreased F wave, sural sparing

Question 17

GBS subtypes

Answer 17

Acute inflammatory demyelinating polyneuropathy
Acute motor-sensory axonal neuropathy
Acute motor axonal neuropathy

Question 18

GBS Tx

Answer 18

IVIG or plasmapheresis, +/- pain management, monitor vitals and vital capacity

Question 19

GBS Prognosis

Answer 19

Peak of symptoms at 2-3 weeks, resolution at 4-6
5% mortality
up to 15% have permanent deficits

Question 20

GBS Pathophysiology

Answer 20

Attack on myelinated PN fibers
Myelinated axons:
- motor neurons
- Ia afferent sensory carrying vibration and positions sense
- preganglionic autonomic fibers

Question 21

GBS classical presentation

Answer 21

Acute weakness –> most peak by 2 weeks, but stabilization by 3-4 weeks
Usually bilateral and symmetric weakness
Axial and radicular pain in 50%
hypo/areflexia
Sensory symptoms prominent but fewer sensory signs
Autonomic involvemetn common
25% remain ambulatory
25% of non-ambulatory require ventilation
CN involvement in 70% (facial most common)
Autonomic involvement in 70%

Question 22

Atypical features for GBS

Answer 22

Severe pulmonary dysfunction with limited limb weakness at onset
Severe sensory signs with limited weakness at onset
Bladder or bowel dysfunction at onset
Fever at onset
Sharp sensory level
Slow progression with limited weakness without respiratory involvement (consider subacute inflammatory demyelinating polyneuropathy or CIDP)
marked persistent asymmetry of weakness
Persistent bladder/bowel dysfunction
Increased number of mononuclear cells in CSF
PMN in CSF

Question 23

GBS Variants

Answer 23

Miller Fisher: triad of ataxia, areflexia, ophthalmoplegia
AMAN: acute motor axonal, good prognosis
Acute sensory variant: sensory roots and DRG only
Acute autonomic ganglionopathy
Axonal variant

Question 24

Immune response in GBS

Answer 24

1/2 patients have serum antibodies to PN gangliosides
GM1 and GM1b Ab associated with AMAN and other axonal variants
GQ1b antibodies seen in 85% of CMF variant
molecular mimicry

Question 25

GBS diagnostics

Answer 25

lumbar puncture CSF - protein elevated by end of 2nd week, 80%
CSF pleocytosis ATYPICAL - look for other infections (HIV, West Nile, CMV, polio)