Inherited Polyneuropathies

Question 1

Describe Acute Intermittent Porphyia

Answer 1

defect in hepatic heme synthesis
Clinical- ABD pain and vomiting, weakness axial> distal mms and PROX sensory loss, peripheral neuropathy and seizures
EMG= fibs proximal mms, decrease CMAP, normal NCV

Question 2

Describe Friedreich’s Ataxia

Answer 2

Affects dorsal column and spinocerebellar tracts, lose large fibers with preservation of unmyelinated fibers
Clinical- limb and trunk ataxia, loss of joint and position sense, areflexia, lose ambulation
EMG- decrease or no SNAPs, decrease VEPs, CMAP normal

Question 3

Describe Fabrys Disease

Answer 3

‘Fire’ axonal degeneration of small fibers from lipid deposits
Clinical: severe burning pain of hands and feet, normal EMG

Question 4

Describe Lipoprotein Neuropathies

Answer 4

Loss of large fibers and paranodal demyelination
Clinical- decreased reflexes and loss of position/vibration sense
EMG- decrease SNAP, fibs, myotonic D/Cs, Large MUPs with decrease recruit, normal CMAP

Question 5

Describe CMT III/Dejernes Sotta/Hypertrophic Polyneuropathy/HSMN Type III

Answer 5

Segmental demyelination, hypertrophic nerves; onion bulb formation
Decreased NCV motor and sensory

Question 6

Describe CMT IV/Refsum’s Diease/Herditary Ataxic Neuropathy (HSMN IV)

Answer 6

Changes in PNS, AHC and cerebellar tracts
Clinical- deafness, night blindness, decrease reflex vibration, position sense, lightening pain in legs and mm wasting
EMG- mildly prolonged with low amp SNAP

Question 7

CMT V/Spinocerebellar degeneration with neuropathy (HSMN V)

Answer 7

Decreased # myelinated fibers; normal # unmyelinated fibers
Clinical- +Babinski, distal wasting legs>arms, no AJ (axonal)
EMG- low amp SNAPs