16: Clinical-Electrophysiologic Correlations

Question 1

What defines hyperacute axonal loss? Acute?

Answer 1

Axonal loss lesions less than 3 days old;

more than several days but less than several weeks old

Question 2

What can be seen with isolated proximal demyelinating lesion with focal slowing and conduction block?

Answer 2

Late responses could be abnormal, and reduced recruitment seen

Question 3

What appears with early reinnervation after severe denervation? What do these units resemble?

Answer 3

Nascent MUAP’s;

they appear like myopathic units as they are SDSA and polyphasic

Question 4

What is characteristic of the CMAP amplitudes at rest for presynaptic disorders?

Answer 4

Usually reduced at rest

Question 5

Which NMJ disorder typically has abnormal SA?

Answer 5

Botulism (severe block with muscle fibers effectively denervated)

Question 6

What helps differentiate inherited from acquired demyelinating polyneuropathies?

Answer 6

Absence of conduction block at non-entrapment sites

Question 7

With myotonic dystrophy, which muscles would be affected in type I vs. type II?

Answer 7

Type I = distal muscles;

Type II = proximal muscles

Question 8

What can account for sensory loss with normal SNAPs?

Answer 8

1. Lesion proximal to the dorsal root ganglion
2. Proximal demyelinating lesion
3. Hyperacute axonal loss lesion (<3 days)