O-3-20. Peripheral sensory nerve conduction disorder in amyotrophic lateral sclerosis

Peripheral sensory nerve involvement is inconspicuous in patients with amyotrophic lateral sclerosis (ALS), while previous reports on the frequency and extent of sensory nerve involvement in ALS are not consistent. We investigated the differences in the peripheral sensory nerve conduction between 160 patients with ALS and 69 control participants. Motor and antidromic sensory nerve conduction studies were conducted for the median, ulnar and sural nerves. In ALS patients, sensory conduction velocity (SCV) was significantly lower in all examined nerves than that in controls. Amplitude of sensory nerve action potential (SNAP) of the sural nerve was significantly lower in patients than in controls. The median/ulnar ratio of SNAP amplitude was significantly lower in patients than in controls, and the median/sural ratio of SNAP amplitude was significantly higher in patients than in controls. SCV and SNAP amplitude in ALS patients showed no significant correlations with disease duration or disease severity. Our findings suggest subclinical loss of the fast conducting sensory nerve fibers or the large dorsal root ganglion cells in ALS. The sural nerve may be the most affected sensory nerve, and the median nerve may be more vulnerable than the ulnar nerve.