Abstract
In the case of unilateral muscular atrophy of upper limb there are several causes. These include Hirayama disease, SPMA and Syringomyelia.
We would like to illustrate one of these diseases with a 29 year old female who had Syringomyelia. She complained of left hand muscle atrophy with minor disturbance.
SNAP and SCV of bilateral ulnar and median nerve were normal.
MCV of bilateral ulnar nerve was normal, but amplitude of M wave of left hypothenar was diminished.
Normal MCV with low amplitude of M wave showed large α-motorneuron and loss of same α-motorneuron.
In the case of Hirayama disease, amplitude of M wave was decreased with slow MCV.
Slow MCV with low amplitude meant loss of α-motorneuron.
We think a diminished mechanism of α-motorneuron in this case is different from the Hirayama disease.
