水俣病及びその他2, 3の神経疾患の筋電図所見

ELECTROMYOGRAMS OF "MINAMATA DISEASE" AND OTHER NERVOUS DISEASES

　熊本県水俣地方に発生した原因不明の神経疾患，すなはち水俣病（Minamata disease）及びその他2, 3の神経病患者について，筋電図検査を行い，比較考察を加えて見たので報告する。

　水俣病の臨床症状及び病理学的所見については，すでに報告^1）−7）せられ，また病因に関しても目下検索が進められているが，ある種の重金属による中毒に疑いを持たれている。患者は，まず手足のシビレ感を訴え，間もなく小脳性失調の諸症状，視野狭窄及び難聴等があらわれ，亜急性乃至慢性の経過をとるのであるが，各症例の主要な神経学的症状については第1表に示した。その内で特徴的なことは，日常動作，例えばボタンをはめるとか，マツチを擦るという動作の失調がすべての例に見られ，知覚障害は，触覚鈍麻が比較的早く回復しても，2点識別，物の識別，或いは振動感覚等の障害が長く残存する傾向にある。

Electromyographic studies of 5 patients afflicted with a special type of nervous dise-ases, which has been found in Minamata City of Kumamoto Prefecture and commonly called "Minamata disease", were made and following results were obtained.

1. Irregular fluctuations of discharge inter vals of neuromuscular units are increased during voluntary contraction of M. tibialis anterior (Case No.1)

2. After every two discharges during the activity of M. tibialis anterior (Case No. 2), a spike discharge is sometimes lost, or the discharge interval is doubled.

3. A slow undulation of the soleus muscle at standing posture of the patients (Case No.3 and No. 4) is more prominent than that found in normal person.

4. Analyses of the grouping voltages recored from arm muscles of a patient (Case No. 5) show that this special type of impulse dis-charge is likely to be originated from distur-bance in cerebral function.

5. These varying features of the electrom-yogram of this disease are different from such nervous diseases as amyotrophic lateral scle-rosis and spinal ataxia, and they may suggest that various parts of the central nervous system is injured in the Minamata disease.