神経筋疾患の診断における筋電図と筋生検の意義

DIAGNOSTIC VALUE OF THE ELECT-ROMYOGRAPHY AND THE MUSCLE BIOPSY IN THE NEUROMUSCULAR DISEASES

I．はじめに

　神経筋疾患の診断には筋電図学的検査と筋生険が広く用いられているが，これら検査法の有用性と限界については必ずしもよく理解されていない。また日常の診療において，時に筋電図および筋生検が臨床神経学的診察所見と一致をみない場合があり，これら検査成績を解釈する上で困難を感ずることがある。

　本論文の目的は，われわれの経験による統計的資料から筋電図と筋生検が診断上いかに関与したかを各疾患別に検討し，神経筋疾患の診療の参考にしようとするものである。

Correlation between the clinical diagnosis and the electromyographic and histologic findings was studied on the eighty-five cases of the various neuromuscular diseases.

Among the twenty-six cases of neurogenic mus-cular atrophy, twenty-four cases (92%) were diag-nosed clinically. Electromyographic examinations confirmed the neurogenic disorders in all cases, but the histological findings of the biopsied muscles revealed neurogenic changes in eighteen cases (69%) and non-specific change in the others, indicating that in the diagnosis of the neurogenic disorders the histological approach seems to be limited. It was also noted that in the neurogenic disorders electro-myogram can reveal the abnormalities in the non-atrophied muscles, before the clinical pictures become manifest. Moreover, in the atypical neuro-genic disorders like Kugelberg-Welander disease, these two examinations were significantly helpful.

In the fifty-nine cases of myopathies, fifty-one cases (68%) were diagnosed correctly only through the clinical observations. Electromyographic exami-nations showed myopathic changes in forty-four cases (75%) of all examined, and histological studies confirmed the myopathic findings in forty-five cases (76%). Generally speaking, the definite diagnosis should be based on observation of the clinical course. However, muscle biopsy was found to give the char-acteristic findings as far as myotonic muscular dys-tropy, polymyositis and other rare myopathies are concerned. Amyloidosis of the muscle, for instance, was confirmed by demonstration of the amyloid his-tochemically. In the atypical myopathies like distal type of progressive muscular dystrophy, both me-thods were helpful for the diagnosis of these con-ditions. The electromyographic and histologic find-ings disclosed abnormalities in few cases of thyro-toxic myopathy, and in almost none of periodic paralysis nor myasthenia gravis. In these diseases neither two examinations were very contributory.

The significance of electromyography and muscle biopsy on the diagnosis of the neuromuscular diseases were discussed.