無動性無言症—両側視床内側部に限局性軟化巣を有した症例

A CASE OF AKINETIC MUTISM: ASSOCIATED WITH WELL LOCALIZED SOFTENING OF BILATERAL MEDIAL THALAMI

はじめに

　特殊な意識障害といわれるAkinetic Mutism （AM）は1941年Cairns^1）らによつて報告されて以来，しばしばKretschmer^2）の失外套症候群と対比して論じられているが，発生機序より考えて，3つの型があると考えられる^3）。すなわち，1）前頭葉性，2）間脳性，3）大脳の全般性障害である。

　今回，われわれは間脳性無動性無言に属すると思われる脳血管障害の1例を経験したのでここに報告する。

A case of akinetic mutism associated with soften-ing of the bilateral medial thalami is reported.

The patient was a 67-year-old female with a chief complaint of tonic clonic convulsion, followed by disturbance of consciousness. The patient's condition had been aggravated by multiple pul-monary infections and merged into typical akinetic mutism.

Autopsy disclosed well circumscribed small cystic encephalomalacias in the mesial aspect of the thalamus and the anterior part of the corpus cal-losum. A large cystic encephalomalacia occupiedthe right visual cortex; the right posterior cerebral artery was occluded and recannalized.

On microscopic examination, diffuse loss of neu-rons was observed in both dorsomedial nuclei, anterior nuclei and the right pulvinar. The nucleus centrum medianum was intact bilaterally. Though the posterior part of the floor of the third ventricle was slightly damaged, the periaqeductal gray was completely preserved.

The case presented here gives rise typical fea-tures of mesencephalic akinetic mutism but dis-tribution of the lesions is somewhat different from those of cases reported before; most of which had their main lesions in the hypothalamo-mesenceph-alic junction instead of the dorsal thalamus. It is well known that the dorsomedial nucleus and the anterior nuclear group have many connections with the frontal lobe, especially the cingulate gyrus, which is one of the most important regions in akinetic mutism of frontal origin. Therefore, it is reasonable that destruction of both anterior and dorsomedial nuclei can produce akinetic mutism. It is noteworthy to mention that the hypotha-lamomesencephalic junction is not an only part, lesions of which cause akinetic mutism of mes-encephalic origin.