特殊な臨床経過をとる脳幹脳炎の存在について—散発性原発性非定型脳炎に関する一問題

A FORM OF ENCEPHALITIS LOCALIZED IN THE BRAIN STEM

I．まえがき

　最近神経病理学の重要な課題のひとつとして非定型脳炎の検討がさかんに行なわれるようになつた^1）。多くの報告例のうち，封入体脳炎（Dawson）亜急性硬化性白質脳炎（van Bogaert），全脳脳炎（Pette-Döring）の3者には一応その分類上の位置が与えられている。またこの3者の相互関係についての考察も広く行なわれ，一方Krücke^2） Haymaker^3）らのHerpes-simplex-virusによる脳炎の検討は非定型脳炎の原因に基づく分類の可能性を示すようになつた。非定型脳炎の病理や臨床についての整理もしだいに行なわれるようになつている。この場合問題となるのは，しだいに報告例が増してみると，上述の3病型は非定型脳炎のうちごく一部分を占めるにすぎず，多くの原因不明でさまざまの臨床経過や病理所見を示す脳炎の症例が存在することである。

　この論文でとりあげる症例も，臨床経過および病理所見上特有の特徴を示し，特殊な非定型脳炎の一群と考えられるものである。私はすでに本症例について簡単に言及したが，ここにやや詳細に問題点を述べることとする。

Three cases of encephalitis are reported, which showed not only peculiar clinical pictu-res, but also some specific pathological find-ings quite different from those of so-called atypical encephalitides.

The patients were all adults. Though the course of the disease is slow and progressive in general, there was also some difinite remis-sion.

Neurological manifestations of this disease are also characteristic. They all showed isola-ted pyramidal tract signs with bulbar symp-toms, without any extra-pyramidal manifesta-tions. Epileptic seizures or involuntary move-ments were not observed in any of three pa-tients. Intelligence seemed well preserved, with minimum psychiatric symptoms.

Cerebrospinal fluid examination revealed moderate pleocytosis and slight elevation of total protein content.

Neuropathological findings were fairly uni-form in all cases. They were found mainly in the brain stem, most marked in the medul-la and pons with some extension up to the hypothalamus and to the cervical cord down-wards. In the cerebral hemispheres, no abnor-mities were found except slight change in the hippocamus and the undersurface of the temporal lobes. There was no tendency for the gray matter to be more severely involved than the white matter.

Microscopic examination showed marked perivascular infiltration of round cells and many glial nodules. "Neuronophagia" was not found. In the brain stem and in the spinal cord, there were fairly well established seco-ndary degenerative processes.

The pathological findings and clinical pict-ure above noted are quite different from those of atypical encephalitides which have previously been reported, and the author would like to propose calling this type of atypical encephalitis "Brain stem encephalitis".