脳幹部腫瘍の1剖検例—脳波および病理学的検討

AN AUTOPSY CASE OF BRAIN STEM TUMORS:EEG ANALYSIS AND PATHOLOGICAL FINDINGS

はじめに

　後頭蓋窩腫瘍の脳波所見に関してはBerger^1）以来多数の報告があり^{2）3）4）5）6）7）}一般に前頭部あるいは後頭部に両側同期性の徐波がburst-likeに出現することが多い。その機序として髄液の通過障害による脳圧充進，特に視床付近に影響をおよぼす第III脳室内圧亢進との関係^8），腫瘍の直接圧迫による脳幹網様体の障害，あるいは脳皮質の浮腫による影響などが考えられる。脳幹部腫瘍では前頭部両側性のθ波のほか比較的monorhythmicなδ波が両側性にみられることが多く^9）臨床症状とは必ずしも平行しないが経過とともに脳波は増悪するのが普通である。

　後頭蓋窩腫瘍の局在と脳波との関連については報告者によつて異なり未だ一定していない。1940年Smith^10）が異常脳波のlateralityは腫瘍と同側に偏在すると報告した。Rheinberger^11）らは23例について異常脳波の現われた側とtumorの存在する側との関連は認められないことを述べ，Dow^12）は51例で特有なfocal signはなかつたと述べている。Bagchi^13）は50例中30例にcontralateral dominanceがみられたといい，川口^7）は片側性脳幹部腫瘍5例中3例が同側性に優勢であつたと述べ，また村松^5）はdelta focusの出現はその部位と関連して意義があると考えている。

A case of brain stem tumor showing unusual electroencephalographic findings was reported.

A 17-year-old boy first noted weakness of the left forearm in the middle of June, 1969. From that time, gradually the left upper, left lower and right lower limb were involved and finally bulbar muscles were involved within five months.

The EEG was first recorded one month after the onset of the initial symptom and showed theta and delta wave bursts in the front-central areas, more dominant on the right side. The EEG re-examined six days and one month after the first one showed the similar pattern to the first. At that time, the site of lesion was suspected to be in the right cerebral hemisphere, but right carotid angiogram showed no abnormality.

From the end of Sept. 1969, he complained of dysphagia. The neurologic examination disclosed pyramidal signs in the left upper and bilateral low limbs, horizotal nystagmus, dysphagia and slight nuchal rigidity. On the November, 10 days before his death, EEG improved markedly and was almost normal.

On autopy, main lesion was located in the medulla oblongata with glioblastoma multiforme, and tumor was expanded from the corpus callosum to the third cervical cord. It is noteworthy that the site of lesion is more dominant on the right side except corpus callosum.

The relationship between the site of the lesion in the posterior fossa tumors and laterality on EEG is inconsistent. Smith reported ipsilateral domin-ance on EEG changes in posterior fossa turners in 1940.

The last EEG turned to normal due to the ex-pansion to the lower brain stern, in particular, the lower pontine of which inhibitory system to be destroyed.