側頭葉～中頭蓋窩に囊胞性病変を伴った側頭葉てんかん

Temporal Lobe Epilepsy Associated with Cystic Lesion in the Temporal Lobe and Middle Cranial Fossa

　要旨　1994年9月から2002年10月の間に，52例の側頭葉てんかん患者に外科的治療を行ったが，うち4例は側頭葉～中頭蓋窩に囊胞性病変を伴っていた。症例1は下側頭回に脳内血腫後の囊胞があり，慢性硬膜下電極記録の結果，囊胞と同側の側頭葉内側部に発作起始域が同定された。症例2は側頭葉先端部に囊胞性腫瘍（ganglioglioma）があり，術中皮質電位記録で囊胞周囲皮質と側頭葉内側部に非同期性に突発性異常波が頻発していることが明らかとなり，2症例とも囊胞・周囲皮質と側頭葉内側部を切除し，発作は消失した。症例3，4は中頭蓋窩くも膜囊胞を伴っていたが，慢性硬膜下電極記録の結果，症例3はmicrodysgenesisが存在したくも膜囊胞とは離れた同側下側頭回，症例4は海馬硬化のあった対側側頭葉内側部に発作起始域が同定され，同部の切除で発作コントロールは容易となった。側頭葉てんかんの発現に髄外囊胞はほとんど関与していないが，脳内囊胞は周囲皮質への圧迫や刺激だけではなく，海馬との生理学的な関係，すなわちkindling現象やsecondary epileptogenesisなど複雑な病態が関与している可能性があり，外科的治療に際しては慢性硬膜下電極記録を含む統合的な術前検査が必要である。

Four patients out of 52 patients with temporal lobe epilepsy （TLE）, who underwent epilepsy surgery in our hospital since September of 1994, had cystic lesions in the temporal lobe and middle cranial fossa. Case 1 had old hematoma cavity in the inferior temporal gyrus and chronic subdural electrode recording revealed the ictal onset zone to be localized in the ipsilateral medial temporal region. Case 2 had cystic ganglioglioma in the temporal tip, and intraoperative electrocorticography demonstrated independent paroxysmal activities from medial temporal region and temporal tip near the cyst. Both area were resected and the patients became seizure free. Case 3 and 4 had arachnoid cysts in the middle cranial fossa. Chronic subdural electrode recording revealed that the ictal onset zone was localized in the ipsilateral inferior temporal gyrus （that had microdysgenesis） in Case 3 and contralateral medial temporal region （that had hippocampal sclerosis） in Case 4, respectively. These finding suggest that co-existence of extra-axial cyst such as Case 3 and 4 is incidental and that arachnoid cyst is less epileptogenic. However, intra-axial cyst such as Case 1 and 2 is epileptogenic and complicated physiological mechanism such as kindling phenomenon or secondary epileptogenesis may effect on the hippocampus. Comprehensive presurgical evaluation including electrocorticography is needed in the surgical treatment of TLE with cystic lesion.