てんかん重積に伴う拡散強調MRI画像の可逆的変化

Transient Abnormalities Associated with Status Epilepticus on Diffusion-weighted MR Imaging

　要旨　てんかん重積に伴う拡散強調画像（DWI）の可逆的な異常所見を認めた2症例について報告した。いずれも局所症状出現後に痙攣発作が明らかとなりMRIが施行された。DWIの高信号は大脳皮質および皮質下白質を中心とし，血管支配に一致せず可逆的であった。T2WIおよびFLAIRでも同部位の可逆的な高信号と脳回の腫大を認めたが，一部永続的な病変も残存した。さらに造影T1WIでは髄膜の増強効果がみられ，MR angiographyでは患側中大脳動脈の可逆的な拡張を認めた。異常信号の病態は細胞性および血管性浮腫の混在であり，急性期脳梗塞をはじめとする他疾患との鑑別において常に念頭におくべき病態である。

　We report on two patients with transient abnormalities on MRI during status epilepticus（SE）. Diffusion-weighted MR imaging（DWI） and T2-weighted and fluid-attenuated inversion recovery（FLAIR） MR images showed cortical and thalamic hyperintensity with swelling of the cortex. The lesions did not respect vascular territories. We also observed an increased signal in the ipsilateral middle cerebral artery on magnetic resonance angiography（MRA）, and leptomeningeal enhancement on postcontrast MRI. Follow-up imaging revealed that the abnormal findings resolved within a few weeks, although a residual area of increased T2 signal intensity persisted. These findings suggest the presence of reversible cytotoxic and vasogenic edema induced by seizure.

　We conclude that this disorder should be taken into consideration in the differential diagnosis of other conditions, including ischemic stroke.

（Received : August 26, 2003）