山梨医科大学雑誌　第8巻2号　065-071(1993)

＜症例報告＞光過敏性てんかんの経過中に小児欠神てんかんを合併した1女児例

畠山和男，相原正男，日野原陽一，
神谷裕子，下田智佳子，中澤眞平

抄　録：光過敏性てんかんの経過中に小児欠神てんかんを合併し，さらに治療終了した後，光過敏性てんかんが再燃した一女児例を報告する。患児は8歳の時，テレビを見ている時に，意識消失及び強直間代性けいれんで発症した。脳波上も点滅閃光光刺激で左側優位の光痙攣反応を認めたため，光過敏性てんかんと診断した。発症5か月後の脳波検査中，過呼吸賦活で発作起始及び終了の明瞭な数秒間の意識消失を伴う3Hz全般性規則性棘徐波複合を繰り返し認めたため，小児欠神てんかんの合併と診断した。14歳時，抗てんかん薬の投与を中止したところ，3か月後，テレビを見ている時に強直性けいれんを再び認めた。脳波上も右半側視野光刺激で左半球に広範に棘徐波を，右側半球には徐波成分を認めた。光過敏性てんかん及び欠神てんかんにおけるてんかん性放電の発生・伝播には視床・中脳を介して大脳皮質に投射される共通伝播経路が想定され，てんかん性放電の左右差は左右の大脳半球ヘ投射される経路の興奮性の差であると考えられる。

キーワード　光過敏性てんかん，小児欠神てんかん，図形・赤色フィルタ-の点滅閃光光刺激，点滅閃光光刺激，光痙攣反応



A Case of Photosensitive Epilepsy Accompanited by Childhood Absence

Kazuo Hatakeyama, Masao Aihara, Yoh-ichi Hinohara, Yuhko Kamiya, Chikako Shimoda,
and Shinpei Nakazawa

An 8-year-old female had generalized tonic-clonic seizures, when she was watching televivsion. EEG showed no remarkable changes during hyperventililation (HV), but there were 3 Hz diffuse irregular spike-and-wave paroxysms precipitated by intermittent photic stimulation (IPS). Neurological and radiological findings were normal. She was treated with phenobarbital. However, follow-up EEG showed 3 Hz rhythmic diffuse spike-and-wave paroxysms accompanied by an impairment of consciousness with abrupt onset and termination. Close scrutiny of spike-and-wave revealed a high amplitude in the left hemisphere. She was diagnosed with Childhood absence epilepsy (CAE) and treated with valproic acid (VPA). VPA was discontinued at fourteen-years of age. Three months later, while watching television, she suffered from generalized seizures. EEG showed no abnormality during HV, but diffuse irregular spike-and-wave paroxysms during IPS and pattern and red flicker stimulation (PRS) and right-hemifield 10 Hz red flickering stimulation, which were seen dominantly in the left hemisphere. She was diagnosed with photosensitive epilepsy and treatment with VPA was resumed.
These findings suggest that spike-and-wave paroxysms are conveyed via the thalamus and midbrain in both CAE and photosensitive epilepsy and that asymmetry of spike-and-wave paroxysms on EEG is due to the difference in excitability between preferential pathways projected to each hemisphere.

Key words: Photosensitive epilepsy, Childhood absence epilepsy, Pattern and red flicker stimulation, Intermittent photic stimulation, Photoconvulsive response.



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