てんかん患者の追跡眼球運動—側頭葉てんかん患者の注意・認知機能の検討を中心にして

Pursuit Eye Movement in Epileptic Patients: A seizure-type dependent difference in its performance

　抄録　てんかん患者，特に側頭葉てんかん患者の注意機能を検討する目的で，追跡眼球運動検査を行った。対象は側頭葉てんかん群（TLE群）37名，その他のてんかん群（NON-TLE群）37名，正常対照17名である。被験者に，0.5Hz視角20度で水平方向に単振動する光の点を一側の眼で追跡させ，水平方向の眼電位図を記録し衝動百分率（衝動成分の振幅の和の頂点間距離に対する比）を求めた。その結果，光点の形に注目させて追跡させた時，精神症状のあるてんかん患者の衝動百分率は精神症状のないてんかん患者より大きかった。TLE群の成績はNON-TLE群より悪かった。NON-TLE群では臨床発作型，発作頻度による衝動百分率の差はなかったが，TLE群では複雑部分発作の頻度の高い者の成績が悪かった。以上の結果から，TEL群では注意・認知機能の障害がより強く，精神症状発現の危険性の高いことが示唆された。さらに，抗てんかん薬の追跡眼球運動に及ぼす影響について考察した。

　The purpose of this study was to examine the attentional functioning of epileptic patients, especially of temporal lobe epileptics. Subjects consisted of 37 epileptics with complex partial seizures (TLE), 37 epileptics with other types of seizures than complex partial seizures (NON-TLE), and 17 normal controls. Subjects were required to eye-track a light spot target which moved sinusoidally in the horizontal axis of an oscilloscope screen with a frequency of 0.5 Hz. The visual angle of the width for target movement was set at 20 degrees. The horizontal electro-oculograms (EOGs) were recorded during the tasks. Amplitude ratios of saccades were calculated according to the following formula : Sum of amplitudes of saccades/peak to peak amplitudes.

　The following results were obtained ;

　1) The amplitude ratios of saccades were larger in the epileptics with schizophrenia-like psychotic symptoms as compared to those without psychotic symptoms.

　2) TLE patients produced larger amplitude ratios of saccades as compared to NON-TLE patients.

　3) Neither seizure type nor seizure fequency exhibited significant effects on the amplitude ratios of saccades in NON-TLE patients. On the other hand, seizure frequency of complex partial seizures exhibited significant effect on the amplitude ratios of saccades in TLE patients. In other words, TLE patients with frequent complex partial seizures more than once a month produced larger amplitude ratios of saccades as compared to TLE patients with complex partial seizures less than once a month.

　4) The amplitude ratios of saccades were larger in epileptics who were treated with phenobarbital (PB) as compared to those epileptics not treated with PB. There was a significant positive correlation between serum concentration of PB and amplitude ratios of saccades. On the contrary, administration of carbamazepine within the range of therapeutic concentration decreased the amplitude ratios of saccades.

　These results suggest that TLE patients, specifically those with high frequency of complex partial seizures, display considerable deficits in attentional functioning.