無酸素脳症後，周期性同期性異常波（PSD）からα昏睡に移行した1例

α-Coma following Periodic Synchronous Discharges due to Anoxic Encephalopathy

　抄録　急激な無酸素脳症後，脳波で周期性同期性異常波（PSD）からα昏睡に移行した脳幹障害を伴わない症例を経験した。症例は59歳男性。窒息のため蘇生を施し，約40分後に自発呼吸が回復したが昏睡状態であった。約1時間後から3日間，眼球を含む全身のmyoclonusが出現し，その際脳波上で3〜5秒続く鋭波，棘波，高振幅徐波を含む突発波が，1.5〜2秒間隔で周期的に繰り返し，その間挿波は電気活動に乏しい平坦波を示すPSDを呈した。diazepamの静注ではPSDを抑制できなかった。PSDの消失と共に，前頭部優勢の10Hz，30μVのα昏睡を示し，両波型とも刺激にも反応しなかった。α昏睡を3日間呈した後，低振幅脳波に至った。脳幹障害は認められなかった。その1カ月後から約2ヵ月間，時にpcriodic spikingを前頭部に示すことがあったが，それも消失し平坦脳波となった。両波型が急激な無酸素脳症後に同一症例の過程でみられた詳細な報告はなく，その発生機序につき示唆を与えると思われる。

　The features of the electroencephalogram (EEG) observed in a case with acute anoxic brain damage are reported. The patient was a 59-year-old male. For three years prior to admission, he had been suffering from gait and urinary disturbances. His condition was diagnosed as the ossification of the posterior longitudinal ligament of the cervical spineand a laminectomy operation was conducted. Three days after the operation, he had difficulty in breathing several times during sleep. This led to sudden suffocation and subsequently to cardiac arrest. After artificial resuscitation revived him from death, he was in a state of coma.

　From 2 hours after revival to 3 days, he had generalized myoclonus with periodic synchronous discharges (PSD) on EEG. PSD consisted of periodic appearance of spikes, sharp waves and high voltage slow waves. The intervals showed electrical silence. Diazepam injected intravenously could elongate the intervals, but it did not bring about the disappearance of the seizure pattern. After 3 full days, both myoclonus and PSD disappeared. However, the patient still remained in a state of coma. The EEG showed also the conspicuous changes known as the a-coma pattern ; 10c/s, 30μv alpha waves dominant in the frontal areas without any slowwaves or seizure pattern. These findings were observed for 3 days. Thereafter the EEG changed to the periodic spiking in the frontal region and gradually to the low voltage record. He was in the state of decerebrate without any disturbance of brain stem functions for 9 months until he expired with pneumonia.

　Though both PSD and a-coma have been observed in separate cases of anoxic encephalopathy, both PSD and a-coma pattern occurring subsequently in the same patient have not been reported so far. We discussed the pathogenesis of both of these EEG patterns in some detail.