National Epilepsy Center, Shizuoka Institute of Epilepsy and Neurological Disorders, Shizuoka, Japan.
Epilepsy Res. 2010 May;89(2-3):220-6. doi: 10.1016/j.eplepsyres.2010.01.004. Epub 2010 Feb 4.
Negative myoclonus (NM) is a sudden brief atonia in muscle that causes jerky lapses of posture. This study employed an electrophysiological technique (silent-period-locked-averaging (SPLA) electroencephalography (EEG)) and a pharmacodynamic imaging technique (123I-IMZ-SPECT) to examine epileptic NM (ENM). Delayed-phase 123I-IMZ-SPECT images, which reflect the specific binding of the tracers to GABA-A receptors, exhibited significant decrease in the left medial frontal area. The deficit in GABA-A receptors indicated that abnormal synchronization was mediated by the lack of inhibitory postsynaptic mechanism. The SPLA-EEG recorded spike-like notches superimposed on the slope of negative slow activity in the contralateral fronto-central region. The slow activity started around 100 ms before and the peak of the spike-like component was 30 ms before the onset of ENM. Since the 123I-IMZ-SPECT shows the actual distribution of the tracers, the abnormal area associated with ENM in this particular patient was supposed to be on the left medial frontal lobe. Scalp EEG, though it cannot always accurately locate the abnormal area, was highly sensitive to be able to detect electrical activities transmitted through neuronal network or volume conductor. Combined use of the two methods provided high resolution both in spatial and temporal domain.
负性肌阵挛（NM）是一种肌肉突然短暂弛缓导致姿势突然丧失的现象。本研究采用电生理技术（静默期锁定平均（SPLA）脑电图（EEG））和药效动力学成像技术（123I-IMZ-SPECT）来研究癫痫性 NM（ENM）。延迟期 123I-IMZ-SPECT 图像反映了示踪剂与 GABA-A 受体的特异性结合，显示左侧额内侧区域明显减少。GABA-A 受体的缺乏表明异常同步是由缺乏抑制性突触后机制介导的。SPLA-EEG 记录到尖峰样切迹叠加在对侧额中央区域的负性慢活动的斜率上。慢活动在 ENM 发作前约 100ms 开始，尖峰样成分的峰值在 30ms 前出现。由于 123I-IMZ-SPECT 显示了示踪剂的实际分布，因此与该特定患者的 ENM 相关的异常区域应该在左侧额内侧叶。头皮 EEG 虽然不能总是准确地定位异常区域，但对通过神经元网络或容积导体传输的电活动非常敏感。两种方法的结合使用提供了在时空域的高分辨率。
