Träff J, Petrovic P, Ingvar M
Department of Clinical Neuroscience, Karolinska Institute/Karolinska Hospital, Stockholm, Sweden.
Acta Neurol Scand. 2000 May;101(5):339-43. doi: 10.1034/j.1600-0404.2000.9c132a.x.
Regional cerebral blood flow (rCBF) during photic myoclonus was studied by means of positron emission tomography in a 51-year-old male patient suffering from MERRF (myoclonic epilepsy with ragged-red fibres). Frequencies of 3 Hz and 5 Hz flash stimulation were used. Both frequencies elicited paroxysmal EEG-abnormalities but only the higher frequency induced generalized myoclonic jerks. We found a left dominated significant increase of rCBF in the thalamus during myoclonus. The thalamic asymmetry was significant when tested with an ROI approach. The myoclonic activity was accompanied by significantly increased activity in the supplementary motor cortex (SMA). Decreases in rCBF were seen in the limbic, temporal and occipital areas during photic stimulation at both flash frequencies, more expressed during myoclonus. The findings observed in this patient indicate a thalamic focus for photic myoclonus in MERRF. We suggest that photic stimulation induced an abnormal discharge in the thalamus, which was fed forwards via thalamo-cortical connections to the precentral motor cortex, to produce the muscle jerks.
采用正电子发射断层扫描技术，对一名患有肌阵挛性癫痫伴破碎红纤维（MERRF）的51岁男性患者进行了研究，以观察光性肌阵挛发作时的局部脑血流量（rCBF）。使用了3Hz和5Hz的闪光刺激频率。两种频率均引发了阵发性脑电图异常，但只有较高频率诱发了全身性肌阵挛抽搐。我们发现，肌阵挛发作时，丘脑的rCBF显著增加，且以左侧为主。采用感兴趣区（ROI）方法进行测试时，丘脑的不对称性很显著。肌阵挛活动伴随着辅助运动区（SMA）的活动显著增加。在两种闪光频率的光刺激过程中，边缘系统、颞叶和枕叶区域的rCBF均出现下降，在肌阵挛发作时更为明显。该患者的研究结果表明，MERRF患者的光性肌阵挛存在丘脑病灶。我们认为，光刺激诱发了丘脑的异常放电，该放电通过丘脑-皮质连接向前传导至中央前运动皮层，从而产生肌肉抽搐。
