da Silva E A, Müller R A, Chugani D C, Shah J, Shah A, Watson C, Chugani H T
Department of Pediatrics, Children's Hospital of Michigan and The Detroit Medical Center, Wayne State University School of Medicine, USA.
Epilepsia. 1999;40 Suppl 4:17-22. doi: 10.1111/j.1528-1157.1999.tb00901.x.
Intermittent photic stimulation (IPS) is an activation procedure used during electroencephalogram (EEG) recording to elicit paroxysmal discharges in individuals with photosensitivity. Specific responses on EEG recording may be provoked by IPS at different frequencies of flickering in normal individuals and in patients with photosensitive epilepsy.
Changes in regional cerebral blood flow (rCBF) were studied during IPS in two groups of subjects by using [15O]-water positron emission tomography (PET): a control group consisting of eight healthy adults with photic driving response during IPS on EEG recording (mean age, 25 +/- 10.5 years) without history of neurologic or psychiatric abnormalities and a patient group consisting of four adults (mean age, 33 +/- 7.5 years) with history of photosensitive epilepsy. [15O]-water PET scanning with concomitant EEG monitoring was performed during baseline and IPS at 4-, 14-, and 30-Hz frequencies.
The control group showed photic driving response at 14-Hz IPS frequency. The patient group showed photoparoxysmal response at 14 and 30 Hz, but not at 4 Hz. Changes in rCBF were determined by means of statistical parametric mapping. Increases in rCBF in occipital cortex (Brodmann's areas 17, 18, and 19) were observed in both groups. In addition, during photic driving responses, the control group showed rCBF increases in the insula and in the thalamus, on the right side. The patient group showed a significant rCBF increase in the hypothalamic region inferior to the left caudate nucleus during photoparoxysmal response. This activation was not found in the control group. Increased rCBF also was observed in the patient group in the head of the left caudate nucleus, in the left hippocampus, and in left insula during IPS without photoparoxysmal response. No activations in these regions were observed during photoparoxysmal response.
These data may indicate involvement of the hypothalamus in photosensitive epilepsy and may suggest a modulatory function of the caudate nucleus, which might be associated with an inhibition of epileptic discharges during IPS in patients with photosensitive epilepsy.
间歇性光刺激（IPS）是一种在脑电图（EEG）记录过程中使用的激活程序，用于诱发光敏个体的阵发性放电。正常个体和光敏性癫痫患者在不同闪烁频率的IPS刺激下，EEG记录可能会出现特定反应。
使用[15O] - 水正电子发射断层扫描（PET）对两组受试者在IPS期间的局部脑血流（rCBF）变化进行研究：一组为对照组，由8名健康成年人组成，他们在EEG记录的IPS期间有光驱动反应（平均年龄25±10.5岁），无神经或精神异常病史；另一组为患者组，由4名成年人组成（平均年龄33±7.5岁），有光敏性癫痫病史。在基线和4Hz、14Hz和30Hz频率的IPS期间进行[15O] - 水PET扫描并同步EEG监测。
对照组在14Hz的IPS频率下表现出光驱动反应。患者组在14Hz和30Hz时表现出光阵发性反应，但在4Hz时未出现。通过统计参数映射确定rCBF的变化。两组均观察到枕叶皮质（布罗德曼区17、18和19）的rCBF增加。此外，在光驱动反应期间，对照组右侧岛叶和丘脑的rCBF增加。患者组在光阵发性反应期间，左侧尾状核下方的下丘脑区域rCBF显著增加，对照组未发现这种激活。在无阵发性反应的IPS期间，患者组左侧尾状核头部、左侧海马体和左侧岛叶也观察到rCBF增加。在光阵发性反应期间，这些区域未观察到激活。
这些数据可能表明下丘脑参与了光敏性癫痫，并且可能提示尾状核的调节功能，这可能与光敏性癫痫患者在IPS期间癫痫放电的抑制有关。
