脳波，ＳＰＥＣＴで発作焦点の移動を認めた脳梗塞後のてんかん発作重積の１例

We report on a patient who had intractable partial seizures caused by a cerebral infarction due to embolic occlusion of the right middle cerebral artery. This 74-year-old woman was admitted to our hospital because of a hemiclonic convulsion on the left side. On admission, she was stuporous, and was unable to follow simple commands. There was a conjugate ocular deviation to the left. She had focal clonic convulsions involving the proximal part of the left arm and the left side of the neck and face. An X-ray CT revealed an inhomogeneous low density area in the right frontoparietal, posterior parietal, and occipital regions. Although a cerebral angiography showed no steno-occlusive lesions, findings showing a localized capillary brush and an early venous filling were noted in a territory of the cortical branches of the right middle cerebral artery. These findings suggested recanalization of the once occluded arteries of embolic origin. EEG findings showed background activity during the interictal state consisting of theta or delta activities of 2-5 Hz in frequency, and an amplitude of 20-40 μV. There was a prominent slowing of the background activity over the right hemisphere. Both ictal and interictal EEGs revealed epileptogenic foci in the right frontocentral area. A SPECT scan during a somatomotor seizure demonstrated focal hyperperfusion of the right perirolandic area, with extensive hypoperfusion of the right parietal and occipital areas. Hyperperfusion in the right perirolandic area corresponded to the epileptogenic lesion that was confirmed by the ictal EEG study. Thus, this patient was diagnosed as having status epilepticus of the somatomotor type during the course of a hemorrhagic infarction caused by embolic occlusion of the right middle cerebral artery. Treatment with diphenylhydantoin, diazepam and clonazepam slightly decreased the frequency of seizures. In spite of high doses of medication, her seizures continued to be poorly controlled. Two weeks after the onset of the seizures, they changed from the somatomotor to the psychomotor type, and were accompanied with perioral automatism. During the psychomotor seizures, the patient was stuporous but mumbled continuously without responding to commands. An ictal EEG during the psychomotor seizure revealed the right temporal epileptogenic focus. Ictal SEPCT scans obtained during the psychomotor seizures demonstrated focal hyperperfusion of the right temporal area. According to both EEG and SPECT findings, it was concluded that the right perirolandic focus during the somatomotor seizure shifted to the right temporal area during the psychomotor seizure. In this case, the increase of the local cerebral blood flow and the disruption of the blood brain barrier may have caused the hemorrhagic change that induced the epileptogenic discharge. It is speculated that a persistent increase of the cerebral blood flow might be the secondary phenomenon that was accompanied with status epilepticus. Icatal SPECT scans revealed more exactly the localization of the epileptogenic focus that corresponded with the EEG. SPECT may be suitable for evaluating the localization of the seizure focus in order to confirm surface EEG findings.