Simultaneous study of interictal EEG and near-infrared spectroscopy in a boy with epilepsy

Abstract

Near-infrared spectroscopy (NIRS) is a useful non-invasive method for the diagnosis of the cerebral metabolism with epileptic foci in cases of intractable epilepsy. We examined the cerebral metabolic state of epilepsy at the interictal state using a simultaneous measurement of electroencephalograph (EEG) and an NIR system in a boy with epilepsy. The subject was a 9-year-old boy with temporal lobe epilepsy. Oxy-hemoglobin (oxy-Hb), deoxy-hemoglobin (deoxy-Hb) and regional cerebral blood volume (rCBV) were estimated using a multi-channel functional NIR (fNIR) system with 24 channels (Hitachi Medical), after obtaining informed consent. Spikes on the EEG were frequently seen on the left parietal and middle temporal area during photo stimulation at the drowsy stage. On the opposite side, spikes were occasionally seen during photo stimulation. Functional NIR findings at the same time were the following: the increase of deoxy-Hb and the slight decrease of oxy-Hb and rCBV firstly from the left middle/post-temporal surfaces, and delaying response at the opposite sides. Besides, the changes of deoxy-Hb, oxy-Hb and rCBF showed the relatively small amplitude. The appearance of the abnormal metabolic state was consistent with the EEG, as spikes became less and less frequent, we then came to the conclusion that NIRS could evaluate the real-time cerebral metabolic state of the epileptic foci, even if the clinical seizure did not occur.