Changes of cerebral blood and tissue oxygenation in temporal lobe epilepsy shown by near infrared spectroscopy

Near infrared spectroscopy (NIRS) appears to be a safe, noninvasive technique useful in the EEG laboratory. NIRS has been used for continuous monitoring of changes in blood and tissue oxygenation of the whole brain. We report our observations of changes in local cerebral oxygenation in temporal lobe epilepsy. Eleven patients (four men, seven women; average age 31.9 years) including two patients after surgical treatment were selected by identifing temporal lobe atrophy and lateralizing the epileptic focus, by means of MRI, SPECT and EEG. Using NIRS (Hamamatsu Photonics Co., Hamamatsu, Shizuoka, Japan), changes in cerebral blood and tissue of oxygenated haemoglobin (HbO₂) and deoxygenated haemoglobin (HbR) produced by hyperventilation (HV) were measured in both the temporal region with the atrophy and the contralateral temporal region. In both temporal regions, HbO₂ values decreased from baseline (at start of HV) after the end of HV, but there was no difference between temporal region with atrophy and contralateral temporal region. However, in nine cases except two cases after surgical treatment, there was difference between them when HV ended. HbR values changed from baseline, but there was no difference between temporal region and contralateral region. Because of results, it is suggested that NIRS may be useful for one of supplementary diagnosis of temporal lobe epilepsy, but it is necessary to investigate further.