Correlation between cerebral perfusion and hyperventilation enhanced focalspiking activity

Single photon emission computed tomography (SPECT) has frequently been used to investigate cerebral brain perfusion (CBP) occurring ictally and inter- ictally in epileptic patients. Several studies have addressed the multimoda l analysis of the modifications occurring in cerebral areas involved in sei zure activity, by correlating SPECT with electroencephalografic (EEG) recor dings during ictal and inter-ictal epileptiform lateralized discharges (IEL Ds). Although these studies have yielded interesting results, variations in regional CBP (rCBP) observed during ictal events are difficult to interpre t since the areas of altered rCBP might reflect not only events restricted to the epileptogenic focus, but also large fluctuations determined by seizu re spread. Inter-ictal rCBP correlates with the area generating the local E EG epileptogenic activity in a limited percentage of studies. Hyperventilat ion (HPV) represents a well established EEG activation procedure aimed at e nhancing epileptiform discharges. Since HPV-enhanced IELDs may help analyze the CBP pathophysiology in inter-ictal epilepsy, in the present study we i nvestigate this specific aspect co-registering EEC with SPECT in subjects a ffected by partial epilepsy responding to HPV with IELD enhancement without seizure precipitation. This study suggests a correlation between localized increase in rCBP and HPV-induced IELDs and provides a tool to discuss unco mmon aspects of the physiology of rCBP during the inter-ictal state in the epileptogenic areas. (C) 2000 Elsevier Science B.V. All rights reserved.