ICTAL MOTOR SIGNS AND INTERICTAL REGIONAL CEREBRAL HYPOMETABOLISM

Early motor manifestations are the main components of focal seizures i nvolving the frontal lobe. We examined the relationship between the in itial ictal motor manifestations and interictal abnormalities of cereb ral glucose consumption (rCMRGlc) as assessed by PET in 48 consecutive patients with focal seizures of neocortical origin. Group data analys is revealed that patients with predominantly unilateral clonic seizure s had a significant contralateral perirolandic hypometabolism and to a lesser degree a contralateral frontomesial hypometabolism. Patients w ith predominantly focal tonic manifestations showed a hypometabolism w ithin the frontomesial and perirolandic regions that was unilateral in all patients with lateralized tonic seizures. Patients with versive s eizures had mainly contralateral metabolic depressions without a consi stent regional pattern. Patients with hypermotor seizures had metaboli c depressions involving frontomesial, anterior cingulate, perirolandic , and anterior insular/frontal operculum areas. In all patient groups, bilateral and symmetric hypometabolism of the thalamus and cerebellum was observed. We propose that this pattern of distinctly abnormal met abolic brain regions demonstrates not only possible epileptogenic zone s but also symptomatogenic brain regions as shown by the associations between clinical manifestations and sets of abnormal brain regions, pa rticularly if epileptogenic zones are in a clinically silent neocortic al brain region. The detection and possible differentiation of symptom atogenic and epileptogenic zones might improve the effectiveness of pr esurgical noninvasive studies.