SUPPLEMENTARY SENSORIMOTOR AREA EPILEPSY - SEIZURE LOCALIZATION, CORTICAL PROPAGATION AND SUBCORTICAL ACTIVATION PATHWAYS USING ICTAL SPECT

We studied clinical signs, EEGs and ictal cerebral blood flow by singl e-photon emission computed tomography (SPECT) in eight patients with i ntractable supplementary sensorimotor area (SSMA) seizures. SPECT scan s were performed after injection of the regional cerebral blood pow tr acer [Tc-99m]HMPAO (hexametylpropylene amine oxime) early in the ictal phase (2-5s after seizure onset). Ictal SPECT demonstrated unilateral predominance of hyper-perfusion of the SSMA in all patients, concorda nt with either lateralizing clinical signs, lateralization of ictal sc alp EEG or with the sire of ictal onset of seizures, obtained from int racranial electrodes. Two distinctive cortical blood-flow propagation patterns were identified in SSMA seizures. The type I pattern consiste d of primary involvement of the ipsilateral SSMA and dorsal premotor a nd motor cortex. The type II pattern consisted of bilateral bur asymme tric mesial frontal propagation. Ictal contraversive head and eye move ments were associated with a type I propagation pattern (P < 0.03). Ac tivation of subcortical structures led to variable hyperperfusion of t he basal ganglia and thalamus. Contralateral cerebellar hyperperfusion was observed in all cases. We conclude that ictal SPECT is a useful m ethod for seizure localization in patients with SSMA epilepsy. The obs erved heterogeneity of clinical features in SSMA epilepsy correlates w ith propagation to, and activation of specific cortical structures, an d is consistent with known anatomical interconnections between the SSM A, ipsilateral cortical and transcallosal cortical structures.