Abstracts

RATIONALE: The value of ictal SPECT studies obtained during complex partial seizures followed by generalized tonic-clonic seizures is controversial. The objective of this study is to evaluate the findings of ictal SPECT in a series of homogeneous patients with epilepsy due to mesial temporal sclerosis. METHODS: Twenty one patients with epilepsy due to mesial temporal sclerosis (pathologically confirmed in 18) had the injection of 99mTc.ECD during CPS (14 patients) and CPS developed generalized tonic-clonic seizures (7 patients), documented by video-EEG for evaluation of the time of the administration of the tracer. RESULTS: All SPECT studies were obtained within the ictal period and showed hyperperfusion more intense in the epileptogenic temporal lobe. Out of 14 studies in CPS, the increase in the blood flow was restricted to temporal lobe in 12. In one there was diffusion to the ipsilateral parietal lobe and in one to the caudate nucleus also ipsilateral. Of the 7 secondarily generalized seizures, in 3 there was diffusion of the hyperperfusion to the suprasylvian areas, in 3 to the ipsilateral basal ganglia and in 1 the increase in blood flow was restricted to the epileptogenic lobe. CONCLUSIONS: The literature suggests that the ictal SPECT studies during secondarily generalized seizures present very little lateralizatory value, although when these had an unilateral predominance, focal hyperperfusion could be detected. Our series show that SPECT studies in CPS evolved to symmetrical generalized tonic-clonic seizures also revealed a greater hyperperfusion in the epileptogenic lobe. This fact has practical importance since generalized tonic-clonic seizures occur more frequently during video-EEG monitoring than usually seen due to the reduced levels of antiepileptic drugs.