Supplementary sensorimotor area seizure and ictal single-photon emission tomography

Focal tonic seizures [supplementary motor seizures in the terminology of Penfield and Jasper (1) are often difficult to diagnose in terms of this chapter was undertaken to investigate whether ictal single-photon emission CT (SPECT) scanning could contribute to the diagnostic accuracy of this epileptic condition. In 15 patients (mean age, 21.3 years; ranges, 3 to 39 years) suffering from focal tonic seizures as the initial and most prominent seizure type, ictal SPECT scans were obtained after injection of 99mTc HMPAO within 30 seconds after clinical seizure onset. In 6 patients (40%; group I), ictal SPECT scans showed a focal hyperperused area concordant with results of other tests of the preoperative work-up (prolonged EEG/video monitoring, MRI, and positron emission tomography PET) using [18F]fluoro-2-deoxy-D-glucose (18FDG)] In 6 patients (group II), results of the ictal SPECT scans also showed findings of other tests of the clinical work-up. In 3 patients (group III), no ictal hyperperfusion could be observed. Results of the other presurgical tests in groups II and III were not sufficient to identify the seizure onset zone with the certainty needed for surgical resection. Ictal SPECT with HMPAO revealed confirmatory results in 40% of the patients with focal tonic seizures. In the remaining patients, results either were not congruent with other findings or did not show any change at all. This may have a twofold explanation: First (and probably most important), the interval between seizure onset and injection was too long considering the usually short duration of this seizure type, and second, the spatial resolution of SPECT imaging might not be sufficient to reveal a small seizure focus.