Abstracts

Nonepileptic seizure (NES) is frequently the diagnosis among patients who undergo extended VEEG monitoring, representing up to 50% of cases evaluated in our inpatient unit. We routinely analyze recorded clinical events, ictal and interictal EEG, postictal serum prolactin levels, and neuropsychological study to differentiate between epileptic seizures (ES) and NES, each of which has limitations in discerning the difference. There are very few reports which have addressed the possible application of single photon emission tomography (SPECT) in this setting, including one series of 11 patients (Spanaki MV, Spencer SS, Corsi M [italic]et al[/italic]., [italic]J Neuroimaging [/italic]1999 Oct; 9(4):210-216).
This study represents a retrospective analysis over 28 months of 60 patients in whom a diagnosis of NES was made after extended inpatient monitoring, based on VEEG analysis, postictal serum prolactin studies, and neuropsychological evaluation. We reviewed adults with NES who underwent ictal SPECT, interictal SPECT, or both. SPECT images of the brain were obtained and reviewed in sagittal, coronal, and transverse planes after injection with 30 mCi of technecium 99m Neurolite. Studies were interpreted by radiologists who were aware of ictal versus interictal status of the patient but were blinded as to seizure type. Results were correlated with NES type and demographic data.
Seventeen (11 women, 6 men) of 60 patients with NES had SPECT in the ictal (2), interictal (4), or both (11) states. Patients ranged in age from 22-72 years (mean 42 years). NES types included 7 with generalized convulsions, 4 with staring spells, 4 with focal motor activity and secondary generalization, and two with focal motor activity alone.
Both patients with ictal SPECT alone had normal studies. Among those with interictal SPECT only, 2 out of 4 were abnormal, demonstrating mildly increased radiotracer uptake in both frontal lobes. Eleven had ictal and interictal SPECT, of which 8 were normal for both studies. Two of the ictal studies showed increased focal uptake compared with coregistered interictal SPECT, and in each case (one frontal, one parietal) the focal radiotracer uptake was contralateral to focal motor activity.
Most ictal SPECT scans for patients with NES were normal, as expected. In two cases there was increased radiotracer uptake contralateral to focal motor activity, even though all other parameters spoke for NES. It is possible that intense motor activity can in itself induce increased radiotracer uptake in SPECT scans.