Abstracts

RATIONALE: We have previously shown that in patients with temporal lobe epilepsy, interictal, temporal polymorphic delta slowing on scalp EEG may correlate with regional FDG-PET hypometabolism in both presence and severity (Epilepsia 2001; S7:24.). The relative contribution of these measures of cerebral dysfunction to the localization of the underlying epileptogenic zone remains unclear. At the end of this activity the participants should be able to discuss the relationship between PET hypometabolism and focal delta slowing with seizure onset as determined by intracranial monitoring.
METHODS: We retrospectively evaluated 32 temporal lobes of 16 consecutive patients between 2000-2002 who had an indeterminate non-invasive evaluation for lateralization of temporal lobe onset and had subsequent intracranial recording with bilateral temporal subdural strips. Scalp EEG interictal delta activity and imaging studies including FDG-PET were reviewed. Statistical analysis was performed using the Spearman rho statistic for categorical correlation.
RESULTS: Fourteen patients had unitemporal seizure onset during intracranial monitoring. Six patients (42.9%) had bilateral PET hypometabolism while 8 (50%) had unilateral PET hypometabolism with correct lateralization in 5 patients (62.5%). Two patients had bilateral delta slowing while unilateral polymorphic delta slowing was seen in 10 patients with correct lateralization in 9 (90%). The presence of interictal delta slowing was significantly correlated with the side of seizure onset obtained from intracranial monitoring (r=0.50, p[lt]0.01) while PET hypometabolism was not. No definite correlation was seen between these two parameters.
CONCLUSIONS: Though a correlation has been previously shown between FDG-PET and focal delta slowing, in patients with difficult to lateralize seizure onset, focal delta slowing may be more specific for the underlying epileptogenic zone.