PERFUSION PATTERNS DURING TEMPORAL-LOBE SEIZURES - RELATIONSHIP TO SURGICAL OUTCOME

We sought to determine whether patterns of ictal hyperperfusion demons trated using [Tc-99m]HMPAO (hexamethylpropylene amine oxime) single ph oton emission computed tomography (SPECT) predict outcome of temporal lobectomy; in particular whether the more extensive patterns of ictal hyperperfusion are associated with poor outcome. We studied 63 patient s who had ictal SPECT studies prior to temporal lobectomy. Hyperperfus ion on ictal SPECT scans was lateralized, and classified into: (i) 'ty pical', (ii) 'typical with posterior extension', (iii) 'bilateral' and (iv) 'atypical' patterns. Outcome (minimum of 2 years follow-up) was classified as either seizure free, or not seizure free. Actuarial anal ysis was used to test the relationship of SPECT patterns with outcome. There were 35 cases with the typical ictal SPECT pattern, 13 posterio r nine bilateral and six atypical cases. The atypical pattern was asso ciated with lack of pathology in the surgical specimen. Outcome was si milar for the typical, posterior and bilateral with 60%, 69% and 67% s eizure free, respectively. In contrast, the atypical group had a worse outcome with only 33% seizure free. Actuarial analysis showed a signi ficant difference in outcome between patients with the typical pattern , and patients with the atypical pattern (P = 0.04). We conclude that extended patterns of ictal perfusion in temporal lobe epilepsy do not predict poor outcome, indicating that extended hyperperfusion probably represents seizure propagation pathways rather than intrinsically epi leptogenic tissue. Atypical patterns of hyperperfusion are associated with poor outcome and may indicate diffuse or extra-temporal epileptog enicity.