RELATIONSHIP OF HIPPOCAMPAL SCLEROSIS TO DURATION AND AGE-OF-ONSET OFEPILEPSY, AND CHILDHOOD FEBRILE SEIZURES IN TEMPORAL LOBECTOMY PATIENTS

Controversy exists as to whether hippocampal sclerosis (HS) is a preex isting cause or a consequence of seizures. We investigated 122 consecu tive patients who underwent anterior temporal lobectomy for intractabl e epilepsy between 1989 and 1992. MRI scans were normal apart from evi dence of HS in 5 cases. The degree of HS was graded from 0 to 4. There was a significant inverse correlation between age of seizure onset an d grade of HS (P < 0.0001), and a positive, correlation between durati on of epilepsy and grade of HS (P < 0.001). Using a dichotomous groupi ng of HS (HPSC- for grades 0 and 1[no/mild HS], and HPSC+ for grades 3 and 4 [moderate/marked HS]), there was a positive correlation between HPSC+ and a history of childhood febrile seizures (CFS) (P = 0.003), earlier age of onset of epilepsy (P < 0.001) and longer duration of ep ilepsy (P < 0.001). There was no correlation with history of particula rly prolonged individual seizures. Partial correlations after controll ing for age at onset of epilepsy showed that there was no longer a sig nificant relationship between HPSC+ and duration of epilepsy. After co ntrolling-for duration of epilepsy, the relationship between HPSC+ and age of onset remained significant (P < 0.001). The correlation betwee n HPSC+ and CFS, controlling for age at onset, was hot significant, A series of logistic regression analyses showed age at onset to be the o nly predictor of HPSC+. It is concluded that this is supportive eviden ce for preexisting HS being a cause of temporal lobe epilepsy and not a consequence of seizures.