The risk of epilepsy developing after complex febrile seizures (CFS) was studied in 477 children admitted between 1991 and 1998 with febrile convulsions at Tel Aviv Medical Center, Israel. Among 57 (12%) diagnosed with CFS and an otherwise normal neurologic exam, 48 were available for follow-up, and 13 (27%) developed epilepsy. Thirty percent had a family history of febrile seizures, but none had a positive family history of epilepsy. The follow-up period was 8-78 months (mean 43 +/- 24 months). Among patients developing epilepsy, the mean age of CFS onset was 11 months compared to 17 months in those without epilepsy. CFS of the partial seizure type had a higher risk of epilepsy (45%) than those with multiple febrile seizures (21%). None of 3 patients with the prolonged type of CFS developed epilepsy at follow-up. Neuroimaging studies performed in 15 patients were all normal, and 10 had partial CFS. Two of the 13 patients with epilepsy treated with anticonvulsants were refractory. 
COMMENT. In this study, 27% of children with complex febrile seizures (CFS) developed epilepsy at follow-up. Of the 3 characteristics that define a CFS (prolonged duration >15 minutes, focal partial pattern, or multiple recurrence with a single fever episode), the partial CFS patient carried a higher risk of developing epilepsy (45%) than patients with multiple seizures (21%). Only 3 of the 57 patients with CFS had prolonged FS and none developed epilepsy. In some previous studies, the risk of epilepsy following CFS has been lower, reported at 4-15% (Nelson & Ellenberg,1976; Verity & Golding, 1991). Berg and Shinnar (1996) found a strong correlation between prolonged CFS and focal features. In my own prospective studies and reports (Millichap, 1960-1968), prolonged FS, an abnormal EEG, and frequent recurrence of FS were associated with an increased risk of epilepsy. Focal EEG abnormalities were more predictive of epilepsy than focal FS patterns. Spontaneous seizures and epilepsy developed in 29% of my patients with CFS over a 2 year follow-up, a figure similar to that reported above by Sapir et al, but the prolonged FS duration was more predictive of epilepsy than the focal pattern. For further reference to FS and epilepsy, see Millichap JG, Progress in Pediatric Neurology III, PNB Publ, 1997;ppl9-36; and Febrile Convulsions. MacMillan, 1968).