The syndromic classification of the International League Against Epilepsy: a hospital-based study from South India.

PURPOSE

To determine the distribution of various epilepsies and epileptic syndromes in the epileptic population treated in a university hospital in a developing country.

METHODS

Data concerning 2,531 patients with epilepsy seen between January 1989 and June 1994 were analyzed using the International League Against Epilepsy (ILAE) classification.

RESULTS

Of 2,531 cases, 48% fell into ILAE categories 1.3, 3.2, or 4.1 (cryptogenic, without unequivocal generalized or focal seizures; or situation-related seizures, respectively). Localization-related epilepsies (LREs) and epileptic syndromes (1.1, 1.2, 1.3) were found in 1,591 (62.9%) patients; of these patients, symptomatic localization-related epilepsies totaled 62.7%. and idiopathic localization-related epilepsies accounted for only 0.7%. Juvenile myoclonic epilepsy was the most common type of idiopathic generalized epilepsy (IGE), comprising 4.9% of the total study population and 7.7% of patients registered in the epilepsy clinic. A combination of childhood and juvenile absence epilepsies were found in only 0.4% of the total study population. Single computed tomography (CT) enhancing lesion (SCTEL) and focal cerebral calcification (FCC) accounted for 22% of the etiologic factors for localization-related epilepsies. Neurologic deficits were found in 9.5% of patients with SCTEL; none were found with FCC. None of the patients with these lesions had any history of antecedent events that suggested CNS involvement. In patients with localization-related epilepsies with unremarkable clinical data, the proportion of CT scans showing SCTELs was 39 (95% confidence interval [CI], 0.35-0.43) and 0.18 (95% CI, 15-0.21) for FCCs. The proportion for both lesions together was 0.57 (95% CI, 0.53-0.61). Seizures did not recur once the lesion resolved in patients with SCTELs. In patients with FCCs, seizure remission was 71.5% (95% CI, 53.7-85.4) at 3 years.

CONCLUSIONS

This study illustrates the rarity in one patient population of some of the syndromes and categories described in the ILAE classification. Childhood and juvenile absence epilepsies together formed a small proportion. SCTEL and FCC were important etiologic factors for localization related epilepsies. The epilepsy associated with SCTEL was a form of benign epilepsy; epilepsy associated with FCC had remission rates similar to other remote symptomatic epilepsies. Without neuroimaging evidence, these 2 lesions would have been missed and the patients might have been grouped under cryptogenic localization related epilepsy. For this reason, we emphasize the need for neuroimaging in patients with localization related epilepsies with unremarkable clinical findings, before classification into the cryptogenic category. In the absence of neuroimaging, such patients should be classified as "probably cryptogenic."