Profile and predictors of symptomatic seizures following acute Japanese and herpes simplex encephalitis

Background: Acute viral encephalitis often manifests with seizures. Studies from India regarding subsequent remote symptomatic epilepsy following acute viral encephalitis are few. Objectives: To describe the incidence, identify the risk factors of acute symptomatic seizures in acute viral encephalitis and analyze the prevalence of seizure recurrence in those patients who had acute symptomatic seizures. Methods: This retrospective hospital based cross-sectional study involved 75 patients (age: 27.44 +/- 18.47 years; Male: Female = 37:38) of acute viral encephalitis viz. herpes simplex encephalitis (HSE: 48) and Japanese encephalitis (JE: 27) with acute symptomatic seizures over a 10 years period. Results: Acute symptomatic seizures was noted in 55 patients (73.3%) patients with acute viral encephalitis: HSE: 35 (72.9%) and JE: 20 (74.1%). The types of seizures were: generalized (n=29; 52.7%) and focal (n=26; 47.3%). Status epilepticus was noted in 10 (18.2%) patients (p<0.001), while cluster seizures were observed in 9 (16.4%). Some of the risk factors of seizures in HSE were imaging abnormalities and higher CSF cell count. Younger patients of JE had higher risk of having seizures and those with seizures did not improve completely compared to without seizure subgroup. Fifty patients with acute symptomatic seizures received parenteral phenytoin, followed by phenobarbitone (n=5), and 14 (25.5%) required a second AED, which was often carbamazepine. Scalp EEG was abnormal in 36/44 (81.8%) with HSE and in 8/15 patients (53.3%) with JE. Among 23/75 patients with viral encephalitis who were followed up for median of 2 years, 34.8% (n=8) of patients developed unprovoked seizures and the others (n=15) were seizure free. Conclusions: Acute symptomatic seizures are common in acute viral encephalitis. A significant proportion of the patients with acute viral encephalitis and acute symptomatic seizures developed unprovoked seizures.