Seizures in Japanese encephalitis

Abstract

Objective: Although Japanese encephalitis (JE) has been reported to be associated with seizures, there is no report on its frequency, pattern and severity and their correlation with electroencephalography (EEG) and radiological findings. In this communication, the analysis of seizures in 65 JE patients seen during 1991-1999 is presented.

Methods: The diagnosis of JE was based on clinical, radiological and serological criteria. The patients were subjected to a detailed clinical evaluation. Frequency and pattern of seizures and other neurological findings were recorded. Cranial CT scan or MRI was carried out in all the patients. Electroencephalograph was recorded using the 10-20 system of electrode placement. Patients' outcome was defined, on the basis of clinical status for 3 months, into poor, partial and complete recovery. The relationship between seizures and other clinical, radiological and EEG parameters was evaluated by the Z test of proportion using the two-tail approach.

Results: The patient's age ranged between 2 and 57 years, 24 were females and 19 were below 13 years of age. Thirty patients had seizures within the first week of encephalitis. The seizures were generalised tonic-clonic in 17 patients and partial motor with secondary generalization in 13 patients. Eleven patients had a single seizure, 8 had two seizures and 11 had multiple seizures. Two patients were presented with status epilepticus. Interictal EEG in the patients with seizures revealed theta to delta slowing in all patients and epileptiform discharges in four patients only. MRI revealed thalamic lesions bilaterally in 24, cortical in 7, basal ganglia in 8 and brainstem in 3 patients out of 26 patients with seizure. In the seizure group, three patients died, nine had poor, eight had partial and nine had complete recovery. Upon comparison of the JE patients with and without seizures, Glasgow coma scale (GCS) score, focal weakness, EEG slowing and cortical and thalamic lesion on CT or MRI were significantly related to the occurrence of the seizures; however, it was not associated with poor outcome.

Conclusions: JE is associated with seizures in 46% of the patients in the acute stage of encephalitis which is easily controlled by monotherapy. Patients with severe encephalitis were associated with higher frequency of seizures.