Clinical and radiological spectrum of Japanese encephalitis.

ABSTRACT

INTRODUCTION: Japanese encephalitis (JE) is mosquito-borne flaviviral encephalitis that remains to be a major health problem in India--it still continues to cause havoc in many parts of the country. We undertook the study to analyze the clinical and radiological spectrum of JE in adults and children. METHOD: This prospective study consists of 148 patients with JE. The diagnosis of JE was based on clinical, epidemiological, radiological features and demonstration of JE virus specific IgM in CSF and serum by JE virus immunoglobulin M capture enzyme-linked immunosorbent assay (MAC ELISA). All patients underwent a detailed neurological examination, CSF study & neuroimaging of brain (either CT or MRI or both). All patients were followed-up at regular interval. RESULT: Seizures were present in adults (52.88%) and in children (43.18%). Dystonia was more common in children 19 (43.18%) compared to adults 19 (18.2%), and Parkinsonian features were observed in both groups 47 (45.19%) of the adults and 20 (45.45%) of the children. JE-specific IgM antibody was detected in both CSF and serum in 81.7%. In neuroimaging, apart from classical involvement of thalami, basal ganglia & midbrain, prominent involvement of hippocampus and other areas of the cortex was also found in 27 (45.6%) patients. Presence of thalamic lesion in CT/MRI showed significant relationship to the development of dystonia. However, no correlation was found between the neuroimaging features and poor clinical outcome. Twenty three patients (15.5%) died during acute phase of illness. On multivariate logistic regression analysis age, prolonged fever, Glasgow coma scale, recurrent seizures and reflex changes were found to be the predictors of outcome at the time of discharge. CONCLUSION: A trend of severe and frequent involvement in younger patients with dystonia and other movement disorders was observed. It should be emphasized that presence of atypical cranial CT/MRI features in JE was not unknown and they need to be differentiated from herpes simplex encephalitis in appropriate clinical setting.