Anterior horn cells are also involved in Japanese encephalitis

Abstract

Introduction: the basis of focal muscle wasting in Japanese encephalitis (JE) has not been systemically studied. Material and methods: Twelve patients with JE were subjected to clinical evaluation, nerve conduction, electromyography (EMG), motor and somatosensory evoked potentials and cranial CT or MRI scans. Spinal MRI was carried out in selected patients. The clinical and the neurophysiological examination were repeated after 3 months. Recovery was defined as poor, partial and complete. Results: Seven of 12 patients with JE had varying degrees of lower motor neuron signs. Electromyography revealed prominent fibrillation and neurogenic changes in the wasted muscles, which improved in the follow-up period in all patients. Motor evoked potentials on spinal stimulation revealed peripheral delay in 2 patients and small amplitude in 4 patients. Spinal MRI showed hyperintense signals on T₂ in the cervical region which correlated with clinical signs. Two of these patients had complete, 3 partial and 2 poor recovery. The patients with mild involvement of spinal cord had better recovery compared to those with severe involvement. Conclusion: Varying degree of anterior horn cell involvement seems to be common in JE.