Prolonged Limb and Respiratory Muscle Weakness Associated with Japanese Encephalitis Virus Infection: A Case Report

Patients diagnosed with Japanese encephalitis (JE) may present with flaccid paralysis. JE has also been reported to be accompanied by anterior horn cell disease or motor axonal polyneuropathy. We report a case of a patient with JE with prolonged limb and respiratory muscle weakness who underwent electrodiagnostic studies, including a phrenic nerve conduction study, 10 months after the onset of paralysis. During that 10-month period, severe weakness of the upper and lower extremities showed no recovery, and the patient required long-term ventilator support through a tracheostomy. Nerve conduction studies and electromyography revealed chronic anterior horn cell disease with abundant denervation potentials involving the craniobulbar, cervical, thoracic, and lumbosacral segments. In addition to the nerves in the upper and lower extremities, the phrenic motor nerves showed abnormalities indicative of diaphragmatic weakness. Therefore, in patients with JE with chronic limb weakness and respiratory difficulty, thorough electrodiagnostic studies should be performed to diagnose the combination of anterior horn cell disease with encephalitis and to evaluate the condition’s severity and prognosis.