Acute Inflammatory Demyelinating Polyneuropathy Following Japanese Encephalitis: A Rare Neurological Sequela

Japanese Encephalitis (JE) is a neurotropic viral infection endemic to Asia, primarily transmitted by Culex mosquitoes. While Central Nervous System (CNS) involvement is well-documented, peripheral nervous system complications such as Acute Inflammatory Demyelinating Polyneuropathy (AIDP)—a variant of Guillain-Barré Syndrome (GBS)—remain exceedingly rare. We report the case of a 20-year-old male presenting with altered sensorium, seizures, and progressive limb weakness. Neuroimaging revealed meningoencephalitis with an acute infarct in the left parietal region. Japanese Encephalitis Virus (JEV) IgM antibodies were detected in Cerebrospinal Fluid (CSF), confirming the diagnosis. The patient subsequently developed respiratory failure and flaccid quadriparesis. Nerve conduction studies showed demyelinating sensorimotor polyradiculoneuropathy, consistent with AIDP. Despite immunotherapy with Intravenous Immunoglobulin (IVIg), neurological recovery was minimal, and the patient remained ventilator-dependent. This case underscores the need for heightened clinical vigilance for atypical peripheral neuropathies in JE patients, as early diagnosis and intervention may alter outcomes.