From Dengue to Demyelination: A Case of Brainstem Neuromyelitis Optica Spectrum Disorder Following Dengue Fever.

Neuromyelitis optica spectrum disorder (NMOSD) is a rare, autoimmune astrocytopathy characterized by demyelination and predominantly affects the optic nerves and spinal cord. Brainstem involvement, although less common, can lead to atypical presentations that complicate timely diagnosis. We present the case of a previously healthy woman in her early 40s who developed a rapidly progressive and ultimately fatal brainstem syndrome following recovery from dengue fever. She initially experienced intractable hiccups a few days after resolution of dengue-related symptoms. This progressed to dysphagia, excessive drooling, slurred speech, and ultimately respiratory compromise. Neurological examination revealed bulbar dysfunction, and she required ventilatory support within days of symptom onset. MRI of the brain demonstrated T2/FLAIR hyperintensities in the dorsal medulla and inferior olivary nucleus, with additional lesions in the frontal and perirolandic cortices. Notably, there was no evidence of optic neuritis or myelitis. Cerebrospinal fluid analysis was positive for aquaporin-4 immunoglobulin G (AQP4-IgG), confirming the diagnosis of NMOSD. Despite receiving high-dose intravenous methylprednisolone, plasma exchange, and rituximab, her condition continued to deteriorate. She developed aspiration pneumonia and sepsis, ultimately resulting in death. This case underscores the importance of considering NMOSD in the differential diagnosis of isolated brainstem syndromes, particularly in the post-infectious context. Arboviral infections such as dengue may act as immune triggers in susceptible individuals. In endemic regions, early recognition of atypical neurological presentations and timely initiation of immunotherapy are essential to improve patient outcomes and reduce mortality from fulminant autoimmune demyelinating disease.