Faculty Bibliography

OBJECTIVE:To determine the underlying etiology in a patient with progressive dementia with extrapyramidal signs and chronic inflammation referred to the National Institutes of Health Undiagnosed Diseases Program. METHODS:Extensive investigations included metabolic profile, autoantibody panel, infectious etiologies, genetic screening, whole exome sequencing and the phage-display assay, VirScan, for viral immune responses. An etiological diagnosis was established post-mortem. RESULTS:Using VirScan, enrichment of dengue viral antibodies were detected in cerebrospinal fluid as compared to serum. No virus was detected in serum or cerebrospinal fluid, but post-mortem analysis confirmed dengue virus in the brain by immunohistochemistry, in situ hybridization, quantitative polymerase chain reaction and sequencing. Dengue virus was also detectable by polymerase chain reaction and sequencing from brain biopsy tissue collected 33 months ante-mortem, confirming a chronic infection despite a robust immune response directed against the virus. Immunoprofiling and whole exome sequencing of the patient did not reveal any immunodeficiency and sequencing of the virus demonstrated wild-type dengue virus in the central nervous system. INTERPRETATION/CONCLUSIONS:Dengue virus is the most common arbovirus worldwide and represents a significant public health concern. Infections with dengue virus are usually self-limiting and chronic dengue infections have not been previously reported. Our findings suggest that dengue virus infections may persist in the central nervous system and should be considered in patients with progressive dementia with extrapyramidal features in endemic regions or with relevant travel history. Further, this work highlights the utility of comprehensive antibody profiling assays to aid in the diagnosis of encephalitis of unknown etiologies. This article is protected by copyright. All rights reserved.

Opsoclonus consists of bursts of involuntary, multidirectional, back-to-back saccades without an intersaccadic interval. We report a 60-year-old man with post-concussive headaches and disequilibrium who had small amplitude opsoclonus in left gaze, along with larger amplitude flutter during convergence. Examination was otherwise normal and brain MRI was unremarkable. Video-oculography demonstrated opsoclonus predominantly in left gaze and during pursuit in the left hemifield, which improved as post-concussive symptoms improved. Existing theories of opsoclonus mechanisms do not account for this eye position-dependence. We discuss theoretical mechanisms of this behavior, including possible dysfunction of frontal eye field and/or cerebellar vermis neurons; review ocular oscillations in traumatic brain injury; and consider the potential relationship between the larger amplitude flutter upon convergence and post-traumatic ocular oscillations.