Dengue encephalitis: what's new?

Abstract

Purpose of review: Neurological manifestations of dengue (NeuroDengue) are uncommon but can often mimic those of other tropical infections. This review aims to present new insights on dengue encephalitis, emphasizing pathogenesis, clinical features, and diagnostic challenges. We highlight unique neuroimaging patterns, observed through MRI, which may aid in diagnosing NeuroDengue. The aim is to significantly enhance early recognition and management of this underreported but severe complication of dengue, providing valuable insights for healthcare professionals.

Recent findings: Recent research has improved our understanding of dengue encephalitis and the neurotropism of the dengue virus in regions such as the thalamus, basal ganglia, and cortex. Notable MRI findings include the 'double doughnut' sign and microhaemorrhages, although these findings are nonspecific and may also appear in other flavivirus encephalitides. A definitive diagnosis requires a positive cerebrospinal fluid (CSF) PCR for the dengue virus, often combined with antibody testing in both CSF and serum. Additionally, elevated levels of IL-6 and TNF-α in CSF indicate enhanced inflammatory responses, which strengthens the early identification of dengue encephalitis and informs potential management strategies.

Summary: Evidence affirms the neurotropic nature of dengue, confirmed by positive CSF PCR results. MRI typically reveals T2 hyperintensities in specific brain areas, along with the presence of micro-haemorrhages, and the 'double doughnut' sign. Recent advancements in diagnostics include analysing CSF dengue antibody indices and neuroinflammatory markers. Dengue serotypes 2 and 3 exhibit heightened neurovirulence, with seizures occurring in 30-40% of cases. While supportive management with fluids is crucial, a subset of patients may benefit from intravenous, immunoglobulin (IVIG) and steroids. Early identification of dengue encephalitis could significantly improve patient outcomes.

Keywords: central nervous system; encephalitis; gengue virus.