Neurological Manifestations of Chikungunya; A Case Series from 2025 Outbreak in Sri Lanka

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Abstract
Background: During the 2024–2025 Chikungunya virus (CHIKV) resurgence in Sri Lanka, atypical neurological manifestations (neuro-CHIKV) emerged. We aimed to define the clinical, diagnostic, and longitudinal profiles of these patients. Methods: This descriptive case series at National Hospital Galle (April–September 2025) evaluated 11 adults (median age 59; five >60 years) presenting with neurological symptoms and serologically confirmed CHIKV infection. Results: Central nervous system (CNS) involvement predominated (n=9). Acute presentations (≤7 days) included encephalitis (n=4) and meningoencephalitis (n=1) and delayed presentations (≥7 days) featured late-onset encephalitis (n=3), acute disseminated encephalomyelitis (n=1), and peripheral syndromes (Guillain-Barré variant, Bell's palsy). Reduced consciousness affected 7 out of 9 CNS cases, occasionally compounded by acute kidney/liver injury or profound hyponatremia. Diagnostically, 30% exhibited atypical cerebrospinal fluid profiles (hypoglycorrhachia or hyperproteinorrhachia without pleocytosis) mimicking bacterial meningitis. Neuroimaging revealed variety of radiological findings such as non-haemorrhagic acute necrotizing encephalopathy, a spinal cord "H-sign" and isolated bilateral caudate/putamina hyperintensities. Early systemic corticosteroids (≤7 days, n=4) correlated with favourable functional recovery, whereas delayed initiation yielded negligible responses in 2 out of 3 patients. Overall mortality was 18.2% (n=2), and 62.5% of survivors exhibited persistent non-severe neurological or rheumatological sequelae at three months. Conclusion: Neuro-CHIKV poses a high-mortality diagnostic challenge due to atypical clinical, biochemical and neuroradiological presentations. Early immunomodulation with therapeutic options such as steroids was associated with favourable neurological recovery and warrants prospective evaluation.