A case of brainstem encephalitis with acute neuropathy associated with prolonged chikungunya viraemia

A 66-year-old man presented to hospital in London, United Kingdom, with back pain and reduced mobility shortly after returning from Chandigarh, India. Examination revealed flaccid paralysis in his lower limbs with absent reflexes and an initially normal upper limb neurological exam. He subsequently developed upper limb weakness with areflexia and truncal, bulbar, and respiratory weakness, and was intubated and ventilated. MRI brain showed features of a brainstem encephalitis centred on the ventral medulla. Neurophysiology showed widespread peripheral acute axonal degeneration, consistent with Guillain-Barré syndrome (acute motor sensory axonal neuropathy variant). He had positive serum chikungunya IgG and IgM and the virus remained detectable by PCR at 34 days post-symptom onset. He had detectable anti-cytokine antibodies. He was treated with high dose steroids, intravenous immunoglobulins, and plasma exchange. He made a good clinical recovery with near normal upper limb and bulbar function, and mild residual leg weakness. In this case we describe a unique neurological presentation of chikungunya infection resulting in concurrent brainstem encephalitis and axonal Guillain-Barré syndrome, associated with a protracted viraemia. Immunological investigations revealed the presence of anti-cytokine antibodies, highlighting the need for improved understanding of host susceptibility to severe manifestations of chikungunya infection.