Summary

Rhomboencephalitis, at least in its acute phase, is often a severely disabling syndrome, and can be life threatening. A range of underlying conditions can lead to this clinical syndrome. Rapid diagnosis to initiate treatment early is key to a beneficial outcome. We report the case of a 22 year old Afro-Caribbean woman, who presented with a two -week history of walking difficulties, upper limb incoordination and slurred speech. Her brainstem function deteriorated at pace, and she developed hypersomnia. A broad diagnostic approach led to prophylactic treatment for the most common infectious causes. This did not improve her symptoms. Non-infectious inflammatory causes were therefore considered and plasma exchange treatment was initiated leading to marked improvement within days. Screening for autoimmune conditions confirmed aquaporin-4 positive neuromyelitis optica spectrum disorder (NMOSD) as the underlying cause. Immunotherapy with rituximab was started. So far, no relapse has been observed. While the definition of NMOSD continues to be refined, aquaporin-4 testing should be considered early in patients presenting with rhomboencephalitis who do not respond to antibiotic and antiviral treatment. Vigilance and early intervention are key to limit morbidity and mortality from NMOSD.