Teaching NeuroImages: Extensive vasogenic edema in Bickerstaff brainstem encephalitis

Ten days after respiratory infection, a 32-year-old woman presented with headaches, ataxia, and diplopia without encephalopathy. Brain MRI revealed extensive white matter, brainstem, and cerebellar vasogenic edema, without gadolinium enhancement, partially regressive during follow-up (figure, A). CSF revealed transient elevated protein level (1.01 g/L) and hypercellularity (123 neutrophils/mm(3)). Negative anti-GQ1b but positive anti-GD1a immunoglobulin G led to the diagnosis of Bickerstaff brainstem encephalitis (BBE). Symptoms resolved within 10 days without treatment. (18)FDG-PET showed bilateral temporo-parieto-occipital and cerebellar hypometabolism (figure, B). Neurologists should be aware that diffuse brain hypometabolism or vasogenic edema can be associated with BBE.(1,2</SUP)