Central neurogenic hyperventilation

A 79-year-old woman developed subacute progressive gait instability. Brain MRI demonstrated patchy nodular enhancement within the brainstem and cerebellum (figure). Brain biopsy was consistent with chronic lymphocytic inflammation with pontine perivascular enhancement responsive to steroids syndrome (CLIPPERS).1 Questioning revealed shortness of breath (figure, video). Blood gas on room air revealed pH 7.59, PaCO2 16, PaO2 103, and HCO3 15.