[Central neurogenic hyperventilation in an awake patient with a primary cerebral lymphoma]

We described clinical and neuropathological findings of a case of primary cerebral lymphoma with central neurogenic hyperventilation (CNH). A 54-year-old awake woman with a primary cerebral lymphoma presented hyperventilation for two weeks. Arterial blood gas showed severe respiratory alkalosis; PH 7.603, PaCO2, 10.5 mmHg, PaO2 129.8 mmHg, HCO2 10.4 mmol/L, BE -8.0, O2SAT 98.9%. Rebreathing from a paper bag, and intravenous administration of diazepam and sodium bicarbonate failed to alter the respiratory pattern. Consecutive CAT scans indicated that CNH didn't occur when the tumor extensively invaded the cerebral cortex, cerebellum, thalamus and basal ganglia but was initiated when the lymphoma invaded the brain stem. Pathological study showed lymphoma cells invaded the cerebral cortex, cerebellum, thalamus and basal ganglia severely, and the brain stem moderately and recently. Contrary to the cases reported by Plum, Lange and Bateman, the lower medulla was also involved. Possible mechanisms for CNH are discussed in relation to the pathological findings and consecutive CAT scan findings.