Central neurogenic hyperventilation in an awake patient with a pontine glioma.

A 57-year-old awake man developed central neurogenic hyperventilation associated with a pontine mass. Serum pH reached as high as 7.72 with serum carbon dioxide of 6 torr. Examination of CSF during overbreathing showed that CSF pH was markedly alkaline. Pathologic study showed a well-differentiated pontine astrocytoma. The combination of alkaline CSF and an infiltrating pontine lesion supports a structural, rather than chemical, mechanism for central hyperventilation.