Hypoglycorrhachia in leptomeningeal carcinomatosis. A pathophysiological study.

We describe a patient with leptomeningeal carcinomatosis in whom no primary malignancy was found in spite of extensive laboratory investigations. The diagnosis was supported, however, by cytological and biochemical CSF examination. Of particular interest in this setting was the low level of glycorrhachia. In order to understand better the mechanism of hypoglycorrhachia, the patient was subjected to I.V. glucose loading; serial samples of blood and CSF were obtained to determine glucose and lactic acid levels. We found that: 1) The low CSF glucose concentration was not increased by I.V. infusion of sugar; 2) the high basal CSF lactic acid level was not further stimulated by I.V. glucose loading. These data suggest that hypoglycorrhachia was not due to an increased utilization of glucose by neoplastic cells that infiltrate the meninges but to abnormal transport of glucose from blood to CSF.