Isolated hypoglycorrachia: leptomeningeal carcinomatosis causing subacute confusion.

We report a 76-year-old caucasian man who presented with a 3-week history of progressive confusion. His past medical history included a left nephro-uretectomy for poorly differentiated transitional cell carcinoma 9 years previously. Besides his confusion, his clinical and neurological examination was unremarkable. Extensive investigation revealed only isolated hypoglycorrachia and mildly elevated CSF protein. Cerebral CT and MRI scans without contrast did not reveal any abnormalities. As his condition continued to decline, an MRI scan of the brain with gadolinium was performed which revealed extensive nodular enhancement of the surface of the cerebellum and brainstem and both temporal lobe convexities. Repeat lumbar puncture showed malignant cells in the CSF and confirmed the diagnosis of leptomeningeal carcinomatosis. This case illustrates that leptomeningeal carcinomatosis should be considered in the differential diagnosis of cognitive decline in the elderly, after other common aetiologies have been excluded. The index of suspicion should be increased in patients with a prior history of cancer.