Rebound phenomenon complicating cerebral dehydration with glycerol. Case report.

A patient with glioblastoma multiforme of the brain was treated with both intravenous and oral glycerol as well as intravenous mannitol in an attempt to reduce increased intracranial pressure. After an initial lowering of the cerebrospinal fluid (CSF) pressure to near normal values during continuous glycerol administration, a secondary rise in CSF pressure above the initial level occurred despite a persistent elevation of plasma osmolality (315 mOsm/kg) and glycerol level (30 mmole/l). Similarly, 4 hours after the administration of a single oral dose of glycerol, CSF pressure increased to levels higher (700 mm H2O) than the original baseline (400 mm H2O).