Cerebrospinal fluid vasopressin and increased intracranial pressure.

Cerebrospinal fluid and plasma vasopressin were measured in patients with cerebral disorders associated with varying levels of elevated intracranial pressure. The mean cerebrospinal fluid vasopressin concentration was significantly increased in patients with pseudotumor cerebri (2.0 +/- 0.2 [SEM] pg/ml), intracranial tumor (2.3 +/- 0.4 pg/ml), and intracranial hemorrhage (1.9 +/- 0.3 pg/ml) compared with control patients (1.2 +/- 0.1 pg/ml). A significant relationship was found between intracranial pressure and the cerebrospinal fluid vasopressin concentration within all groups of patients and in the whole sample as well (r = 0.79; p less than 0.001). In the groups of patients with intracranial tumor, hydrocephalus, and intracranial hemorrhage, some individuals showed plasma vasopressin concentrations inappropriate to the corresponding plasma osmolality, but no relationship was found between intracranial pressure and plasma vasopressin concentration. It is suggested that increased intracranial pressure is a stimulus to centrally released vasopressin. The clinical importance of increased cerebrospinal fluid vasopressin concentrations is still not known.