Vasopressin in the cerebrospinal fluid of patients with normal pressure hydrocephalus and benign intracranial hypertension.

We have studied plasma and cerebrospinal fluid vasopressin (CSF-AVP) and osmolality in 28 patients with cervical or lumbar pain syndromes (control patients), 11 patients with normal pressure hydrocephalus (NPH) and in 5 patients with benign intracranial hypertension (BIH). Vasopressin concentration in lumbar CSF to a high extent reflected the actual ventricular CSF-AVP concentration. In all groups CSF-AVP was lower than plasma AVP. Mean CSF-AVP in the control group was 1.3 pg/ml +/- 0.1 (SEM). In the NPH patients, who all suffered from severe dementia, CSF-AVP level was not different from that found in the control group (1.4 pg/ml +/- 0.2). In contrast to the findings in the two other groups CSF osmolality in BIH patients was higher than plasma osmolality (P less than 0.0). CSF-AVP in the BIH patients, characterized by an elevated intracranial pressure (ICP), was higher than in the control group (2.7 pg/ml +/- 0.4, P less than 0.001).