Intracranial pressure during wakefulness and sleep in 55 adult patients with chronic hydrocephalus.

OBJECTIVE: To record the levels of intracranial pressure (ICP) during wakefulness and sleep in hydrocephalic adults and to correlate the ICP levels with symptoms and degree of improvement after surgical treatment.

METHODS: ICP and patient behavior were registered overnight (17-26 h) in 29 patients with noncommunicating and 26 with communicating hydrocephalus. Mean ICP was calculated during wakefulness (sitting or lying supine) and during sleep. Clinical symptoms and changes after surgery were scored on a continuous scale.

RESULTS: Mean ICP during sleep was 13.4 mmHg (11.1-15.7 mmHg) in noncommunicating hydrocephalus versus 10.1 mmHg (8.8-11.4 mmHg) in communicating hydrocephalus (P < 0.001). Patients with idiopathic communicating hydrocephalus had higher ICP, 11.4 mmHg (9.9-12.9 mmHg), than patients with secondary communicating hydrocephalus, 8.6 mmHg (6.5-10.6 mmHg). ICP was higher during sleep than when the patients were awake lying supine, 10.9 mmHg (8.7-13.1 mmHg) in noncommunicating versus 6.8 mmHg (5.3-8.3 mmHg) in communicating hydrocephalus (P < 0.0001). The mean ICP in the sitting position was 2.4 mmHg (0.5-4.3 mmHg) in noncommunicating versus 0.5 mmHg (-0.7-1.8 mmHg) in communicating hydrocephalus. All but one patient with communicating hydrocephalus had a normal ICP (< or = 15 mmHg) versus 20 of the 29 patients with noncommunicating hydrocephalus. ICP levels showed no correlation with either symptoms or improvement after surgery.

CONCLUSION: ICP is higher during sleep than during periods of awake lying supine (P < 0.001) and is not correlated with either symptoms or the rate of improvement after surgery. ICP is normal in most adults with hydrocephalus.