A study of perioperative lumbar cerebrospinal fluid pressure in patients undergoing acoustic neuroma surgery.

The objective of this study was to measure changes in cerebrospinal fluid (CSF) pressure and cerebrovascular hemodynamics following acoustic neuroma surgery. The subjects were 32 patients undergoing translabyrinthine or retrosigmoid excision of acoustic neuroma. CSF pressure and the amplitude of the CSF pressure pulse wave were measured using lumbar catheters, and all variables were recorded minute by minute on a microcomputer. Transcranial doppler (TCD) was used to measure flow velocity in the middle cerebral artery in 10 patients to monitor changes in cerebral hemodynamics. In the 24 hours after surgery, all patients showed a statistically significant rise in CSF pressure from 11.4 mm Hg (standard deviation [SD] 6.1) to 19.6 mm Hg (SD 5.2) and a corresponding fall in the compliance of the CSF compartment. These changes were reversed within 48 hours, and the CSF pressure fell below the preoperative level over the next 4 days without any drainage of CSF. The results of this study demonstrate a transient increase in CSF pressure and decrease in craniospinal compliance that is provoked by surgery. The most plausible explanation for this disturbance is impaired CSF absorption, which resolves rapidly in most patients without therapeutic CSF drainage.