Effect of intrathecal saline injection and Valsalva maneuver on cerebral perfusion pressure during transsphenoidal surgery for pituitary macroadenoma.

Cerebrospinal fluid pressure (CSFP) was monitored through a lumbar intrathecal catheter in 32 patients undergoing transsphenoidal excision of pituitary macroadenomas. In the first 20 patients, standardized intermittent Valsalva maneuvers were followed by intrathecal saline injections in 2.5-ml increments. Their effects on CSFP, mean arterial pressure (MAP), and therefore, cerebral perfusion pressure (CPP) were compared. The increase in CSFP produced by one Valsalva maneuver (4 +/- 2 mm Hg) was similar to that produced by a single increment of intrathecal saline (4 +/- 2 mm Hg), but the effect of saline was more sustained. With Valsalva maneuvers, the maximum CSFP produced was 13 +/- 4 mm Hg, and the CPP decreased to 50 +/- 14 mm Hg, whereas with saline, the maximum CSFP was 25 +/- 7 mm Hg, and the CPP decreased to 59 +/- 13 mm Hg. Because the increase in CSFP was greater and better sustained with intrathecal saline, Valsalva maneuvers were omitted in the next 12 patients. Peroperative data, including surgical conditions, and post-operative morbidity, with special reference to low-pressure headache and meningeal infection, were analyzed in all 32 patients. Operative conditions produced with intrathecal saline were judged excellent or good in 75% of patients. However, because this technique can decrease the CPP excessively, we recommend that it be used only with continuous CSFP monitoring.