Delayed symptomatic hyponatremia in transsphenoidal surgery: Systematic review and meta-analysis of its incidence and prevention with water restriction

Delayed symptomatic hyponatremia (DSH) is an unpredictable postoperative complication after transsphenoidal pituitary surgery. Universal postoperative sodium screening and water restriction are two strategies to detect or prevent the development of DSH. We performed a meta-analysis of studies characterizing the rate of DSH using sodium screening and water restriction protocols.Literature search was done using MEDLINE/PUBMED, EMBASE, and Cochrane databases. Inclusion criteria are (1) development of DSH after endoscopic or microscopic transsphenoidal, sellar surgery, and (2) reporting of a standardized postoperative sodium screening protocol for monitoring or prevention of DSH.A total of 23 publications fulfilled the inclusion criteria resulted in a total of 5870 patients. Two meta-analyses were conducted. Of the 19 studies (N = 4488 patients) examining rate of DSH after sodium screening, DSH rates ranged from 0% to 19.7%. In the first meta-analysis, using a random-effect estimate of the combined proportions, the overall rate of DSH was 5.60% (4.0%-7.1%, I2 = 96.54%, T2 = 0.0007). In the second meta-analysis, a fixed-effect model of four studies consisted of 1382 patients. Eight hundred fifty-two patients were included prior to and 530 were included after water restriction protocol. Meta-analysis showed an odds ratio (OR) of 5.02 (95% CI: 2.16-11.65) favoring water restriction.This meta-analysis summarized rates of DSH with sodium screening protocol to be 5.60% (4.0%-7.1%) and showed a decreased risk of DSH after implementation of a water restriction protocol. The results are limited due to few studies examining fluid restriction (N = 4) and heterogeneity in water restriction protocols. No adverse events were seen with fluid restriction protocol. Prospective and multicenter studies should be conducted to further investigate the utility of water restriction following transsphenoidal pituitary surgery.