Olfactory outcomes after endoscopic skull base surgery: A systematic review and meta-analysis

Abstract

Objectives: Determine the effect of endoscopic skull base surgery (ESBS) on long-term olfactory outcomes after surgery.

Methods: An English-language search was conducted using the Cochrane, MEDLINE, Scopus, and Embase databases from January 2000 to October 2017 for adult patients undergoing ESBS with subjective and objective olfaction outcomes. Two authors independently examined articles to identify those meeting inclusion criteria. Studies examining objective olfactory outcomes after ESBS were included in the meta-analysis. A random-effects meta-analysis of patients undergoing sellar and parasellar ESBS was conducted to compare preoperative and postoperative olfactory outcomes using the University of Pennsylvania Smell Identification Test (UPSIT) and Cross-Cultural Smell Identification Test (CCSIT).

Results: Among 339 eligible articles, 29 articles met inclusion criteria. Twenty-five of these focused on sellar and parasellar tumors. Individual articles not meeting criteria for meta-analysis were qualitatively reported. Meta-analysis showed there was no difference in preoperative and postoperative olfactory function after sellar and parasellar ESBS based on the UPSIT (five studies, mean difference [MD] = -1.03; 95% CI: -3.98, 1.93; P = .50) and the CCIST (three studies, MD = -0.77; 95% CI: -3.03, 1.49; P = .50). A pooled overall meta-analysis revealed similar results (eight studies, effect size = -0.30; 95% CI: -0.79, 0.18; P = .22). However, heterogeneity for all meta-analyses was high (I² > 95%, P < .01), suggesting significant variation in the included studies.

Conclusions: Based on published objective olfaction outcomes after sellar and parasellar ESBS, there was no significant difference between preoperative and postoperative olfaction. Further prospective studies using validated objective measures of olfaction are required to improve our understanding on this subject.

Level of evidence: 2a Laryngoscope, 129:1998-2007, 2019.

Keywords: Olfaction; anterior skull base; chordoma; endoscopic skull base; expanded endonasal approach; meta-analysis; pituitary; smell; systematic review; trans sphenoid; transclival; transcribriform; transnasal.