Do sinus computed tomography findings predict olfactory dysfunction and its postoperative recovery in chronic rhinosinusitis patients?

BACKGROUND: Olfactory dysfunction secondary to chronic rhinosinusitis (CRS) is a mixed disorder of conductive and sensorineural olfactory impairment. Although endoscopic sinus surgery has some beneficial effects on olfaction, the outcomes are challenging to predict. The aim of this study was to assess the olfactory outcomes after surgery, to investigate the correlation between the severity of regional computed tomography (CT) findings and olfactory performance, and to identify the predictors of postoperative outcomes based on unilateral olfactory threshold analysis.

METHODS: This study included 167 CRS nostrils of 97 patients with/without polyps (68/99 nostrils) undergoing sinus surgery between January 2007 and December 2011. Olfactory function was evaluated using the butanol threshold test (BTT) before and 6 months after surgery. Clinical and nasal factors from sinus CT scan (sinuses, ostiomeatal complex, olfactory cleft [OC], nasal polyps, and unilateral Lund-Mackay CT score) were analyzed to correlate them with pre- and postoperative olfactory performances.

RESULTS: Eighty-two percent of the CRS nostrils had anosmia or hyposmia. After surgery, 42% of them showed an improvement in BTT score. Despite improvement, most of the subjects remained with residual hyposmia. The BTT scores deteriorated after surgery in 23% of the total subjects. The disease severity of the OC, posterior ethmoid, and frontal sinus were the significant risk factors for CRS-related anosmia. The strongest risk factor for anosmia was totally obstructed OC (odds ratio [OR], 16.56; 95% CI, 4.31-63.71; p = 0.000). The nostrils with anosmia or partly opacified anterior ethmoid benefited from surgery with respect to olfaction.

CONCLUSION: Our results can give support to the combined use of the butanol threshold and sinonasal CT findings in the evaluation of olfaction in CRS patients and help us counsel the patients about the likelihood of postoperative olfactory recovery.