Validation of Olfactory Questionnaire for Olfactory Assessment after Endoscopic Endonasal Skull Base Surgery

Objective: To evaluate the usefulness of olfactory questionnaire for olfactory assessment after endoscopic endonasal skull base surgery.

Methods: Retrospective review of patient who underwent endoscopic skull base surgery in Seoul National University Bundang Hospital were performed. The subjects were classified into five olfactory function categories based on self-olfactory function assessment: (1) normosmia (“I can always smell.”), (2) mild hyposmia (“I can often smell.”), (3) moderate hyposmia (“I can sometimes smell”), (4) severe hyposmia (“I can seldomly smell”), and (5) anosmia (“I can never smell”). Patients who were normosmia preoperatively and were followed up at least 6 months were analyzed. Quantification of olfactory function was also assessed by Butanol Threshold Test (BTT), Cross Cultural Smell Identification test (CCSIT), and olfactory questionnaires, composed by 14 questions with 1 question on odor occurring in daily life, 9 on specific ordors familiar to Koreans, 3 on trigeminal nerve-related odors, and 1 on olfactory status. Preservation of olfaction was defined when the patient had normal or mild hyposmia by the self-olfactory function assessment after surgery. To assess diagnostic ability for olfactory preservation, receiver operating characteristic (ROC) curves were generated for Butanol Threshold Test (BTT), Cross Cultural Smell Identification test (CCSIT), and questionnaires. A cross table analysis was performed to calculate the sensitivity and positive predictive value (PPV) when olfactory preservation was defined differently by the quantified of olfactory function test; more than 90% of the preoperative value.

Results: Data of 120 patients were collected. Mean age was 46 ± 14.7 years and the male-to-female ratio was 60:60. Preoperative mean values of CCSIT, BTT, and olfactory questionnaire were 9.1 ± 1.7, 9.09 ± 1.73, and 53.76 ± 5.62, respectively. After surgery, 43 patients (35.8%) showed olfactory preservation. Mean CCSIT, BTT, and olfactory questionnaire were 8.86 ± 1.68, 9.58 ± 1.78, and 48.86 ± 9.96, respectively for those who had olfactory preservation. The mean CCSIT, BTT, and olfactory questionnaire were 5.4 ± 3.11, 5.93 ± 2.5, and 13.47 ± 12.73, respectively for those without olfactory preservation. The area under curve (AUC) of CCSIT, BTT, olfactory questionnaires were 0.836, 0.877, 0.977, respectively. Sensitivities for detecting olfactory preservation were 65.1, 72, and 76.7% for BTT, CCIST, and olfactory questionnaires, respectively. Positive predictive values were 62.2, 63.2, and 94.2% for BTT, CCIST, and olfactory questionnaires, respectively.

Conclusion: Despite objective olfactory preservation, many patients have subjective olfactory loss. Questionnaires seem to be superior to objective function test when evaluating postoperative olfactory function after endoscopic endonasal skull base surgery.

 

MissingLinkText

No conflict of interest has been declared by the author(s).

Publication History

Article published online:
15 February 2022