Pathophysiology of Acquired Cholesteatoma Associated With Habitual Sniffing: An Analysis Based on Mastoid Cell Development and Contralateral Ear Status.

OBJECTIVE: To examine the association of habitual sniffing with mastoid cell development and contralateral ear abnormalities in acquired pars flaccida cholesteatoma. STUDY DESIGN: Retrospective comparative study. SETTING: Two tertiary referral hospitals. PATIENTS: A total of 124 adults (133 ears) underwent primary surgery for acquired pars flaccida cholesteatoma between 2012 and 2026. INTERVENTIONS: Primary cholesteatoma surgery. MAIN OUTCOME MEASURES: Mastoid cell development score classified according to the Japan Otological Society criteria and abnormal contralateral ear findings. RESULTS: Habitual sniffing was identified in 67 of 133 ears (50.4%). The sniffing group had higher MC scores than the non-sniffing group, indicating better mastoid cell development (1.48±0.68 vs. 1.17±0.67; effect size r=0.222; P=0.010). Ordinal logistic regression showed that habitual sniffing was independently associated with better mastoid cell development [odds ratio (OR)=2.35; 95% confidence interval (CI), 1.15-4.87; P=0.020]. Among 110 ears with evaluable contralateral endoscopic findings, contralateral abnormalities were more frequent in the sniffing group than in the nonsniffing group (71.4% vs. 35.2%; OR=4.536; P=0.0002). Binary logistic regression showed that habitual sniffing was independently associated with abnormal contralateral ear findings (OR=4.57; 95% CI, 1.94-11.34; P=0.0007). CONCLUSIONS: Habitual sniffing was associated with better mastoid cell development and frequent contralateral ear abnormalities in acquired pars flaccida cholesteatoma, suggesting a distinct pathophysiologic subgroup related to dynamic negative pressure loading.