Three-Dimensional Assessment of Mastoid and Bony Eustachian Tube Asymmetry in Unilateral Cleft Lip and Palate Versus Alveolus.

ObjectiveTo compare three-dimensional volumetric asymmetry of the mastoid air cell system and bony eustachian tube between patients with unilateral cleft lip and palate (UCLP) and unilateral cleft lip and alveolus (UCLA).DesignRetrospective, exploratory cross-sectional study.SettingA single tertiary referral center in Japan.Patients/ParticipantsForty-one Japanese patients with preoperative computed tomography imaging, including 22 with UCLP and 19 with UCLA. Mastoid air cell volume was analyzable in 19 patients with UCLP and 15 with UCLA after excluding scans with mucosal thickening or opacification that precluded reliable air-space segmentation.InterventionsNone.Main Outcome Measure(s)Three-dimensional volumes of the bony eustachian tube and mastoid air cell system were measured bilaterally. Inter-side asymmetry was calculated as non-affected-side volume minus affected-side volume and compared between groups using Welch t tests.ResultsBony eustachian tube asymmetry did not differ significantly between the UCLP and UCLA groups (0.048 ± 0.076 vs 0.017 ± 0.050 cm3; P = .135). Mastoid air cell asymmetry was significantly greater in the UCLP group (1.371 ± 1.677 vs -0.171 ± 0.884 cm3; P = .002), with a large effect size (Cohen d = 1.11).ConclusionsPatients with UCLP exhibited greater mastoid air cell volumetric asymmetry than patients with UCLA, whereas bony eustachian tube asymmetry did not differ significantly. These findings represent computed tomography-based morphologic differences and should not be interpreted as direct evidence of functional middle ear impairment.