Effect of Veau Class on Levator Veli Palatini Muscle Composition

Objective: To examine levator veli palatini muscle composition in patients with nonsyndromic cleft palate and investigate the impact of Veau class.

Design: Prospective cohort study.

Setting: Tertiary care academic hospital.

Patients/participants: Thirteen patients with nonsyndromic cleft palate were recruited.

Interventions: During primary palatoplasty, a sample of levator veli palatini muscle was excised and prepared for histological analysis.

Main outcome measures: Fat and collagen content were determined utilizing Oil Red and Sirius red stains, respectively, while muscle fiber cross-sectional areas were calculated from H&E-stained samples, with analysis using histomorphometric methods. Immunofluorescent staining of myosin heavy chain isoforms was performed.

Results: Patients underwent repair at 10.8 months of age (interquartile range [IQR] 10.2-12.9). Fat content of the levator veli palatini muscle was low in both groups, ranging from 0% to 5.2%. Collagen content ranged from 8.5% to 39.8%; neither fat nor collagen content showed an association with Veau classes. Mean muscle fiber cross-sectional area decreased with increasing Veau class, from 808 µm² (range 692-995 µm²) in Veau II to 651 µm² (range 232-750 µm²) in Veau III (P = .02). There was also a nonsignificant decrease in proportion of type I muscle fibers with increasing Veau class (44.3% [range 31.4%-84.4%] in Veau II vs 35.3% [range 17.4%-61.3%] in Veau III).

Conclusions: Muscle fiber area in levator veli palatini muscles decreases in Veau III clefts in comparison to Veau II. The impact of these differences in velopharyngeal dysfunction requires further analysis of a larger cohort.