Background: Velopharyngeal inadequacy (VPI), which has a significant negative impact on speech intelligibility and resonance quality, may be caused by physiological inadequacy. The current study aimed to investigate the maximal velar and pharyngeal motions and levator muscle shortening in the children with repaired cleft palate and different speech outcomes as well as children without cleft palate by using magnetic resonance imaging techniques without general anesthesia.
Methods: Three groups of sex- and age-matched children were recruited: children with repaired cleft palate and adequate velopharyngeal function condition (VPC), children with repaired cleft palate and VPI, and the normal controls (noncleft). The children were trained to perform sustained /a:/, /i:/, /ts:/, and /m:/, while keeping the head still during magnetic resonance imaging scan. The maximal velar elevation and stretch, pharyngeal medial constriction, velopharyngeal ratio (VP ratio), and levator muscle shortening ratio were measured and compared across the 3 groups.
Results: The VPI group showed the least maximal velar stretch, lowest maximal velar height, smallest maximal pharyngeal constriction, and lowest maximal VP ratio among the 3 groups. The VPI and VPC groups differed significantly in velar and pharyngeal mobility. The effective VP ratio at rest has a strong correlation with that during sustained phonation across the 3 groups. The maximal velar stretch ratio correlates to the maximal pharyngeal constriction ratio strongly in the VPI group only.
Conclusions: The VPI group had significantly reduced velar and pharyngeal mobility during speech compared with the VPC and noncleft groups. The possible physiological causes of VPI after primary palatal repair were discussed.