Effect of Cleft Palate Repair on the Susceptibility to Contraction-Induced Injury of Single Permeabilized Muscle Fibers from Congenitally-Clefted Goat Palates

Abstract

Objective-Despite cleft palate repair, velopharyngeal competence is not achieved in ~15% of patients, often necessitating secondary surgical correction. Velopharyngeal competence postrepair may require the conversion of levator veli palatini muscle fibers from injury-susceptible type 2 fibers to injury-resistant type 1 fibers. As an initial step to determining the validity of this theory, we tested the hypothesis that, in most cases, repair induces the transformation to type 1 fibers, thus diminishing susceptibility to injury.Interventions-Single permeabilized levator veli palatini muscle fibers were obtained from normal palates and nonrepaired congenitally-clefted palates of young (2 months old) and adult (14 to 15 months old) goats and from repaired palates of adult goats (8 months old). Repair was done at 2 months of age using a modified von Langenbeck technique. NIH-PA Author ManuscriptNIH-PA Author Manuscript NIH-PA Author ManuscriptMain Outcome Measures-Fiber type was determined by contractile properties and susceptibility to injury was assessed by force deficit, the decrease in maximum force following a lengthening contraction protocol expressed as a percentage of initial force.Results-For normal palates and cleft palates of young goats, the majority of the fibers were type 2 with force deficits of ~40%. Following repair, 80% of the fibers were type 1 with force deficits of 20% ± 2%; these deficits were 45% of those for nonrepaired cleft palates of adult goats (p < .0001). (Elahi et al., 2004;Forrester and Merz, 2004; CDC, 2006). Following surgical repair, 10% to 20% of patients are still not able to achieve velopharyngeal closure (Marrinan et al., 1998), resulting in abnormal speech and other functional deficits that often necessitate secondary surgical correction. This outcome is typically a consequence of either inadequate palatal length or insufficient movement of the pharyngeal walls or soft palate. Soft palatal movement is dependent on the proper functioning of soft palate musculature (Kogo et al., 1996;Marrinan et al., 1998;Berry et al., 1999). Levator veli palatini (LVP; abbreviations listed in Table 1) muscle fibers from normal palates are aligned transversely across the posterior soft palate and when activated during velopharyngeal closure, retrodisplace and elevate the palate (Kogo et al., 1996;Marrinan et al., 1998;Berry et al., 1999). Impairment of LVP muscles of patients with cleft palates may contribute to the incidence of velopharyngeal dysfunction postrepair. Conclusion-TheThe functionality of the LVP muscle is dependent on the fiber-type composition (Hanes et al., 2006; Rader et al., 2006). For normal palates of adult humans (Stal and Lindman, 2000;Lindman et al., 2001) and goats (Hanes et al., 2006; Rader et al., 2006), LVP muscles consist primarily of slow oxidative (type 1) fibers. In contrast, the LVP muscles in nonrepaired cleft palates are oriented in a longitudinal direction, abnormally insert on the posterior hard palate, and at least for adult goats, are predominantly...

Isolation and Characterization of Satellite Cells from Rat Head Branchiomeric Muscles

“…In contrast, cleft muscles contain a higher proportion of fast fibers and also a reduced capillary supply compared with normal soft palate muscles [29][30][31] . Fast fibers are more prone to contraction-induced injury [31][32][33] . The accompanying poor capillary supply may also promote fibrosis 34,35 .…”

The Effects of Age at Cleft Palate Repair on Middle Ear Function and Hearing Level

“…The hearing level returns to normal at an average of 6 years after the operation, and the longest noted delay was 17 years. An animal study conducted by Rader et al (2008) demonstrated that the palate muscle fiber may exhibit adaptive alterations after palatoplasty, that is, type II muscle fibers transformed into type I after surgery and gradually form a normal distribution of muscle fiber types, which benefits speech and hearing restorations.…”

Strategies to Improve Regeneration of the Soft Palate Muscles After Cleft Palate Repair

“…25 Further, fast fibers are more prone to contraction-induced injury. 24,26,27 Muscle Regeneration in the Soft Palate…”