Intrinsic laryngeal muscle regeneration following endotracheal intubation

The larynges of 33 premature and term neonates who were intubated for the management of respiratory difficulties were studied. In addition to the changes commonly associated with endotracheal intubation (epithelial erosion, ulceration, squamous metaplasia, edema, inflammation, and perichondritis), the intrinsic laryngeal muscles were damaged in 26 of the 33 cases and, in 4 cases, oriented striated skeletal muscle regeneration was found. The active synthetic nature of the myotube formations in the latter cases was confirmed by the demonstration of concentrated vimentin intermediate-filament immunoreactivity. In view of the frequency of neonatal intubation, the probability of muscle damage, and the generally infrequent critical sequelae of this procedure, regeneration of the intrinsic muscles may help to explain the excellent functional recovery of the neonatal larynx. This phenomenon also occurs in the postintubated adult larynx and is therefore not limited to the neonatal period. In addition, these findings support the fact that skeletal muscle regeneration occurs in nonmyopathic human skeletal muscles following injury, as has been shown in experimental animal models.