The laryngeal cough reflex in congenital muscular torticollis: is it a new finding?

Cinical experience has shown us that some infants with congenital muscular torticollis have a cough reflex while stretching the sternocleidomastoid muscle. The objective of this study is to present a case series with the maneuver inducing the cough reflex and facial color change and to provide the possible mechanism underlying this phenomenon. This is a case series from a prospective cohort. Among 290 children with congenital muscular torticollis who came to a single torticollis clinic from January to December 2008, the children who showed cough reflex were consecutively enrolled. Twenty-four infants (8.28%) showed the cough reflex. The age of first presentation with congenital muscular torticollis was 37.65 +/- 19.60 days old. They showed 57.5 +/- 7.3 degrees of the passive cervical rotation to the congenital muscular torticollis side at the initial visit. The mean thickness of the sternocleidomastoid muscle in those with cough reflex was 13.79 +/- 1.96 mm at the side of congenital muscular torticollis and 5.43 +/- 0.85 mm on the contralateral side. The cough reflex disappeared, and 90 degrees of passive cervical rotation to the congenital muscular torticollis side were regained with stretching exercises and/or surgical release in all 24 children. One of the possible mechanisms for this cough reflex is surmised to be the mechanical irritation of the internal branch of the superior laryngeal nerve during the maneuver, which is one of the branches of the vagus nerve and is responsible for the sensation of the mucous membrane of the larynx. 8.28% of the infants with congenital muscular torticollis showed positive sign of cough reflex and had at least double or more thickness of the sternocleidomastoid muscle compared with that of unaffected sternocleidomastoid muscle and, at the same time, had 60 degrees or less of passive cervical rotation toward the affected side. To the best of our literature review, this laryngeal cough reflex is a new finding that has never been described before. One of the possible mechanisms for this cough reflex is surmised to be the mechanical irritation of the internal branch of the superior laryngeal nerve during the maneuver, which is one of the branches of the vagus nerve, acting as the afferent nerve of laryngeal cough reflex.