Longitudinal followup study of ultrasonography in congenital muscular torticollis.

High-resolution ultrasonography was used to examine affected sternocleidomastoid muscles in patients with congenital muscular torticollis at different times. Thirty-one female and 42 male patients were recruited and classified as having one of four types of fibrosis based on the sonograms. Compared with initial assessment, 22 (95.6%) patients with Type I fibrosis and 22 (57.9%) patients with Type II fibrosis had a change in classification at the end of the study. Among the patients with Type I fibrosis, the classification of one patient was changed to Type III fibrosis, the classifications of two patients were changed to normal muscle, and the classifications of the other patients were changed to Type II fibrosis. For patients with Type II fibrosis, the classifications of two patients were changed to Type III fibrosis, the classifications of three patients were changed to Type IV fibrosis, and the classifications of the other patients were changed to normal muscle. No changes in classification of patients with Types III and IV fibrosis occurred during followup. Patients with Type IV fibrosis had a significantly high incidence of surgical intervention. Congenital muscular torticollis is a dynamic disease. Ultrasonography can be valuable in observing the alteration. Aggressive management may be necessary for patients with Type IV fibrosis.