Digital Analysis of Ultrasonographic Images in Children With Wry Neck

Torticollis is a clinical sign or symptom that could be the result of a variety of underlying disorders. Among the etiologies, Congenital muscular torticollis (CMT) with impairment of the sternocleidomastoid (SCM) is the most frequent cause of torticollis in infants. CMT is a postural deformity detected at birth or shortly after birth, primarily resulting from unilateral shortening and fibrosis of the SCM muscle. Infants with CMT display head tilt to one side, which is often combined with rotation of the head to the opposite side. CMT is estimated to occur in one infant of every 300 live births. Plagiocephaly is reported as a coexisting impairment in 80% to 90.1% of children with CMT.

The pathophysiology and etiology of SCM impairment in CMT is still unknown. Prominent theories related to the cause of SCM impairment in CMT include intrauterine crowding, muscle trauma during a difficult delivery, soft tissue compression leading to compartment syndrome, and congenital abnormalities of soft tissue differentiation within the SCM muscle.

Children with CMT can be assigned to one of three clinical subgroups: 1) children with a palpable swelling or pseudotumor of the sternocleidomastoid, 2) children with SCM tightness but no tumor, and 3) children with all the features of muscular torticollis without muscle tightness or tumor.

In 2002, Chih-Chin Hsu et al. reported that CMT could be classified into four types. Type I denoted a heteroechoic mass in the affected muscles; Type II represented diffuse echogenic dots and lines against the hypoechoic background with no detectable mass. The alignment of perimysium appeared irregular instead of parallel on longitudinal sonograms; Type III indicated diffuse hyperechoic echogenicity along the entire muscle and almost no hypoechoic background could be seen; and Type IV had a hyperechoic band in the involved muscles. The study also evaluated the histology of each type of fibrosis. Type I and II fibrosis revealed hyperplastic fibrous tissue mingled with muscle fiber. Mature fibroblasts with complete absence of normal muscle tissue could be found in Type III fibrosis and the fibrotic bands in Type IV fibrosis. The majority of Type I and II fibrosis improved after conservative treatment. However, Type III and Type IV had more probability in need of surgical correction. However, this categorization lacks of objective and quantitative measurement and can be different by subjective judgement of different physicians. The purpose of this study is tried to perform digital analysis of ultrasonography images to establish an objective, quantitative method and to assess its relevance with clinical symptoms and prognosis.

General Design:

This study is planned to quantify ultrasonography image of wry neck patients by digital analysis.

Subjects:

This study will collect the children younger than 1 y/o who were impressed or suspected to have torticollis in physical medicine and rehabilitation clinic. The case number is estimated around 60 in a 3-year-period enrollment. . Exclusion criteria include torticollis by other known causes like strabismus, trauma, neurogenic problems, congenital malformation or bony deformity (e.g. hemivertebrae of cervical spine). Informed consent will be given to the parents before enrollment.

Investigation Steps:

1. Ultrasonography examination and digital analysis: Ultrasonography which contains both sides of the sternocleidomastoid muscle in transverse and longitudinal view for comparison of lesion side and sound side will be performed by expert physicians using a 14-megahertz linear-array transducer after the initial enrollment and every six months later. Digital analysis of the images will be carried by a member expert in computer science.
2. Evaluation of clinical manifestations: Evaluation of clinical manifestations includes measurement of side difference of angles in bilateral neck lateral flexion, rotation and habitual head position will performed using an arthrodial protractor by a trained member at the beginning of physical therapy and one month later, then every 2-3 months. Each measurement will be repeated 3 times to get the mean value. All cases will be followed for 1 and a half years, however, if the symptoms got completely recovery (the neck range of motion and position completely equal to sound side) or any complications resulting from the evaluation, the evaluation will be stopped.
3. Evaluation of influence of rehabilitation effect:

The parents will be inquired by a questionnaire one month later and then every 2-3 months to realize the treatment effect of the wry neck. The duration and frequency of massage and stretch programs by the therapist or the family or the other methods to treat the problem like wearing a neck collar, proper positioning… etc will be included in the semi-quantitative questionnaire.

Data Analysis:

Some representative image features will be expected to be computed from the SCM ultrasonic images. These features include area, both max and min Feret's diameters, and brightness of echogenicity in the region of interest. The ultrasonic image of the affected side would be compared with that of the sound side from their corresponding texture features. The Pearson's correlation will be performed to analyze the relevance of quantitative side differences of texture features in ultrasonography and clinical manifestations including side differences of neck rotation, lateral flexion and habitual head position between lesion sides and sound sides. Linear regression will be also used to adjust the influence of the treatment effect.