Birth Complications and Intrauterine Constraints in the Etiology of Congenital Muscular Torticollis: A Nationwide Registry Study

Congenital Muscular Torticollis (CMT) is a condition affecting infants, characterized by a shortened and tightened sternocleidomastoid muscle (SCM), resulting in abnormal head positioning. Despite various theories, the exact etiology of CMT remains unclear. Two primary hypotheses include birth trauma and intrauterine crowding. Some studies have suggested an association between CMT and operative deliveries, whereas others have found no such association. Similarly, intrauterine crowding, such as in multiple pregnancies, has been proposed as a contributing factor due to mechanisms like ischemia or compartment syndrome.

While most children with CMT experience a mild condition that resolves with stretching and physiotherapy, a notable overrepresentation of complicated deliveries has been observed among patients requiring surgical intervention for CMT. This study aims to further explore these hypotheses by analyzing data from the Norwegian Medical Birth Registry (MFR).

Study Objectives The primary objective of this study is to compare the prevalence of operative deliveries and indicators of intrauterine crowding between individuals diagnosed with CMT and the general population. The study seeks to determine whether complicated deliveries and/or crowding are overrepresented among patients with CMT. Specifically, the study will investigate whether there is an increased occurrence of restricted intrauterine conditions or operative deliveries in CMT patients compared to the general birth cohort. If a significant association is found, it would support the hypothesis that these factors contribute to the development of CMT.

Expected Outcomes By conducting this study, we expect to contribute to a better understanding of the potential causes of CMT. The findings may improve early identification and potentially influence obstetric and neonatal management strategies.

Methods This is a registry-based study utilizing anonymized data from the Norwegian Patient Registry (NPR) and linking it to the MFR. The study will identify a cohort of individuals diagnosed with CMT and a matched control group (1:4) from the general population.