Snapshot A 2-day-old boy is evaluated in the newborn nursery for a neck deformity. He was born at 39 weeks gestation and was noted at birth to have bilateral clubfeet. On exam, the top of his head is tilted to the left and his chin is rotated to the right. His left sternocleidomastoid muscle is dystonically contracted. An ultrasound of his neck demonstrates no masses or cysts. Introduction Clinical definition "packaging deformity" caused by a contracture of the sternocleidomastoid (SCM) muscle "torticollis" is derived from Latin words "tortus" (crooked) and "collum" (neck) Epidemiology Demographics most common cause of infantile torticollis usually noted in first 3 months of life Risk factors traumatic delivery Etiology Unknown etiology but may be due to birth trauma or intrauterine malposition intrauterine compartment syndrome of the SCM muscle Pathoanatomy normal anatomy SCM muscle origins anterosuperior manubrium and medial clavicle insertion mastoid process of temporal bone actions flexes neck to the ipsilateral side and rotates head to the contralateral side innervation spinal accessory nerve (cranial nerve XI) aberrant anatomy contracture of the SCM will lead to head tilting to the affected side and head rotation to the unaffected side Associated conditions other packaging disorders congenital talipes equinovarus (clubfoot) metatarsus adductus developmental dysplasia of the hip (DDH) plagiocephaly (asymmetric skull flattening) Presentation Symptoms head tilt and rotation noticed by parents the condition is typically not painful associated neck pain should suggest an alternative diagnosis Physical exam child's head is tilted to the affected side and the chin is rotated to the unaffected side palpable contracted SCM muscle resides over time and becomes a tight band as the patient ages Imaging Ultrasound indication used to differentiate between contracted SCM and a neck mass or cyst findings contracted muscle tissue in the case of congenital torticollis cystic or solid mass in the case of a congenital neck mass Treatment Conservative physical therapy to stretch affected SCM muscle indication first-line treatment Medical botulinum toxin injection indication second-line treatment if physical therapy is not effective Complications Permanent rotational deformity Positional plagiocephaly asymmetric flattening of the skull due to an imbalanced positioning of the skull while the infant is supine Facial asymmetry Differential Congenital neck mass cysts and tumors can be distinguished from a contracted SCM by ultrasound branchial cleft cyst thyroglossal duct cyst sternocleidomastoid tumor of infancy Atlantoaxial rotatory subluxation neck pain is common SCM spasm may occur on the same side as the chin in contrast to congenital torticollis in which the chin will be rotated away from the affected side