A 2-month-old girl is brought to the clinic for a well-child visit. Her parents are concerned about the back of her head being flat on the right. The infant usually sleeps on her back in a crib but she sometimes naps in a car seat or stroller. She is breastfeeding well and receives vitamin D supplementation. Birth history is significant for a full-term cesarean delivery due to breech presentation. Physical examination shows flattening of the right occiput with anterior displacement of the right ear and forehead. The patient demonstrates a preference to tilt her head to the left while rotating the chin to the right. When the head is turned to the right, there is a firm mass in the inferior portion of the left sternocleidomastoid. The mass does not transilluminate. The hips are stable with no clicks or clunks. Which of the following is the most likely underlying cause of this patient's presentation?

Question

A 2-month-old girl is brought to the clinic for a well-child visit.  Her parents are concerned about the back of her head being flat on the right.  The infant usually sleeps on her back in a crib but she sometimes naps in a car seat or stroller.  She is breastfeeding well and receives vitamin D supplementation.  Birth history is significant for a full-term cesarean delivery due to breech presentation.  Physical examination shows flattening of the right occiput with anterior displacement of the right ear and forehead.  The patient demonstrates a preference to tilt her head to the left while rotating the chin to the right.  When the head is turned to the right, there is a firm mass in the inferior portion of the left sternocleidomastoid.  The mass does not transilluminate.  The hips are stable with no clicks or clunks.  Which of the following is the most likely underlying cause of this patient's presentation?

Quizplus · Accepted Answer

11ec25c8_d746_c982_bc81_254fc43f5b2f_MD0003_00 This infant with a neck mass, ipsilateral head tilt, and contralateral chin deviation has congenital muscular torticollis (CMT). CMT is a postural deformity in which the sternocleidomastoid (SCM) muscle is tight and contracted, likely due to intrauterine crowding (eg, breech positioning [as in this patient], multiple gestation, oligohydramnios). Associated conditions that are also related to prenatal positioning include developmental dysplasia of the hip, metatarsus adductus, and clubfoot. CMT is evident from birth but typically comes to medical attention at age 1-6 months with a head preference to one side. When an infant lies down with the head facing the preferred side, positional plagiocephaly often occurs, which entails flattening of the head on that side as well as anterior displacement of the ear and forehead ipsilateral to the flattening. Limited range of motion of the neck is also present on examination, and SCM thickening or a well-circumscribed mass from muscle fibrosis may be palpable. positional plagiocephaly Treatment strategies include positioning (eg, increased tummy time), passive stretching, and physical therapy. Missed or delayed diagnosis can lead to craniofacial asymmetry. (Choice A) Cystic hygromas are congenital lymphatic malformations located in the posterior triangle of the neck. They are often detected prenatally and associated with aneuploidy. Postnatal examination shows a fluctuant mass that transilluminates. Cystic hygromas (Choice B) Clavicle fractures can occur from birth injury (eg, shoulder dystocia) and present with crepitus, swelling, and decreased range of motion of the ipsilateral upper extremity. Clavicle fractures do not affect the neck. (Choice D) Craniosynostosis (premature closure of cranial sutures) results in skull deformity but not anterior displacement of the ear and forehead. In addition, head tilt and a neck mass would not be seen. Craniosynostosis (Choice E) Acquired torticollis from a posterior fossa tumor is extremely rare and may present with head tilt secondary to tonsillar herniation or compensation for visual disturbances. Neurologic findings (eg, cranial nerve palsy) would be expected on examination, not a neck mass. Educational objective: Congenital muscular torticollis is a postural neck deformity due to tightening of the sternocleidomastoid muscle and presents with ipsilateral head tilt and contralateral chin deviation. A fibrotic neck mass may be present on examination, and limited range of motion of the neck increases the risk of positional plagiocephaly. References: Congenital muscular torticollis and positional plagiocephaly. (http://www.ncbi.nlm.nih.gov/pubmed/24488831) Physical therapy management of congenital muscular torticollis: an evidence-based clinical practice guideline: from the Section on Pediatrics of the American Physical Therapy Association. (http://www.ncbi.nlm.nih.gov/pubmed/24076627)

A 2-Month-Old Girl Is Brought to the Clinic for a Well-Child