Congenital muscular torticollis is an asymmetrical deformity of the head and neck in which the head is tilted toward the side with the shortened muscle and the chin rotated towards the opposite side. This is caused by unilateral contracture of the sternocleidomastoid muscle.
The term torticolis is derived form two Latin words, tortus, meaning “twisted,” and collum, meaning “neck,.”
Wryneck is a lay term is used to describe torticollis arising from any cause.
The condition is more common in girls than in boys.
The immediate cause of the deformity is fibrosis within the sternocleidomastoid muscle, which subsequently contracts and shortens. The exact pathogenesis of the fibrosis is unknown. Edema, degeneration of muscle fibers and acute inflammation lead to fibrosis.
Brooks also found that permanent occlusion of only the arterial supply of the muscle resulted in extreme atrophy ad necrosis of the muscle but did not cause fibrosis and replacement with fibrous tissue. Intramuscular hemorrhage with or without interference with the nerve or arterial supply did not produce fibrosis. Jepson, in 1926, and Middleton, in 1930, did similar experimental work and arrived at essentially the same conclusions as Brooks.
Right side is involved in about 75 percent of cases.
The exact cause of fibrosis of the sternocleidomastoid muscle in congenital muscular torticollis is not known. Intrauterine malposition is commonly associated with the deformity and possibly it is due to a local ischemic process resulting from intrauterine malposition.
On section, the “tumor” appears white and glistening, in gross appearance resembling a soft fibroma. Microscopic study shows that it consist of dense fibrous tissue. In an older child, after the disappearance of the tumor, tissue excised from the sternocleidomastoid muscle shows that the muscle has been replaced fibrous tissue.
Other findings in the muscle consist of muscle giant cells, loss of transverse striations, vacuolozation, and disruption of endomysial sheaths.
The deformity may be present at birth or it may become evident about the second or third weeks.
The head is tilted towards side of the affected muscle, and the chin is rotated to the opposite side. Rotation of the neck to the side of the deformity and lateral motion to the opposite side are limited.
Palpation reveals a hard, nontender, fusiform swelling, or tumor, in the sternocleidomastoid muscle. Usually both the sternal and clavicular heads are involved. Occasionally only the sternal head is affected. The superior portion of the muscle close to its mastoid attachment is rarely, if ever, involved.
It gradually enlarges during the ensuing two to four weeks, reaching the size of the distal phalanx of the adult thumb. Then it begins to regress and gradually disappears in two to six months.
If the contracture is not treated secondary deformities of the face and head develop. The face on the side of the contracted muscle becomes flattened because of external pressure. The infant usually sleeps in prone posture.
Spontaneously, as it is more comfortable, the neck is rotated so that the affected side is down. Ipsilaterally, the face is flattened by remodeling to conform to the bed. A word of caution is appropriate plagiocephaly can be congenital owing to synostosis of the coronal fissures; this is ruled out by radiograms of the skull.
With skeletal growth, asymmetry of the face increase. The levels of the eyes and ears change, defects that are less noticeable when the head is tilted to one side and more obvious when the head and neck are straight in the midline. Eyuestrain may result from ocular imbalance. A lower cervical-upper dorsal scoliosis with concavity towards the affected side may develop.
If the deformity is not corrected the soft tissues of the affected side undergo adaptive shortening as growth proceeds. The deep cervical fascia becomes thickened and contracted. The scalenus anterior and medius muscles become shortened. Later, the carotid sheath and the enclosed vessels contract.
In rare cases of double torticollis, in which both sternocleidomastoid muscles are affected, the neck is in the midline but appears short, the chin is elevated, and the face is tilted upward.