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Sternomastoid Tumour of Infancy and Congenital Muscular Torticollis 249

of fibrosis is present and in what proportion. More than 50% of children
1
with CMT will have SMT at the time of presentation. The anterior
border of the sternomastoid muscle may reveal a tight band of muscle,
especially in older children. Bilateral sternomastoid tumour with torticollis
creates difficulty in confirming the diagnosis from examination.
Infants with a head tilt will prefer to look away from the affected
muscle. The most important part of the physical exam is to determine the
presence and severity of limitation of passive neck rotation. Gentle neck
rotation with the baby supine and head held over the side of the examining
table should normally allow the chin to reach to or past the shoulder,
90–110 degrees from the neutral position (Figures 38.3 and 38.4). With
CMT, there is limited rotation towards the affected side, which can be
graded as mild (>80 degrees), moderate (45–80 degrees), or severe (<45
degrees) (Figure 38.5). 6
The head should be examined from the back and top of the baby to Figure 38.3: Normal rotation of the neck to the left past the shoulder.
document any plagiocephaly, a flattening of the contralateral occiput that
results from persistent lying on one side; this is sometimes accompanied
by contralateral flattening of the forehead (Figure 38.6).
Mild facial asymmetry may be noted, even at an early presentation;
this asymmetry worsens when the torticollis is severe and untreated. The
degree of hemifacial hypoplasia can be determined by the angle between
the plane of the eyes and the plane of the mouth (Figure 38.7).
Older children with long-standing torticollis may have secondary
compensation resulting in musculoskeletal deformities, including elevation
of the ipsilateral shoulder to maintain a horizontal plane of vision, twisting
of the neck and back to maintain a straight line of sight, and wasting
of the neck muscles from disuse atrophy (Figure 38.8).There may be
accompanying muscle spasm with cervical and thoracic scoliosis.
Developmental dysplasia of the hip (DDH) is seen in 5–8% of
children with CMT, so this should be screened for on the initial physical
examination. Clues on inspection are asymmetric thigh folds and apparent Figure 38.4: Limitation of passive neck rotation towards the right (affected) side.
leg length discrepancy; the Ortolani and Barlow tests for hip stability
should be done. The American Academy of Pediatrics recommends
an ultrasound at 6 weeks of age or radiographs of the hips at 4 months
of age in children at higher risk, which includes girls having breech
presentations. No specific mention is made of torticollis as a risk factor,
7
but DDH may occur in at least 4% of infants with torticollis, so it may be
5
prudent to screen children with hip ultrasound if it is available. Metatarsal
adductus and calcaneovalgus may also be associated with abnormal
intrauterine positioning.
Differential Diagnoses
The clinical features of SMT when associated with CMT are pathogno-
monic and should not be confused with other lateral neck masses, such as
cystic hygroma, branchial cyst, or hemangioma. Enlarged cervical nodes
are rare in infancy, as are neoplasms. Figure 38.5: Measurement of passive range of neck motion from the midline.
Congenital torticollis may present without an SMT, but most will still
have some palpable thickening and shortening of the muscle. If there is
a head tilt without any limitation of rotation of the neck, then causes of
postural torticollis should be considered. These would include congenital
hemivertebra, Klippel-Feil syndrome (atlanto-axial fusion), strabismus,
and Sandifer syndrome caused by chronic gastro-oesophageal reflux (see
Table 38.1). Familial and hereditary sternomastoid muscle aplasia have
also been reported. 8,9
Investigations
Clinical examination confirms the diagnosis of sternomastoid tumour
and torticollis in most cases, and no investigations are routinely required.
However, imaging studies can occasionally be used to exclude other condi-
tions when the clinical findings are equivocal or atypical.
Plain cervical radiographs are of limited use in nontraumatic infant
torticollis due to their low true-positive yield; more false-positives were
10
identified in one retrospective review. In only 1 of 502 cases was there a
Figure 38.6: Right occipital flattening (plagiocephaly) with left sternomastoid
craniocervical anomaly, and the study concluded that physical examination shortening.
could safely eliminate the need for routine radiography in infant torticollis.