Mandibular Deformation - Clinical Tree

KEY POINTS

Congenital compression of the chin can limit jaw growth before birth and result in asymmetric jaw retrusion.
An asymmetric mandible can be secondary to an altered cranial base or a condylar abnormality secondary to genetic or environmental factors.
Skin redundancy under the chin suggests pressure-induced growth restriction of the jaw.
Asymmetric mandibular growth deficiency is often associated with muscular torticollis and can indicate associated congenital muscular torticollis.
Failure to treat underlying muscular torticollis can result in persistent mandibular asymmetry, facial scoliosis, and rotatory cervical spine subluxation.
Effective treatment of torticollis can resolve most of the associated jaw asymmetry by the end of the second year.

GENESIS

Intrauterine constraint and positional deformation have been proposed as possible extrinsic causes of mandibular hypoplasia. Congenital compression of the chin against either the chest or intrauterine structures may limit the growth of the jaw before birth; when asymmetric jaw retrusion is more commonly left-sided ( Fig. 23.1 ). If the compression is of prolonged duration, there may be pressure indentation or skin necrosis on the upper thoracic surface. As shown in Fig. 23.1 , one deformational cause of asymmetric mandibular growth deficiency is prolonged oligohydramnios. Asymmetric mandibular growth deficiency with a laterally tilted mandible is most commonly the result of head rotation with one side of the mandible compressed against the shoulder or chest, and it is commonly associated with muscular torticollis on the same side as the deficient mandible ( Fig. 23.2 ). Such asymmetric mandibular growth deficiency is often the first indication that an infant might have associated congenital muscular torticollis.

FIGURE 23.1, A , This infant was delivered abdominally from an extrauterine location behind the uterus with marked distortion of the face and jaw. Respiratory insufficiency associated with oligohydramnios led to death shortly after birth. B and C , This infant was also an abdominal pregnancy; her head was under the mother’s stomach, and her feet were under the gallbladder. D–F , This infant experienced prolonged oligohydramnios with transverse lie owing to premature rupture of the amnion at 26 weeks, with delivery at 36 weeks. D and E , There is striking mandibular growth restriction with necrotic neck folds. F , At age 30 months, mandibular growth deficiency persisted.

FIGURE 23.2, These twins were born at term to a primigravida woman; the left twin was carried in a prolonged vertex presentation low in the uterus. This twin had severe congenital left muscular torticollis at birth ( A and B ), which responded well to neck physical therapy, although mild jaw asymmetry was still evident at age 7 months ( C–E ).

If the ear on the side of the small jaw is dysplastic or microtic, or if there are associated ear tags or epibulbar dermoids, a diagnosis of oculoauriculovertebral sequence (OAVS), Goldenhar syndrome, or craniofacial microsomia should be considered ( Fig. 23.3 ). OAVS is etiologically heterogeneous, and a careful family and gestational history, renal ultrasound, and cervical vertebral radiographs may help evaluate the possibility of an associated syndrome ( Figs. 23.4–23.6 ). Muscular torticollis with mandibular asymmetry results from late gestational fetal constraint, whereas OAVS with mandibular asymmetry occurs in early gestation as part of a malformation syndrome. Symmetric undergrowth of the jaw occurs with Pierre Robin malformation sequence with associated posterior cleft palate and glossoptosis ( Fig. 23.7 ). This condition is etiologically heterogeneous, with an estimated incidence of 1 in 8500–14,000 live births. The concept that this may result from intrauterine constraint in some cases is based in part on an increased incidence of Pierre Robin in twins. Skin redundancy under the chin suggests pressure-induced growth restriction of the jaw, especially when there is no associated cleft posterior palate ( Fig. 23.8 ), whereas unilateral mandibular growth deficiency with an associated sulcus that corresponds with compression by the shoulder suggests congenital muscular torticollis (see Fig. 22.3A ). In an eloquent study by Parada et al. in 2015, they were able to generate a murine model phenocopy of the human Pierre Robin sequence, culturing maxilla and palate tissue separate from the tongue and mandible. They were able to rescue the tongue and palate phenotype, highlighting the interconnection of early palate, tongue, and mandible development.