Craniofacial Anomalies, Part 2 - Plastic Surgery Internal

visceral arches, the intervening first pharyngeal pouch
and first branchial cleft, and the primordia of the
temporal bone. 38
Originally craniofacial microsomia was thought to
represent a progressive skeletal and soft-tissue deformity
that worsens over time, 39 but subsequently
Polley 40 assessed longitudinal cephalometric data from
26 patients with unoperated hemifacial microsomia
and demonstrated that the condition is not
progressive. These findings were further confirmed
by Kearns et al 41 in 67 subjects. The disorder varies
widely in presentation and may range from simple
preauricular skin tags to composite mandibular and
maxillary hypoplasia. Its management depends on
the severity of the defect and the functional and
aesthetic reconstructive needs. 42-46
Pruzansky 44 described three types of mandibular
deficiency in craniofacial microsomia according to
the anatomical area affected (Table 2).
This classification was modified by Mulliken and
Kaban, 47 who subdivided Type II into Type IIA, in
which the glenoid fossa-condyle relationship is maintained
and the TMJ is functional, and Type IIB, in
which the glenoid fossa-condyle relationship is not
maintained and the TMJ is nonfunctional.
Munro’s 42,44 classification extended the skeletal
anomaly to include the orbit. This system aims at
providing a basis for surgical reconstruction and consists
of five types denoting increasingly severe hypoplasia
of the facial bones (Table 3). Isolated microtia
is considered to be a microform of craniofacial
microsomia. 48
Meurman 46 recognizes three grades of auricular
deformity, as follows: Grade I: distinctly smaller,
SRPS Volume 10, Number 17, Part 2
malformed auricle but all components are present;
Grade II: only a vertical remnant of cartilage and
skin is present, with atresia of the external meatus;
Grade III: complete or nearly complete absence of
the auricle.
David and colleagues 49 proposed a multisystem
classification of hemifacial microsomia in the TNM
style. The physical manifestations of hemifacial
microsomia are graded according to five levels of
skeletal deformity (S1–S5) equivalent to the Pruzansky
classification for S1-S3, plus S4 representing orbital
involvement and S5 representing orbital dystopia.
Auricular deformity (A0–A3) is similar to the classification
described by Meurman. Tissue deficiency
(T1–T3) is graded as mild, moderate, or severe. The
SAT sytem allows a comprehensive and staged
approach to skeletal and soft-tissue reconstruction.
Early macrostomia repair (1–2 months of age)
yields excellent functional and cosmetic results. 50
More extensive reconstruction, including composite
correction in moderate to severe deformity, is reserved
for early childhood (age 5–6) but should not wait
until facial growth is complete. 39,42–44,51–54 The mandible
is usually corrected first in the hope that repositioning
the jaw will unlock the growth potential of
the functional matrix to allow normal growth of the
mandible 55,56 and release abnormal growth tendencies
of the maxilla.
In mild cases, Posnick prefers to wait for skeletal
maturity, and employs traditional orthognathic
surgery to achieve favorable aesthetic results. 50 Distraction
osteogenesis provides excellent correction
in cases of mandibular deformity up to Type IIB. 57,58
In cases of Type III deformity, a costochondral
TABLE 2
Mandibular Deficiency in Craniofacial Microsomia (Pruzansky)
5