LAUSR

STUDY DESIGN Observational and morphological study with three-dimensional (3D) computed tomography (CT) analysis. OBJECTIVE To discover the morphology and configuration deformities of craniovertebral junction (CVJ) and upper cervical spine in children with unilateral hemifacial microsomia (HFM). To determine whether there are specific HFM patients who are at higher risk of certain cervical vertebral anomaly. SUMMARY OF BACKGROUND DATA The evaluation for cervical vertebrae anomaly in HFM children, especially in craniovertebral junction (CVJ) region, is underreported. METHODS Eighty-eight unilateral HFM children (64 males, 24 females) with 4 Pruzansky-Kaban types (I, IIa, IIb and III) underwent cranial and cervical CT scanning from skull to C5 in neutral position. The 3D morphology and configuration of the occipital condyle, atlas and axis, etc. were evaluated on the presence of deformed detailed structures of CVJ region. RESULTS No C1 deformation was found in type I group. Six (14.3%) type IIa cases, 7 (33.3%) type IIb cases and 6 (37.5%) had lateral masses asymmetry of C1 (P < 0.05). Five (55.6%) type I cases, 17 (40.5%) type IIa cases, 12 (57.1%) type IIb cases and 10 (62.5%) type III cases had C2 anomaly (P > 0.05). The incidence rate of C1-C2 instability for 4 groups were 33.3% (type I), 33.3% (type IIa), 33.3% (type IIb) and 31.3% (type III), respectively (P > 0.05). CONCLUSION For HFM children, the incidence of C1 deformation increased from type I to type III. The probability of C2 anomaly and C1-C2 instability in children with different types of HFM is nearly the same. The craniovertebral junction of every HFM child must be monitored carefully for C1-C2 instability before any surgical procedure to avoid atlantoaxial dislocation and spinal cord injury.