Craniofacial Dysmorphology in Unilateral Coronal Synostosis Using Three-Dimensional Landmark-Based Analysis With Generalized Procrustes Superimposition.

BACKGROUND

Geometric morphometric analysis with Procrustes superimposition is an advanced computational tool that can be used to quantify dynamic changes in complex three-dimensional structures. The present study couples high resolution CT imaging with a Geometric Morphometric approach in order to further understand the complex dysmorphology that occurs in unilateral coronal synostosis (UCS).

METHODS

Forty-one UCS patients and 41 age- and sex-matched controls received high-resolution CT imaging. Thirty-one anatomical landmarks were identified on each imaging set. A geometric morphometric workflow was used to perform a Procrustes superimposition to register landmarks into a common space. Procrustes-aligned landmarks were used to derive angle calculations, lengths, and other anatomical measurements. Three-dimensional coordinates were also used to perform a principal components analysis (PCA).

RESULTS

Unilateral coronal synostosis patients exhibited significant angular deviation at the levels of the inferior skull base, mid-posterior fossa, and vertex. Both left- and right-sided UCS patients showed increased lengthening in the transverse (left-right) dimension, exhibiting increased length between the left and right EAC (P = 0.047). Conversely, UCS patients revealed shortening in the midline AP dimension as evidenced by the decreased Nasal root-Lambda (P < 0.0001) and Nasal root-superior dorsum sellae (P = 0.01) distances compared with controls. PCA revealed that 25.26% of variation in shape among the patients sampled to be driven by flattening of the skull and that18.93% of variation was driven by right-sided deformity and mediolateral expansion.

CONCLUSIONS

Significant dysmorphology between UCS patients and controls was quantified using Geometric Morphometric approach, which may be useful in further characterizing the dynamic craniofacial changes in UCS.