ORBITAL DYSMORPHOLOGY IN UNILATERAL CORONAL SYNOSTOSIS

Unilateral coronal synostosis (UCS) produces overt craniofacial dysmor phology UCS surgery in infancy aims to release the osseous restriction and normalize the fronto-orbital deformity. The quantitative effect o f this surgery on the orbit and its contents is unknown. This study wa s conducted to quantify the preoperative orbital dysmorphology and its surgical outcome in patients with unilateral coronal synostosis. Twen ty-eight UCS patients had preoperative three-dimensional computerized tomographic (CT) scans (at mean age 4.0 months), cranio-orbital recons tructive surgery (at 4.7 months), and postoperative scans (at 18.1 mon ths). The CT data were analyzed using a computer workstation and Analy ze(TM) biomedical imaging software. Four measurements were performed o n both ipsilateral (same side as synostosis) and contralateral (opposi te to synostosis) orbits of each scan: orbital index (OI, 100 x height /width of orbit), orbital cavity volume (OV), ocular globe volume (GV) , and ventral globe index (VGI, 100 x globe volume ventral to the ante rior surface of orbital cavity/GV). The data were analyzed for statist ical significance using Student's t test. Preoperatively, the 01 was s ignificantly greater on the ipsilateral than on the contralateral side (113.7 vs. 87.3). There was a significant improvement on both sides o f the orbit postoperatively, with ipsilateral 99.1 and contralateral 9 2.1. However, the difference between both sides remained significant. The OV was smaller in the ipsilateral orbits both pre- and postoperati vely, with ipse/contralateral ratios of 95.8 and 95.2, respectively. I mportantly, the GV was consistently smaller in the ipsilateral orbits preoperatively, with an ipse/contralateral ratio of 93.3. The ratio in creased to 97.1 postoperatively, a statistically significant change. I n the ipsilateral orbits, the preoperative VGI was significantly great er. The VGI improved postoperatively. These data indicate that UCS aff ects the development of the osseous orbit as well as its soft-tissue c ontents. After cranio-orbital surgery, there is diminution of asymmetr y of both the bony orbit and its soft-tissue contents. Partial normali zation of orbital dysmorphology occurred during the first postoperativ e year. UCS surgery in infancy does not prevent growth of orbital hard or soft tissues, and it seems to permit normalization of previously i mpaired growth.