Comparing Cephalic Index and Midsagittal Vector Analysis in Assessing Morphology in Sagittal Synostosis: A CT-Based...

Assessment of cranial dysmorphism in sagittal synostosis is often subjective but objective measures can be applied. These include cephalic index (CI) and midsagittal vector analysis (MSVA).

To assess discriminant validity, construct validity, and responsiveness of CI and MSVA measured from computed tomography (CT) in patients with sagittal synostosis.

Patients with nonsyndromic isolated sagittal synostosis with complete preoperative (n = 30) and postoperative (n = 13) CT data were included. Age-matched control group (n = 24) comprised of normocephalic patients who underwent CT for reasons related to trauma.

Retrospective CT evaluation of CI and MSVA was conducted and correlated with a dysmorphism numeric rating scale (D-NRS) that measured surgeon-rated severity of sagittal synostosis. Responsiveness of CI and MSVA was evaluated using dysmorphism global rating of change (D-GRC).

Thirty patients with sagittal synostosis were demographically similar to 24 normocephalic patients. The difference in CI and MSVA was statistically significant between normocephalic and scaphocephalic patients. Cephalic index had a good correlation with D-NRS (r = -0.665, ρ = -0.667), but not with MSVA (r = 0.250, ρ = 0.203). Change in CI (r = 0.738, ρ = 0.657) was well correlated with D-GRC, but not with MSVA (r = -0.409, ρ = -0.301).

Cephalic index appears to quantify the severity of sagittal synostosis better than MSVA. Cephalic index also has better responsiveness than MSVA to measure a reduction in severity of disease; however, MSVA is a better descriptive craniometric measurement. Midsagittal vector analysis was able to quantify the shift in morphology in sagittal synostosis following surgical treatment.