Intracranial Volume and Cephalic Index Outcomes for Total Calvarial Reconstruction among Nonsyndromic Sagittal Synostosis Patients

Abstract

Controversy abounds as to how craniosynostosis affects intracranial volume and whether more extensive procedures achieve superior results. Intracranial volume and cephalic index were evaluated among nonsyndromic sagittal synostosis patients undergoing cranioplasty. Twenty-four children with isolated nonsyndromic sagittal synostosis underwent a total calvarial reconstruction. Volume and cephalic index measurements were taken 1 month preoperatively, 1 month postoperatively, and at 1-year follow-up. Data obtained were compared against normative value curves, and interval shifts between curve SD ranges were noted. The absolute percentage difference between the observed intracranial volume or cephalic index and the correlated normative mean value (absolute mean percentages) was calculated for each scan. Preoperatively, intracranial volume for patients younger than 30 months (n = 19) was within the normal range (+/-1 SD), whereas it exceeded 1 SD in all patients older than 30 months (n = 5). Postoperatively and at follow-up, intracranial volume range was unchanged for patients younger than 30 months but was decreased to normal for 60 percent of those older than 30 months. Absolute mean volume percentage showed a small increase from preoperatively for patients younger than 12 months (p < 0.05), no change for patients aged 12 and 30 months, and decreased for patients older than 30 months (p < 0.05). Postoperatively, all patients demonstrated a normal intracranial volume growth rate. As for cephalic index, preoperatively, 92 percent of patients fell below the minimum normal values. At follow-up, 100 percent had a cephalic index in the normal range (p < 0.05). Nonsyndromic sagittal synostosis results in an age-dependent increased intracranial volume and decreased cephalic index. Total calvarial reconstruction (1) appears to allow for the expansile forces of the growing brain to be distributed and may relieve an underlying abnormality; (2) does not affect postoperative intracranial volume growth rate; and (3) enables normalization of cephalic index.