Ultrasound screening of the lambdoid suture in the child with posterior plagiocephaly.

Abstract

The child with posterior plagiocephaly may have positional molding or unilateral lambdoid synostosis. Molding responds to conservative treatment, lambdoid synostosis requires surgical reconstruction. CT is diagnostic, but uses ionizing radiation, may need sedation, and the incidence of lambdoid fusion is only 2-3%. The purpose of this prospective study was to evaluate ultrasound as a screening test of lambdoid sutural patency using CT as the reference standard. In total, 41 children having head CT examinations were enrolled over 6 months. Of those, 29 were referred for abnormal head shape and suspected synostosis, of whom two had lambdoid fusion; 12 were referred for indications not related to head shape and found to have a normal study. Ultrasound scanning and interpretation of the lambdoid sutures was performed blinded to the CT reference standard. The lambdoid suture was read as patent or fused if a hypoechoic gap could or could not be seen between the hyperechoic calvarial bones, respectively. The mean sensitivity and specificity of ultrasound in distinguishing a patent from fused lambdoid suture by three blinded pediatric radiologists was 100% and 89%, respectively. Sonography of the lambdoid sutures shows excellent preliminary promise as a screening test of lambdoid sutural patency.