Unilateral lambdoid synostosis: morphological characteristics.

The accurate diagnosis of unilateral lambdoid synostosis versus deformational occipital plagiocephaly has remained a complex and controversial issue in the field of craniofacial surgery. Over the past 30 years, numerous studies have been published describing the treatment for "lambdoid synostosis," the diagnosis having been ascribed despite radiographically patent sutures and pathology specimens displaying fibrous, nonfused suture lines. Over the past 16 years, 204 patients with unilateral occipital plagiocephaly have been seen at our unit, only 2 of whom (approximately 1%) manifested the clinical, radiographic, and pathological features of true lambdoid synostosis. Radiographically, there was evidence of sutural fusion on plain films and two- and three-dimensional computed tomographic scans. Clinical features included a trapezoid head shape as viewed from the vertex, ipsilateral occipitomastoid bossing, contralateral parietal bossing, and anteroinferior ear displacement. Pathology specimens showed bony sutural fusion. These characteristics are contrasted to those of patients with deformational plagiocephaly and those found in other published studies on occipital plagiocephaly.