Differential diagnosis of the trapezoid-shaped head.

Objective: To recognize several conditions that result in a trapezoid head shape and review and contrast their various physical findings.

Methods: A detailed review of all patients seen in the Craniofacial Clinic at the Children's Hospital and Regional Medical Center in Seattle, Washington, over a 10-year period from 1991 to 2001, with the diagnosis of craniosynostosis and plagiocephaly was performed. During this period, 690 patients had a surgical correction of craniosynostosis, and 1537 patients had posterior plagiocephaly.

Results And Conclusions: The shape of the head when viewed from the vertex position in an axial plane can be a significant diagnostic aid when evaluating a patient with plagiocephaly. Positional molding causes the vast majority of plagiocephaly. This deformational change results in a parallelogram-shaped head. A much more rare cause of plagiocephaly is lambdoid synostosis. With premature fusion of one of the lambdoid sutures, the head takes on a very characteristic trapezoid shape when viewed from the vertex. Unilateral coronal synostosis that occurs on the same side as either posterior positional molding or unilateral lambdoid synostosis will also result in the trapezoid head shape. Furthermore, on the rare occasion when anterior and posterior deformational plagiocephaly occurs on the same side, the trapezoid head shape may be the consequence. The choice of appropriate treatment modality requires systematic evaluation of the patient with a trapezoid-shaped head to determine the etiology of the deformation.