Validation of a simple method for measuring cranial deformities (Plagiocephalometry)

Craniofacial measuring is essential for diagnosis or evaluation of growth and therapies. Skull deformities in children are mainly caused by craniosynostosis or by external pressure in positional skull deformations. Traditional anthropometry does not sufficiently analyze craniofacial shape. In computed tomography (CT) scanning, radiation loads are considerable. Both CT and magnetic resonance imaging (MRI) scanning require anaesthesia in children for accurate imaging, due to their long acquisition time. This makes CT and MRI unsuitable for long term follow-up of pediatric patients unless there is a compelling reason. Other non-invasive three-dimensional (31)) surface scanners still have limited practical use.Van Vlimmeren et al(6) presented plagiocephalometry (PCM) as a simple and versatile instrument to quantify skull deformities with high intrarater and interrater reliability, but no comparison was made with the actual skull shape.At the Erasmus University Medical Center Rotterdam, Sophia Children's Hospital PCM was compared to 3D-CT scanning in 21 children with craniosynostosis early in life. The PCM ring proved to fit closely to the skin with mean differences less than 1 mm (P <0.05). The shape of the PCM ring was not significantly changed when taken off the head (P > 0.05). Finally, no significant differences are shown between measurements on the skull (CT-scan) and PCM ring off the head (P > 0.05). This study proves that PCM is a reliable method for analysis of skull deformities. The measurements are in agreement with 3D-CT scanning as golden standard. Although only 2-dimensional measurements are performed by PCM, the combination of simplicity, reliability, and validity make it a promising tool for daily practice.