[Clinico-radiological study of the skull deformation in the plagiocephaly without synostosis]. / Etude clinico-radiologique des déformations du crâne dans les plagiocéphalies sans synostose.

ABSTRACT

UNLABELLED The aim of this study was to analyze the mechanism of the skull deformation observed in frontal and occipital plagiocephaly without synostosis. POPULATION AND METHODS: From 1987 to 2001, 96 plagiocephalies without synostosis, 72 males and 24 females, were examined. There were 72 Frontal Plagiocephalies (FP) and 24 Occipital Plagiocephalies (OP). The clinical examination of the neck muscles was performed to find out a torticolis with or without retraction. All patients underwent a 3D CT scan of the skull to exclude a craniostenosis. Cephalic Index (CI) was also calculated. RESULTS: The FP had a torticollis in 89.3% of cases associated with a muscle retraction (54.8%), a tonus asymmetry (16.6%), or in association (28.6%). The skull had a parallelepiped shape and the greater axis was oblique. The CI was 0.85. The OP had a torticollis in 50% of case associated with a retraction (28.6%), a tonus asymmetry (57.1%), or the association (14.3%). The skull had a square shape with an occipital flat and the CI was 0.95. DISCUSSION: The FP and OP are two deformations whose mechanism is different. The FP corresponds to a three plans skull asymmetry secondary to muscle traction on the base of the skull, and the OP corresponds to a posterior localized asymmetry of the skull secondary to compression. CONCLUSION: The traction and/or compression deformation start in utero or in the newborn period and the supine position is an aggravating positional factor.