Major clinical features of synostotic occipital plagiocephaly: mechanisms of cranial deformations.

PURPOSE: The clinical diagnosis of most common single-suture craniosynostosis is easily set, based on the stereotype of deformities and knowledge of the mechanisms of cranial deformations. However, synostosis of unilateral lambdoid suture, probably due to its lower incidence and similarity with other non-synostotic deformities affecting the posterior portion of the skull, makes its clinical diagnosis more difficult and imprecise. The aim of this study is to evaluate the most easily and accurate clinical characteristics to be recognized in the synostotic occipital plagiocephaly. METHODS: This study consisted of clinical evaluation of eight patients with synostotic occipital plagiocephaly, whose diagnosis was further corroborated by computed tomography. RESULTS: We identified the following: unilateral occipital flattening in eight out of eight patients (100 %), bulging of ipsilateral mastoid process in eight out of eight (100 %), "edge effect" of ipsilateral lambdoid suture in eight out of eight (100 %), inferior deviation of the ear in eight out of eight (100 %), "Dumbo" ears in eight out of eight (100 %), horizontal slant of the bimastoid line in seven out of eight (87.5 %), tilt of the head viewed from behind in seven out of eight (87.5 %), trapezoidal contour of the skull in top view in six out of eight (75 %), contralateral parietal bossing in six out of eight (75 %), and bossing of the contralateral forehead three out of eight (37.5 %). CONCLUSIONS: The most important clinical features specific to the clinical diagnosis of synostotic occipital plagiocephaly, not present in the positional posterior plagiocephaly, were bulging of the ipsilateral mastoid process, edge effect of the synostotic lambdoid suture, tilt of the head, and slant of the bimastoid line viewed from behind, inferior deviation of the ear, and contralateral parietal bossing.