Classification and pathogenic models of unintentional postural cranial deformities in infants: plagiocephalies and brachycephalies

Unintentional postural deformities of the skull have increased in a pseudoepidemic manner in the last 15 years. Although dorsal decubitus and prenatal risk factors can play a role in the genesis of such deformities, we think that a crucial determinant is a postnatal defect of cervical mobility responsible for the infant's posture (ie, positional preference) when supine. Indeed, muscular factors, which limit the range of head and neck movements, have been underestimated in the genesis of skull deformities. Here, we have retrospectively analyzed data from 181 infants with unintentional skull deformities and propose a classification of these deformities into 3 types based on their pathogenic model and clinical appearance: fronto-occipital plagiocephalies due to severe muscle hypertonia in which the myogenic component is the first implicated, occipital plagiocephalies with muscle imbalance due to neurogenic muscle hypertonia, and posterior brachycephalies with neurogenic muscle hypertonia of the suboccipital muscles due to trauma to the occipitovertebral junction. Future studies on the size and density of specific muscles or group of muscles should help us to better understand their involvement in the pathogenesis of postural deformities. Our findings also highlight the importance of carefully assessing cervical mobility during the first week of life to detect possible limitations and to prescribe (if needed) an adapted rehabilitation. Rehabilitation should be associated with postural measures put in place when infants sleep supine to prevent the appearance of skull deformations.