POSTERIOR CRANIAL DYSMORPHISM - CLASSIFIC ATION AND ORIGINAL TECHNIQUE - TURNED BIPARIETAL FLAP TRANSPOSITION

The deformation of the posterior part of the skull (occipito-vertebral region), induced directly or indirectly, occurs in numerous pathologi cal situations. Its significance is frequently overlooked. Lesions of the cranial content, alterations of the lambdoid suture or other prema ture synostosis, abnormal constraint related to posture or to muscular activity can modify the posterior curvature of the skull, generally f lattening it.The authors propose a classification based on three point s : Intracranial pathology : alterations of the brain or CSF fluid can induce either insufficient (microencephaly) or excessive (hydrocephal us, Dandy Walker or Arnold Chiari malformations) expansion. Bone patho logy : craniosynostosis: sagittal synostosis (scaphocephaly) induces a bulging and coronal synostosis a flatness of the posterior skull. Bil ateral premature lambdoid synostosis (pachycephaly) produces total fla tness of the back of the skull. Extrinsic pathology: dysmorphism is of ten asymmetrical and results from extracranial mechanical application dysfunction such as inborn torticollis, cervical spine pathology (Klip pel-Feil syndrome), or prolonged decubitus during the first year of Li fe. The authors describe a personal technique for correcting this dysm orphism : the turned biparietal flap transposition. The back of the sk ull is remodelled (either asymmetrical or bilateral flatness), and pat ients with no need for a helmet can lie on their backs immediately aft er the operation.