Occipito-Vertebral Dissociation in Connection with Extensive Cervical Spine Malsegmentation in a Boy with Möbius Syndrome

Abstract

Mobius1 syndrome has drawn attention to patients with congenital, non-progressive bilateral facial and abducens palsies. Anomalies of other cranial nerves, such as the hypoglossal (XII), craniofacial, or orofacial nerves, and limb malformations are often encountered in association with Mobius syndrome. The etiology and pathogenesis of Mobius syndrome are still controversial. Patients with Mobius syndrome are generally asymptomatic, but increasing age and injury may precipitate symptoms. Though most cases are sporadic, a few families with hereditary Mobius syndrome have been described.1–4 Vertebral abnormalities are not a well-known feature in patients with Mobius syndrome. None the less, fusion of one or more contiguous segments results from the embryological failure in normal spine segmentation.5 This phenomenon is most likely the result of a decreased local blood supply during the third to eighth week of fetal development.6 In patients with vertebral fusion premature degenerative changes at adjoining motion segments are common, as this condition results in greater biomechanical stress in adjoining segments. Discal tears, rupture of transverse ligaments, fractures of the odontoid process and spondylosis are common consequences. Injuries to the atlanto-occipital region can range from complete atlanto-occipital or atlanto-axial dislocation to nondisplaced occipital condyle avulsion fractures.7–10 In the present case study, we detected pre- and postnatal injuries by analyzing the details of cervical spine ligamental and osseous disruptions by MRI imaging. The combination of occipito-vertebral dissociation (distraction-separation) associated with extensive cervical spine malsegmentation can be considered as a novel syndromic variant associated with Mobius syndrome.