Occipitocervical synostosis: case report

Fusion of atlas with the occipital bone is a rare congenital anomaly known as occipitocervical synostosis, occipitalization of atlas, assimilation of atlas or atlanto-occipital fusion. We describe two cases of occipitocervical synostosis identified amongst one-hundred dry adult human occipital bones from the collection of Ege University, School of Medicine, Department of Anatomy (incidence 0.5%). The synostosis was complete type for both cases. Occipitocervical synostosis is clinically important as it may cause narrowing of foramen magnum which may compress the brainstem, vertebral artery and cranial nerves, and during surgical approaches to the craniovertebral region. Keywords: atlanto-occipital fusion; occipital bone; occipitalization of atlas; occipitocervical synostosis