Craniocervical Junction Syndrome: Anatomy of the Craniocervical and Atlantoaxial Junctions and the Effect of Misalignment on Cerebrospinal Fluid Flow

The craniocervical junction (CCJ) is comprised of the inferior surface of the skull, the atlas and axis, as well as muscles and connective tissues that attach the skull to the cervical spine. The CCJ encloses the central nervous system (CNS), encephalic vasculature and the cerebrospinal fluid (CSF) system. The CCJ spans the brainstem to the spinal cord, including the vascular system as well as connecting the cerebrospinal fluid (CSF) cisterns within the skull to the CSF channels in the spinal canal. Malformation and misalignment of the craniocervical junction can cause a constellation of cerebral and other neurological signs and symptoms collectively called craniocervical syndrome (CCS). The signs and symptoms of craniocervical junction syndrome may be due to mechanical strain causing deformation of dura mater, vasculature and other structures of the cranial vault resulting in irritation of and dysfunction of affected tissues. Deformation of the CCJ may also obstruct blood and CSF flow. Chronic ischemia, edema and hydrocephalus can cause degenerative cascades that can in turn lead to neurodegenerative diseases