Craniocervical Junction Disorders

In one kind of CV junction disorder, the odontoid process is out of normal position, compressing the brainstem from the front.

Spine disorders may occur in the area where the skull base and upper cervical spine vertebra come together — a region called the craniocervical junction. The craniocervical junction is made up of the occipital bone (the bone that forms the base of the skull) and the first two bones in the upper spine. These are located in the neck and are called the atlas and axis.

The large opening at the bottom of the occipital bone is called the foramen magnum. Important structures pass through this opening, including the lowest part of the brain (brain stem), which connects to the spine, along with some nerves and blood vessels. Because the brain stem controls most of the body’s vital functions, disorders here can result in serious neurological problems.

Craniocervical junction disorders may also be referred to as upper cervical disorders or craniovertebral (CV) junction disorders.

Craniocervical junction disorders may be caused by:

Bones that have fused incorrectly
Tumors, primary or metastatic eroding structures in this region
Rheumatoid arthritis or other conditions causing a pannus
Previous skull or spine surgery weakening this region such as Chiari decompression
Bones that have been fractured from serious trauma
Ligamentous injury from trauma causing alignment of strength deficits
Ligamentous injury from a collagen disorder such as Ehlers-Danlos or Down syndrome

Disorders that affect the craniocervical junction can put pressure on the spinal cord, brain or cranial nerves, causing paralysis, weakness and loss of sensation.

What Causes Craniocervical Junction Disorders?

Some craniocervical junction disorders are congenital, which means they are present at birth. Some of these disorders — called isolated disorders — affect only the craniocervical junction. Craniocervical junction disorders can also be the result of conditions that affect many other parts of the body, such as achondroplasia (a genetic condition that affects bone growth) and Down syndrome. Many patients with craniocervical issues have congenital issues with Collagen production or integrity meaning the MRI scans can look ok but there is excess movement of the bones which can impact upon the nerve or brainstem with motion. Ehlers Danlos Syndrome is a major disorder in which collagen strength is diminished leading to hypermobility in many joints including the craniocervical junction.

Craniocervical junction disorders may also occur later in life. They can result from injuries, such as a motor vehicle or bicycle accident, falls or diving. Conditions that can also cause craniocervical junction disorders later in life include: