Atlantoaxial Instability

Children with atlantoaxial instability have excess mobility in their necks. In severe cases, this extra mobility causes the bones of the neck to compress the spinal cord, which can cause temporary or permanent spinal cord injury.

Your spine is made up of bones called vertebrae that are stacked on top of each other from the bottom of your back to the top of your neck. The front of each vertebra is solid bone and has a ring in the back. The spinal cord runs through these rings.

The atlantoaxial joint is the joint between the top two vertebrae, “C1” and “C2.” This joint makes it possible to move your head from side to side or up and down, providing more mobility than in any other part of the spine.

If the atlantoaxial joint becomes too mobile, however, your child may have a head tilt or put their spinal cord at risk.

• Head tilts to one side
• Neck pain and headaches
• Trouble grasping objects or other motor functions
• Unsteady crawling or walking

Atlantoaxial instability is a rare condition that can be caused by an accident or trauma. In some cases, it develops for no known reason.

Some conditions increase the chance a child will develop atlantoaxial instability:

• Down syndrome, a genetic condition often accompanied by loose joints and low muscle tone
• Morquio syndrome, a genetic condition that damages tendons and ligaments
• A tumor or other abnormalities in the neck or skull

Diagnosing atlantoaxial instability starts with a physical exam and review of your child’s symptoms and any health conditions that could be related. Your child’s doctor will also assess your child’s range of motion, pain, and changes in your child’s coordination or movement.

The following imaging studies can help diagnose atlantoaxial instability:

• X-rays show the overall alignment of the spine and if the bones move excessively.
• CT scans provide detailed pictures of the vertebrae in the neck to identify signs of fracture.
• MRIs provide images of tissues and structures around the spine to help doctors look for signs of damage.

If your child has mild atlantoaxial instability with few symptoms, their spine specialist may suggest bracing or halo gravity traction with physical therapy. If this is the case, your child should have regular follow-up visits so their doctor can monitor their spine over time and watch for any signs of spinal cord damage.

In most cases, children with atlantoaxial instability need spinal fusion surgery to stabilize the spine. Because atlantoaxial instability involves the spine, spinal cord, and surrounding nerves, your child’s surgical team ideally should include specialists in both pediatric neurosurgery and spinal surgery.

• The neurosurgeon will reposition any bones that are compressing the spinal cord or surrounding nerves.
• The spine surgeon will stabilize the spine with rods and screws and place bone grafts around the vertebrae.

Following surgery, your child will need to wear a brace to stabilize their neck while they heal and the vertebrae will fuse into solid bone.

The Complex Cervical Spine Program at Boston Children’s Hospital treats infants, children, and young adults with atlantoaxial instability and other rare cervical spine abnormalities. As the first and largest multidisciplinary program of its kind in the country, we have proven that combining the expertise of specialists in neurology, neurosurgery, and orthopedic surgery improves the safety and outcomes of complex spine surgeries. 

The Pediatric Rehabilitation Medicine Program develops intervention and rehabilitation strategies for children with atlantoaxial instability to help them achieve function and independence. By working with patients and families to understand how their condition affects their quality of life, we’re able to develop therapy and interventions to help them meet their goals. We also work closely with all of the specialists involved in a child’s care to ensure their rehabilitation plan is safe, effective, and appropriate to their needs.