What is Atlantoaxial Instability?
Atlantoaxial instability or AAI occurs when there is too much of movement between the first two vertebrae of the neck commonly known as atlas (C1) and axis (C2) due to bony or ligament anomalies. These vertebrae surround and protect the spinal cord, so the lack of stability of the joint could injure the spinal cord and may cause neck pain.
Causes of Atlantoaxial Instability
- Trauma: It can occur after an accident, for example a car accident or sport injuries.
- Infection: It can be caused by an upper respiratory tract infection or infection after an operation on the neck and head.
- Rheumatoid arthritis which affects the upper cervical spine.
- Anomalies such congenital scoliosis (curvature of the spine), neurofibromatosis (genetic disorder of the nervous system) and osteogenesis imperfecta (extremely fragile bones)
- Tumours from cancer can weaken the vertebrae and result in AAI.
- Down syndrome
- Larsen syndrome
- Morquio syndrome
- Metatropic dysplasia
- Kniest syndrome
- Odontoid abnormities
- Scott syndrome
- Ankylosing spondylitis
Symptoms and signs of AAI
From the list above you can see there are many possible causes of AAI which is a complicated medical condition. Some patients with serious instability may not suffer from distress or show any symptoms at all. On the other hand some with less severe instability experience extensive problems.
Symptoms may include neck pain or limited head movement, getting weak progressively and occasionally, abnormal gait, difficulty in walking, loss of motor skills, loss of bowel or bladder control, increased muscle tone in the legs, or paralysis in all four limbs. Some patients may suffer from pain at the back of the head, affecting their cranial nerves and a sensation of whirling and loss of balance.
How to diagnose AAI
For an accurate assessment it is recommended that a detailed examination of the nervous system be conducted by a neurologist. This will include screening by physical inspection as well as x-ray. The physical examination may reveal any changes that might exert pressure on the spinal cord. X-rays will be taken of the head and neck for lateral view (side) with the head in a normal position and with the head flexed forward and tilted back.
If the space between the first and second vertebrae is more than 5 millimeters, then it is suggestive of AAI. If the x-rays do not show the exact dislocation, or when tumors are suspected, then CT scans and MRI are recommended.
How to treat AAI
There are several treatment options for AAI and the aim is to protect the spine, decompress the adjacent nerves, lessen any deformity and finally stabilizing the spine.
Medication such as anti-inflammation drug has limited effect on AAI and is used only to reduce inflammation. Traction and brace are other conventional treatment methods.
Chiropractic procedure such as cervical spinal manipulative therapy, or neck cracking, can be risky and result in undesirable side effects. Those suffering from chronic neck pain, headaches and back pain can try massage therapy as it can be pleasant and more relaxing, but it must be done properly to avoid injury.
If surgery is required, a procedure known as posterior fusion can be performed to fuse the two cervical vertebrae to relieve pain and reduce the symptoms.
Children with Down Syndrome should avoid strenuous exercises that exert great amount of strain on their neck and will cause neck pain. These include football, gymnastics, diving and swimming the butterfly stroke, and high jump. They should also have more frequent medical and x-ray follow-ups.