What is the Atlantoaxial Joint?
The atlantoaxial joint is where your first cervical vertebra, called the atlas, connects with the second cervical vertebra, which is known as the axis.
The atlas, which has a hollow ring shape, holds your head and allows you to nod your head up and down. The axis contains a peg-like bone that goes up through the center of the atlas and connects with the atlas bone to form a pivot joint. This joint allows your head to rotate.
What Causes Atlantoaxial Instability?
Atlantoaxial instability occurs when you have excessive movement between the atlas and axis. Instability leads to atlantoaxial subluxation or dislocation between the two bones, which in turn can result in compressed nerves.
The causes of atlantoaxial instability fall into three general categories:
- Congenital Conditions: Congenital conditions that may result in atlantoaxial instability include -
- Down syndrome
- Ehlers-Danlos syndrome
- Osteogenesis imperfecta
- Neurofibromatosis
- Morquio syndrome
- Larsen syndrome
- Spondyloepiphyseal dysplasia
- Chondrodysplasia punctata
- Metatropic dysplasia
- Kniest syndrome
*Of all the possible congenital conditions, Down syndrome is the most common cause of atlantoaxial instability.
- Traumatic Injury: Traumatic head injuries, such as those that occur in contact sports or during a car accident, may result in atlantoaxial instability when the trauma damages the ligaments or causes an atlas or axis fracture.
- Inflammatory Disease: When atlantoaxial instability develops in adults, it’s often due to inflammation caused by rheumatoid arthritis. Though rare, inflammation may also develop due to an infection. Whatever the source, ongoing inflammation weakens the ligaments and erodes the bones.
What Symptoms Develop Due to Atlantoaxial Instability?
Atlantoaxial instability causes symptoms such as:
- Neck pain
- Headaches
- Vertigo
- Spasticity
- Pain that’s worse with motion
- Head twisted to one side
- Neck weakness
- Difficulty swallowing
- Tingling or weakness in the arms or legs
You may also develop trigeminal neuralgia, a nerve condition that causes facial pain triggered by movements such as speaking, chewing, or brushing your teeth.
How is Atlantoaxial Instability Treated?
After performing a thorough physical examination, your provider at The Metropolitan Neurosurgery Group orders an X-ray, CT scan, or MRI to determine the severity of your condition. Atlantoaxial instability that causes minimal symptoms may only need close monitoring and conservative treatment, such as temporary immobilization and range-of-motion exercises.
When the joint is unstable, however, surgery is the only treatment available. Your neurosurgeon at The Metropolitan Neurosurgery Group may perform an occipitocervical reduction and fusion or a C1-2 stabilization, surgeries in which the bones are realigned and, with the use of screws and rods, restore stability.
If you sustain a head or neck injury or develop neck pain, call The Metropolitan Neurosurgery Group today.
