What Is Atlantoaxial Subluxation?

Atlantoaxial dislocation refers to the loss of normal mating relationship between the atlantoaxial and pivotal vertebrae (the first and second cervical vertebrae) caused by congenital deformity, trauma, degeneration, tumor, infection, inflammation, and surgery. Pathological changes in the disorder and / or nerve compression.

Basic Information

English name

atlantoaxial dislocation

Visiting department

orthopedics

Common locations

Cervical spine

Common causes

Congenital malformation, trauma, degeneration, tumor, inflammation, surgery, etc.

Common symptoms

Pain in the neck of the neck, torticollis, restricted neck movements, unstable or weak grips, weak walking, weak stools, muscle atrophy, paralysis, dizziness, etc.

Causes of atlantoaxial dislocation

The causes of atlantoaxial dislocation can be divided into three categories: congenital, traumatic and congestive. Congenital atlantoaxial dislocation is mainly due to the development of the dentate process of the vertebrae and / or the insufficiency of the transverse ligament of the atlas, which is the pathological basis of congenital atlantoaxial dislocation. The developmental abnormalities of the dentate process can be divided into the following types:

1. The dentate process, that is, the dentate process, is not fused to the vertebral body.

2. The terminal bone, that is, the dentate process tip, is not fused with the dentate process root.

3. The dentate process is not developed, that is, the dentate process is absent.

4. Dentate process basal hypoplasia, that is, only dentate process tip.

5. The dentate apex does not develop, that is, there is only a short dentate apical root.

Clinical manifestations of atlantoaxial dislocation

1. Pain in neck and neck.

2. Torticollis and neck movement are restricted.

3. Upper spinal cord injury can be manifested as muscle tension in the whole body, unstable or weak grips, easy to break water cups and rice bowls; weak walking, easy to fall; weak stools; atrophy of limb muscles; severe paralysis, or even endanger life.

4. Dizziness, tinnitus, blurred vision, chest tightness, palpitations, and elevated blood pressure.

5. Patients with Arnold-Chiari deformity and cerebellar tonsil hernia may have symptoms such as low general muscle strength and easy fall.

Atlantoaxial dislocation

1. X-ray inspection

(1) Anterior atlantotoid space (AD1): 5 to 10 mm has a transverse ligament rupture and some auxiliary ligament ruptures, and 10 to 12 mm indicates that all ligaments are broken.

(2) Spinal cord compression occurs when the atlantoaxial spinal canal space (SAC) is less than 14 mm. Spinal cord compression may occur in patients with 15-17 mm, and no spinal cord compression symptoms occur in patients with 18 mm or more.

(3) Atlantoaxial instability index (II) has symptoms of spinal cord compression greater than 30%, and indications for surgery when greater than 40%.

2.CT inspection

Can clearly observe the atlantoaxial structure changes and the degree of spinal cord compression.

3.MRI examination

Can more clearly observe the spinal cord compression morphology, location, degree, scope, and whether the spinal cord signal is abnormal.

Atlantoaxial dislocation treatment

The treatment of atlantoaxial dislocation is to relieve the spinal cord compression, stabilize the cervical spine joints, and prevent relocation.

Conservative treatment

For spontaneous atlantoaxial dislocation, jaw occipital traction is generally required for 3 weeks. After the reduction is stable, a plaster including head, neck and chest is made and fixed for 6 to 8 weeks. Such as unilateral dislocation can be surgically reduced and cast fixed. For anterior dislocation of the atlas due to congenital detachment of the dentate process, hypoplasia of the dentate process, and development of the atlantotransverse ligament, cranial traction is feasible until autogenous sacrum and occipital bone are restored under local anesthesia. It is not necessary to perform laminectomy with 1st to 3rd cervical spine fusion, or wire occipital bone fixation to 1st to 3rd cervical spine.

2. Surgical treatment

For a long time of dislocation, the dentate process heals and fixes at the displacement, and it cannot be reset after traction. The pressure on the ventral and dorsal sides of the spinal cord can be treated with surgery.

Prognosis of atlantoaxial dislocation

Atlantoaxial dislocation may compress the upper cervical spine due to slight head and neck injuries or excessive flexion and extension of the cervical spine. Patients may suddenly die with paralysis of the spine or even paralysis of the respiratory muscles, which requires timely diagnosis and treatment.