Atlantoaxial dislocation

Introduction to atlantoaxial dislocation Atlantoaxial dislocation refers to the loss of normal mating relationship between the atlantoaxial and atlantoaxial (first and second cervical vertebrae) osteoarticular surfaces caused by congenital malformations, trauma, degeneration, tumor, infection inflammation and surgery. Pathological changes in disorders and/or nerve compression. basic knowledge The proportion of illness: 0.18% Susceptible people: no specific population Mode of infection: non-infectious Complications: cerebellar tonsil

Causes of atlantoaxial dislocation

(1) Causes of the disease

The causes of atlantoaxial dislocation can be divided into three types: congenital, traumatic and congestive. The congenital atlantoaxial dislocation is mainly due to the development of the odontoid process and/or the instability of the transverse ligament of the atlas. It is the pathological basis of congenital atlantoaxial dislocation.

(two) pathogenesis

The odontoid process is a pivot between the anterior arch and the transverse ligament of the atlas. At the 6th month of embryonic development, there are two lateral ossification centers at the root of the odontoid. At the time of birth, these two ossification centers It is fused into a bone column, which appears in the ossification center of the odontoid tip when the baby is 2 years old, and has a cartilage disc between the dentate root and the vertebral body. At the age of 12 years and adolescence, the dentate root and the vertebral body, The dentate root and the tip gradually merge. If the mesoderm cells of the first neck segment of the fourth occipital ganglion stop moving during the embryo, the development or dysplasia of the odontoid process may occur, and the developmental malformation of the odontoid process may be Divided into the following types:

1. Tooth-like bone: the odontoid is not fused with the vertebral body.

2. Terminal bone: the dentate tip is not fused with the dentate root.

3. The odontoid process is not developed: that is, the odontoid process is absent.

4. Dysplasia basal dysplasia: that is, only the dentate tip.

5. The dentate tip is not developed: that is, there is only a short dentate root.

The odontoid process is not fused with the vertebral body or is too short. This pathological change makes the atlas vertebrae unstable on the pivotal vertebrae. Even if the head is slightly traumatized or the head and neck are overactive, causing repeated injury, the atlantoaxial dislocation can gradually occur. Or subluxation, especially in the occipital fusion malformation, is more prone to atlantoaxial dislocation, because the extension and flexion of the ankle joint is lost, this activity is transferred to the atlantoaxial joint, thereby increasing the tension of the transverse ligament of the atlas Gradually make it stretch and slack, over time, causing instability of the atlantoaxial joint, combined with the influence of head gravity, the occurrence of atlantoaxial dislocation or subluxation, because the unfused odontoids move more with the anterior arch, so the anterior dislocation More common, less dislocation.

Congestive atlantoaxial dislocation, also known as spontaneous atlantoaxial dislocation, often secondary to inflammation of the neck, such as inflammation of the throat, rheumatoid arthritis, ankylosing spondylitis, etc., more common in children before the age of 13, Adults can also occur. This dislocation can be unilateral or bilateral, and congestive atlantoaxial dislocation is acquired, and will not be described here.

Atlantoaxial dislocation prevention

The disease is caused by trauma directly acting on the cervical vertebra, such as kicking, falling or riding across the injury. Therefore, pay attention to living habits, high-risk workers, such as construction workers, mining workers are prone to damage, should pay attention to protect themselves in the course of work. Pay attention to calmness and avoid emotional conflicts leading to the disease. Secondly, early detection, early diagnosis and early treatment are also important for the prevention of this disease.

Atlantoaxial dislocation complications Complications cerebellar tonsil

It may be complicated by congenital diseases such as skull base collapse and cerebellar tonsil malformation.

Atlantoaxial dislocation symptoms common symptoms dysphagia spinal cord compression

1. Symptoms of dislocation itself: The symptoms of atlantoaxial dislocation have neck pain, sometimes to the shoulders, neck muscle spasm, and head movement disorders.

2. Symptoms of surrounding tissue and organ involvement: In the anterior atlantoaxial dislocation, the anterior arch of the atlas is protruding to the posterior pharyngeal wall, and dysphagia occurs. The posterior process of the spinous process is obvious and often tender. If it is unilateral anterior dislocation, it appears. The head posture is abnormal, the head and neck are biased toward the dislocation side, and the lower jaw is turned to the opposite side.

3. Spinal cord compression symptoms: In the atlantoaxial dislocation, the anterior and posterior diameter of the spinal canal is narrowed to a certain extent, and the spinal cord can be compressed, and the spinal cord is compressed. Especially the odontoid is in situ and the atlas is displaced by the spinal cord. To be serious, the patient may have symptoms of upper cervical spinal cord compression after minor trauma to the head and neck, such as transient limb pain or numbness. When the dislocation is aggravated, different degrees of hard limbs of the extremities may occur, accompanied by dysfunction of the bowel and bladder.

4. Vertebral artery compression symptoms: simple atlantoaxial dislocation generally does not produce brain symptoms, but atlas dislocation can make the vertebral artery stroke more curved or cervical flexion and extension activities are affected, and even partial or complete vertebral artery occlusion occurs, and the vertebrae - Insufficient blood supply to the basilar artery, and medullary and spinal cord blood supply disorders.

Atlantoaxial dislocation examination

X-ray cervical plain film is the main method for diagnosing this disease. The performance of atlantoaxial dislocation on cervical X-ray film is:

1. Orthotopic mouth opening piece: the distance between the odontoid process and the block on both sides of the atlas is asymmetrical, and the asymmetry of the bilateral block and the joint of the vertebral body or the disappearance or overlap of the joint space of one side is a sign of dislocation.

2. Lateral radiograph: the distance between the anterior arch of the atlas and the front of the odontoid is not more than 2.5mm in normal, and not more than 4.5mm in children. If it exceeds this range, it is anterior dislocation, and the odontoid is not fused or fractured. The free odontoid tip is often displaced forward with the anterior arch of the atlas, and sometimes at the upper edge of the anterior arch of the atlas, and the lateral tomography is more clear.

The symptoms of cervical spinal cord compression are not obvious. If you want to check the instability of the atlantoaxial joint, you can take a side of the patient's seat and bend it back to observe the presence or absence of subluxation. If necessary, CT scan of the cervical spine is feasible. Sagittal reconstruction, the observation is more clear.

Diagnosis and diagnosis of atlantoaxial dislocation

diagnosis

Atlantoaxial dislocation is not difficult according to its clinical manifestations and cervical X-ray examination, but other combined malformations should be noted.

Differential diagnosis

1. Cervical spondylosis: This disease is more common in middle-aged and elderly people. It is caused by cervical disc degeneration, bone hyperplasia and ligament hypertrophy. It has a series of symptoms and signs such as cervical nerve root, cervical spinal cord, vertebral artery and cervical sympathetic nerve compression. X-ray examination of the cervical spine is helpful for diagnosis. Cervical spondylosis is characterized by obvious cervical disc degeneration and hyperosteogeny on the X-ray. Cervical myelography can show spinal stenosis.

2. Cervical disc herniation: occurs mostly in young and middle-aged patients. Patients have a history of head and neck trauma. Symptoms appear after injury. X-ray examination has no obvious bone changes or atlantoaxial joint disorders. Cervical angiography shows intervertebral space. Narrowing, complete or incomplete infarction of the spinal canal, CT scan is more helpful to identify and determine the extent.

3. Cervical spinal canal tumor: more common in young adults, the patient's symptoms are progressively aggravated, and progresses faster, manifested as spinal cord and nerve roots at the same time, cervical X-ray examination showed pedicle deformation flattened, root spacing Widening, the posterior margin of the vertebral body is sunken, and sometimes the intervertebral foramen enlargement or vertebral destruction can be seen. The myelography or CT scan can confirm the diagnosis.

4. Cervical myelitis: It can be seen at any age. Patients often have a history of fever or infection. On this basis, the disease gradually develops, the course of disease is longer, and the condition is good or bad. Because the lesion is irregular, the symptoms and signs of the patient are also Changeable, unclear flatness, scattered distribution, lumbar puncture visible high cerebrospinal fluid protein, leukocytosis, lymphatic, often incomplete subarachnoid obstruction, spinal iodine angiography showed characteristic dotted, sometimes visible A tumor-like cup-shaped defect or contrast agent enters the cyst, and the level of obstruction does not match the symptom plane.

5. Cervical tuberculosis: patients have a history of tuberculosis, often complained of neck pain, limited head and neck activity, and increased pain, severe symptoms of cervical nerve and cervical spinal cord compression, blood sedimentation, sometimes in the posterior pharyngeal wall The lump can be seen, affecting swallowing, puncture can suck out pus, cervical X-ray examination can show 1 or 2 or more vertebral body destruction, and dislocation, deformity and so on.

6. Syringomyelia: patients often have deformity of the occipital foramen such as skull base depression, the disease develops slowly, there is characteristic sensation separation performance, lumbar puncture examination is normal, X-ray examination has no atlantoaxial joint disorder, CT Scanning or MRI is helpful in diagnosing and differential diagnosis.

7. Calcification of the posterior longitudinal ligament: the disease occurs in the cervical vertebrae, the patient's posterior longitudinal ligament is thickened and calcified, so that the anteroposterior diameter of the spinal canal becomes smaller, the cervical vertebrae are pressed, and the quadriplegia of the cervical vertebrae appears. There is a long strip of calcification, and the atlantoaxial joint is normal.

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