Atlantoaxial joint dislocation

Introduction to atlantoaxial dislocation The atlantoaxial joint is a general term for the connection between the first cervical vertebrae and the second cervical vertebrae, including three independent joints, namely, two atlantoaxial joints and one atlantoaxial joint. Atlantoaxial joint dislocation is the most common injury of the upper cervical vertebra. If it is not treated in time, the degree of dislocation is often progressively increased, resulting in high pressure on the spinal cord and life-threatening. Due to its potential risk, it should be actively treated. basic knowledge The proportion of the disease: the probability of the population is 0.004% Susceptible people: no specific population Mode of infection: non-infectious Complications: occipital neuralgia, spinal cord compression

The cause of atlantoaxial joint dislocation

The causes of this disease include the following:

Traumatic dislocation:

1. Combined with odontoid fractures: the sacral vertebrae with a odontoid fracture are displaced together, and the leading edge of the posterior arch of the atlas is measured from the posterior superior angle of the vertebral body or the posterior edge of the fracture line. The effective space occupied can be used to estimate the narrowing of the buffer gap and the compression of the spinal cord. 2. Simple anterior dislocation of the atlas: no dislocation of the atlantoaxial joint without odontoid fracture, there must be extensive damage of the ligament between the atlantoaxial, due to the presence of odontoid, the spinal cord is clamped in the odontoid and atlas Between the back arches, it is more vulnerable.

Congenital malformation dislocation:

There is abnormal development in the neck of the occipital neck. The acute dislocation of the atlantoaxial joint is more likely to occur after trauma than in normal subjects. In most cases, atlantoaxial joint instability occurs gradually after puberty. Two common types are: 1. segmental disorder, manifested as occipital condyle Vertebral fusion into the neck 2 ~ 3 vertebral body fusion; 2. odontoid hypoplasia.

Spontaneous dislocation:

Adult cases are often secondary to rheumatoid arthritis, and children are often secondary to infection in the neck. The essence of atlantoaxial rotation fixation is old dislocation. Fielding (1977) refers to the atlantoaxial rotational subluxation state that occurs after spontaneous or mild trauma, which is called atlantoaxial rotation fixation. Later (1983) he Also known as rotatory shift.

Pathological dislocation:

It is also a slow dislocation, and the difference from spontaneous dislocation is that there are osteoporotic lesions of the atlas and/or the atlas. In China, atlantoaxial tuberculosis is more common, and occasionally in atlantoaxial tumors or osteomyelitis.

[Pathogenesis]

Anatomical features and damage mechanisms:

The atlantoaxial joints include:

(1) The lateral joint of the atlantoaxial joint consists of the left and right at the subarachnoid articular surface and the superior articular surface of the axial vertebra;

(2) The anterior and posterior joints of the odontoid process are located in front of the odontoid process and between the dentate and odontoid anterior arch of the atlas and the transverse ligament of the atlas, forming two synovial cavities around the atlantoaxial joint. The ligament and lamella have transverse ligament of the atlas, ligament ligament, pterygoid ligament, ligament and ligamentum flavum between the posterior arch of the atlas and the vertebral arch. 90% of the rotational motion of the head occurs in this joint. The movement is flexible, and there are many ligaments connected to the occipital bone, atlas, abaxial vertebra and other cervical vertebrae. When the skull is subjected to sudden flexion, the kinetic energy of the head is mostly concentrated on the transverse ligament, and the odontoid is just in the center. The formation of a "cutting" external force can cause the transverse ligament rupture, and the vertical violent effect of the sacral burst fracture (Jefferson fracture), the separation of the atlas vertebral block and the vertebral arch fracture can also cause the transverse ligament tear. The transverse ligament is attached to the front of the two sides of the atlas and is combined with the anterior arch to form a fibrous structure, which surrounds and restricts excessive movement of the odontoid, and protects the atlantoaxial stability. When the transverse ligament is damaged or broken, it can occur. Dislocation or subluxation of the joint This is a serious injury, often accompanied by spinal cord injury, it can be immediately fatal.

Atlantoaxial joint dislocation prevention

The disease is caused by traumatic factors, so pay attention to production and life safety, avoiding trauma is the key to prevention and treatment of this disease, in addition to the active prevention and treatment of rheumatoid arthritis and deep neck infection.

Atlantoaxial joint dislocation complications Complications, occipital neuralgia, spinal cord compression

The clinical manifestations of this disease mainly depend on the severity of transverse ligament injury and the degree of anterior atelectal dislocation and whether it causes compression on the spinal cord. The local manifestations are mainly suboccipital and occipital neck pain, and the activity is limited. If spinal cord injury is combined, the following are the following: Several situations occur:

(1) The respiratory center is timely and is fatal at the site of the injury;

(2) There is a transient nerve after the injury, which shows a short limb paralysis or limb weakness, but can be quickly improved and even restored;

(3) quadriplegia, incontinence and respiratory dysfunction, which is the most serious, if the timely and effective treatment is not obtained, the dislocation of the atlas is more serious, and the spinal cord pressure is also increased;

(4) Delayed neurological symptoms, the injury does not occur at the time and in the early stage, and gradually appears as the head and neck activity increases. The typical clinical manifestation of atlantoaxial dislocation is head and neck tilt, if one side shifts forward, The head is tilted away from the affected side to the healthy side; neck pain and stiffness, occipital neuralgia, etc., spinal cord compression symptoms and signs rarely occur, sometimes tiny trauma can cause rotation of the atlantoaxial joint, head in the rotational position Instead of the movement of the atlas above the pivotal axis, the two can only have a little activity.

Atlantoaxial joint dislocation symptoms common symptoms spinal cord compression atlantoaxial dislocation ligament rupture neuralgia

Most patients presented with chronic onset, with intermittent symptoms, recurrent episodes and progressive exacerbations; some patients were significantly aggravated after minor trauma. Typical clinical symptoms include the following:

1. Symptoms of cervical radiculopathy: neck pain, restricted neck activity, stiffness, especially limited rotation of the head and neck, pain in the head and neck;

2. The symptoms of high cervical spinal cord disease caused by compression of the spinal cord junction area: such as weakness of the limbs, unstable walking, inflexible hands, abnormalities in the second stool, etc.; also include numbness of the trunk, limbs, acupuncture and even burning sensation.

3. Respiratory dysfunction: usually occurs in severe or advanced cases. Due to the compression of the spinal cord junction, the occurrence of respiratory dysfunction is a gradual process of aggravation - the early stage of atlantoaxial joint dislocation, respiratory function is normal; later it will manifest as physical exertion when breathing is laborious; serious patients at rest There are breathing difficulties, or the number of calm breaths > 30 times, coughing weakness, coughing effort; end-stage patients with respiratory failure until death.

4. In addition, if the skull base depression, cerebellar tonsil sputum or syringomyelia is combined to affect the medulla oblongata and brainstem, dysphagia, dysarthria (unclear articulation), unclear vision, dizziness, tinnitus and other low positions may also occur. Cranial nerve symptoms.

Physical examination: general signs include limited head and neck activity, tenderness of the neck and occiput. Patients with high myelopathy have elevated limb muscle tone, hyperreflexia and pathological reflex. Patients with a skull base depression may have ataxia, closed eyes, dysarthria, and nystagmus.

Examination of atlantoaxial dislocation

Physical examination: general signs include limited head and neck activity, tenderness of the neck and occiput.

Auxiliary inspection:

Imaging examination is the main basis for determining atlantoaxial joint dislocation.

The X-ray plain film shows the joint space of the caries. In normal adults, the gap is no more than 3 mm, and the child is 5 mm. There is no change in the adult's gap during the flexion and extension of the head and neck, but the child has changes, but the range of variation is also Within 1 mm, if the gap is increased to 5 mm or more, instability or dislocation is considered to exist.

CT and MRI scans can help diagnose the type and cause of dislocation, such as the presence or absence of odontoid malformation defects, rheumatoid arthritis, congenital insufficiency, and so on.

Diagnosis and diagnosis of atlantoaxial dislocation

A clear history of trauma can be differentiated from the subluxation caused by inflammation. Except for other parts of the upper cervical vertebrae, X-rays must be taken. The main features of X-ray images are the odontoid process and the atlas. The block spacing is asymmetrical, but the cooperation of the opening is not good, the projection position may be skewed, causing the gap between the two to be abnormal, or the anatomical structure of the area may not be satisfactorily displayed, and if necessary, the film may be taken several times to eliminate misdiagnosis caused by improper projection position.

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