odontoid malformation
Introduction
Introduction to odontoid malformation The odontoid process is an important osseous joint structure of the upper cervical vertebra joint, which is used to maintain the stability of the atlantoaxial joint by binding the odontoid to a certain anatomical range by means of the transverse ligament. Dysplasia and transverse ligament dysplasia are the main congenital factors contributing to atlantoaxial instability. It is not uncommon to find such malformations, accounting for about 4/5 of the neck and neck deformities. The etiology of odontoid malformation is not well understood. The odontoid originates from the mesenchyme of the first cervical vertebra in the embryonic stage. During the development of the odontoid process, two ossification centers are present, and the embryonic development is fifth. Appeared at the end of the month, and soon merged into an ossification center. The ossification center of the ossification center is located between the odontoid process and the vertebral body. Under normal circumstances, the tarsal plate is completely healed until about 5 years old. The spurs are integrated with the central vertebrae. During the above development, due to the influence of certain congenital factors, the odontoids may not be developed, resulting in odontoid dysplasia or odontoid dysplasia; The mesenchymal tissue on the transverse surface between the vertebral body and the vertebral body continues to have no cartilage and ossification, resulting in odontoid deformity. basic knowledge The proportion of illness: 0.005% Susceptible people: no specific people Mode of infection: non-infectious Complications: torticollis
Cause
Dentate developmental malformation
The etiology of odontoid malformation is not well understood. The odontoid originates from the mesenchyme of the first cervical vertebra in the embryonic stage. During the development of the odontoid process, two ossification centers are present, and the embryonic development is fifth. Appeared at the end of the month, and soon merged into an ossification center. The ossification center of the ossification center is located between the odontoid process and the vertebral body. Under normal circumstances, the tarsal plate is completely healed until about 5 years old. The spurs are integrated with the central vertebrae. During the above development, due to the influence of certain congenital factors, the odontoids may not be developed, resulting in odontoid dysplasia or odontoid dysplasia; The mesenchymal tissue on the transverse surface between the vertebral body and the vertebral body continues to have no cartilage and ossification, which causes odontoid deformity. In addition, acquired trauma or infection can affect the blood supply of the odontoid tip. The odontoid dysplasia.
Prevention
Odontoid developmental malformation prevention
This disease is a congenital disease and there are no preventive measures.
Complication
Dentate dysplasia complications Complications
Atlantoaxial instability often occurs.
Symptom
Dentate dysplasia symptoms common symptoms nodular cervical pain buried in the alveolar process spinal cord compression
Clinical manifestations combined with imaging examination can make a clear diagnosis of congenital odontoid deformity and atlantoaxial dislocation.
X-ray examination: including the lateral position of the cervical vertebrae, the lateral position of the extension and flexion, and the anterior and posterior position of the opening. If necessary, the tomographic examination can be performed to observe the characteristics of the odontoid deformity and the atlantoaxial dislocation, and to infer the spinal cord compression. Status, X-ray film features are as follows:
(1) dentate stenosis: such as or dysplasia, can be seen in the atlantoaxial X-ray lateral slice and the anterior and posterior opening of the odontoid;
(2) odontoid type: free odontoid bone is connected with the anterior arch of the atlas and has a large gap between the vertebral body and the vertebral body. The lateral position of the flexion and extension can be found that the free bone of the odontoid and the atlas are moved forward together. Bit.
CT scan: By analyzing the image on the scan level, you can understand the type of odontoid deformity and the degree of atlantoaxial dislocation:
(1) If the dentate sinus is absent, no odontoid appears on the corresponding scanning plane;
(2) In patients with odontoid dysplasia, only small odontoid shadows or point ossifications appear on the scanning plane;
(3) In the case of free odontoid bone, a double-toothed shadow may appear in the atlas of the atlas, indicating that the odontoid process is displaced forward with the atlas.
Magnetic resonance imaging can be used to understand the atlantoaxial dislocation and spinal cord compression caused by odontoid malformation. It can also provide the relationship between bone, ligament, dura mater and spinal cord, providing a reliable basis for the design of treatment options. The main MRI manifestations of odontoid deformity and atlantoaxial instability are synchronous forward displacement of the anterior and posterior arch of the atlas, and the free odontoid can be displaced forward synchronously with the atlas, and the spinal cord is compressed.
Examine
Examination of odontoid malformation
X-ray examination
Including the lateral position of the cervical vertebrae, the extensional flexion lateral position and the anterior and posterior position of the anterior and posterior position, if necessary, the tomographic examination can be used to observe the characteristics of odontoid deformity and atlantoaxial dislocation, and to infer the spinal cord compression state, X-ray The special tablets are as follows: (1) odontoid stenosis or dysplasia can be seen in the atlantoaxial X-ray lateral radiograph and the anterior and posterior anterior segment of the occlusal odontoid short or absent; (2) odontoid type: free The odontoid bone is connected with the anterior arch of the atlas and has a large gap between the vertebral body and the vertebral body. The anterior extension of the vertebral body can be found that the free bone of the odontoid is displaced forward together with the atlas.
CT scan
By analyzing the image on the scanning plane, you can understand the type of odontoid deformity and the degree of atlantoaxial dislocation. (1) If the odontoid defect is absent, there is no odontoid on the corresponding scanning plane; (2) In patients with odontoid dysplasia, only small odontoid or point ossification occurs on the scanning plane; (3) in the case of free odontoid, a double-toothed shadow can appear in the ankle ring, indicating odontoid follow-up The vertebra is displaced forward.
Magnetic resonance imaging examination
Can understand the atlantoaxial dislocation caused by odontoid deformity and spinal cord compression; at the same time can provide the relationship between bone, ligament, dura mater and spinal cord, provide a reliable basis for the design of treatment options, odontoid deformity and The main MRI manifestations of atlantoaxial instability are synchronous forward displacement of the anterior and posterior arch of the atlas, and the free odontoid can be displaced forward synchronously with the atlas, and the spinal cord is compressed.
Diagnosis
Diagnosis and differentiation of odontoid malformation
Atlantoaxial dislocation caused by odontoid deformity should be differentiated from traumatic dislocation, spontaneous dislocation and pathological dislocation.
