Traumatic occipitocervical dislocation
ANATOMY OF THE SPINE
The human spine is formed by individual vertebrae and connective tissue discs in between. The vertebrae form the spinal canal. There are seven cervical, twelve thoracic, and five lumbar vertebrae. The intervertebral discs are the link between the individual vertebral bodies.
Normal anatomy of the spine. Longitudinal section and cross sections through the cervical, thoracic and lumbar spine.
The little joints that link the vertebrae together are known as facet joints. They help to stabilize the spine and, together with the intervertebral discs, allow a certain degree of mobility of the spinal cord. The spinal canal should be wide enough to allow nerve roots to float freely in cerebrospinal fluid.
The front border of the spinal canal is built by the vertebral bodies and intervertebral discs, the side by the intervertebral joints (facets) and back by the ligamentum flavum (yellow band) and vertebral arches. Discs consist of an outer fibrous ring (annulus fibrosus), which surrounds an inner gel-like center (nucleus pulposus).
The spinal cord and nerve roots lie within the spinal canal. The spinal cord extends downwards approx. to the 1st lumbar vertebra. Below, only nerve roots are present in the spinal canal. At the level of the intervertebral disc the nerve roots pass through the neural root foramina to exit the spinal canal. The spinal cord and nerve roots conduct electric-like signals from the skin and joints to the brain, and process of movement is initiated from the brain to the muscles.
The connection between the head and the spine is the atlanto-occipital joint. It consists of the condyles of the occipital bone and the upper joint surfaces of the 1st cervical vertebra. The 1st cervical vertebra is called the atlas. The atlas is connected to the 2nd cervical vertebra (axis) below as well.
Atlanto-occipital dislocation is a highly unstable craniocervical injury, resulting from damage to ligaments and/or bony structures connecting the skull to the cervical spine. Although the atlanto-occipital dislocation represents about 1% of all cervical spine injuries it is the most common cause for cervical spine injury related fatalities in motor vehicle accidents.
CAUSE OF SYMPTOMS
Cervical vertebral fracture
SYMPTOMS AND SIGNS
Pain and stiffness in the neck
THE DIAGNOSIS IS BASED ON Medical history Clinical exam Radiographs Computer tomography Magnetic resonance imaging (MRI)
In most cases surgical treatment is required.
WHAT IS THE GOAL OF SURGERY?
To restore the protective function of the spine
HOW IS SURGERY PERFORMED?
Posterior occipitocervical fusion and if necessary decompression
WHICH OTHER DISEASES SHOULD BE EXCLUDED (DIFFERENTIAL DIAGNOSIS)? Other fractures of the spine Osteoporosis Pathologic vertebral fracture Ankylosing spondylitis (Bechterew's disease)