Cervical Spine Stenosis
Cervical spinal stenosis is the narrowing of the spaces in the cervical spine leading to compression of the nerves or the spinal cord. The narrowing is usually caused by age-related wear and tear of the structures of the cervical vertebral column, usually affecting patients aged 50 years and more. The patients commonly complain of neck pain but may also complain of symptoms such as numbness and tingling of the arms.
The cervical vertebral column extends from the base of the skull to the upper chest. Apart from providing stability and aiding in the movement of the head, the cervical vertebral column creates a central canal that provides a safe conduit for the spinal cord to travel from the brain down the body.
The spinal cord carries the nerve transmissions from the brain and helps in moving the body, relaying the sensations from various parts, and coordinating the activities of different organ systems and limbs. The spinal cord gives numerous branches as it descends down the central canal known as nerve roots which unite to form different nerves of the body. The nerves branch out through the intervertebral foramen created by two vertebrae stacked on each other.
The cervical spine stenosis results from compression from the spinal cord or the nerve roots as they pass through the cervical vertebral column. The most common cause is the wear and tear arthritis of the cervical spine in the elderly population. The arthritis of the cervical spine may lead to the formation of bone spurs known as osteophytes. The osteophytes may arise from the facet joint or the vertebral body and may compress the neural structures.
Spondylolisthesis is a condition where the vertebrae are not aligned properly over one another. The malalignment of the vertebrae may compress the spinal cord or the nerve roots leading to cervical spinal stenosis.
The intervertebral disk is tissue present between two adjoining vertebrae that cushion the spine and provides stability to the spine. The soft gel-like interior part of the intervertebral disk may at times herniate through the outer annulus fibrosis. The herniated disk in the cervical spine may narrow the space for the spinal cord or the nerve roots causing spinal stenosis.
Ligamentum flavum is a thick band of tissue present behind the spinal cord inside the central canal. Any thickening or buckling of the ligamentum flavum may cause significant narrowing of the canal leading to stenosis.
In some patients, the neural canal may be narrower by birth. These patients are particularly vulnerable to cervical spinal stenosis due to any pathological condition leading to further narrowing. Some genetic conditions like osteopetrosis, Paget’s disease, or achondroplasia may also lead to cervical spinal stenosis. Other diseases implicated in spinal stenosis are acromegaly, ankylosing spondylitis, and fluorosis.
Other causes of cervical spinal stenosis include any injuries to the cervical spine causing collapse or dislocation of the vertebrae or displacement of the fragment inside the canal. All of which may cause narrowing of the space available for nervous tissue.
Depending upon the location of the narrowing in the vertebra, the spinal stenosis may be classified as central, lateral, or foraminal. The central stenosis may be caused by posterior disk herniation, vertebral bone spurs, or buckling of the ligaments of the canal. Lateral recess stenosis is usually a result of facet bone spurs. The far lateral or foraminal stenosis may result from a disk herniation in the foramen or malalignment of the vertebrae.
Pathology of age-related cervical spinal stenosis
With increasing age, the content of the tissue forming the intervertebral disk changes leading to small tears in the disk. This leads to loss of disk height and building of the disk and the posterior longitudinal ligament into the central canal. This may cause buckling of the ligamentum flavum and subsidence of the facet joints. The facet joints try to restabilize the spine by forming new bone leading to bone spurs which may impinge upon the neural structures from behind. The bone spurs formed from the vertebral body endplate may compress the neural structures from the front.
Patients commonly report symptoms of neck pain and pain in both arms. The neck pain may be described as shooting down the arms or electrical sensations in the arms. Cervical spinal stenosis may also result in a sensation of numbness and tingling in one or both the arms. In cases of a single nerve compression known as radiculopathy, the symptoms may be present only in the distribution of the involved nerve.
In advanced cases, as the disease progresses, patients may complain of the clumpiness of the hands and arms due to weakness and loss of coordination. In some cases of advanced stenosis, there may be loss of bowel bladder control and weakness of the feet and legs.
The condition is usually diagnosed by the orthopedic surgeon on physical examination after eliciting an elaborate history of the symptoms. The physician may perform physical examinations to test for the integrity of the nervous system in all four limbs and certain reflexes. The physician may also move the patient’s neck to elicit pain and symptoms. All the physical examination tests are directed to localize the level of compression in the cervical spine.
An X-ray is usually the first investigation of choice to look for bony abnormalities in the cervical spine. A CT scan often reveals more detail of the bony structures compared to an X-ray. The various soft tissue and nervous structures are made visible on an MRI, through which the physician can localize the level of stenosis. An MRI also aids in planning any surgery needed to relieve the symptom of stenosis if needed.
The treatment of cervical spinal stenosis is usually conservative/non-surgical. Conservative treatment includes physical therapy, pain relief medication, and cold/heat therapy. Cortisone injections may be given through caudal, interlaminar, or transforaminal route. The cortisone injections provide symptomatic relief by reducing inflammation associated with stenosis.
Surgical management usually involves creating more space for the neural structures. Laminotomy involves the removal of part of the lamina (roof of the vertebrae) to create more space. Laminectomy involves removal of the lamina which is often combined with additional measures to stabilize the spine. The vertebral opening for the nerves branching out may be widened by a procedure known as a foraminotomy. During the surgery, herniated disks and bone spurs may also be removed to create more space in the canal.
Laminoplasty is a procedure in which a hinge is created without removal of bone tissue and the canal is widened. The widened canal may be fixed with wires or special threads. In cases of multiple level stenosis or when any procedure may result in instability of the spine, cervical spine surgery is performed from the front which is often combined with the fusion of two or more vertebrae.
The images above show a rasp used during the anterior decompression and fusion surgery. The rasp is used to prepare the end plate for insertion of bone cage and subsequent fixation of the vertebrae using the plate shown above.