Cervical Disk Injuries
Article updated and reviewed by Luc D. Jasmin MD, PhD, Assistant Professor of Neurological Surgery and Principal Investigator, Pain Research, University of California, San Francisco on June 20, 2005.
The cervical spine is the part of the neck made of seven vertebrae (bones shaped like blocks) separated from one another by a disk. A disk is donut-shaped cushion, and there are seven disks in the cervical spine. The center (the nucleus pulposus) of the disk is filled with a soft material, which is surrounded by a fibrous ring (the annulus fibrosus). Disks serve many functions: (1) they allow flexion-extension of the neck; (2) they serve as cushions to absorb shock; and (3) they join neighboring vertebrae to each other. Two strong ligaments, the anterior cervical ligament and the posterior cervical ligament, also join the vertebrae. The posterior cervical ligament often prevents a herniated disk from compressing the spinal cord. The spinal cord is located right behind the cervical disks. On each side of the spinal cord the cervical nerve roots come out. The cervical nerve roots contain the sensory and motor fibers going to neck, shoulders, and arms. A midline bulging or extrusion of the nucleus pulposus through a tear in the annulus fibrosus will compress the spinal cord, while a lateral bulging or extrusion of the nucleus pulposus will compress the neighboring cervical root.
In most people, cervical disk injury is a slow progressive disease occurring over decades. The stress and micro-traumas imposed by the constant motion of the cervical spine, and at times the awkward positions of the neck for prolonged periods of time, all take their toll on the cervical disks. The disks also age over time. They loose their elasticity, dry-out, and become calcified. The nucleus pulposus looses its elasticity and the annulus fibrosus weakens, bulges, and is prone to tears. If a tear in the annulus is large enough, the nucleus pulposus will leak out. This is called a disk herniation. Sometimes, pieces of the disk leak out and become trapped around a nerve root or the spinal cord. This is called a free-fragment.
When it ages, the disk gradually collapses, which allows the vertebrae on each side to have excessive motion (small movements barely visible with the naked eye). The increased motion leads to accelerated wear and tear of the joints that articulate the vertebrae with each other, causing the bone to overgrow in a failed attempt to stabilize the spine. The bone overgrowths are knows as bony spurs or osteophytes. In most people this slow disease, which can be seen on plain X-rays, CT scan, or MRI, will cause very few symptoms. In fact, over half of the population over age 50 has some sign of disk injury, but very few will seek treatments by a physician. Those that will come to the physician usually have significant neck pain, which can be accompanied by arm pain, weakness, and loss of sensation or abnormal sensations (such as tingling). In those that are more likely to suffer from cervical injury, there is growing scientific evidence that certain individuals have inherited genes that put them at a higher risk of cervical disk disease. Also, individuals born with a narrow cervical canal, the bony canal behind the cervical disc where the spinal cord is located, are more likely to injure their spinal cord when they suffer from cervical disk disease. Genetic counseling for cervical disk disease is not yet available.
In addition to the slow progressive disease, acute disk injury can occur in people of all ages (although this is rare in children), usually after lifting a heavy load or from a direct injury to the spine, with or without an accompanying fracture of a cervical vertebra.
Most cervical disk syndromes are caused by injuries that involve hyperextension, which results in compression of the anatomic structures.
Flexion injuries in the cervical area do not result in nerve compression.
Pain, loss of sensation or new sensations, and weakness are the main symptoms and signs of cervical disk injury. The most common symptom is pain and it is usually the only one. Rarely, cervical disk injury is complicated by compression of either a cervical nerve root or even more rarely by a compression of the spinal cord. When compression of the nervous tissue occurs, patients will report abnormal sensations other than pain and will report loosing strength in one arm (nerve root compression) or in both arms and legs (spinal cord compression).
1. Pain is the most common complaint, and can be felt in the neck or arm.
a. Pain is usually limited to the neck and upper back between the shoulder blades. It occurs because of low-grade inflammation of the disk and the cervical vertebra joints. While the disease is chronic, inflammation can flare up after a minor added injury or for other reasons that are not yet well understood. Less commonly, neck and shoulder pain occur because the disk bulges acutely (herniates) and stretches the posterior longitudinal ligament. With conservative treatment, this pain usually goes away in a few weeks, but it is likely to happen again, especially if the affected individual does not change his/her lifestyle.
b. Rarely, the pain will be felt down the arm. This pain can be lightning, caused or aggravated by movements of the neck, or can be dull and persistent. Pre-existing neck pain is also present in many individuals. After the arm pain starts, some people report feeling less pain in their neck. When arm pain is present, it is usually because of a combination of disk herniation and bony spurs compressing a nerve root. A free disk fragment can also intrude on a cervical root and cause quite a bit of pain in shoulder or down the arm.
2. Sensory symptoms other then pain.
When felt in only one arm, they are due to compression of a cervical root and felt in the territory of the cervical root. The C4 root mainly supplies the shoulder with nerves, while the C5 root supplies primarily the arm. The C6 root supplies nerves to the radial side of the forearm, the C7 root addresses the arm and forearm, and the C8 and the T1 root handle mostly the hand. Broadly speaking, two types of sensory symptoms are felt: loss of sensation and new sensations. A loss of sensation is simply numbness. New sensations include tingling (pins and needles), heat, or cold sensations.
If the spinal cord is compressed, most patients report losing sensation in their hand and in the lower part of their body. They have difficulty feeling the floor when they walk and can not feel that their bladder is full. This is an emergency and patients should be brought to the hospital right away.
3. Motor symptoms and signs.
Weakness of one arm (the other one being normal) only signals a compression of a nerve root. A compression of C4 results in a weak shoulder; C5 indicates a weak bicep muscle; C6 represents a weak wrist, thumb, and index finger; C7 is a weak tricep, extension of the fingers, and pectoralis muscles; C8 designates weak flexion of the fingers; and T1 corresponds to a weak hand.
If the spinal cord is compressed, patients report having difficulty walking and weak legs and hands. These can be the only symptoms and should be treated as an emergency.
1. Acute care.
Intense pain from disc injury typically does not require surgery. Patients should seek the advice of a physician when there is something unusual about the pain and added symptoms, such as tingling or weakness in the arm or especially weakness of the legs. For most non-complicated disk injury pain, a physician will advise conservative treatment involving rest, neck immobilization, pain medication, and physical therapy. A comfortable posture for the neck is essential, especially at night when the muscle tone is low. A soft or hard collar may be helpful. Pain medication includes standard analgesics such as acetaminophen, anti-inflammatory such as the non-selective or selective cyclo-oxygenase inhibitors, muscle relaxant, and opiates. Physical therapy can include treatments such as massage, gentle traction, ultrasound, and whirlpool. For more severe cases, a physician my might recommend a local injection of anesthetic and steroids under X-ray guidance to decrease the local inflammation and ease the pain.
Surgery is indicated when a cervical disc compresses the spinal cord or a nerve root to the point that permanent neurologic deficit might occur. Surgery is also recommended for patients that have failed all conservative treatments and the cause of the pain is clearly visible on CT-scan, CT-myelogram, or MRI. Anterior discectomy with fusion or an artificial disc is the most straightforward procedure for central or anterolateral disk herniation. A posterior laminotomy and foraminotomy is recommended when technical limitations for anterior access exist or when surgery was already done at the same spinal level in the past.
2. Long-term care.
Exercise at least three times a week together with a proper posture can prevent new injuries to your neck. The exercise program should be progressive and include daily stretching. Often a change of career is warranted and people working in a fixed position all day (such as at a computer) need to identify and avoid the postures that trigger their pain, and take at least five minutes every hour to stretch and take a short walk. Regular use of cyclo-oxygenase inhibitors is not recommended because they might increase the risk of heart disease.
What is the anatomical problem that is causing the pain?
Is it caused by an injury or degeneration, or both?
Is there nerve root compression?
Is there spinal cord compression?
How can this be remedied?
What is the medical treatment for the condition?
What are the surgical options?
What are the chances that I might need a second surgery in the
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Who will perform the surgery?
What are the benefits, complications, and risks of surgery (the likelihood of all the major complications should be given in percentage)? Remember that none of the treatments will reverse the aging process of the neck, and that some symptoms are likely to persist even after a perfect surgery.
What is the expected recovery period?
What medications should I not take before and after the surgery?