Mechanical Causes: Neck Pain (Cervical Spine)
It is important to understand the basic anatomy of the cervical spine to appreciate how mechanical stresses can cause neck pain. The natural history of aging and the passage of time contribute to the wear and tear of the anatomical structures that make up the cervical spinal column.
Bones, ligaments, muscle, fat, and repaired tissue all make up the anatomy and as these become overgrown and distorted, they can affect the neural structures running within to become pinched or compressed causing various symptoms and signs.
Listed below are some examples of conditions that are associated with neck pain.
Cervical Disc Prolapse
(See Abnormal Spinal Anatomy section)
In the event of a traumatic force, some of the soft disc material breaks through the fibrous tough outer lining. This loose fragment or bulged disc material will extrude out to the side of the spinal canal and impinge on the exiting nerve root at the lower level (e.g. C6 at C5-C6). This may result in arm or hand pain and/or numbness (commonly referred to as Cervical Radiculopathy).
If the space for the nerve root (foramen) is already compromised because of associated disc space collapse or bone spurs (osteophytes), the added impingement of the disc may irritate the nerve root and cause a radiculopathy (arm pain). If the foramen is not compromised, the radiculopathy may be temporary and relieved with conservative treatment.
Herniated cervical disc treatment options
In general, most cervical disc herniations or cervical radiculopathy will heal with time and conservative treatment and will not require surgery. The following includes an overview of:
Conservative treatments for cervical radiculopathy
As in the lumbar spine, the first line or treatment is generally a couple days of rest and non-steroidal anti-inflammatory drugs (NSAID’s).
If the pain is severe and/or continues for more than a couple of weeks, oral steroids can be useful to decrease inflammation. Oral narcotic agents can be added for severe pain, but should only be taken for a short time (less than two weeks).
If the pain lasts for more than two to four weeks, conservative treatments may include:
Physical therapy for exercises to help relieve the pressure on the nerve root
Chiropractic treatments for manual manipulation to help relieve the pressure on the nerve root
Manual traction to help open up the cervical foramen where the nerve root exits the spinal canal. If this therapy helps relieve the pain, a home traction unit can be prescribed. Traction should be initiated under a physical therapist's supervision.
For pain that does not get better with medical and physical treatments, epidural injections or peri-radicular blocks may be considered. Epidural injections effectively relieve pain approximately 50% of the time, and if they do work they may be repeated every two weeks up to a total of three times within one year.
Cervical radiculopathy (herniated cervical disc) surgical treatments
(See Forms Section for information on surgical procedures)
If 6 to 12 weeks of conservative treatment fails to relieve the arm pain, then surgical removal of the disc may be reasonable.
An MRI scan or CT with myelogram can confirm the presence of a disc herniation and the level that is affected. If the patient’s symptoms and neurological deficit match the results of the scan, surgery is reliable in terms of relieving arm pain and has a low complication rate.
The disc may be removed from the back of the neck (posterior approach) or from the front (anterior approach). Generally, surgeons favor the anterior approach for most cervical disc herniations.
Anterior surgical approach for a herniated cervical disc – may be favored if there is any disc space collapse, as the approach allows the surgeon to "jack open" the disc space and place a bone graft to keep it open. This procedure opens up the foramen, which gives the exiting nerve root more room
Posterior surgical approach for a herniated cervical disc – may be favored for a large soft disc that is lateral (to the side of) the canal
Both spine surgeries can usually be done with a short hospital admission.
Spinal Stenosis
Spinal stenosis is a narrowing of the spinal canal, which places pressure on the spinal cord. Stenosis in the upper part of the spinal cord is called cervical spinal stenosis. While spinal stenosis can be found in any part of the spine, the lumbar and cervical areas are the most commonly affected.
What Causes Spinal Stenosis?
Some patients are born with this narrowing, but most often spinal stenosis is seen in patients over the age of 50. In these patients, stenosis is the gradual result of aging and “wear and tear” on the spine during everyday activities. There most likely is a genetic predisposition to this since only a minority of individuals develops advanced symptomatic changes. These patients may have a predisposing Congenital cervical canal stenosis. As people age, the ligaments of the spine can thicken and harden (called calcification). Bones and joints may also enlarge, and bone spurs (called osteophytes) may form. Bulging or herniated discs are also common. Spondylolisthesis (the slipping of one vertebra onto another) also occurs and leads to compression. When these conditions occur in the spinal area, they can cause the spinal canal to narrow, creating pressure on the spinal nerve.
Symptoms of Stenosis
The narrowing of the spinal canal itself does not usually cause any symptoms. It is when inflammation of the nerves occurs at the level of increased pressure that patients begin to experience problems. Patients with lumbar spinal stenosis may feel pain, weakness, or numbness in the legs, calves or buttocks. In the lumbar spine, symptoms often increase when walking short distances and decrease when the patient sits, bends forward or lies down. Cervical spinal stenosis may cause similar symptoms in the shoulders, arms, and legs; hand clumsiness and gait and balance disturbances can also occur. In some patients the pain starts in the legs and moves upward to the buttocks; in other patients the pain begins higher in the body and moves downward. This is referred to as a “sensory march”. The pain may radiate like sciatica or may be a cramping pain. In severe cases, the pain can be constant. Severe cases of stenosis can also cause bladder and bowel problems, but this rarely occurs. Also paraplegia or significant loss of function also rarely, if ever, occurs.
Myelopathy
Myelopathy is a term that means that there is something wrong with the spinal cord itself. This is usually a later stage of cervical spine disease, and is often first detected as difficulty walking due to generalized weakness or problems with balance and coordination. This type of process occurs most commonly in the elderly, who can have many reasons for having trouble walking or problems with gait and balance. However, one of the more worrisome reasons that these symptoms are occurring is that bone spurs and other degenerative changes in the cervical spine are squeezing the spinal cord. Myelopathy affects the entire spinal cord, and is very different from isolated points of pressure on the individual nerve roots.
Myelopathy is most commonly caused by spinal stenosis, which is a progressive narrowing of the spinal canal. In the later stages of spinal degeneration, bone spurs and arthritic changes make the space available for the spinal cord within the spinal canal much smaller. The bone spurs may begin to press on the spinal cord and the nerve roots, and that pressure starts to interfere with how the nerves function normally.
Determining the amount of weakness that is present according to a standardized system can be used to assess the severity of each case of myelopathy. For example, according to the system of Nurick, myelopathy is graded from 0 to 5, with 5 being the most severe. The characteristic changes that occur at each different grade are as follows:
Grade 0:
signs and symptoms of root involvement but without evidence of spinal cord disease.
Grade 1:
signs of spinal cord disease but no difficulty in walking.
Grade 2:
slight difficulty in walking but does not prevent full-time employment.
Grade 3:
severe difficulty in walking that requires assistance and prevents full-time employment and avocation.
Grade 4:
ability to walk only with assistance or with the aid of a frame.
Grade 5:
chairbound or bedridden.1
Myelopathies are also classified using the modified Frankel classification scale for cord damage due to any cause:
Grade A:
complete motor and sensory involvement.
Grade B:
complete motor involvement, some sensory sparing including sacral sparing.
Grade C:
functionally useless motor sparing.
Grade D:
functional motor sparing.
Grade E:
no neurologic involvement.2
Symptoms
Myelopathy can be difficult to detect, because this disease usually develops gradually and also occurs at a time in life when people are beginning to slow down a little bit anyway. Many people who have myelopathy will begin to have difficulty with things that require a fair amount of coordination, like walking up and down stairs or fastening the buttons on clothing. If you have had a long history of neck pain, changes in coordination, recent weakness, and difficulty doing tasks that used to be easier because your body seemed more responsive in the past, are definite warning signs that you should see a doctor.
Diagnosis
Surgery is usually offered as an early option for people with myelopathy who have evidence of muscle weakness that is being caused by nerve root or spinal cord compression. This is because muscle weakness is a definite sign that the spinal cord and nerves are being injured (more seriously than when pain is the only symptom) and relieving the pressure on the nerves is more of an urgent priority. However, the benefits of nerve and spinal cord decompression have to be weighed against the risks of surgery. Many people who have myelopathy due to degenerative cervical disorders are older and often a bit frail. Spine surgery can be a difficult stress for someone who is older or who has many different medical problems. However, your surgeon will be able to discuss the risks and benefits of surgery with you, and what the likely results are of operative versus non-operative treatment.
Cervical Disc Degeneration
Cervical disc degeneration is one of the first processes of cervical spondylotic pathological change.
Process of disc degeneration
An understanding of the anatomy is needed to appreciate the disease process of degenerative disc disease. Please refer to the Spinal Anatomy Section.
Acute traumatic injury combined with the aging process and smoking, can accelerate the degeneration of the vertebral column.
(1) Nucleus Pulposus: reduced moisture in the nucleus pulposus, fiber network and mucus-like matrix and fibrous tissue is gradually replaced by the cartilage cells, eventually becoming fibrocartilagenous material. This pathological change of the intervertebral disc develops over many years and also depends on certain risk factors. SMOKING is the worst but ironically the most reversible factor. Diabetes, steroid use, previous trauma, and arthritis may accelerate the process.
(B) Annulus fibrosus: Intertwining Kris-cross tough fibres of the annulus start to harden and lose elasticity. They start to buckle and break and allow the stiffening nucleus pulposus to start protruding through. The disc space starts to narrow and the foraminae start to narrow also compressing nerve roots. Cracks start appearing in the annulus and this usually is difficult to reverse.
(C) Cartilage: cartilage degeneration due to thinning leads to loss of structural integrity of the end-plates. The end-plates are important zones where the blood supply nourishes aspects of the disc. Attachment zones between the annulus fibrosis and the cartilage become weak, and lead to a crescendo effect of degeneration. With this comes loss of integrity and mineralization of the vertebral bodies and therefore bony compromise, osteoporosis, and structural instability.
Disc Degeneration in the Elderly
Cervical disc nucleus pulposus is comprised of about 80% water. Flexibility and dynamisms correlate closely with the water content. Water content decreases with age (about 90 per cent of newborn infants, 14-year-olds reduced to 80%, 70-year-old is only 70 %).
Elastic tension diminishes, making it susceptible to compression. The annulus fibrosus bulges outward, weakening the crossing fibres. Vascular supply also diminishes with age, and the disc receives supply mainly from small capillaries from the radicular branches which may be compressed from the degenerative structural changes of the vertebral column.
As the intervertebral disc degenerates, the intervertebral space narrows, relaxing, the intervertebral joints and these become lax. This places strain on the end-plates and the vertebral bodies which may lead to subsidence and partial collapse.
This in turn may compress the spinal cord and/or the exiting spinal nerve roots that supply the limbs, trunk, and torso
