Cervical Disc Protrusion and Lesions

Cervical disc disorders include herniated nucleus pulposus, degenerative disc disease and internal disc disruption.

• Herniated nucleus pulposus implies extension of disc material beyond the posterior margin of the vertebral body. It may occur from a single whiplash injury but repetitive injuries are more common.
• Degenerative disc disease involves tears, loss of disc height and degeneration of the nucleus. It is part of the normal aging mechanism but is accelerated by smoking,¹ poor nutrition, atherosclerosis and repetitive injury.
• Internal disc disruption includes damage to the disc without external deformity. It may result from whiplash or other injury to the neck.

There is no disc between C1 and C2 (atlas and axis), and only ligaments and joint capsules limit excessive motion. Disc degeneration or herniation can injure the spinal cord or nerve roots and cause stenosis with or without myofascial pain. When the contents of a disc herniate, they release substances that cause a chemical irritation of the nerves. The aetiology of symptoms in any patient may be multifactorial.

Herniated nucleus pulposus tends to affect those under 40 years old whilst degenerative disc disease affects those over 40 with an increasing incidence with advancing age. There is an equal sex incidence but women tend to have more severe symptoms.

In the neck, the most common disc to herniate is C6,7. Cervical radiculopathy is said to affect C7 (70%), C6 (19-25%), C8 (4-10%), and C5 (2%).

It is quite common to find abnormalities on MRI scans of those who do not complain of any symptoms.

Make the following enquiries:

• Ask about speed of onset. An abrupt onset suggests acute injury. Insidious onset suggests a degenerative process.
• Note the time since the injury, if there was an injury.
• Ask about the mechanism of injury.
• Note the distribution of pain. 90% will be in the neck and 10% in the upper limb.
• Make a systematic enquiry about general health. Fever suggests infection. Unintentional weight loss suggests malignancy.

Pain

Note the nature of the pain:

• Pain from the disc without nerve root involvement, is typically vague, diffuse, and distributed axially.
• Activities that raise pressure in the disc such as lifting or a Valsalva manoeuvre, will exacerbate symptoms. Lying down decreases pressure in the disc and eases pain.
• Driving causes vibration that aggravates disc pain.
• There may be primarily motor or sensory involvement. This may produce pain that is deep, dull, and aching or sharp, burning, and like an electric current.

Note the distribution of pain:

• Referred pain from a disc to the upper limb is usually not in a typical dermatome distribution.
• Radicular pain has a dermatomal or myotomal pattern into the upper limb.
• Cervical radicular pain most commonly radiates to the interscapular region although pain can be referred to the occiput, shoulder, or arm as well.
• Neck pain is frequently absent in radiculopathy.
• There may be distal limb numbness and proximal limb weakness in addition to pain. Atrophy may be noticed.
• A herniated disc can produce thermal changes (thermatomes) in specific distributions.
• Referred radicular pain or sensory deficits may not comply with traditional dermatomal maps.

• The neck will show a decreased range of movement. This is very common with pain and spasm from any cause.
• Extension and rotation increase pain. The Spurling manoeuvre is when the patient's neck is extended, bent laterally, and held down. It elicits radicular symptoms.
• Lhermitte's sign is that flexion of the neck causes electric shock-like sensations that extend down the spine and shoot into the limbs. It implies that a disc is impinging on the cord.
• Pain improves when the neck is flexed or on abduction of the affected arm over the top of the head. This is called the abduction sign.
• There may be diminished sensation to pain, light touch, or vibration in the distal upper limb.
• Proximal limb weakness occurs with significant motor root compromise but pain will also impair strength and this must be distinguished.

Neurological examination of the relevant area is required:

• Diminished or absent reflexes may occur, corresponding to the root level.
• Increased upper and lower limb reflexes or other upper motor neurone signs suggest myelopathy and demand urgent evaluation and action.
• If pain originates from the disc but there is no nerve root involvement, there will be normal neurological examination. There may still be exacerbation of pain with axial compression and relief of pain with distraction of the head.
• Myofascial tender or trigger points are often found.
• Tenderness with movement in the posteroanterior plane may suggest disc pathology.

It is easy to diagnose that pain originates from the neck but being sure that there is a disc lesion usually requires imaging studies. Neck pain in the general population is very common.² Most will not be a disc lesion. The assessment of simple neck pain is described by Clinical Knowledge Summaries.³ There may be cervical spondylosis or various forms of arthritis in the neck. Regional pain syndrome, myofascial pain and fibromyalgia are also possibilities.

Blood tests may be guided by suggestions of other rheumatological pathology.

• FBC may show anaemia of chronic disease or evidence of infection.
• Elevated ESR is nonspecific but suggests an inflammatory process.
• Rheumatoid factor should be requested if rheumatoid arthritis is considered and HLA-B27 may indicate ankylosing spondylitis.

Imaging studies are important but they must be interpreted in the light of the clinical picture as positive findings are quite common in people without any complaints.⁴ People with abnormal x-rays are more likely to develop symptoms⁵ but this is not an indication for treatment in anticipation.

• Plain x-ray of the cervical spine may be used to evaluate chronic degenerative changes, metastatic disease, infection, spinal deformity, and stability.
• CT scans are very useful if fracture is suspected and helical CT can give much information.
• CT myelography is sometimes used.
• MRI scans are best at showing soft tissue lesions such as discs. There are a variety of techniques that may be used.

The integrity of nerves may be assessed by nerve conduction studies and electromyelography.

The finding of a disc lesion does not mean that surgery is indicated and in most cases conservative management is the most satisfactory. There may even be spontaneous regression of a herniated disc.⁶

• Exercises, including the McKenzie approach may be best.
• Stabilization exercises and posture training may also be valuable.
• Heat and massage may relieve muscle spasm.
• Analgesics may relieve pain and help muscle spasm. NSAIDs are usually best but stronger analgesics may be required. If pain is severe, analgesia may be enhanced by tricyclic antidepressants or anticonvulsants such as gabapentin or carbamazepine.
• Traction may be used.
• Collars should be used for a few days only, if at all.
• Some people advocate manipulation but the potential dangers of manipulation of the neck are discussed in the article on manipulation and the technique should be used with caution. Despite some enthusiasm,⁷ manipulation under anaesthetic must be used with especial care as the patient will not resist injudicious excessive movement.

Even cervical herniated nucleus pulposis with radiculopathy can usually be managed conservatively. However, if there are significant neurological abnormalities such as UMN signs in the limbs or bladder disturbance, surgical decompression is indicated. Anterior cervical fusion can produce very satisfactory results.⁸

If an intervertebral disc compresses the spinal cord, it can produce myelopathy with weakness, hyperreflexia, and neurogenic bowel and bladder dysfunction. There may be significant upper limb weakness or numbness. Intractable axial or radicular pain can result.

Beware of missing serious underlying disease including malignancy, infections producing abscesses and inflammatory conditions.

This is variable but the results of conservative management are often good. Surgery also has good results but is indicated in only a minority. It is likely that the attitude of the patient to active rehabilitiation is very important for a good result. However, the general prognosis for neck pain is not good and it is often chronic and persistent.