Spinal Disc Problems (including Red Flags Signs)

See related articles:

• Assessment and management of low back pain
• Sinister causes of back pain
• Acute spinal cord compression
• Back pain-non-sinister causes
• Back pain in children
• Cervical disc protrusions and lesions

Pain in the back and neck is extremely common and whilst most may be classified as simple back pain, the clinician must always be aware of "reg flag" warning signs, which merit investigations or even emergency admission.

Disorders of intervertebral discs include herniated nucleus pulposus, degenerative disc disease and internal disc disruption.

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.

In the upper part of the vertebral column, the spinal cord fills more of the foramen than lower down and the cord ends about the level of L1 in an adult. Impingment on the foramen is more likely to cause neurological problems in the upper than the lower spine but herniated discs are more common in the lumbar region.

Herniated nucleus pulposus is most common in those of less than 40 years old whilst degeneration of discs tends to affect those over 40 with the prevalence increasing with advancing age. Degenerative disc disease affects men and women equally but men are more susceptible to traumatic injury as they are more likely to engage in heavy lifting and contact sports.

Disc lesions of the lumbar spine are rather more common than the cervical spine and disc lesions of the thoracic spine are rare.

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.
• Ask and record the mechanism of injury.
• Note the nature of the pain:
  • Pain from the disc without nerve root involvement, is typically vague, diffuse, and distributed axially.
  • Actions 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, especially in the neck.
  • 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 (including referred pain):
  • Referred pain from a disc to a 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.
  • Symptoms from lumbar lesions are usually in the low lumbar region and buttocks but can include referral to the lower thoracic or upper lumbar region, abdomen, flanks, groin, genitals, thighs, knees, calves, ankles, feet, and toes.
  • 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.
• Make a systematic enquiry about general health. Fever suggests infection. Unintentional weight loss suggests malignancy.

The area to be examined will be guided by the history but be generous in the area examined as symptoms may be relatively distant from the site of the lesion. Look for signs of muscle wasting.

Neck

• 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.
• 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.
• Myofascial tenderness or trigger points are often found.

Thoracic Spine

• Look at the back. Muscle spasm may be obvious. It may produce scoliosis. Run a finger down the spine to detect scoliosis and palpate the paravertebral muscles for spasm.
• Ask the patient to keep his feet still and to rotate his shoulders first one way, then the other. Note pain at the extreme. Note restriction or asymmetry of rotation.
• Use the thumb to press down the dorsal spines in turn. Is any tender?
• Perform a neurological exam of lower limb.

Lumbar Spine

• Again, look at the back. Muscle spasm may be obvious. It may produce scoliosis. Run a finger down the spine to detect scoliosis and palpate the paravertebral muscles for spasm.
• Ask the patient to bend forwards. Note restriction by pain on bending or a tendency to rotate on bending.
• Ask the patient to lie supine on the couch. Using the left hand to hold the knee in extension and the right hand under the heel, perform straight leg raising, noting the angle of elevation where it stops. Note if limitation was due to pain and if so where or if it was simply due to tight hamstrings or pain in the back. Do the same with the other leg.
• Palpate the abdomen. Is there a full bladder?
• Ask the patient to roll on to the front and perform the femoral nerve stretch test. Hold the lower thigh firmly with the left hand and grasp the ankle with the right hand. Bend the knee and note any pain. Note the angle at which it occurs and where the pain occurs.
• Test for springing pain along the dorsal spines of the lumbar vertebrae.
• Perform a neurological examination of the lower limbs as indicted by the history. Check knee and ankle reflexes.
• Always test the area around the anus and perineum for loss of sensation and record your findings whether positive or negative. This will include the posterior third of the scrotum or labia majora but the anterior two thirds is supplied by L1. Rectal examination may reveal a lax sphincter.

It is easy to diagnose that pain originates from the neck or back but being sure that there is a disc lesion usually requires imaging studies. Back and 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 as is the assesment of low back pain.¹ There may be cervical spondylosis or various forms of arthritis in the neck. Regional pain syndrome (algodystrophy), myofascial pain and fibromyalgia are also possibilities. It is also important to be aware of the red flags for malignancy as a cause of back pain.⁴

• Most back pain seen in the surgery is simple back pain and imaging studies are not required initially unless any red flags are present.
• Blood tests may be appropriate if rheumatological or systemic diseases are suspected.
• Imaging studies should be used sparingly - they must be interpreted in the light of the clinical picture as positive findings are quite common in people without any complaints. This applies to both the lumbar⁵ and cervical spine.⁶ People with abnormal x-rays are more likely to develop symptoms⁷ but this is not an indication for treatment in anticipation.
  • Plain x-ray 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 electromyography.

The finding of a disc lesion does not mean that surgery is necessarily indicated and in most cases conservative management is the most satisfactory. There may even be spontaneous regression of a herniated disc.⁸

• 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.
• Some people advocate manipulation but the potential dangers of manipulation, especially of the neck, are discussed in the article on manipulation and the technique should be used with caution. Despite some enthusiasm,⁹ manipulation under anaesthetic is potentially very dangerous as the patient will not resist injudicious excessive force.
• Where surgery is required, less invasive procedures are to be recommended. Laser lumbar discectomy has been reviewed by NICE.¹⁰

A prolapsed intervertebral disc can impinge on the spinal cord or spinal nerves and if this happens then urgent operation to release the pressure is imperative before irreversible damage occurs. Red flags are discussed above.

Prognosis is variable. By and large, the prognosis for neck and back pain shows that many people continue to have long term pain. Those that are found to have disc lesions do not necessarily do any worse than others. Conservative management and a positive attitude can produce very satisfactory results. A study of sciatica with proven disc pathology showed that even conservative management produced good results.¹¹