Pain from Disc Prolapse
Disc lesions become extremely common with increasing age. So does back pain and neck pain. Disc prolapses can press on nerve roots, causing pain to refer down the leg, classically at least past the knee, or from the neck down the arm. Disc degeneration alone, without pressure on the nerve roots tend to cause more local pain in the lower back or neck. This pressure can lead to oedema surrounding the nerve which can exacerbate the pain. This oedema can respond very effectively to epidural injections. If the disc lesions is extensive enough to cause motor weakness, then one may consider surgery, however, this will only be helpful if done within 2 days of onset of weakness, especially if the bowel and bladder sphincters are affected.
Having said all that, too often, patients are told that the cause of their pain is related to their discs, usually disregarding other contributing factors to the pain. There are also several structures that can refer pain to the limbs aside from the nerve roots. And always remember that a CT or MRI pictures the patient’s spine when he lies still, not when he is in motion. Nothing can clinically assess the musculoskeletal system in motion better than a thorough clinical examination. Therefore, the connection between low back pain, even if radiating to the leg, and the disc lesions is not clear-cut. Likewise, with the neck and the arm. The fact that a person shows a disc lesion on a CT or MRI scan does not confirm that the pain is due to the disc lesion. There are often several other secondary biomechanical factors that contribute to the pain.
Causes of pain radiating from the low back to the leg:
- Pressure on nerve roots due to disc prolapses
- Pressure on nerve roots due to facet joint arthritis or thickening of the ligaments
- Trigger points in various muscles
- Referred pain from some of the sacroiliac ligaments
- Referred pain from ligaments of the hip joint
- Nerve entrapment by muscles (e.g., piriformis)
- Referred pain from internal organs
Similarly, sources of pain radiating from the neck to the arm include:
- Pressure on cervical nerve roots
- Pain referred from various neck and shoulder muscles
- Nerve entrapments by various muscles (scalene muscles)
- Pain referred from ligaments, usually within the neck
- Shoulder tendons
- Internal organs
Patients must be evaluated clinically very thoroughly, especially when considering operative intervention. Failure to address other causes of the pain will lead to treatment failure; if the patient is operated in such cases, failed back surgery syndrome can result. This affects between 10 and 40% of patients undergoing back surgery, though there are other causes for this as well though I believe that the major cause is lack of a thorough evaluation right from the start. It is therefore imperative to make sure that the findings on imaging match the clinical findings before any operative intervention is considered.
Studies of the success of surgery for the treatment of low back pain and sciatica show varying results. Generally, success rates of studies reported by orthopedists show much better results than by non-surgical practitioners which means there is clear positive bias by the surgeons towards operative repair. Success rates range from 90% improvement to no difference between operative intervention and non-operative treatment after 2 to 5 years. It is important to note that the success of subsequent operations is reduced with each successive operation, so if one should think at least twice before the first operation, one must think ten times before the second and the third.
My guidelines are:
- First, as general published guidelines write, ascertain that the pain is congruent with pressure on a nerve root from disc lesions and that the clinical picture is supported by the MRI findings.
- Before opting for operative intervention, be absolutely sure that the disc is the cause of the pain. Have a very thorough clinical evaluation.
- Have an epidural injection if necessary, and preferably under fluoroscopy. Pulsed radio-frequency can alleviate more chronic pain.
- Prior to opting for operative intervention, treat other causes of pain present, even if a disc lesion is present. Sometimes the pain is reduced and the component of the disc pain seems less dominant. See sections on IMS and prolotherapy.
- Address faulty ergonomics