Low Back Pain and Sciatica
4 out of 5 adults will suffer with their backs at some stage in their lives. It is easiest to divide back pain into 4 phases. Acute phase, prolonged acute phase, developing chronic phase and chronic phase.
Acute Phase
In the absence of serious trauma acute back pain is often triggered by a trivial event, such as bending over to pick something up or even sneezing. The pain is usually anything but trivial however. The magnitude of this pain is in part due to the protective mechanisms that fall into place. Back pain from any cause results in acute muscle spasm of the erector spinae and associated muscle groups. This muscle spasm is often more painful than the original problem and if left unchecked causes profound immobility.
In most people this acute phase will last only a few days and will lead on to a period of feeling bruised and generally sore, this is part of the normal healing process.
Whether this acute phase continues depends on a number of things but two of the more important are how well the acute phase is treated and what the cause of the muscle spasm is. If the acute phase is not properly and aggressively treated it very easily passes onto the Prolonged Acute Phase.
Treating muscle spasm
Rest: Sometimes an overnight rest, can break the spasm of an acute event. It is not worth resting beyond this, and indeed it can be counter productive as the goal is to return to normal activity as soon as possible.
Drugs: The only really effective drugs at reducing muscle spasm in the very acute phase are benzodiazepines such as Diazepam, although pain killers will often help.
Acupuncture: Where muscle spasm is associated with trigger points acupuncture can be truly miraculous at relieving it, and extremely satisfying for the therapist.
Other modalities: Heat, cold, massage and stretching can all help relieve muscle spasm and reduce chronicity.
Underlying problems
Facet Joint pain  
The facet joints are the small joints behind the vertebral discs that provide articulation and posterior support for the spine. They are small and quite easily damaged. They are the source for back pain in around 40% of people. The most vulnerable facet joints are the bottom 3 pairs of joints. Risk factors for facet joint pain include: loss of disc height due to previous disc collapse, scoliosis or other causes for unequal loading of the joints such as unequal leg length or pelvic tilt. Facet joint pain is typically felt across the low back but will often radiate as far down the legs to the knees. Facet joint pain will often settle on its own but if it is preventing a patient from getting back to work or has gone on for several weeks it merits treatment. Some patients require their facet joints to be injected with steroids and local anaesthetic. This has to be done under X-ray control and can be performed as a day case procedure. This has the dual benefit of helping to diagnose the source of the pain and treating it. The steroids reduce the inflammation in the joint and allowing a return to normal movement, which encouraging the healing process. If the pain is only partially relieved by facet joint injections the likelihood is there is more than one source for the patient's pain. Patients with multiple pain generators require more complex pain management.
Discogenic pain  
The intervertebral discs in the back have a nerve supply, when they are damaged this can cause low back pain. It is not unusual for patients with damaged discs to get pure low back pain, there is often also associated nerve root pain, causing the pain to radiate down the leg, often as far as the foot. If the disc is causing the pain an abnormality will usually show up on the MRI scan and the patient will often respond well to an epidural steroid injection.
If the pain continues to return despite several epidural steroid injections it is worth investigating further with discography. This is where the disc is pressurised to see if the pain can be replicated, this would only be done if disc removal or replacement is being considered.
Nerve root pain
If low back pain is radiating down towards the foot or there is associated weakness or numbness then nerve root compression has to be suspected. Again this is likely to show up on MRI. Sometimes specific nerve root injections are appropriate again to assist in diagnosis. If the pain recurs the nerve roots can be pulsed with radio frequency energy resulting in longer lasting pain relief.
Sacroiliac joint pain
In 15 to 20% of patients the sacro-iliac joints are the cause of low back pain. This often radiates into the buttock or down as far as the knee. Sacro-iliac joint disease is often difficult to diagnose, sometimes there is tenderness on examination, sometimes X-rays or MRI scans show abnormality. If steroids injected into the joint gets rid of the pain this is strongly suggestive that the sacro-iliac joint is the cause of the pain. These injections can be repeated but if pain relief is not long lasting radiofrequency denervation of the joint may be the answer.
Piriformis syndrome
Low back pain radiating down to the buttock or into the groin can be caused by disease of the piriformis muscle. Again this is often difficult to diagnose as there is no abnormality on MRI or X-ray. The piriformis muscle can be injected under contrast enhanced X-ray control. This allows accurate placement of steroid which can sometimes produce miraculous results.
Other Important Factors to consider
  • Posture
  • Weight
  • Smoking
  • Exercise
  • Other risk factors
These can all be discussed during a consultation and would certainly be investigated if the pain is moving into the chronic phase. Chronic low back pain nearly always requires a multifaceted approach, involving physical therapy, pschyotherapy, drugs, injections and neuromodulation, more on this elsewhere in the website.
A number of good patient information leaflets can be found on the Royal College of Anaesthetists faculty of pain medicine website.
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