The lumbar nerve roots emerge from the spine and at this point they are vulnerable to impingement from a disc prolapse, causing inflammation and/or compression of the nerve and the symptoms of sciatica. Sciatic leg pain is not common, affecting 3 to 5% of adults and both sexes equally. Men are more likely to get it in their 40s and women in their 50s, with pain symptoms lasting over six weeks in up to a quarter of cases. Physiotherapists are routinely asked to supervise the management of sciatica.
When the intervertebral disc material prolapses it causes injury by two mechanisms: direct mechanical compression of the nerve and chemical irritation. The disc material should not be outside the disc and its toxic chemicals help swelling both of the nerve and its surrounding structures, resulting in blockage of the circulation and of the nerve’s normal message conduction. While the prolapse is responsible for the sciatica it has not been shown that the bigger the prolapse the more severe the person’s pain.
The lower back suffers very high forces which have to be transmitted through the lower lumbar discs, caused by the leverage imposed by bending forward at the waist, lifting things in front of the body and doing upright activities. The hydraulic disc system generates high internal disc pressures, three to five times that taken by the bones, which stresses the annulus of the disc walls. Structural degeneration can occur in the walls and allow splits to appear, in some cases widening to permit herniation of the central material.
Patients report that the onset of sciatica is rapid and accompanied by back pain, although pre-existing back pain may ease when the leg pain starts. Worse with coughing, sneezing and sitting down, the pain is better standing up or lying flat. Typical pain distribution is through the buttock then down the back of the leg to the ankle and foot or down the side instead. Sciatica does occur in disc levels L1 to L3 but only in for five percent of cases, the pain being in the front of the thigh and not in the lower leg. Some patients present with individual areas of pain rather than the whole picture.
A thorough history performed by the physio will uncover any red flags, an indication of a possibly serious underlying medical condition responsible for the pain. Loss of weight or appetite, severe pain at night, a history of cancer, unwellness or fever, bowel or bladder control difficulties, young or older patients, all these things ring warning bells and the physio will refer the patient on to a medical specialist for evaluation. The location, nature and response to activities and postures of the pain will be noted by the physiotherapist.
The physiotherapist begins with postural observation of the patient which can show an inability to stand up or a thoracic shift to one side. Spinal movements are performed and the pattern of movement limitation noted, with a full neurological examination of the lower limbs. The physio is looking for deficits in muscle power, reflexes or feeling which are related to the specific nerve root involved. The straight leg raise may be performed to check the stretch reaction of the spinal nerve.
The McKenzie technique works on pain centralisation, the tendency for pain to move towards the back from the legs, suggesting a disc problem, and many physios use this technique. Pain in the front of the thigh and over the knee can be referred from the hip joint, so the physiotherapist will assess the lower limb joints to check the diagnosis. A thorough examination informs the physiotherapist of the likely diagnosis and how they might treat the syndrome, or that the patient needs to be referred to a medical practitioner for a consultation and investigation.
Treatments for sciatica due to disc prolapse are many and physiotherapists can choose to use mobilisations and manipulations, lumbar stabilising exercises, the McKenzie treatment path, soft tissue mobilisations such as massage and myofascial release, using analgesics, education about the condition, advice on resting and the best position to relieve extreme sciatica pain. Sciatica naturally settles in time in the vast majority of cases and physios would encourage patients to establish an exercise regime over the long term.
If you would like to make a comment, please fill out the form below.
