by Jonathan Blood Smyth

Sciatica results from a structure impinging on a lumbar nerve root, causing compression and/or inflammation enough to cause neurological changes in the skin, reflexes and muscles served by the affected nerve. Not a common syndrome, it is estimated that 3-5% of the population suffer this kind of problem at some time. It affects men and women equally with men most susceptible in their forties and women in their fifties. Up to a quarter have symptoms which last more than six weeks and referral to physiotherapists for acute management is routine.

Disc prolapse can result in the internal nuclear material being extruded past the outer disc wall, physically compressing the nerve root which runs nearby. The nuclear material is also chemically irritating to the nerve structure and these irritants make the nerve and nearby structures swell, partly blocking the local circulation and the nerve's message transmission. Disc prolapse is typically the cause of proper sciatica but the size of the prolapse is not closely related to the amount of pain the person suffers.

The great forces which we impose on the low back mean the lumbar intervertebral discs suffer structural changes and prolapses. Many activities involve a significant level of leverage, such as flexing over, performing movements in an upright position and lifting with the arms away from the body. This greatly magnifies the forces on the discs and due to their fluid mechanics they suffer 3-5 times the loads on the skeleton. This can cause the disc walls to degenerate, giving weak areas and predisposing to prolapse at some time.

The onset of lumbosacral radiculopathy is often sudden with low back pain and any back pain may disappear at the start of the leg pain. Worsening factors are sneezing, coughing and sitting with lying down or standing up common easing factors. Sciatic pain typically occurs in the buttock, back or side of the leg and calf and into the foot. If the disc prolapse is higher up (prolapses at disc levels L1 to L3 are 5% of the total) the pain may be in the front of the thigh no further than the knee. A patient may have an isolated area of pain and still have a prolapse.

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.

About the Author:
Jonathan Blood Smyth is a Superintendent Physiotherapist at an NHS hospital in the South-West of the UK. He specialises in orthopaedic conditions and looking after joint replacements as well as managing chronic pain. Visit the website he edits if you are looking for physiotherapists in Manchester.