Sciatica is the term used to describe a radiating pain down the back of the leg which can range from the buttock all the way to the foot.
Sciatica is caused by a pinch or irritation of the nerve, most frequently at the root where the nerve emerges from the spinal cord.
Pain can be felt at any point along the length of the sciatic nerve and is often most intense where the nerve bifurcates particularly in the buttock and back of the thigh.
There are many causes of sciatic nerve root irritation, perhaps the most common and best known is a herniation of the intervertebral disc, aka “ slipped disc”. This is where the jelly-like interior of the disc bulges against the outer casing of the disc which then puts pressure on the nerve root.
Other causes of sciatica include,
Osteophytes encroaching on the nerve root (osteophytes are small bony spurs which grow around the edge of joints affected by arthritis)
Spinal stenosis, which is a narrowing of the gap between the vertebrae and can cause compression on the nerve root.
Growths such as a spinal tumour can also compromise the nerve root.
Spondylolysthesis is when a vertebra slips forward over the one below. So this can also narrow the small gap where the nerve root exits the spine.
As there are so many possible causes of sciatica it is important to get the correct diagnosis particularly if the problem keeps recurring.
Physiotherapy assessment will include mapping the distribution of the pain, pins and needles or numbness, checking reflexes and looking for any sign of muscle weakness. Assessment of the lumbo-sacral spine will also be required even though not everyone suffering from sciatica also suffers from low back pain. Passive straight leg raise and “slump test” as demonstrated in the diagram below are not only tests to confirm sciatica but can also be used as part of the treatment. A positive slump test is when the patient is able to straighten the leg of the unaffected (good side) but is unable to do so on the affected side. There will also be pain felt in the buttock of the affected side and, in more severe cases, may even bring on tingling or numbness in the foot.
The first aim of treatment is to reduce the pain. Your doctor may prescribe anti-inflammatories or painkillers. If the symptoms persist and do not respond to treatment then a steroid infiltration (injection) may be suggested.
Physiotherapy treatment will also address the pain using interferential diathermy or Tens. These are both forms of electrical therapy which are painless and used to reduce the irritability of the nerve.
Vertebral mobilisations and passive stretching techniques are used to help reduce the compression on the nerve root and improve the range of movement of the spine to avoid a recurrence of the sciatica. Core strengthening and postural exercises will also help to protect against further compression.
Mild cases of sciatica caused by an awkward lift or poor posture will often resolve themselves with rest and analgesics. Sitting for long periods can exacerbate the pain whereas a gentle walk will often reduce sciatic symptoms.
If treatment is not successful then an MRI scan may be needed for a more in-depth diagnosis, for example in the case of a ruptured disc or tumour when surgery might need to be taken into consideration.
It is important to mention that sciatica can mimic and be mimicked by a range of other conditions and so a full assessment by your physiotherapist is advised as a first differential diagnostic examination.