Sciatica is a non-medical term that refers to low back pain with radiation of the pain along the course of the sciatic nerve. It may be caused by true 'radicular pain' (see also Cervical Radiculopathy and Lumbar Radiculopathy) where pain extends from the top of the affected leg along the sciatic nerve, which is at the back of the leg. In some cases, sciatica can also affect the calf muscle and the foot.
It may also be caused by pain arising from other structures in or near the spine. In other words, it could be referred pain.
Radicular pain, i.e. pain along the course of a nerve root due to various causes, must be distinguished from radiculopathy, where there is overt loss of function of a given nerve root.
Because sciatica is a vague non-medical term, the conditions included in the use of the term include:
- A herniated disc.
- An osteophyte ('bone spur') on one or more vertebrae.
- Tissue inflammation or presence of a tumour putting pressure on the nerve.
- Spinal stenosis.
- Trauma (i.e. an injury) .
- Peridural fibrosis - formation of scar tissue after previous spinal surgery.
There are a number of recognised risk factors for developing sciatica…
- Age – older people are more prone to the condition due to normal degeneration (see degenerative disc disease) in the spine.
- Body weight – people who are overweight or obese have greater stress placed on the spine which can trigger sciatica.
- Work-related – e.g. previous trauma.
- Diabetes – diabetes is a risk factor due to the higher risk of nerve damage with the condition.
Common symptoms of sciatica include…
- Pain that spreads from the lower back area down to the buttocks and down the back of the leg, sometimes to the calf and foot.
- Pain type can vary from a sharp stabbing pain, to a burning sensation to a slight ache, although it is more normal for the pain to be deep and constant.
- Pain may be aggravated by coughing, sneezing or walking or sitting for long periods.
- Less commonly, some form of muscle weakness or tingling 'pins and needles' may be present.
Sciatica often only affects one side of the body.
Tests / Diagnosis
The first step in diagnosing sciatica is a full medical examination which generally involves tests of muscle strength and reflexes, and a review of where the pain occurs and which movements and postures cause pain.
In some cases, further tests may be recommended which may include…
- Imaging tests, including X-rays, CT or MRI scans, although these should only be ordered if there is a sound medical reason to do so.
- Electromyography ('EMG') which tests muscle function and indicates whether the pain is caused by nerves or muscles.