Sciatica describes back-related leg pain, caused by irritation to the sciatic nerve, or the nerve branches that form the sciatic nerve.
Branches of the lower lumbar and upper sacral spinal nerves exit the spine and form the sciatic nerve. Once formed, the sciatic nerve gives sensory supply to the skin of the buttocks, back of the thigh and all of the lower leg and foot, except for the inner side. In addition to pain sciatica can also produce numbness and tingling in these areas.
As the sciatic nerve also gives motor supply to many leg muscles, then muscle weakness may also be a seen with sciatica.
Groin pain can commonly be referred from the low back, especially the sacroiliac joints. Groin would not be considered sciatica, however, because the groin is not in the distribution area of the sciatic nerve.
CAUSES OF SCIATICA
Sciatica describes a set of symptoms rather than a diagnosis. There are many possible causes of sciatica. The main three are:
- Disc bulge/prolapse – this causes irritation or compression of a spinal nerve root and produce radicular pain that corresponds to the nerve root affected. It may also be associated with loss of reflexes, changes to pinwheel sensation or muscle weakness.
- Injury to facet joints – these are small joints located at the back of the spine. They can cause similar sciatica symptoms to disc prolapse, but it does not follow the distribution of a spinal nerve and is therefore called referred pain.
- Piriformis Syndrome – The sciatic nerve passes through (or in some cases in front of) the piriformis muscle, deep in the buttock. Spasm of the piriformis can produce sciatica symptoms.
The management of sciatica will differ according to what is causing the sciatica symptoms.