(Or more broadly: radicular pain, “trapped nerve”)
Sciatica is a commonly misused term. Technically it only refers to pain in the distribution of the sciatic nerve, which typically presents as a clear line of pain down the back of the leg.
Sciatica is a radiculopathy (irritation of the nerve) often caused by an intervertebral disc pressing on or pinching the sciatic nerve. There are many other causes, but some patients are told that it’s something they “have to live with” and that their only source of pain relief will be medication. Depending on the cause, this may not be the case. An Osteopath can work with you to diagnose the cause of your pain and look into treatment options.
Other nerves can be affected in this way, but as they are not the sciatic nerve, they do not cause sciatica. They may simply be referred to as a radiculopathy of the affected nerve, but treatment options would be similar if the mechanism was mechanical, such as pain caused by a muscle irritating the nerve, or a degenerating disc.
Some causes of radiculopathy are illustrated here. In figure C we see how a bulging disc can compress the nerve within the spinal canal. Similarly, if the disc herniates and releases its contents into the spinal canal, the nerve can also be chemically irritated. In figure D we have a similar result from a spondylolisthesis- a movement of components in the spinal canal compress the nerve, again causing irritation. Another cause of radicular pain can be a deep gluteal muscle, piriformis, which leads specifically to piriformis syndrome.