Sciatica is such a common complaint that most people know it refers to leg pain coming from the back. This, however, is more a description of symptoms rather than an actual diagnosis, because it does not describe why this pain is occurring. The term "sciatica" is one of a number of catch-all phrases that are commonly used for simplicity. When someone comes to see me for a case of "sciatica", this only gives me an idea of where it hurts, not why. There are a number of different conditions that can cause back pain with radiation down one or both legs, and figuring out which of these is occurring makes fixing it much easier.

The word sciatica, in its true sense, means pain in the sciatic nerve. The nerve roots from the bottom of the spine come together to form the sciatic nerve, a thick cord that runs from the pelvis down the back of the thigh before branching to two smaller nerves at the knee. If the sciatic nerve is being irritated or damaged pain will be felt along its course, often right down to the toes. True sciatica occurs if the nerve is being damaged specifically, such as by a blow to or fall on the buttock, or more commonly from prolonged sitting on an imposing object such as a wallet. This is differentiated from less direct insults on the nerve, which are more common causes of back and leg pain.

The most likely cause of what most people would call "sciatica" would really be an impedance of one or more of the nerve roots at the spine that make up the sciatic nerve. This is usually due to a bulging, or herniation, of a spinal disc. These discs are the shock absorbers between vertebrae in the spine and, like a balloon or tire with a weakened wall, they can bulge out if damaged and press on the nerve roots exiting the spinal canal. This causes significant pain as well as neurological symptoms such as numbness and weakness that are specific to the particular nerve being affected. Since the sciatic nerve is comprised of five of these nerve roots, it is unlikely that the entire sciatic nerve is "pinched"; rather, components of it are affected which can still be felt right down to the toes. Disc herniations can be quite serious, and should be monitored closely for progression of symptoms or pathological causes. Symptoms that are in both legs at the same time or are causing any loss of control warrant immediate medical attention. If symptoms do not abate with conservative treatments over time, surgery may be required to remove the tissue that is pressing on the nerve.

Sciatica can also be caused by less serious conditions such as a dysfunctioning joint or a tight muscle. The piriformis muscle runs underneath the gluteals and functions to turn the leg outwards. If it is strained or injured, or otherwise becomes too tight, it can impede the sciatic nerve that runs underneath it, producing pain down the course of the nerve. "Piriformis Syndrome" can be a source of great pain, but is often overlooked as a cause of the problem despite the fact it can be quite amenable to soft tissue therapy.

In my experience, most cases of "sciatica" are actually problems not with the sciatic nerve at all, but a spinal joint nearby. The sacroiliac (SI) joints are probably the most common cause of lower back and leg pain I see in my practice. The SI joints are formed where the pelvis meets each side of the sacrum, and can be found by feeling for a bony bump on each side just above the buttocks. When one or both SI joints are irritated pain is not only felt at the joints themselves, but also in a typical referral (or "ghost pain") pattern into the buttocks, groin, and thighs.

While this pain can be severe enough to be incapacitating, the cause is much less serious than it seems, and usually responds well to conservative treatment. While back pain that involves the legs can have a range of severity and specific symptoms, the cause is often misunderstood or glazed over by blanket labels. As with any mechanical musculoskeletal problems, the sooner you have it properly diagnosed and treated, the better chance you have of making your personal experience of sciatica a distant memory.