According to Dorland's Medical Dictionary, the word sciatic comes from the Latin word sciaticus, which is derived from the Greek word ischiadikos. It means "pertaining to or located near the ischium." The ischium is the pelvic bone that is commonly referred to as the "sit bone." The word sciatic is usually used in reference to the largest and longest nerve in the body---the sciatic nerve. This nerve originates near the sit bone and runs down the back of the thigh. "Sciatica" is a painful condition that causes inflammation or compression of the sciatic nerve.
Anatomy
The sciatic nerve is formed by several smaller "nerve roots" that originate in the lower spine and pelvic region. These roots come together to form a common trunk in the lower buttock region. This trunk, about the thickness of a heavy-duty extension cord, is the sciatic nerve. The sciatic nerve extends to the level of the knee where it branches into smaller nerves that travel to the lower leg and foot. The whole thing is quite like an inverted tree with its roots trunk and many branches.
Symptoms of Sciatica
Pain is the primary symptom of sciatica. This pain usually originates in the lower back or buttock. It may stop at the buttock or it may radiate all the way to the foot. It tends to be an intense pain that may be highly variable depending on body position. Generally, positions that stretch the sciatic nerve will increase the pain of sciatica. Bending forward at the waist or lying on your back while raising a straight leg are examples of postures that place tension on the sciatic nerve.
In addition to pain, conditions that cause sciatica often cause some numbness or altered sensation in the involved leg. Weakness in the painful leg is also common.
Causes of Sciatica
According to a July 2009 publication of the Journal of the American Medical Association (JAMA), the four most common sources of sciatica are:
1. Herniated disc pushing on a nerve root
2. Degenerative spinal arthritis causing stenosis (narrowing) of the spinal canal leading to pressure on a nerve root
3. Vascular problems due to abnormalities of blood vessels in and around the spinal canal
4. Tumors compressing a nerve
Piriformis Syndrome is also a potential cause of sciatica. In this condition, a small muscle in the buttock called the piriformis becomes overly-tight or inflamed. The proximity of the piriformis to the sciatic nerve leaves the nerve vulnerable to compression from a tight piriformis.
Treatments for Sciatica
Appropriate treatments will vary according to the specific cause of sciatica. For the more common causes of disc herniation or spinal arthritis, rest and analgesics may be appropriate initially. In cases where associated weakness and numbness are not severe, physical therapy or chiropractic treatments may be beneficial. Massage or acupuncture may help relax muscles and ease symptoms. For cases where there is marked weakness and numbness, prompt surgical intervention may be necessary.
Imitators of Sciatica
Not all pain that radiates into the hip and thigh is from the sciatic nerve. A tight or strained hamstring muscle will certainly cause pain in the back of the thigh. Inflammation of a bursa under the sit bone or at side of the hip can cause a pain that mimics sciatica as can irritation of the sacroiliac joint. These conditions, while painful, usually will not cause any numbness or weakness in the leg.
Your health care provider will be able to accurately diagnose the source of your pain and advise you on an appropriate treatment plan.
References
- "Dorland's Illustrated Medical Dictionary 26th ed."; WB Saunders Company; 1981
- JAMA Patient Page: Sciatica; July 2009
