Sciatica, which typically presents with low back pain, pain in the buttock and down the leg, affects almost half the population at some point in their lives and results from pressure being applied to part of the sciatic nerve. The sciatic nerve is the largest nerve in the body and is formed by spinal nerve roots in the low back and travels through the buttock and down the back of the leg.
The disks that lie between the vertebrae may develop bulges or ruptures resulting in pressure on the sciatic nerve.
Osteoarthritis can result in boney formations called osteophytes, also known as bone spurs, which can traumatize and apply pressure to the sciatic nerve.
Stenosis is a narrowing of the passage a nerve traverses and in the case of the sciatic nerve, this narrowing may take place in the spinal canal or where the nerve roots that form the sciatic nerve exit the spinal column.
Piriformis syndrome is not universally considered a cause of sciatica as some authorities define sciatica as originating in the low back only, but the mechanism and the symptoms are essentially the same in those experiencing Priformis syndrome. The piriformis is a muscle that lies deep in the buttock; the sciatic nerve passes over, under or through this muscle. When the piriformis becomes irritated or injured, it can apply pressure to the sciatic nerve resulting in symptoms identical to sciatica originating from the low back, with the exception there may not be low back pain. This is a common cause of sciatica and frequently missed as a cause.
A far less common cause of sciatica is tumors involving the spinal cord. The tumor may be malignant or benign, but the mechanism is the same; compression of the nerve.
External forces from traffic accidents, falls and other injuries can result in inflammation, swelling or direct trauma to the sciatic nerve. The end result is irritation to or pressure on the sciatic nerve.
About this Author
Michael Wedge maintains an alternative and complementary medicine practice in Alaska. He has been involved in health care for more than 30 years. Originally trained as a paramedic, a career he held for more than 10 years, he went on to study and obtain graduate degrees in acupuncture and oriental medicine, and clinical hypnotherapy with additional training in medical thermography.