Sciatica is an extremely common complaint with many causes. It is important to accurately diagnose the cause of sciatica in order for appropriate treatment to begin. Sciatica is the name given to any sort of pain that is caused by irritation or compression of the sciatic nerve.
Anatomy of Sciatic Nerve
The sciatic nerve is the largest single nerve in the body and is composed of individual nerve roots that start by branching out from the spine in the lower back and combine to form the “sciatic nerve”.
The sciatic nerve starts in the lower back at lumbar segment 3 (L3).
At each level of the lower spine a nerve root exits from the inside of the spine and then comes together to make up the large sciatic nerve.
The sciatic nerve runs from the lower back, down the back of each leg
Portions of the sciatic nerve then branch out in each leg to innervate certain parts of the leg – e.g. the buttock, thigh, calf, foot, toes.
Symptoms of Sciatica
Sciatica is often characterized by one or more of the following symptoms:
- Constant pain in only one side of the buttock or leg (rarely can occur in both legs)
- Pain that is worse when sitting
- Burning or tingling down the leg (vs. a dull ache)
- Weakness, numbness or difficulty moving the leg or foot
- A constant pain on one side of the rear
- A sharp pain that may make it difficult to stand up or to walk
Causes of Sciatica
There are 6 lower back problems that are the most common causes of sciatica:
Lumbar Disc Herniation
A herniated disc occurs when the soft inner core of the disc (nucleus pulposus) leaks out, or herniates, through the fibrous outer core (annulus) and irritates the nerve root which becomes part of the sciatic nerve.
Degenerative Disc Disease
Degenerative disc disease (DDD) is an aging process of a disc which causes it to harden and become less flexible. The weakened disc results in excessive micro-motion at that spinal level, and inflammatory proteins from inside the disc become exposed and irritate the area including the nerve roots which form the sciatic nerve.
A small stress fracture allows one vertebral body to slip forward on another. The increased biomechanical forces of one slipped vertebral body can cause the disc in between to become damaged. The space around the nerve reduces causing irritation to the nerve root which forms the sciatic nerve.
Lumbar Spinal Stenosis
Lumbar spinal stenosis is related to natural aging in the spine and is relatively common in adults over age 60. The condition typically results from a combination of one or more of the following: enlarged facet joints, overgrowth of soft tissue, and a bulging disc. The stenosis process places pressure on the nerve roots, causing sciatica pain.
The sciatic nerve can get irritated as it runs under the piriformis muscle in the buttock. If the piriformis muscle irritates or pinches a nerve root that comprises the sciatic nerve, it can cause sciatica-type pain.
Sacroiliac Joint Dysfunction
Irritation of the sacroiliac joint can irritate the L5 nerve, which lies on top of the sacroiliac joint, causing sciatica-type pain.
For most people, the good news is that sciatica will improve with chiropractic treatment. Overall, the vast majority of episodes of sciatica pain heal within a six to twelve week time span. Following initial pain relief, a program of sciatica treatment and exercise should be pursued in order to alleviate pain and prevent or minimize any ongoing sciatic pain.