Sciatica: Symptoms and Possible Causes

Is sciatica a spinal disorder or a symptom of a spinal disorder?

Written by Steven R. Garfin, MD
Reviewed by Richard D. Guyer, MD

The term sciatica is commonly used to describe pain traveling in the distribution of the sciatic nerve, so it's more accurate to say that it's a symptom of a spinal disorder not a spinal disorder itself. The sciatic nerve is the largest nerve in the human body, about the diameter of a finger. Before jumping into the symptoms associated with sciatica, it's helpful to have an idea of where the sciatic nerve is and what it does.
Sciatic nerve fibers begin at the 4th and 5th lumbar vertebra (L4, L5) and the first few segments of the sacrum. The nerve passes through the sciatic foramen just below the piriformis muscle (rotates the thigh laterally), to the back of the extension of the hip and to the lower part of the gluteus maximus (muscle in the buttock, helps with thigh extension).

The sciatic nerve then runs vertically downward into the back of the thigh, behind the knee and branches into the hamstring muscles (calf) and further downward to the feet.

Sciatic Symptoms

Nerve Compression Can Cause Sciatica
Compression of the sciatic nerve can cause any of the above-cited symptoms. Rarely is nerve damage permanent, and paralysis is seldom a danger since the spinal cord ends before the first lumbar vertebra. However, increasing trunk or leg weakness or bladder and/or bowel incontinence is an indication of cauda equina syndrome, a serious disorder requiring emergency treatment. If you are experiencing those symptoms right now, please seek immediate medical treatment.

Lumbar (low back) spine disorders known to cause sciatic nerve compression include the following:

Dr. Garfin very nicely described the causes of sciatica and helped explain away the myths related to sciatica. However, not all buttock and leg pain is sciatica as there are many other structures in the spine that can cause these types of pain. For example, the sacroiliac joint (the joint between the pelvis and sacrum, the lowest segment of the spine) can cause or refer pain to the buttock and so can a sprain of the facet joints, which are the connecting joints in the back part of the spine. Sometimes a tear of the disc can refer pain down into one's leg. If buttock and leg are associated with any neurologic symptoms of numbness or weakness it is "real sciatica" and needs to be evaluated by a spine care specialist. If severe neurologic symptoms occur along with bowel or bladder control problems, this is an emergency and needs to be evaluated as soon as possible.—Richard D. Guyer, MD

How Your Physician Diagnoses Sciatica
The physician's examination includes the patient's medical history, a review of current medications, a physical and neurologic examination, and, if warranted, x-rays, CT scan and/or MRI studies. A proper diagnosis requires an analysis of the patient's pain. The patient is often provided a Pain Diagram to illustrate pain distribution and sensation (eg, tingling and burning).

The physician's questions may include:

The patient's range of motion is observed. Reflexes and muscle strength are tested. The physician may use one or more movement tests to determine the source or cause of the pain.

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