What is Sciatica?

Sciatica refers to pain that radiates along the path of the sciatic nerve. This nerve, the longest in the body, originates in the low back and then runs through the pelvis and buttocks and down each leg. When acute, sciatica can be disabling. It can also present in a more chronic indolent manner, creating a linear pull or tightness in the buttock radiating down the back of the leg to the foot. Sciatica is a descriptive term about a condition. It is never a diagnosis. For treatment of sciatica to be successful, a diagnosis as to what is causing it must first be determined.

Causes of Sciatica

Lumbar Spine

Disc Herniation

This is one of the most common causes of sciatica. When a disc in the low back herniates, its inner gel-like substance leaks out and can irritate or compress one of the nerve roots that form part of the sciatic nerve. This is usually the disc between L4-5 or L5-S1. The pain is often acute, following a lifting or twisting injury and can be debilitating. Numbness in the foot and weakness of muscles in the foot that derive their innervation from the sciatic nerve may be present. Sitting is often poorly tolerated and being supine (on the back) with knees bent may provide some relief.

Spinal Stenosis 

This condition develops slowly over time and is the natural developmental consequence of deterioration in the disc and the secondary arthritic changes in the joints of the spine that accompany it. Everyone ultimately develops some degree of spinal stenosis although most are without symptoms. Here again, lifting or forward bending may be a trigger that produces symptoms in someone who was previously asymptomatic. In sciatica due to spinal stenosis the pain is usually more chronic presenting as a linear pull in the leg frequently present with walking or standing. Patients often note changes in their functionality, seeing their ability to walk curtailed or having to sit rather than stand at a party or when visiting a museum.


Spondylolisthesis is a condition in which a vertebra slips forward or backward on an adjacent vertebra. It may be a congenital condition, but more frequently is part of progressive arthritic change in the spine. The sciatica it produces is often the more chronic type. 

Tumors or Infections 

Although rarer, these conditions must always be considered. They are usually accompanied by other signs of systemic illness such as fever, chills or weight loss. A detailed clinical history will often raise the level of suspicion for this diagnosis.

The Pelvis 

The sciatic nerve, after its lumbar and sacral nerve roots join, runs through the pelvis. Any inflammatory condition or scar tissue in the pelvis may irritate the sciatic nerve. This may include endometriosis, previous pelvic inflammatory disease or scar tissue from abdominal or pelvic surgery. In these instances, the sciatic pain is usually the more indolent variety. It often presents as tightness in a hamstring muscle. The sciatic nerve runs beneath the hamstring and the hamstring tightens to protect the irritated nerve.

Piriformis Syndrome

The piriformis muscle runs from the sacrum to the lateral hip crossing the middle of the buttock. Beneath it runs the sciatic nerve. Although many practitioners ascribe sciatica to piriformis tightness, in our experience it may be a contributing factor, but is rarely the sole cause of sciatica. It should, however, always be considered and stretching the piriformis is an integral part of any rehabilitation program for sciatica.


The hormone, Relaxin, present in pregnancy increases the laxity of ligaments leading to imbalances in the pelvis that can put pressure on the sciatic nerve.

At the Physicians’ Back Institute, Drs. Irène and Robert Minkowsky are experts in determining the cause of an individual’s sciatica and building a rehabilitation program based on sound clinical findings. The more precise a diagnosis, the more likely that treatment is effective and long lasting.



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