Sciatic back pain, or sciatica, is pain that runs through the buttock and one leg originating in the nerves at the base of the lumbar spine, or the sciatic nerve. If has several causes, usually not from an issue with the nerve itself, but with the surrounding tissues or spine. There are three “usual suspects” or causes that are the most common: herniated disc or discs; spinal stenosis; and isthmic spondylolisthesis.
One cause of Sciatic Back Pain is a herniated disc or radiculopathy
This occurs when the soft internal material in a spinal disc escapes out and presses on a spinal nerve root. There are different reasons why this happens, the most common being annular tears. When this happens in the lumbar spine it is the sciatic nerve that gets irritated.
A Second Is Spinal stenosis
Another cause is spinal stenosis, which is the narrowing of the spine causing pain. There are two types of spinal stenosis, central canal stenosis, where the narrowing occurs in the spinal canal, and neuroforaminal stenosis, where narrowing occurs in the holes located on the sides of the spinal column. With the first type the narrowing occurs in the enter part of the spine where the spinal cord lies. With the second type the narrowing occurs in the holes located on the sides of the spinal column. The nerves that branch out from the spinal cord.
Lastly is Isthmic spondylolisthesis
Isthmic spondylolisthesis is another common cause. It occurs when there are small stress fractures in the spine. They are small enough to go unnoticed, but can cause one vertebrae to slip forward over another one. When that happens the space between the disc space collapses pinching the nerves in and around the vertebrae. When it happens in the lower or lumbar spine, it can cause sciatica.
There are others, but these three are the most common.
