Spinal Stenosis: Nerve Compression in the Spine

Spinal stenosis is a condition that involves both the bony structures and the nerves of the spine.

The bony structures of the spine are the vertebrae. They provide structure for our bodies and protect the spinal cord, which carries messages between the brain and body. There are about 33 interlocking vertebrae and they are articulated in a way that provides support for the chest and abdomen while allowing us the flexibility to twist and bend. The spine has two forward curves--cervical and lumbar--and two backward curves--thoracic and sacral, which help it absorb mechanical stress.

The spinal cord travels through the spinal canal from the head to the lower back. The posterior longitudinal ligament lines the canal between the spinal cord and the back of the vertebrae, providing additional support and protection for the spinal cord. All messages between the brain and body are carried by the spinal cord in a top-down fashion. If the spinal cord is severed, you lose all sensation and function below the injury.

A pair of spinal nerves leaves the spine between each pair of vertebrae. They split off of the spinal cord and innervate the structures parallel to that vertebra. The nerves pass out of the spinal canal through the neural canal and exit the spine through the space between vertebrae.

Whenever the spinal canal or one of the neural canals is narrowed or obstructed, you have spinal stenosis. The symptoms of spinal stenosis depend on which nerve or nerves are being affected.

Cervical spinal stenosis occurs in the neck and can involve either the cord or spinal nerves. If spinal nerves are involved, you will have pain, numbness, tingling and/or weakness of the neck, shoulders and/or arms. If the cord is involved, you may also have symptoms affecting your legs, usually uncoordinated movement and difficulty walking.

Thoracic stenosis is rare because there is less curvature in the thoracic spine, and therefore less stress on the joints between vertebrae. The spinal canal is normally narrower in the thoracic spine, however, so it takes less obstruction to cause symptoms.

Lumbar stenosis is common, and involves the lower back. Lumbar stenosis causes pain in the lower back and leg and may also cause weakness in one or both legs.

Spinal stenosis can be caused by narrowing of the spinal canal, narrowing or obstruction of the neural canal or narrowing or obstruction of the space between vertebrae. Stenosis can be congenital or it can be caused by injury, tumor, medical conditions or degenerative changes due to aging.

In the early stages, anti-inflammatory medications, physical therapy and other medical measures take care of the symptoms. Ultimately, the only way to correct spinal stenosis is with surgery to relieve pressure on the nerves.