As you might recall from Chapter 3, 31 pairs of nerve roots exit from the spinal cord through spaces between the vertebrae. When those spaces are compromised, nerves can be compressed, which equals pain. Conditions that can compress nerves include:

• Spinal stenosis: A narrowing of the spinal canal
• Degenerative disc disease: Loss of fluid in the intervertebral discs
• Herniated disc: The bulging or rupturing of an intervertebral disc
• Bone spurs: Extra growth on vertebra often due to osteo­ arthritis
• Spondylosis: Spinal osteoarthritis causing joint dysfunction

Exerpt from Chapter 3: Nerve Roots

The nerves of the peripheral nervous system (PNS) extend down the spinal canal and branch out in 31 pairs at openings in the vertebrae called foraminae. They are messengers to and from your brain(or central nervous system), sending pain signals and initiating movement—like, 'Hey, take your hand off the stove, it's hot!' These nerves reflexively cause your spine to twist and turn when you walk to keep you in balance. And they keep you glued to your car seat as you turn a corner at high speeds!
 

The Back and Beyond
As spinal root nerves branch out, they become like a fine web of nerves distributed throughout the body. That's why you might feel what is called referred pain (pain felt in one part of the body when the source of irritation is actually located elsewhere). For example, if a nerve root exiting the lower back is pinched, you might feel pain or tingling down your leg. Sometimes it might be numbness or weakness, not pain. Releasing the compressed nerve usually gets rid of pain and normal sensation returns.

Discectomy
This procedure removes the part of your intervertebral disc that is pressing on a nerve. There are three general types: classic discectomy, microdiscectomy, and percutaneous discectomy. The main variable among them is the size of the incision. The choice depends on your unique situation. Although percutaneous discectomy is the least invasive, it is also the least effective for large herniations.

Surgical imaging technology has enabled surgeons to perform more advanced, less invasive procedures (with smaller incisions). Surgeons can now use microscopes, magnifying loupes, or endoscopes to see the spine in greater detail.

Definition
Surgeons commonly use surgical loupes, which are magnifying lenses wore like glasses. These are often custom made to take into account the surgeon's vision.

Percutaneous discectomy is the least invasive and often done as an outpatient procedure. The surgeon makes a small puncture through the skin and, using X­-ray technology and a needle, suctions out troublesome disc material. These surgeries are usually done when disc herniations have not ruptured but only bulged. Only select patients are ideal candidates for this procedure and the long-­term effectiveness of it has been called into question.

In microdiscectomy, the surgeon makes a small incision (about an inch or two long). Either tubular or blade-­based retractors are placed through the incision to push aside muscle and soft tissue. A small section of bone and ligament is removed to expose the disc. Then a magnifying device (surgical loupes or a microscope) is used to see the damaged disc more easily. Disc fragments are removed from around the nerve. Some additional removal of fragments within the disc space is done to reduce recurrence of herniation.

A classic discectomy requires a larger incision, but provides better visualization of the tissue. In most cases, however, a microdiscectomy can provides the surgeon with enough visualization to do the job adequately. Also, understand that in a discectomy the entire disc is usually not removed. The annulus (outer portion) and a part of the nucleus (inner portion) are left intact to support surrounding vertebrae.

Foraminotomy
There is a space between every pair of vertebrae called the intervertebral foramina or neural foramina. When disc, ligament, or bone spurs creep into the space, the nerves within can get squeezed. This procedure involves removing part of the vertebral bone or excess tissue (such as the disc or ligaments) to create a larger space for the nerve root.

Definition
In anatomical terms, a foramin (the plural form of which is foramina) refers to any opening. It's usually in reference to a space within or between bones, but it can mean a natural opening within tissues as well.

To reach the intervertebral foramina, an incision is made in the back and muscles are separated and retracted much like in the microdiscectomy procedure described in the preceding section. Excess tissue and/or bone are cut away until the desired opening has been created and the nerve is no longer compressed.

Laminotomy and Laminectomy
The spinal canal may narrow due to spinal stenosis, spondylolisthesis, or bone spurs. This procedure widens the space of the spinal canal by removing a section of bone called the lamina. A laminotomy creates an opening in the lamina; laminectomy is the removal of the lamina and or a portion of it. Depending on how much of the spinal canal has been compromised, one vertebra or several may need to be trimmed. If a significant amount of bone has been removed, the area may be too unstable. The spine may require stabilization by spinal fusion (see the next article [Spinal Fusion, Dynamic Fusion, and Disc Replacement]).

As scary as it may sound to have the top of your vertebral bones cut off, know that the spinal cord won't be as exposed as you might imagine. The spinal cord is surrounded by bones on either side and it's also encased by muscles and connective tissue. Patients with a laminectomy can typically resume normal activity with no restrictions after a period of healing.

Jason Highsmith, MD is a practicing neurosurgeon in Charleston, NC and the author of The Complete Idiot's Guide to Back Pain. Click here for more information about the book.