Lumbar decompression back surgery

Decompression is a surgical procedure that is performed to alleviate pain caused by pinched nerves (neural impingement).

In this type of back surgery, a small portion of the bone over the nerve root and/or disc material from under the nerve root is removed to give the nerve root more space and provide a better healing environment.

Several conditions may cause neural impingement, including spinal stenosis, a disc herniation, isthmic spondylolisthesis, degenerative spondylolisthesis, or (rarely) a spinal tumor.

There are two common types of spine surgery decompression procedures:

• Microdiscectomy (or microdecompression)

• Limenctomy (or open decompression)

How the decompression back surgery is performed
With modern spine surgery techniques, both a microdiscectomy and laminectomy can usually be done with a minimum amount of morbidity (e.g. post-operative discomfort) and a high degree of success in alleviating low back pain and/or leg pain.

Sometimes in addition to the decompression procedure a spine fusion surgery is also necessary in order to achieve adequate decompression of a nerve root. This is especially true if the nerve root is compressed as it leaves the spine (in the foramen), known as foraminal stenosis.

Foraminal stenosis is difficult to decompress simply by removing bone because if the bone is fully removed in the location of the foramen it is generally necessary to also remove the facet joint. Removing the facet joint leads to instability, so a spinal fusion is necessary to provide stability.

The foramen can be opened either through an anterior approach (by "jacking" open the disc space in the front of the spine) or by distracting between two pedicle screws inserted posteriorly (through the back of the spine). After the foramen is opened up a spine fusion is also done to keep it open so the instrumentation does not fail and the foraminal stenosis does not return later.

Microdiscectomy (microdecompression) spine surgery

In a microdiscectomy or a microdecompression spine surgery, a small portion of the bone over the nerve root and/or disc material from under the nerve root is removed to relieve neural impingement and provide more room for the nerve to heal. A microdiscectomy spine surgery is typically performed for lumbar herniated disc.

Microdiscectomy helps leg pain
A microdiscectomy surgery is actually more effective for treating leg pain (radiculopathy) than for lower back pain. The impingement on the nerve root (compression) can cause substantial leg pain, and while it may take weeks or months for the nerve root to fully heal and any numbness or weakness get better, patients normally feel relief from leg pain almost immediately after a microdiscectomy surgery.

Microdiscectomy spine surgery procedure
A microdiscectomy spine surgery is performed through a small (1 inch to 1 1/2 inch) incision in the midline of the low back.

• First, the back muscles (erector spinae) are lifted off the bony arch (lamina) of the spine. Since these back muscles run vertically, they can be moved out of the way rather than cut.

• The surgeon is then able to enter the spine by removing a membrane over the nerve roots (ligamentum flavum), and uses either operating glasses (loupes) or an operating microscope to visualize the nerve root.

• Often, a small portion of the inside facet joint is removed both to facilitate access to the nerve root and to relieve pressure over the nerve.

• The nerve root is then gently moved to the side and the disc material is removed from under the nerve root.

Importantly, since almost all of the joints, ligaments and muscles are left intact, a microdiscectomy spine surgery does not change the mechanical structure of the patient's lower spine (lumbar spine).

When to have microdiscectomy spine surgery
In general, if a patient's leg pain due to a disc herniation is going to get better, it will do so in about six to twelve weeks. As long as the pain is tolerable and the patient can function adequately, it is usually advisable to postpone back surgery for a short period of time to see if the pain will resolve with conservative (non-surgical) treatment alone.

If the leg pain does not get better with conservative treatments, then a microdiscectomy surgery is a reasonable option to relieve pressure on the nerve root and speed the healing. Immediate spine surgery is only necessary in cases of bowel/bladder incontinence (cauda equina syndrome) or progressive neurological deficits. It may also be reasonable to consider back surgery acutely if the leg pain is severe.

Microdiscectomy spine surgery is typically recommended for patients who have experienced leg pain for at least six weeks and have not found sufficient pain relief with conservative treatment (such as oral steroids, NSAID's, and physical therapy). However, after three to six months, the results of the spine surgery are not quite as favorable, so it is not generally advisable to postpone microdiscectomy surgery for a prolonged period of time (more than three to six months).

After the microdiscectomy surgery
Usually, a microdiscectomy spine surgery procedure is performed on an outpatient basis (with no overnight stay in the hospital) or with one overnight in the hospital. Post-operatively, patients may return to a normal level of daily activity quickly.

Some spine surgeons restrict a patient from bending, lifting, or twisting for the first six weeks following surgery. However, since the patient's back is mechanically the same, it is also reasonable to return to a normal level of functioning immediately following microdiscectomy spine surgery. There have been a couple of reports in the medical literature showing that immediate mobilization (return to normal activity) does not lead to an increase in recurrent lumbar herniated disc.

Microdiscectomy spine surgery success rate
The success rate for a microdiscectomy spine surgery is approximately 90% to 95%, although 5% to 10% of patients will develop a recurrent disc herniation at some point in the future.

A recurrent disc herniation may occur directly after back surgery or many years later, although they are most common in the first three months after surgery. If the disc does herniate again, generally a revision microdiscectomy will be just as successful as the first operation. However, after a recurrence, the patient is at higher risk of further recurrences (15 to 20% chance).

For patients with multiple herniated disc recurrences, a spine fusion surgery may be recommended to prevent further recurrences. Removing the entire disc space and fusing the level is the most common way to absolutely assure that no further disc herniations can occur. If the posterior facet joint is not compromised and other criteria are met, an artificial disc replacement may be considered.

Recurrent herniated discs are not thought to be directly related to a patient's activity, and probably have more to do with the fact that within some disc spaces there are multiple fragments of disc that can come out at a later date. Unfortunately, through a posterior microdiscectomy spine surgery approach, only about 5 to 7% of the disc space can be removed and most of the disc space cannot be visualized. Also, the hole in the disc space where the disc herniation occurs (annulotomy) probably never closes because the disc itself does not have a blood supply. Without a blood supply, the area does not heal or scar over. There also is no way to surgically repair the annulus (outer portion of the disc space).

Following a microdiscectomy spine surgery, an exercise program of stretching, strengthening, and aerobic conditioning is recommended to help prevent recurrence of back pain or disc herniation.

Microdiscectomy surgery risks and complications
As with any form of spine surgery, there are several risks and complications that are associated with a microdiscectomy spine surgery procedure, including:

• Dural tear (cerebrospinal fluid leak). This occurs in 1% to 2% of these surgeries, does not change the results of surgery, but post-operatively the patient may be asked to lay recumbent for one to two days to allow the leak to seal.

• Nerve root damage

• Bowel/bladder incontinence

• Bleeding

• Infection

However, the above complications for microdiscectomy spine surgery are quite rare.

Lumbar laminectomy (open decompression)

Similar to a microdecompression, a lumbar laminectomy (open decompression) is a surgical procedure that is performed to alleviate pain caused by neural impingement. The laminectomy surgery is designed to remove a small portion of the bone over the nerve root and/or disc material from under the nerve root to give the nerve root more space and a better healing environment

A laminectomy is effective to decrease pain and improve function for patients with lumbar spinal stenosis . Spinal stenosis is a condition that primarily afflicts elderly patients, and is caused by degenerative changes that result in enlargement of the facet joints. The enlarged joints then place pressure on the nerves, and this pressure may be effectively relieved with a lumbar laminectomy.

Laminectomy surgical procedure
The lumbar laminectomy (open decompression) differs from a microdiscectomy in that the incision is longer and there is more muscle stripping.

• First, the back is approached through a two-inch to five-inch long incision in the midline of the back and the left and right back muscles (erector spinae) are dissected off the lamina on both sides and at multiple levels.

• After the spine is approached, the lamina is removed (laminectomy) which allows visualization of the nerve roots.

• The facet joints, which are directly over the nerve roots, may then be undercut (trimmed) to give the nerve roots more room.

Post-operatively, patients are in the hospital for one to three days, and the individual patient's mobilization (return to normal activity) is largely dependent on his/her pre-operative condition and age. Directly following the procedure, patients are encouraged to walk. However, it is recommended that patients avoid excessive bending, lifting or twisting for six weeks in order to avoid pulling on the suture line before it heals.

Laminectomy success rate
The success rate of a laminectomy surgery is favorable. Following surgery, approximately 70% to 80% of patients will have significant improvement in their function (ability to perform normal daily activities) and markedly reduced level of pain and discomfort.

The laminectomy surgical results are much better for relief of leg pain caused by spinal stenosis, and not nearly as reliable for relief of lower back pain. Lumbar spinal stenosis is often created by the facet joints becoming arthritic, and much of the back pain is from the arthritis. Although removing the lamina and part of the facet joint can create more room for the nerve roots it does not eliminate the arthritis. Unfortunately, the symptoms may recur after several years as the degenerative process that originally produced the spinal stenosis continues.

In certain instances the success rate of a decompression for spinal stenosis can be enhanced by also fusing a joint. Fusing the joint prevents the spinal stenosis from recurring and can help eliminate pain from an unstable segment. Fusion surgery is especially useful if there is a degenerative spondylolisthesis associated with the stenosis. Generally speaking, if there is multi-level stenosis from a congenitally shallow canal a fusion is not necessary; however, if the stenosis is at one level from an unstable joint (e.g. degenerative spondylolisthesis), then a decompression surgery with a fusion is a more reliable procedure.

Laminectomy risks and complications

The potential risks and complications with a laminectomy procedure include:

• Nerve root damage (1 in 1,000) or bowel/bladder incontinence (1 in 10,000). Paralysis would be extremely unusual since the spinal cord stops at about the T12 or L1 level, and surgery is usually done well below this level.

• 1 to 3% of the time a cerebrospinal fluid leak may be encountered if the dural sac is breached. This does not change the outcome of the surgery, and generally a patient just needs to lie down for about 24 hours to allow the leak to seal.

• Infections happen in about 1% of any elective cases, and although this is a major nuisance and often requires further surgery to clean it up along with IV antibiotics, it generally can be managed and cured effectively.

• Bleeding is an uncommon complication as there are no major blood vessels in the area.

• In approximately 5 to 10% of cases, postoperative instability of the operated level can be encountered. This complication can be minimized by avoiding the pars interarticularis during surgery, as this is an important structure for stability at a level. Weakening or cutting this bony structure can lead to an isthmic spondylolisthesis after surgery. Also, the natural history of a degenerative facet joint may lead it to continue to degenerate on its own and result in a degenerative spondylolisthesis. Either of these conditions can be treated by fusing the affected joint at a later date.

General anesthetic complications such as myocardial infarction (heart attack), blood clots, stroke, pneumonia or pulmonary embolism can happen with any surgery. Although in the general population these complications are rare, laminectomy surgery for spinal stenosis is generally done for elderly patients and therefore the risk of general anesthetic complications is somewhat higher.