Lumbar MicroDiscectomy

What does minimally invasive mean?

Minimally Invasive means minimal damage to normal tissue. Minimally Invasive Discectomy includes any procedure that keeps the skin incision very small and avoids undue retraction to spine muscles. Lumbar MicroDiscectomy (using a microscope) and endoscopic disectomy (operating through a camera) are 2 different forms of MID. They both involve small skin incisions and minimal muscle retraction. The most important feature of both procedures is providing adequate light to visualise the nerves deep within the spine. In some case use of magnifying surgical loupes combined with specialised lighting can provide the same view. We use all three techniques in our practice and customise the operation for each individual patient.

Does a discectomy helps leg pain?

A minimally invasive discectomy 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 discectomy procedure.

Minimally invasive lumbar microdisectomy surgery technique

A lumbar microdiscectomy 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 a lumbar microdiscectomy

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. In some cases a spinal injection of cortisone may help to relieve pain while the natural process of healing occurs. Although the injection itself is not a cure, it may provide a window of pain relief in order to allow a better physiotherapy exercise program.

If the leg pain does not get better with conservative treatments, then minimally invasive 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.

Minimally invasive lumbar microdiscectomy 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 surgery for a prolonged period of time (more than three to six months).

After microdiscectomy surgery

Usually, a discectomy procedure is performed with a single overnight stay in the hospital. Post-operatively, patients may return to a normal level of daily activity quickly. I recommend 2 weeks off work and driving.

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 lumbar microdiscectomy. There have been a couple of reports in the medical literature showing that immediate mobilisation (return to normal activity) does not lead to an increase in recurrent lumbar herniated disc. However we prefer that heavy lifting is not done for at least 6 weeks after surgery.

Minimally invasive discectomy 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 only way to absolutely assure that no further disc herniations can occur.

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

Surgery risks and complications

As with any form of spine surgery, there are several risks and complications that are associated with a lumbar microdiscectomy, 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 flat for one to two days to allow the leak to seal and avoid the headache associated with this condition. Almost all patients will suffer a significant headache if a dural tear occurs. The headache settles spontaneously within 24 to 48 hours when the CSF has reformed. There is usually no long term consequence.
• Nerve root damage – risk < 1%
• Bowel/bladder incontinence . Extremely rare.
• Bleeding. This may cause a post op wound blood clot that requires further surgery to remove the haematoma. Patients on blood thinning medications such as aspirin and clopidrogel should stop taking this medication for at least 7 days before surgery and preferably 2 weeks before surgery. Warfarin should be stopped for 3 days and blood clotting tests performed prior to surgery to make sure that it is safe to proceed.
• Infection. Usually treated with antibiotics.
• DVT (Blood clot in deep veins of legs)

However, the above complications for minimally invasive spine surgery are quite rare and your surgeon will take al precautions possible to avoid risks.