A microdiscectomy is typically performed in the case of a lumbar herniated disc.
The center of the disc protrudes through the outer ring (annulus) and subsequently
puts pressure on a nerve, causing pain to radiate down the patient’s leg and into the foot. In this procedure, a small portion of the bone over the nerve root and disc material from under the nerve root is removed to relieve the pressure and provide room for the nerve to heal.
A microdiscectomy surgery is more effective for treating leg pain (radiculopathy) than for lower back pain. The compression on the nerve root can cause substantial leg pain, and while it may take weeks or months for the nerve root to fully heal and for any numbness or weakness to get better, patients normally feel relief from leg pain almost immediately after a microdiscectomy surgery.
Who should have this surgery?
This procedure is usually recommended for patients who have experienced leg pain for four to six weeks and who have tried conservative treatment (such as oral steroids, epidural steroid injections, NSAID’s, and physical therapy) without successfully relieving the pain. However, it is not advisable to wait too long before having this surgery, because the results are not as good if the surgery is postponed more than three to six months. Besides time, one needs to also factor in the level of the pain and the amount of disability the patient is experiencing. If the symptoms are mild, a longer course of conservative treatment may be reasonable, whereas if the symptoms are severe more immediate surgery is reasonable.
Microdiscectomy success rate
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. Recurrence rates after a patient has a disc herniation are between 5 and 10%. 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). If herniation continues to recur, a fusion procedure might be considered.
Recurrent disc herniations are probably due to the fact that within some disc spaces there are multiple fragments of disc that can come out at a later date. Through a posterior microdiscectomy approach, only about 5 to 7% of the disc space can be removed and most of the disc space cannot be seen. Also, the hole in the disc space where the 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 outer portion of the disc space (the annulus).
Usually, a microdiscectomy procedure is performed on an outpatient basis (with no overnight stay in the hospital) or with a one night stay in the hospital. Post-operatively, patients may return to a normal level of daily activity quickly. The success rates for pain relief are between 90 and 95%.
Some 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 after a microdiscectomy, it is also reasonable to return to a normal level of functioning immediately following surgery. There have been reports in the medical literature showing that immediate mobilization (return to normal activity) does not lead to an increase in recurrent lumbar herniated disc. Although a patient may be technically allowed to resume their normal activities immediately, they should expect reduced activities due to incisional discomfort for one to three weeks.
Following a microdiscectomy surgery, a program of stretching, strengthening, and aerobic conditioning is recommended to help prevent recurrence of back pain or disc herniation.
Microdiscectomy surgical procedure
A microdiscectomy is performed through a small (1 inch to 1 1/2 inch) incision in the midline of the 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 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 moved to the side and the disc material is removed from under the nerve root.
Microdiscectomy risks and complications
As with any form of spine surgery, there are several risks and complications that are associated with a microdiscectomy procedure. Complications are quite rare in this procedure, but possibilities include:
- Dural tear (cerebrospinal fluid leak). This occurs in 1% to 2% of these surgeries. It 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 (1 in 1,000)
- Bowel/bladder incontinence (extremely rare)
- Infection (1%)
- Recurrent disc herniations (5-10%)
Follow-up care for a microdiscectomy usually includes a combination of the following:
- Pain management. Immediate post-operative pain can be managed with a combination of non-steroidal anti-inflammatory drugs (ibuprofen such as Advil, Nuprin, or Motrin; or naproxen such as Naprosyn or Aleve) and a mild pain pill such as Darvocet or Vicodin. As the discomfort subsides (usually about 1 to 2 weeks) the patient can move toward substituting Tylenol for the narcotic pain medications. Ice may also be applied to the back to decrease pain within the first 48 hours after surgery.
- Stretching program. Most surgeons feel that to minimize tethering of the nerve root by scar tissue, gentle stretching exercises should be done in the early postoperative period. Scar tissue in and of itself is not painful, but if it tethers the nerve root short as the patient heals this can result in chronic pain. The stretching should be done about 5 to 6 times a day for 6 to 12 weeks, since this is the time period in which the scarring occurs. It is generally advisable to do the stretching exercises frequently and gently. Stretching too hard may result in pain, and one should only take the stretch to the point of pain to avoid inflaming the nerve. If a patient feels too much pain after surgery to do any stretching, it would be wise to wait until he or she is more comfortable.
- Back strengthening exercises. After the soft tissue has healed (usually 2 to 3 weeks after surgery), it is important to start back strengthening exercises.There are a wide variety of possible exercises to achieve the desired results, and it is important to choose exercises that are safe and well tolerated so that they will be done on a regular basis. About 15 minutes of appropriate stretching and strengthening exercises per day is advisable for the first one to three months.
- Early return to activity. Early mobilization may help patients heal sooner, as the pre-operative pain has usually caused patients to limit their motion, and limited motion is a common cause of pain. Walking is very gentle on the back, and a postoperative walking program with a goal of walking about 3 miles a day is advisable. Return to work is based on how quickly the patient feels better and on what type of work the patient does.
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