Minimally Invasive Surgery

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In somewhat older age groups (50+), due to disc degeneration, multiple discs can bulge and/or herniate, and the ligaments can buckle into the spinal cord or nerve roots resulting in spinal stenosis (pinching of not only the nerves down the arm, but the spinal cord itself). Cervical stenosis can place pressure on the spinal cord. The result of pinching of the spinal cord can be an insidious loss of coordination, loss of balance during walking, and even bowel and bladder incontinence.

If most of the compression is in the back, this condition can be treated with a posterior laminectomy. The objective of this procedure is to remove the lamina (and spinous process) to give the spinal cord more room. The spinal cord is especially sensitive to injury, and once the progression of pinching leads to significant loss of function, this function may not be reversible even with removal of the offending agent(s).


In the figure at right, the spinal cord (blue) is shown being compressed at multiple levels in the cervical spine by the discs from the front and the ligaments from the back (yellow). The spinal cord looks like an hour-glass in the areas in which it is compressed.


GENERAL PROCEDURE

1. Surgical approach

  • The skin incision is in the midline of the back of the neck and is about 3 to 4 inches long
  • The paraspinal muscles are then elevated off of the lamina.


2. Removal of the lamina

  • A high speed burr can be used to make a trough in the lamina on both sides right as it joins the facet joint.
  • The lamina with the spinous process can then be removed as one piece, or can be removed piecemeal.
  • Removal of the lamina and spinous process allows the spinal cord to float backwards and gives it more room.

3. Cervical Fusion

  • Cervical laminectomies are sometimes done with a cervical fusion. If a posterior laminectomy is done without a cervical fusion, there is a post-operative risk of developing instability that may lead to pain and deformity. Therefore, there is a risk that a fusion will be needed at some point in the future.

4. Posterior Laminoplasty

  • In order to reduce the risk of post-operative instability and to avoid a fusion, some surgeons will recommend lifting the lamina on one side and leaving a hinge on the other side (posterior cervical laminoplasty).
  • The advantage of this technique is that it increases the size of the canal but leaves the posterior tether that helps keep the spine stable.
  • The disadvantage is that it may not be as easy to decompress the nerves on both sides as they exit the foramen.




AFTER SURGERY

If the surgery simply prevents progression of the spinal cord damage (myelopathy) and there is no loss of function due to the surgery, both the patient and surgeon should consider the treatment successful.

Patients will feel some pain after surgery, especially at the incision site. While tingling sensations or numbness is common, and should lessen over time, they should be reported to the doctor. Most patients are encouraged to be up and moving around within a few hours after surgery. After surgery, your doctor will give you instructions on when you can resume your normal daily activities.

Signs of infection like swelling, redness or draining at the incision site, and fever should be checked out by the surgeon immediately. Keep in mind, the amount of time it takes to return to normal activities is different for every patient. Discomfort should decrease a little each day. Most patients will benefit from a postoperative exercise program or supervised physical therapy after surgery. You should ask your doctor about exercises to help with recovery.


OUTCOME

The results of the surgery are variable since some people have more extensive disease than others. In general, after the surgery most patients can expect to regain:

  • Some spinal cord function
  • Improvement in their hand function and walking/balancing capabilities
  • Surgery is very effective in reducing the pain in the arms and shoulders caused by nerve compression. However, some neck pain may persist.
  • Decreased numbness in the hands (if there was a lot of numbness prior to the surgery, it probably won’t go away completely)

The outcome of decompression treatment for the spinal cord impingement is more variable than surgery for nerve root impingement. Decompressive procedures such as laminectomy generally arrest progression of the spinal disorder. The amount of recovery of neurologic function such as balance, coordination, bowel or bladder incontinence depends on the amount and duration of compression, as well as the presence of any permanent damage to the spinal cord.


POSSIBLE RISKS/COMPLICATIONS

A laminectomy may not be successful in releasing compression on the spinal cord if the spine is not in lordosis (normal swayback). In such a case, anterior cervical corpectomy may be necessary to treat the spinal cord compression.

As with cervical corpectomy (also done for cervical stenosis with myelopathy) the principal risk is deterioration in neurological functioning after the surgery.

To help manage this risk, the spinal cord function is often monitored during surgery by Somatosensory Evoked Potentials (SSEP’s). SSEP’s generate a small electrical impulse in the arms/legs, measure the corresponding response in the brain, and record the length of time it takes the signal to get to the brain. Any marked slowing in the length of time may indicate compromise to the spinal cord.

Other potential risks include:

  • Dural tear (cerebrospinal fluid leak)
  • <1% infection rate
  • Bleeding
  • Increased pain
  • Instability in the spinal column
  • Progressive kyphosis
  • Death
  • image
    A dural tear, which occurs 1% - 2% of these surgeries, does not change the result of surgery, but post-operatively the patient may be asked to lay recumbent for one to two days to allow the leak to seal. Usually a laminectomy performed at a few levels is a safe procedure without significant long term complications or possibility of instability that may be caused by the removal of the laminar structure of the spine. When multiple levels are involved, a multi-level laminectomy can be done alone, but sometimes without the support of the lamina, the spine can fall forward (into kyphosis) resulting in a very serious and dangerous situation, which is not easily reconstructed without considerable risk. In the image at right, note the resultant curve going the opposite way after the laminectomy, resulting in the spinal cord (blue) being draped over the bone and soft tissue. To avoid the above problems that can result with lamina removal, instead the lamina can be reconstructed. This procedure is called the laminaplasty.