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Avoiding Adverse Events Associated with Anterior Cervical Spine Surgery

Posted on: 12/31/2008
The cervical spine, or the upper part and the neck, can be hurt in many ways, from trauma and injury to osteoarthritis, the so-called wear and tear arthritis. Most often, conservative - nonsurgical treatment- is all that's needed to help the patient heal, but there are times when surgery is necessary.

Nonsurgical treatments included nonsteroidal anti-inflammatory drugs (NSAIDs) to help reduce inflammation and pain, physical therapy, manipulation, injections of medications such as anesthetics or steroids, and by avoiding activity that can cause or worsen the pain. If these methods don't work, then surgery is generally the next step.

There are different approaches to surgery of the upper neck and back, and one approach is the anterior approach, coming from the front of the neck rather than the back. This was first done to fuse bones together by two researchers, Robinson and Smith in 1955, and has been adapted and improved upon ever since. Most often, this approach is successful and there are few complications, called adverse effects. However, surgeons are aware that adverse effects are possible and they must do whatever they can to reduce the risks of complications. They must also explain to the patients the types of risks involved in the surgery.

The authors of this article reviewed the different types of events that could affect patient outcome after surgery and/or make it so the patient must undergo more treatment, tests, or monitoring. The authors write that the most common and most likely serious adverse events that occur with these surgeries usually happen either during surgery, within one week of surgery, or between one and six weeks after surgery.

Adverse events that may happen during surgery (intraoperatively include injuries to the esophagus, the tube that carries food from the mouth to the stomach. This is a serious injury that can be life threatening and it occurs in about 0.2 to 0.4 percent of all such surgeries. To avoid the injury, surgeons are encourage to place their retractors (instruments that hold back body tissue so they can access where they are operating) in a such a way that avoids touching the esophagus.

Discovering if the esophagus isn't always easy as the injury might not be obvious. If there is any doubt, the authors suggest that a general or thoracic surgeon be called in to see if damage has been done and if so, to correct it. Also, if there is any doubt, it's recommended that a feeding tube be inserted (through the nose down into the stomach) until further studies are done. This would avoid the patient trying to swallow food through a damaged esophagus.

If the injury is missed, the mortality rate can be as high as 20 percent, even if this is discovered early after surgery, within a day. This rises to as high as 50 percent if the injury is discovered and treated later on. If a patient who had this surgery shoes any sign of infection, the surgeon should be suspicious about the esophagus and investigate right away.

Injuring the vertebral arteries is another risk. The vertebral arteries send "clean" oxygenated blood past the vertebrae, the bones in the back, to the back of the brain. This is a very rare complication and can be avoided in many cases by making an opening in the surgical area that seems wider than needed so that the arteries can be found and avoided.

If the surgeon does nick or damage the artery, the bleeding should be controlled by blocking the wound. The problem that may happen though, is that the artery may become blocked and there's a 3.8 percent risk of this happening if it's on the left side and 1.8 percent chance if it's on the right. Because of this, it's recommended that the surgeon do an angiography (test that allows the surgeon to see if the artery is blocked) while the patient is still having surgery.

The dura mater is the outer fibrous tissue that covers the brain. With anterior cervical surgery, there is a possibility that the dura is damaged or torn. The effects of the tear depend on where the tear is and how easily it can be repaired. If the dura is easily reached and repaired, then damage is limited. Unfortunately, sometimes repairs don't always hold up so some surgeons may put a drain in just in case, to drain any excess fluid. In some cases, patients are also encouraged to sit upright right after surgery and this seems to help reduce pressure from leaking spinal fluid.

The surgery also puts the spinal cord itself at risk although, again, it's not common. Such injuries happen in about 0.2 to 0.9 percent of cases. Certain people are at higher risk of spinal cord injury from the surgery. These are people who have myelopathy (problems with the spinal cord itself, cervical kyphosis ("hunched" neck or extreme upper back), spinal cord atrophy (wasting away of the spinal cord), or spinal instability or fractures.

If, during surgery, it's suspected that the spinal cord has been injured, it must be inspected right away and an x-ray may need to be done. After surgery, the patients should be watched closely for any signs of nerve trauma or damage. If needed, other imaging tests should be done, as well.

The nerves that surround the area but aren't part of the spinal cord are called peripheral nerves. These may become damaged during the surgery. If this happens, it's most often from the pulling, or traction, or eve direct pressure on the nerves. This most often can be avoided by proper positioning of the patient for surgery and avoiding being aggressive with traction, holding back parts of the body to access the area that is being operated on.

During the early postoperative period, the first week after surgery, patients could have an acute airway compromise, which means something has affected their airway and ability to get air in and out of the lungs. When this happens, they may need to be re-intubated (have the breathing tube inserted again) to allow them to breathe. It's estimated that this happens in about 1.7 to 2.8 percent of cases.

Acute airway compromise can have a few causes, such as blood forming into a pool and putting pressure onto the airway, leaking cerebral spinal fluid, hardware or bone graft breaking off or moving from the surgery, obesity, sleep apnea, long surgery time (over five hours), repeat surgery, or tissue swelling. It appears that the highest risk time for this complication is during the second and third days after surgery.

To lower the risk of this complication, surgeons are encouraged to try to keep the surgeries less than five hours long, don't use too many intravenous fluids and keep the patients intubated until it is obvious that they will be able breathe without difficulty. If they haven't been able to have the tube removed after a week, the surgeon should consider putting in a tracheotomy (opening in the trachea through the neck) for breathing.

Epidural hematomas are bubbles or areas of built up blood that can cause pressure on surrounding body tissues, nerves and organs. In this case, they would be in the epidural space, which is one of the spaces along the spine. Radiculopathy z(nerve irritation) occurs in about 0.2 to 0.5 percent of cases and is most likely caused by excess traction during surgery.

After the first week, the other complications that could arise include dysphagia (trouble swallowing), dysphonia (hoarse voice or difficulty speaking), bone graft extrusion (bone graft bulging), or infection.

There are also some adverse effects that can occur because of the newer technologies now available to surgeons. This includes off-label use (not approved by the FDA) of a specific protein that helps stimulate bone formation. Surgeons have been using bone morphologic protein with a fair amount of success, but it doesn't work for everyone and it seems to be as high as 23 to 27 percent of patients.

Arthroplasty, replacement of bones or joints, has been done in the lower back for quite some time, but it's not yet approved for the cervical spine. They have been used in studies and in Europe, they have an adverse event rate of 6.2 percent.

The authors conclude that the rate of adverse events is low, but they do occur and surgeons may lower risk by learning what actions contribute to the chances of developing the complications.

Alan H. Daniels, MD, et al. Adverse Events Associated with Anterior Cervical Spine Surgery. In Journal of American Academy of Orthopaedic Surgeons. December 2008. Vol. 16. No. 12. Pp. 729-738.

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