News Anterior Cervical Decompression and Fusion for Spondylotic Myelopathy In the past, cervical laminectomy (removing the posterior aspects of the spinal canal) to decompress (relieve pressure on) the spinal cord had been the procedure of choice to treat spondylotic myelopathy resulting from cervical arthritis. However, the majority of the abnormal anatomy producing spinal cord compression is located anteriorly to (in front of) the spinal cord itself. This is only indirectly addressed by a posterior cervical laminectomy. In fact, chronic spinal instability exacerbating the disease process may be caused by cervical laminectomy. In addition, a thick fibrous scar forms at the operative site in the postoperative period, at times replacing the bony compression and reproducing the original symptoms after an extended postoperative period. For these reasons, many surgeons prefer either anterior decompression of the spinal cord and nerve roots, or an adaptation of laminectomy known as laminoplasty, depending on the patient's anatomy. Anterior cervical decompressions have two significant benefits: 1. Direct removal of the anterior source of spinal cord compression. 2. Stabilization of the spine by way of a fusion, eliminating motion and the development of further degenerative changes at the operated levels. Results Overall, most surgical series point to a significant improvement for most patients who undergo an anterior cervical decompression and fusion (by either multiple discectomies or corpectomy) before irreversible spinal cord injury has occurred. At a minimum the operation can remove the source of spinal cord injury and arrest the progression of the disease. The prognosis is generally proportional to the severity of spinal cord compression, with more advanced cases having a poorer prognosis. Timely intervention may thus play a role in determining the patient's final outcome. The surgical procedure The surgery is performed with the patient in the supine position under general anesthesia. Usual requirements include adequate padding of bony and soft tissue structures. Sequential compression boots are applied to the patient's lower extremities to avoid development of blood clots during the operation. Most surgeons prefer to use Somatosensory Evoked Potentials (SSEPs) or Motor Evoked Potentials (MEPs) to monitor spinal cord function during the surgery. However, this is not essential. The surgical procedure is done as follows: The procedure begins with either a longitudinal or transverse incision in the lower front of the neck. The underlying musculature of the neck is carefully dissected, allowing the surgeon to expose the anterior cervical spine by retracting the esophagus and trachea toward midline and the carotid artery and associated structures laterally. Muscles and membranes overlying the anterior cervical spine are dissected as well, and retractors are placed to protect the soft tissues of the neck as the operation proceeds. After the surgical level(s) have been confirmed by X-ray or fluoroscopy, intervertebral discs are removed at the level(s) to be decompressed. In some instances it is only necessary to remove the abnormal discs, with or without small bone spurs at their margins. If multiple levels are to be decompressed, especially if large osteophytes are present, the surgeon may opt to remove the vertebral bodies between the evacuated disc spaces. Biting instruments (rongeurs) of varying sizes and shapes and high speed drills are used to remove the remaining bone and disc material, creating a trough measuring 15-16 mm in width extending superiorly and inferiorly across the entire longitudinal extent of the involved portion of the cervical spinal cord. Removal of the vertebral body(s) comprises a 'corpectomy'. Bone and disc are removed down to the level of the posterior longitudinal ligament (PLL), which overlies the dura directly. The surgeon may chose to remove the PLL if it is felt that it contributes to the compression of the spinal cord, or there are fragments of herniated disc material beneath it. In that case the posterior longitudinal ligament is then carefully grasped and incised, and then removed in a piecemeal fashion. The surgeon will often use either an operating microscope or surgical loupes to provide for magnification and illumination as the operation proceeds. Although the dural sac is visualized during the decompression, the spinal cord and nerve roots are not directly seen. After the spinal cord and nerve roots have been decompressed at the appropriate levels, the portions removed must be reconstructed so as to support the normal loads of the cervical spine. This means either inserting bone grafts within each disc space ('interbody' grafts), or inserting a longer 'strut' graft which spans the defect created in the process of removing a vertebral body(s). In either case the intent is to promote the formation of a living bridge of bone between the previously distinct vertebrae (a fusion). The surgeon may employ either the patient's own bone (autograft) or banked human cadaver bone (allograft), or an synthetic scaffold into which bone graft may be inserted (metal or carbon fiber cages). The reasons for selecting among these are many and complex. Patient and surgeon should discuss these issues pre-operatively, keeping in mind that the chosen strategy will influence the likelihood of healing success. Failure of bone graft healing is among the principal reasons for repeat surgery in these cases. In many cases, the surgeon will recommend internal fixation of the operated/grafted segments with a titanium plate and screw device, which is secured to the remaining vertebral bodies at the margins of the corpectomy, providing for further stability and promoting adequate fusion as well as preventing dislodgement of the bone graft. Factors thought to increase the probability of bone graft/fusion failure include: 1) increasing numbers of levels to be fused, 2) smoking or other sources of nicotine, 3) patient non-compliance with activity restriction and/or brace wear, 4) poor bone quality (osteoporosis), 5) certain medications (e.g. predisone, anti-inflammatories, chemotherapy), 6) malnutrition, etc. The usual length of stay in the hospital varies from one to four days. Potential risks and complications While uncommon, as with all surgery there are a number of risks and potential complications that can occur, including: Hemorrhage or formation of a wound hematoma Damage to the carotid or vertebral artery resulting in a stroke or excessive bleeding, even death Damage to the recurrent laryngeal nerve resulting in hoarseness Damage to the superior laryngeal nerve resulting in swallowing disturbance Damage to the esophagus or trachea resulting in infection Damage to the dura, resulting in a cerebrospinal fluid leak or pocket of cerebral spinal fluid beneath the incision (pseudomeningocele) Mechanical complications of the graft and plate (including graft migration, breakage of the plate, screw pullout, etc.) Wound infection Development of painful pseudoarthrosis (failure of adequate fusion to occur) Damage to the spinal cord or nerve root(s) resulting in pain, weakness, paralysis, loss of sensation, loss of bowel or bladder function, impaired sexual function, etc. Postoperative care Immediately after the surgery, patients will experience some difficulty swallowing or a sore throat due to manipulation of the esophagus. This usually resolves within several days, but symptoms may persist to a troublesome degree. The pain associated with the procedure is relatively minimal, as most of the exposure is obtained by dissecting tissue, not dividing it. Pain at the graft site (where bone graft is obtained from the hip) is more of a concern if iliac crest graft is utilized. Nonsteroidal anti-inflammatory medications (NSAID's) inhibit bone formation, which is required for the fusion to take hold, and are to be avoided. The same is known for all types of tobacco products. External bone stimulators may be used to theoretically aid fusion formation for selected patients. Postoperatively, the surgeon may prescribe a cervical collar for a specific period of time to assist in healing and avoid extremes of neck range of motion. In most instances, adequate healing (fusion) occurs within a three to six months. The surgeon may require sequential x-rays over time to document adequate healing and ensure appropriate alignment at the operative site. The surgeon will also provide instructions regarding specific lifting and activity restrictions for the patient. Thomas M. Wascher, M.D., FACS For more information call 920-882-8200 or 1-888-231-5236 Back to News     5320 West Michaels Drive   |   Appleton, WI 54913-8400   |   Phone: (920) 882-8200 or (888) 231-5236   |   Fax: (920) 882-8210