In the cervical spine, centrally located herniated discs that are right in front of (anterior to) the spinal cord cause spinal cord compression. This could lead to pain, numbness, and weakness not only in the arms but also in the body and legs. These central disc herniations require an anterior discectomy with either a fusion or total disc replacement. In contrast, if the disc herniation or bone spur (osteophyte) is located to one side (laterally), usually the nerve root is compressed with or without spinal cord compression. In these cases the nerve foramen or canal is narrowed instead of the central canal (central stenosis).
The narrowing of the nerve foramen or canal (foraminal stenosis) can be treated by either an anterior discectomy or from a posterior approach called a foraminotomy. The cervical foraminotomy can be performed because it opens the nerve foramen lateral to the spinal cord. Thus the spinal cord is not manipulated. The nerve foramen and therefore the nerve root traveling within the foramen are decompressed. The nerve root can even be gently retracted to reach herniated discs or osteophytes in front of (anterior to and on the other side of) the nerve root.
The benefit of a foraminotomy is that it does not require a fusion or an implant like a total disc replacement. Thus more of the natural anatomy is preserved. Also the posterior approach avoids retraction of the neck structures including the esophagus which often can give temporary or sometimes longer term swallowing difficulty. Hoarse voice is rare complication of anterior cervical discectomy and is also avoided by foraminotomy.
The disadvantages of foraminotomy include pain from neck muscle dissection and inadequate access to the disc space. Since disc herniations are located anterior to the foramen and nerve root, coming from behind (or posterior to) the nerve root makes it more difficult to access an anteriorly located disc herniation or bone spur. Thus the advantage of preserving the anatomy with a foraminotomy is sometimes offset by a less complete decompression of structures anterior to the nerve.
The decision to pursue an anterior discectomy versus a posterior foraminotomy should be made with a thorough evaluation and discussion/ explanation with an experienced spine surgeon who is comfortable with both approaches. Otherwise you fall into the old adage of “when you are a hammer, everything looks like a nail,” meaning that surgeons that only perform mostly one technique will usually only recommend that one method of treatment.
Surgery for the cervical spine is somewhat different from the lumbar spine. The presence of the spinal cord in the cervical spine limits what a surgeon can do from the back of the neck. Central herniated discs in the cervical spine cannot be treated from the back of the neck like in the lumbar spine because the cervical spinal cord cannot be retracted like nerves in the lumbar spine.
Central herniated discs require removal of the disc from the front of the neck. After removal of the disc and bone spurs impinging on the spinal cord and nerves, the empty disc space needs to be replaced by something to convey the weight of the head from the vertebrae above to the next vertebrae. In most cases this is done through a bone graft between the vertebrae in the empty disc space leading to a fusion. A plate is usually used to hold the vertebrae above and below the fusion immobile to enable the fusion.
Because of the success of hip and knee joint replacement, total disc replacement has been touted as the holy grail of cervical disc surgery. Instead of fusing the disc space, an artificial disc capable of joint motion is placed into the empty disc space. It is thought that the mobility of the artificial joint relieves the extra strain that is placed upon neighboring (adjacent) levels after a fusion. Thus theoretically, the adjacent level degeneration seen with cervical fusions may be reduced with total disc replacement. Recent studies have shown that artifical disc replacement surgery is associated with better outcomes than fusions in terms of further surgery down the road. Additionally, some insurance areas are finally starting to recognize artificial disc replacement as a standard therapy rather than as experimental.
Laminectomy of the cervical spine is one of the most commonly performed cervical spine surgeries. Because the cervical spine is more mobile than the rest of the spine and because the cervical spine is holding up the weight of the head (essentially a small bowling ball), it is perhaps more susceptible to instability than the thoracic or lumbar spine. Thus it is important to preserve the natural anatomy as much as possible.
Multi-level laminectomy of the cervical spine can lead to instability which can progress to POST-LAMINECTOMY SYNDROME and even to neurological dysfunction from progressive malalignment and curvature (kyphosis) of the cervical spine. The alternative to laminectomy for cervical spinal stenosis is laminoplasty. Instead of removing the lamina, only one side of the lamina is disconnected. On the other side, a hinge is created so that the lamina can be opened like a door on a hinge. Then a plate is placed on the opened side to keep the door open. This procedure is able to create more room for the spinal cord while preserving the lamina and spinous process for muscles to attach. Over the last several years, Dr. Hua has avoided cervical laminectomy surgery in favor of laminoplasty.