This is surgery that involves removing a disc (or discs) in the neck and stopping all movement at that level (or levels).
When is Anterior Cervical Discectomy & Fusion used?
It is used when a disc, or the bone that the disc is attached to (the vertebra), causes compression to a nerve root or the spinal cord itself. This would cause a severe pain down the arm (if a nerve was compressed), or weakness of the arms and legs with some difficulty with balance or fine finger movements (if the cord is compressed).
However, the pain down the arm is not always a pain; it may be numbness, weakness, a feeling “of insects crawling on the skin”, like an “electric shock” or a “searing pain”; in medical terms, a sensory or motor disturbance.
Similarly the patient or doctors do not always notice compression of the cord immediately. It may simply be that the patient is told that they “walk like they are drunk” (because the balance control is lost), or they may start to avoid wearing shirts or ties (because the fine finger control is lost).
Most people with nerve compression will settle quickly. If they don’t then a cervical fusion is an option. It relieves the compression of the nerve very effectively. It is an operation, however, that very rarely requires to be operated on as an emergency. Compression of the cord however requires decompression as soon as possible because once the cord starts to degenerate, decompression will not necessarily improve the symptoms as the cord is already actually damaged as opposed to “merely inconvenienced”.
What does the operation involve?
The operation is done from the front of the neck either from the left or the right side. It is a very anatomical operation, in that once the skin and platysma (a very superficial muscle in the neck) are cut; all the other structures (larynx/trachea (voice box/windpipe), oesophagus (gullet), carotid artery) are simply pushed out of the way to allow access to the spine. This means that there is little significant tissue trauma as a consequence of the incision itself and at the end of the operation the only structures that need closing are the platysma and skin. At the spinal level the disc is excised so that the root/cord is decompressed and an implant is inserted where the disc used to be +/- a metal plate on the front of the spine to stabilise it. Often the plate is not used in 1 level fusions. The implant may be the patients own bone (often taken from the pelvis (autologous graft), or it may be a metal implant of some kind.
What are the risks?
The risks are (from superficial to deep):
- Skin: infection
- Vessels: bleeding
- Superficial Nerves: injury to the recurrent laryngeal nerve will affect some of the muscles that operate the voice. This is generally not a problem unless both nerves (left and right) have been injured. It is for this reason that previous neck surgery is important for the surgeon to know about
- Oesophagus: difficulty swallowing (often short-lived after the operation), perforation of the oesophagus (a rare event but can cause a dangerous infection)
- Implant-related: dislodgement, non-union, metal breakage.
- Nerve root or cord: if a nerve root is too damaged before the operation, or is injured at operation, then the patient may be left with permanent pain/numbness/weakness down the arm in a particular distribution. If the cord is injured, this can lead to paralysis of part of both arms and everything below (legs, bowel, bladder)
What is the outcome?
This is an effective operation with a success rate between 85-90% of relieving arm symptoms (and in some cases leg symptoms such as wobbliness when walking).