Brachalgia is the medical term for arm pain due to a trapped nerve in the cervical spine. This is caused by either a disc prolapse (rupture, herniation, bulge) pressing on the nerve root and the purpose of surgery is to remove the lump of disc pressing on the nerve and thereby relieve the symptoms. It is not uncommon for the cause of the trapped nerve to be due to more widespread degenerate changes than a simple disc prolapse. These degenerate changes (cervical spondylosis) cause thickening of the bone edges next to the disc (osteophytes) and thickening (hypertrophy) of the facet joint and ligamentum flavum. Whatever the cause, the purpose of the surgery is to ensure that the nerve root is adequately decompressed by removing the tissue compressing the nerve whether it be disc or osteophyte and thereby relieve the pre-operative symptoms.
Two operations can be employed to achieve this end. The most common is an anterior cervical discectomy. This involves, under general anaesthetic, a horizontal incision in the front of the neck after which the surgeon descends upon the front of the cervical vertebra. Although passing some important structures such as the carotid artery, jugular vein, oesophagus and trachea, the approach is relatively atraumatic rather than requiring cutting of any significant structures within the neck itself. Once arriving at the front of the cervical vertebra, the surgeon ensures the correct level with an intra-operative x-ray. With an anterior cervical discectomy, almost the entire disc is removed by which technique the surgeon can pass through to the back of the vertebra where the nerve root lies. In the case of brachialgia due to a disc prolapse, by this technique the lump of disc which has herniated out can be removed. In the case of osteophytic thickening, these bone spurs are drilled away, again with the same object of decompressing the nerve root.
At the end of the procedure there is, therefore, a space between the 2 vertebrae where the disc has been removed. Into this space is inserted a fusion device called a Brantigan cage which is effectively a hollow box made of carbon fibre into which is packed some synthetic bone. Traditionally, the fusion devise was a piece of bone from the patient’s hip (iliac crest). The incision required to obtain this bone was often more painful than the operation on the neck itself and, therefore, these days we use both synthetic carbon fibre graft and synthetic bone to save the pain and discomfort related to the hip. Post-operatively, the patient can mobilise on the day of surgery and is generally home within 2 days of the surgery. Despite being a relatively minimally invasive procedure, it remains a serious neurosurgical operation and we would recommend 6 weeks off work. We also recognise that often it is difficult to take a period of time off and the nature of this recovery period would be the subject of discussion between you and your surgeon.
The other, and less frequently employed, operation to decompress the nerve root-causing brachialgia is a posterior cervical foraminotomy. Rather than approaching the cervical spine from the front of the neck, this approach is made through a midline incision in the back of the neck. The muscles are stripped off the spinous process and lamina of the relevant part of the cervical spine. The precise position of the incision is determined by an intra-operative x-ray. Once the spine has been reached a fine drill is used to remove part of the bone overlying the canal through which the nerve root leaves (foraminotomy). Also removed at the time of this operation is the area of ligamentum flavum that is often thickened and contributing to the compression of the nerve root. This operation can be done as a primary procedure for a nerve root entrapment-causing brachialgia and is sometimes used as a second operation to augment the anterior decompression such that by the end of both, the nerve root is decompressed both anteriorly and posteriorly. This dual approach is relatively infrequently required.