Cervical disc herniations generally cause neck and arm pain due to compression of nerves in the neck. The compression of the nerves can cause numbness, tingling, weakness or loss of coordination in the upper and lower limbs, depending on which structures are compressed.
The spine consists of a column of 33 bones called vertebrae. The first 7 vertebrae make up the cervical spine. Between the vertebrae, are intervertebral discs which are composed of cartilage. The discs have a central, softer component called the nucleus and a more firm outer layer called the annulus. The discs act as shock absorbers and help permit movement of the spine. The spinal cord travels from the base of the brain to the base of the spine through the centre of the vertebral column just behind the discs in the “spinal canal”. At each level, a pair of spinal nerves, one on the left and one on the right, arises from the spinal cord and leaves the spinal canal through the intervertebral foramen. Normally, this foramen is wide enough that the nerve is free of any pressure.
Compression of a spinal nerve or the spinal cord in the neck can occur due to degeneration (wear and tear), a herniated or ruptured disc, trauma, a tumour or due to bone spurs. When a disc herniates, it can compress the spinal cord or the spinal nerve. This generally occurs after the age of 30 as the discs lose their elasticity. Most disc protrusions will cause neck pain and some arm pain. 90% will heal with resorption of the disc over the course of anywhere from 2 weeks to 3 months. In 10% of cases, the herniated disc material is large and causes severe pain and severe compression of the nerves. For patients with severe nerve or spinal cord compression, surgery is indicated.
Surgery on the cervical spine can be performed either through the front of the neck or through the back of the neck. Surgery through the front of the neck has the advantage of being less invasive than posterior procedures as the structures anterior to the spine are mobile and can be moved easily out of the way, minimizing trauma to the muscle. The disadvantage of anterior procedures is that in most cases to access the spinal cord and nerves, all of the disc has to be removed i.e. an anterior cervical discectomy needs to be performed. The cavity made by the discectomy has to be filled with either a fusion device or an artificial disc i.e. a disc replacement.
Surgery performed on the cervical spine from a posterior direction can also be performed through minimally invasive techniques, however some of the cervical musculature needs to be reflected away from the bone to access the spinal column. The nerve roots and spinal cord however can be easily decompressed. The advantage of the posterior surgery is that the majority of the normal disc is left intact and only a small portion of the disc material i.e. the disc herniation is removed. Both types of surgery take around 1.5 hours. Patients are normally in hospital for 1-2 days. In general following cervical disc surgery, patients can return to all normal activities.