There are altogether 23 discs in our entire spine, and they are located in between the bones or vertebrae of the spine. They function as shock absorbers and at the same time allowing some flexibility at the spine.
The normal healthy disc consists of a central gel-like nucleus pulposus surrounded by a ring-like structure or annulus fibrosus. When the disc becomes damaged due to major injury, or more commonly due to repeated “wear and tear” processes in our daily activities, the central gel like nucleus pulposus is no longer able to “hold on” to the water content which provides the cushioning effect of the spine.
At the same time, the outer ring like annulus fibrosus starts to exhibit signs of tears. These processes allow the disc material to protrude out of their normal boundaries, coming into close contact with the nerves that are running through the spinal column.
To confirm the presence of prolapsed disc and to ascertain the severity of the prolapsed disc, an MRI scan of the neck or cervical spine may be done (Figure 1). At the same time, bending x-rays of the neck may be needed to look for any mis-alignment of the cervical spine.
Figure 1
Treatments
(1) Conservative
(2) Spinal Injections
Spinal injections may be considered if one does not improve significantly with conservative treatment, and yet not debilitating enough to require formal surgery. Spinal injections are done as a day case where patients can admit and discharge on the same day. Such a procedure is performed under sedation. These injections are done under the guidance of a CT scanner machine to allow the Doctor to place his needles accurately at the location where he thinks the nerve is being affected. This is also known as a nerve block. In addition, the Doctor may also perform radiofrequency ablation of the affected disc, thereby reducing the amount of protrusion so that the irritation to the nerve(s) will be reduced.
(3) Surgery
Surgery may be recommended if the patient does not improve with the above-mentioned treatments, or the initial presentation warrants surgery (for example cervical myelopathy). The surgery entails removing the disc that is compressing the nerve(s), allowing recovery of the nerve(s). Such surgery is usually performed from the front of the neck. Following the removal of the disc, reconstruction of the disc will be undertaken. The reconstruction options will be either:
(i) cervical disc replacement where an artificial disc prosthesis is inserted.
(ii) cervical fusion is done using a cage filled with allograft/bone material; usually obtained from the bone bank to avoid harvesting bone from the patient’s hip. The cage can be further stabilized with a titanium plate and screws in front providing immediate stability.
Cervical Disc Replacement
Cervical Fusion
Postoperative Care
To confirm the presence of prolapsed disc, and to ascertain the severity of the prolapsed disc, an MRI scan of the low back or lumbar spine may be done (Figure 1). At the same time, bending x rays of the low back may be needed to look for any mis-alignment of the lumbar spine.
Figure 1 shows a right sided prolapsed disc on a cross sectional MRI view of the low back.
Treatments
(1) Conservative
(2) Spinal Injections
Spinal injections may be considered if one does not improve significantly with conservative treatment, and yet not debilitating enough to require formal surgery.Spinal injections are done as a day case where patients can admit and discharge on the same day. Such a procedure is performed under sedation. These injections are done under the guidance of a mobile x-ray machine to allow the Doctor to place his needles accurately at the location where he thinks the nerve is being affected. This is also known as a nerve block. In addition, the Doctor may also perform radiofrequency ablation of the affected disc, thereby reducing the amount of protrusion so that the irritation to the nerve(s) will be reduced.
(3) Surgery
Surgery may be recommended if the patient does not improve with the above-mentioned treatment, or the initial presentation warrants surgery (for example, significant weakness and/or numbness of the leg or bladder incontinence). The surgery entails removing the disc that is compressing the nerve(s), allowing recovery of the nerve(s). The surgery is routinely performed nowadays in a minimally invasive manner, using small metal tubes that also function as retractors keeping the soft tissues away from the surgical area. The tubes are “docked” at the area where the prolapsed disc is, and this is done under the guidance of the x-rays (see Figure 2). A microscope is used throughout the surgery, allowing the Doctor to see the nerve(s) and prolapsed disc clearly. The affected disc will then be removed using micro instruments.
Figure 2