What is an Intervertebral Disc Injury?
The Intervertebral Discs (IVDs) sit between the vertebrae and act as a shock absorbing cushion. The IVD is soft enough to allow the spine to move and bend around its centre point. IVD injury occurs when there is long-term abnormal pressure within a disc from the surrounding vertebrae. An IVD injury can occur suddenly or over a long period of time and the fluid in its centre is able to protrude through the outer layers of the disc. The body assumes this fluid is foreign and initiates an inflammatory response. Not only does the IVD protrusion become inflamed it can also compress, irritate and stretch local nerves exiting the spine which can lead to symptoms in the upper or lower limb.
The IVD fluid most commonly protrudes towards the back and side of the IVD (posterolaterally) as this is its weakest area, however, in rare cases, the disc can protrude centrally and cause more severe compression on the spinal cord and delicate nerve structures. The images below demonstrate a normal disc and a posterolateral IVD protrusion with subsequent nerve compression and irritation.
Intervertebral Disc demonstrating (left) Normal and (right) herniated/injured
IVD injury is extremely common and is secondary to trauma or abnormal spinal stress. When multiple vertebrae get stuck forward this shifts the centre of gravity in a forward direction and adds extra stress and pressure to the front aspect of the IVD. This, therefore, increases the hydrostatic pressure towards the back of the IVD leading to the susceptibility of injury over time. An injured IVD can take up to 18 months to heal fully (McGill 2010) if the abnormal pressure surrounding the disc is not rectified. If the excess pressure is not removed then the IVD will undergo repetitive injury.
If the spinal cord is tethered within the spinal canal this can cause the cord to be stretched over the disc bulge which can lead to symptoms in the arms or legs such as pain, numbness, tingling and weakness (Breig 1978; Yamada 1996).
Cauda Equina Syndrome
IVD injury can also lead to a rare but serious medical condition called Cauda Equina Syndrome (CES). CES is a result of severe spinal cord compression in the lower spine, usually resulting from a significant IVD injury and protrusion. The Symptoms of CES can include loss of bowel and/or bladder function and numbness around the anus or testicles. If you have recently injured your low back and have experienced any of these symptoms then you need to visit your A&E department immediately.
IVD injury can lead to disc derangement, leaving a permanently misshapen IVD. Symptoms can be treated successfully by correcting the surrounding mechanical dysfunction and adverse spinal cord tension, allowing the IVD to heal. Associated symptoms (pain, weakness, numbness/tingling) in the arms or legs will also be eliminated quickly. Please contact us if you would like to know more.