Disc Injuries
What is a spinal disc injury?
The disc is a spinal structure that lies between the vertebrae of the spine and works to transmit loads and distribute weight evenly in the spine.
The disc comprises two components; the nucleus pulposus is the gelatinous structure at the centre of the disc that distributes the load applied to the spine. The annulus fibrosus is the outer area of the disc made of rings of strong collagen fibres; it provides strength to the disc and attaches it to the adjacent vertebrae.
A disc may bulge or herniate, causing irritation or compression of the nerves exiting the spinal cord. This, in turn, can result in altered sensation, weakness and pain in the area of the body that they innervate. When this occurs, it's called radiculopathy. Disc injuries commonly arise in the lower neck (cervical) and lower back (lumbar) regions.
4 Types of disc herniations
A disc bulge describes a general enlargement of the disc circumference beyond the margins of the adjacent vertebrae due to weakness of the disc's outer wall.
A disc protrusion involves a smaller area of the disc protruding beyond the margins of the adjacent vertebrae.
Disc extrusion occurs when a fissure within the annulus fibrosis allows the nucleus to herniate through.
Disc sequestration is an extrusion where the nuclear material is separated from the rest of the disc.
In the cases of extrusions and sequestrations, the nerve is irritated by physical compression and a chemical reaction, which occurs due to the body's immune response to the nucleus material outside the disc.
In younger populations, disc injuries occur due to repetitive loading of the spine. The cause of disc injury differs in older people; as the water content of the nucleus decreases with age, it becomes less capable of withstanding stress and more likely to bulge under load. In addition, the annulus loses its capacity to contain the nucleus, which may lead to infiltration by the nucleus under enough stress, resulting in a herniated disc.
What are the signs of a disc injury?
Discs usually react to high loads over time or change as part of the normal aging process, and disc bulges or herniations can often be asymptomatic.
For example, discogenic (disc-caused) pain is often sudden from a lifting or twisting motion. However, as mentioned above, discs injury usually occur over time, and these movements are often only the catalyst pushing the disc to the edge. When pain is felt, it is often in the region of the spine that is affected and down the arms or legs.
Pain is often more significant in the morning because at night, while we are not weight-bearing, the discs fill up with fluid; this increases the pressure on the nerve and can result in a more significant feeling of pain when waking up, hence the morning stiffness. Inflammation also builds up while we are not moving, leading to more substantial pain following rest periods.
Diagnosis
Diagnosis is made clinically through a series of tests and observations. Changes in posture and gait are common, as well as decreased range of motion. In addition, several orthopedic tests are used to reproduce the patient's symptoms.
If a spinal nerve is irritated, reflexes, strength, and sensation will be altered in the area innervated. These are called neurological findings, and an MRI may be prescribed further to determine the exact level and extent of the herniation.
In some acute cases, the pain levels may be extremely high and physical examination may be limited early on to prevent aggravation of the symptoms.
Prognosis
Most disc-related pain will resolve within 6 to 12 weeks and respond well to conservative care. However, studies have shown that discs can take up to one year after the injury to heal. This is because the blood and nerve supply to the discs is minimal, slowing healing down.
Each patient responds differently, and it is impossible to give an exact timeline for all disc injuries. Bulges are the least severe form of disc injury and will usually heal faster as there is no damage to the walls of the disc. Extrusions and sequestrations are more severe forms of disc herniations and typically have a longer healing time; however, the immune reaction to the nucleus material will help speed up the process.
Treatment recommendations for Disc Injuries
In the acute stages of injury, the focus is to reduce the swelling and inflammation to help the pain. Putting the spine in light traction reduces the disc's load; pelvic blocks are commonly placed under the hips to wedge and unload the spine under gravity while maintaining some level of comfort. Soft tissue therapy is also essential to soften the area's muscle spasms.
Phase 1: Acute care
The second phase of care aims to stabilise the area by adding rehabilitation exercises to engage the muscles and take pressure off the spine and discs. A resilient and robust spine and paraspinal muscles are the best defence against more episodes of discogenic pain.
Phase 2: Stabilisation
The second phase of care aims to stabilise the area and increase joint stability by adding rehabilitation exercises.
Phase 3: Strengthening and maintenance
Finally, maintenance care helps prevent the risk of re-injury and monitor progression. As discs can take up to one year to heal, it is essential to maintain movement and build strength in the area while recovering continues and post-healing to prevent reoccurrence.
Considerations are made for corticosteroid injections and possible surgery when the condition has failed to improve after six weeks of care or in cases where symptoms are severe.
Home advice
In the acute stages, anti-inflammatory medication may help alleviate the pain, and applying heat to the area has been known to help. Movement is recommended while remaining within the low pain range, for example, taking short walks throughout the day. Avoiding lifting and bending that unnecessarily loads the injured disc is also recommended in the early stages. The patient can perform a gentle range of motion exercises and stretches that favour extension. In addition, if the low back is involved, modifying sleep posture by placing a pillow between the knees when sleeping on the side will prevent spine rotation and decrease the load on the disc. As we stabilise, strengthening exercises can be prescribed to increase spinal stability.
Dr Elsa de Froberville
BscAnat., BscChiro., BChiro.
Chiropractor | Spine & Sports Centre
References
Dydyk, A. M., & Mesfin, F. B. (2017). Disc herniation.
Djuric, N., Yang, X., el Barzouhi, A. et al. Lumbar disc extrusions reduce faster than bulging discs due to an active role of macrophages in sciatica. Acta Neurochir 162, 79–85 (2020).
Kim ES, Kim CY. The association between continuity of care and surgery in lumbar disc herniation patients. Sci Rep. 2021 Mar 10;11(1):5550.
