Disc Herniation

What is a disc herniation?

A herniated disc is one of the most common spinal injuries and involves damage to the intervertebral disc, which is connective tissue found between vertebrae in your spine. Herniated discs are often referred to as disc bulges or informally (and inaccurately!) referred to as slipped discs. It is important to address this term as discs cannot physically slip, they are firmly anchored to the vertebrae by exquisitely strong connective tissue. The disc allows for slight movement while acting as a ligament to hold the vertebrae together and plays a key role as a shock absorber for your spine. Each disc has two parts:

  • the anulus fibrosus, which is a firm outer layer composed mainly of collagen
  • the nucleus pulposus, a gel-like inner core which helps to distribute pressure evenly across the disc in order to prevent the excessive forces at any one point on the vertebrae.  

Disc herniation occurs when a tear in the firm outer ring of the disc allows the inner core to bulge out beyond the outer ring and is a common cause of back pain1. However, there are many instances of disc herniations occurring without pain and being found on MRIs in people without any symptoms2. People who experience back pain associated with a herniated disc often can recall a specific incident usually involving excessive strain or shear forces to the spine.

What causes a disc herniation?

The majority of herniations occur in the lower back, the second most common area is in the lower neck, while the thoracic region only accounts for approximately 1-2% of cases4. Herniations may develop suddenly or gradually over weeks and months. Gradual herniations are the most common and are often associated with age related wear and tear of the disc, referred to as degenerative disc disease3. Cases of sudden herniation are often associated with fully flexing the spine under load, repeatedly, or for prolonged periods of time.

There are four stages of herniated discs:

  • Bulging- disc material extends beyond the margin of the vertebrae
  • Protrusion- nucleus pulposus impinges on the annulus fibrosis 
  • Extrusion- nucleus pulposus emerges through fibres of the annulus fibrosis
  • Sequestration- nucleus pulposus emerges through fibres of the annulus fibrosis into the epidural space causing disruption of ligaments.  

Whether it is a sudden or gradual onset, herniation often occurs due to internal pressure in the disc causing the contents of the inner core to be pressed against the stretched or damaged outer ring. With sufficient pressure the inner core may bulge out. The combination of the outer ring being stretched or weakened along with increased internal pressure can result in the rupture of the outer ring which then allows the contents of the nucleus pulposus to leak out of the disc where it may press against nerves in the back and result in pain. This mechanical compression of the nerve by the disc can cause a radiculopathy and the disc material may also cause an increase in local inflammation. 

What are the symptoms of a herniated disc?

Symptoms of a herniated disc can vary depending on the location of the herniation as well as what local tissues are involved. They can range from very little to no pain, if the disc is the only tissue affected, to severe pain that radiates into the arms or legs if local soft tissue or nerve roots are involved. For those that experience pain it is often described as “burning” or “stinging” in quality. 

The most common signs and symptoms include:

  • Pain at the site of the injury
  • Pain, numbness, or tingling in the arms when the herniated disc is in the neck or in the legs when the herniated disc is in the lower back.
  • Pain that worsens with bending, twisting, or long periods sitting. 
  • Muscle spasms.
  • Weakness or a heavy feeling in limbs

What is the best treatment for a herniated disc?

The disc has a strong capacity to heal, previous studies have found full complete resolution of symptoms with conservative management in 96% of sequestrations, 70% of extrusions, 41% of protrusions and 13% of bulges5. With these rates of success, surgery is considered a last resort treatment in severe cases that do not respond to conservative care.

Physiotherapy plays a major role in the treatment of disc herniations. It is recommended for education, symptom management, restoration of functional deficits, and resumption of daily activities and exercise. Active exercise therapy is the preferred treatment and may involve directional preference movements (McKenzie method), flexibility, strengthening, and motor control exercises in order to improve strength and resilience of the back as well as improve confidence and stability and reduce the risk of future back injuries. 

Conclusions

  • Herniated discs may result from gradual wear and tear or from repeated/prolonged high-force bending/twisting in the spine
  • Herniated discs may vary in symptoms from being pain-free to severe pain, numbness, and weakness.
  • Discs have are very strong and have a very high capacity for healing. 
  • Complete resolution of symptoms is seen in over 60% of disc injuries with conservative management. 
  • Surgery is considered a last resort treatment. 

References

  1. Dydyk AM, Ngnitewe Massa R, Mesfin FB. Disc Herniation. [Updated 2022 Jan 18]. In: StatPearls [Internet]. Treasure Island (FL): StatPearls Publishing; 2022 Jan-. Available from: https://www.ncbi.nlm.nih.gov/books/NBK441822/
  2. Jensen, Maureen C.; Brant-Zawadzki, Michael N.; Obuchowski, Nancy; Modic, Michael T.; Malkasian, Dennis; Ross, Jeffrey S. (1994). “Magnetic Resonance Imaging of the Lumbar Spine in People without Back Pain” (PDF). New England Journal of Medicine. 331 (2): 69–73
  3. Goel, A.P., Wang, E.J. and Bicket, M.C., 2020. Degenerative Disc Disease. In Spine Pain Care (pp. 181-188). Springer, Cham.
  4. Moore, Keith L. Moore, Anne M.R. Agur; in collaboration with and with content provided by Arthur F. Dalley II; with the expertise of medical illustrator Valerie Oxorn and the developmental assistance of Marion E. (2007). Essential clinical anatomy (3rd ed.). Baltimore, MD: Lippincott Williams & Wilkins. p. 286. ISBN 978-0-7817-6274-8.
  5. Chiu CC, Chuang TY, Chang KH, Wu CH, Lin PW, Hsu WY. The probability of spontaneous regression of lumbar herniated disc: a systematic review. Clin Rehabil. 2015 Feb;29(2):184-95. doi: 10.1177/0269215514540919. Epub 2014 Jul 9. PMID: 25009200.
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