Disc Bulge & Disc Herniation
The term ‘disc bulge’ and ‘disc herniation’ seem to strike immediate fear into anyone who receives the diagnosis. Something that I commonly hear as a health professional when undertaking a detailed past medical history assessment, is “I have a herniated disc”. On further questioning I ask when and how it was diagnosed, to which they almost always state it was years ago and on a CT or MRI scan. This gives me a great opportunity to educate the patient about disc injuries, their healing capacity, why scans are overrated and why a ‘disc bulge’ or ‘disc herniation’ is not a life sentence or something to fear.
Before I discuss the anatomy and provide statistics on discs, I must quell the common belief that discs slip. A “slipped disc” does not happen! Your discs are woven and tightly adhered to the vertebral bones/end plates. So don’t fear the idea your disc is fragile and can easily “slip out of place”, this simply does not occur and our discs are very adaptable structures of the human body.
Disc injuries are certainly a common cause of pain, however whether it is the disc or not causing the pain is difficult to say. As has been explained in many of my blogs about pain, the experience and perception of pain is highly multifactorial. What I mean by this is that tissue structure (tissue injury) is one factor influencing the pain experience. Other factors, which a lot of research suggests may be bigger influences to the pain experience include; stress, anxiety, poor sleep, fear on movement and negative beliefs or catastrophising thoughts. I will provide more evidence about pathological disc structure and pain later when I present evidence on MRI studies. When the painful symptoms of sciatica are present however, evidence has shown that approximately 85% of sciatic cases are due to a herniated disc (Ropper & Zafonte, 2015). I encourage you to read our very informative blog on sciatica ‘Is it really sciatica?’ Although most cases show a herniated disc to be present, once again the pathological structure and the onset of symptoms is not well correlated.
What are the discs and what are they made of?
There are 23 intervertebral discs in the spine. We have 6 in the cervical region (neck), 12 in the thoracic region (middle back) and 5 in the lumbar region (lower back). These intervertebral disc articulate with a superior vertebra bone and an inferior vertebra, forming an intervertebral joint. The discs play a large role in shock absorption through the spine, as well as providing range of motion to the trunk, allowing it to be quite flexible. They are composed of the inner gel-like nucleus pulposus, the outer fibrocartilaginous annulus fibrosus, and the cartilaginous vertebral end-plates that anchor the discs into the adjacent vertebral bones. The nucleus pulposus makes up most of the central aspect of the disc and is composed largely of water. However, it is also composed of collagen and other cells that play a role in maintaining its integrity. The annulus fibrosus is composed of a large number of collagen and fibrous cells, which are stacked together in a ring shape. The annulus fibrosus plays a huge role in enforcing the strength of the disc, minimising the large compressive loads it is sustained to. Overall, it is important to remember that our discs are very strong, resilient, and robust structures. They are not fragile and it requires quite a lot for them to become injured.
What are the types of disc lesion?
There are a number of disc lesions that can occur. However, a lot of these so called “lesions” may just be a normal part of ageing.
Disc Degeneration
Disc degeneration is a broad term used to describe changes to the disc as a result of the normal ageing process. It can include the subcategories of degeneration, annular fissure and even herniation. There are many times where a patient fearfully describes their “degenerative discs” that were shown on an MRI scan. However, these changes are mostly just due to normal ageing and as such should not be pathologized.
Annular fissures are seen to be another normal finding that occurs as a result of ageing. They are separations of the annular fibres from other annulus fibres, or from the attachment at the vertebral end plate.
It is very likely these normal age-related changes to the discs do not result in the experience of pain. As such, they should not be a focus or concern if a scan shows these findings.
Disc Bulge
A disc bulge is when the disc tissue extends beyond the circumference of the vertebral bone apophyses. It is classified as a disc bulge when the disc tissue extends more than 25% throughout the circumference of the disc.
Disc Herniation
A disc herniation is a localised disc material displacement of less than 25% beyond the edges of the disc space. A disc herniation is further subcategorised into an extrusion or protrusion.
A disc protrusion is classified as a disc herniation where the base of the disc is thicker than the localised displaced tissue. A disc protrusion can be further subcategorised into whether the protrusion is contained or uncontained. A contained disc protrusion is where the disc material is within the limits of the annulus or the posterior longitudinal ligament (PLL) of the spine. If it is classified as an uncontained disc protrusion, the disc material is therefore not within the space of the annulus and the PLL.
A disc extrusion is where the material of the disc herniation is thicker than the base of the disc. If this occurs the disc extrusion can be further subcategorised into a lesion known as a sequestration. This is where the disc material has actually detached itself from the rest of the disc.
Should I get a scan?
There are large amounts of evidence that show that scans do not tell the whole story. I commonly get asked “should I get a scan?” The fact is that scans (MRI’s, CT’s) only show a visualisation of what may be at fault. However, pain is very complex and multifactorial. Tissue injury or pathology on a scan may not be why you are experiencing pain. A study by Brinjikji et al., 2015 investigated a large number of participants without any symptoms. So these participants had no pain, stiffness or reduced function. What they found was that for every decade of the ageing process, we get an increased likelihood of disc degeneration, disc bulging and even disc protrusions. Remember that all these individuals had no symptoms, however according to their scans they had pathology. The study really highlights that scans are not really needed (especially in the presence of back pain), unless you have red flags present, or it has been a number of weeks without an improvement in symptoms. A summary of these findings can be found below.
Discs do heal
Another major reason why you should not fear the diagnosis of disc bulge/herniation is that they have a great capacity to fully heal. The disc has been shown to spontaneously resorb back to its original environment based off numerous studies. There has even been evidence that the degree of healing is better the more severe the injury is based off the amount of bulging/herniation. The key to management is to work on your improving/maintaining your function so that you can continue to function whilst the healing process is taking place. Although complete healing is ideal, as we just discussed it is not always necessary. You can eventually be completely symptom free and functioning to your previous capacity with a disc bulge/herniation.
The key to disc injury management
Having confidence in function, getting good sleep, reduced stress and anxiety, as well as being physically active are the absolute key to management of disc related injuries. The Reform Lab Osteopathy can assess you and determine an appropriate management plan based off your clinical findings. We will work out your current limitations and capabilities. From here, we will aim to get you back lifting weights (yes squatting and deadlifting) in the first 1-2 weeks if your goals are to lift weights. For those with different goals, we will tailor the rehabilitation/treatment plan to your needs so you can live the life you want to be living.
References
Ropper AH, Zafonte RD. Sciatica. N Engl J Med 2015; 372:1240-8