Discogenic back pain

Overview

Discomfort can refer to several forms of pain that originate in muscles, bones, vertebral joints other than the intervertebral disc, or other tissues in the spine. The release of nociceptive chemicals and growth factors by a deteriorated intervertebral disk might result in nerve ingrowth into the disc. A discogenic disease appears to be the source of pain in around 28 to 40% of all people suffering from low back pain.

 

What is Discogenic back pain?

Discogenic pain is distinct from disc herniation with concomitant radiculopathy and is caused by activation of pain sensitive afferents inside the annulus fibrosus.

LBP is one of the most significant clinical and socioeconomic worldwide health problems. The prevalence of LBP is stated to be 31%, with a lifetime prevalence of 60% to 80%. LBP is a complex illness including physiological, psychological, and neurological alterations. In LBP sufferers, intervertebral disc (IVD) degeneration is a major source of pain. Back pain linked with IVD degeneration without herniation, anatomical deformity, or other evident causes of discomfort and impairment is usually referred to as discogenic back pain or axial back pain.

Spinal surgery is particularly helpful in treating diseases such as spinal deformity, radicular discomfort from herniation, spinal stenosis, and spondylolisthesis, among others. Axial back pain, on the other hand, is multifactorial and lacks a distinct source of discomfort, which can be caused by IVDs and related motion segment structures such as facet joints, ligaments, and spinal muscles. Axial LBP, which is assumed to be caused by disc degeneration (discogenic pain), is so difficult to describe, diagnose, and treat. It frequently necessitates extensive therapy, has mixed to poor surgical results, and opioids are frequently recommended.

Many investigations have shown that pain is very sensitive to IVD abnormalities on MRI, particularly highintensity zones and Modic alterations, even though this sensitivity is not always exclusive to pain presentation. The lack of IVD degeneration on MRI correlates with much lower pain, making it a more specific measure.  

There is currently no generally acknowledged standard for discogenic pain. Because IVD degeneration is difficult to identify and is frequently implicated in illnesses in neighboring spinal tissues, better nomenclature and consensus on spine pathology definitions and diagnosis is an important continuing topic of research.

 

Clinically Relevant Anatomy

The intervertebral disc (IVD) is the main joint that connects two vertebrae in the spinal column. Each IVD is made up of three parts:

1. The nucleus pulposus (NP), a gelatinous inner part;
2. The annulus fibrosus (AF), an outer ring of fibrous tissue that encloses the nucleus pulposus;
3. Two endplates of hyaline cartilage. 

The endplates function as a contact between the disc and the vertebrae, covering the annulus fibrosus and the nucleus pulposus at the higher and lower levels.

The cells in the annulus fibrosus's outer portion are fibroblast-like cells that run parallel to the collagen fibers, whereas the cells in the inner annulus fibrosus are chondrocyte-like cells The nucleus pulposus is composed of collagen fibers that are haphazardly ordered and elastin fibers that are radially structured, all surrounded by a highly hydrated aggrecan-containing gel. The nucleus pulposus contains a few chondrocyte-like cells.

The intervertebral disc absorbs strain energy and transfers loads down the spine in a manner akin to a thick-walled fiber-reinforced pressure vessel. The outer annulus fibrosus, which is predominantly a tensile element, offers structural stability as the vessel wall with collagen fibril families stacked in concentric lamellae of diverse orientation (between 45° and 65° off spinal axis)

The nucleus pulposus is mostly made up of hydrophilic proteoglycans, which absorb water and pressurize the disc. It also transfers weight to the annulus fibrosus and vertebral endplates and helps to keep the disc height stable. The disc's graded qualities vary with degeneration, which may be seen morphologically, biochemically, and mechanically.

Discogenic pain is caused by degenerative changes in the intervertebral disc as a result of aging or trauma. An adult's healthy disc has dispersed nerves that are mostly localized to the outer lamellae. Nerves in degenerated discs go through deeper intradiscal structures until they reach the inner third of the annulus and the nucleus. These neurons carry nociceptive neurotransmitters and induce cytokine synthesis, eliciting nociceptive information from inside the disc.

 

Categorization of back pain

LBP has been classified in a variety of ways. First, LBP is classified as either specific or nonspecific. Despite recent advances in diagnostic methods like as radiography, nonspecific LBP has been found to account for 80% to 90% of total LBP. Furthermore, therapy options for chronic nonspecific LBP are murky; results are frequently mixed due to difficulties identifying the pain origin and multifactorial features. Nociceptive and neuropathic pain linked with muscle and fascia damage, spinal osteoarthritis, osteoporosis, and radicular back pain are examples of specific pain.

Back pain can also be classified according to its cause: discogenic LBP, radicular LBP, facet joint osteoarthritis back pain, muscle and fascia generated back pain, and spontaneous occuring LBP. Although the particular reasons of discogenic back pain are frequently complicated and can be difficult to identify and treat, discogenic pain can be classified as a unique type of back pain, mostly consisting of nociceptive and neuropathic pain.

Myofascial back pain is a form of pain caused by a myofascial structure such as muscle and fascia. Sprains, spasms, and contusions are common complications. Back pain caused by joint osteoarthritis covers the facet joint as well as the sacroiliac joint as one of the causes of LBP.

Radicular back pain is a form of pain that radiates into the lower extremities along the path of a spinal nerve root. Both nerve root compression and inflammation can induce radicular discomfort. Herniated discs, foraminal stenosis, peridural fibrosis, spondylolisthesis, and spondylolysis can all cause nerve root compression. Herniated IVD causes inflammatory cytokines, which are thought to impact the dorsal root ganglia and produce radiculopathy.

LBP refers to a pain process of the central nervous system(CNS), regardless of the etiology . Chronic LBP can cause irreversible CNS dysfunction, with central sensitization thought to play an essential role in chronic pain, including hyperalgesia. Chronic pain issues might be difficult to treat clinically since the spinal disease may not remove the central sensitization.

 

Causes of Discogenic Pain

When the nerve receptors in the annulus's outer section are inflamed, discogenic pain arises. Inflammation or a combination of disc problems frequently irritates nerve receptors, resulting in neck or lower back discomfort.

Internal disc disruption (IDD) is a discogenic condition that develops when disc rips or breaks occur to allow the nucleus and annulus to connect. As a result, a substance known as proteoglycans may be produced, producing inflammation and discomfort.

Genetics may potentially play a role in the development of discogenic pain. Some genetic signals have the potential to alter the chemical structure of the discs and cause metabolic changes in the organism. As a result, the disc may degrade more quickly than usual.

Aside from disc condition and heredity, mechanical and dietary variables can also contribute to discogenic pain. 

 

Symptoms of Discogenic Low Back Pain

Combining these characteristics with radiological criteria improves diagnosis confidence. The symptoms of lumbar discogenic disorders are not felt in the same manner by every patient. Most people who have persistent low back pain say that it radiates into the buttock and leg. This discomfort can be felt unilaterally or bilaterally, but there is no radicular pain. These individuals may also develop aversion to sitting.

Nuclear pulposus migration, which results in directional preference, is an essential mechanism in the diagnosis of discogenic pain. Mechanical loading methods (MLS), such as repetitive motions and prolonged posture, can result in proximal movement and relieve distal discomfort. According to studies, the mechanism underlying this reaction is generated by a decrease or migration of a painful and improperly misplaced nucleus pulposus to a more central position in the lumbar disc, generating less pain.

Centralization is associated with directional preference, the direction of MLS that results in centralization. Reducible discogenic pain (RDP) can be identified in patients who have a directional preference related to discogenic pain. A reliable diagnosis can be achieved by analyzing reactivity to an MLS, CT/MRI/discography findings, and other clinical characteristics. A treatment plan can be developed based on this diagnosis.

Experienced practitioners speculated that there may be other types of discogenic pain, such as non-reducible discogenic pain, discitis, unstable disc, and adolescent disc. Endplate modifications, differences in annular tears, and inflammatory/immune responses are examples of pathoanatomical and pathophysiological abnormalities that may constitute clinically relevant subgroups. Practitioners seeking to identify discogenic pain should be aware of these potential subgroups and their implications for patient presentation.

 

Diagnosing Low Back Discogenic Pain

90% of the causes of chronic low back pain may be identified using diagnostic methods. Internal disc disruption (IDD)-induced low back pain (IAD) and internal endplate disruption-induced low back pain (IED) are the two forms. Clinically and pathologically, the term IAD is more accurate than IDD. Lumbar intervertebral discs without herniation are responsible for 26%-42% of persistent low back pain. It causes nociceptive pain syndrome. The pain originates in the innervated outer third of the annulus.

Internal disc disruption (IDD) causes lumbar discogenic pain, which can be diagnosed and treated Internal disc disruption is still a problem. As an indirect indicator of IDD, magnetic resonance imaging (MRI) can detect a high-intensity zone. Provocative discography can give unique information regarding the source of pain as well as disc morphology. It might also help you choose the best treatment for your painful annular tear.

A subsequent CT scan with disc stimulation has little diagnostic value. The clinical profile of discogenic pain is unrelated to degenerative changes. There is no distinction between this and other types of back pain. It has a prevalence of 39%, making it one of the most common causes of back pain in people who have a specific source of pain.

 

Differential Diagnosis

• Lumbosacral Disc Injuries - The causal cause of lumbosacral spine intervertebral disc injuries is low back discomfort (LBP). It is more common than muscle strain or ligamentous sprain. There is no one intervertebral disc lesion that has been definitively established as a source of pain.
• Lumbosacral Facet Syndrome - Zygapophyseal -joints are not the only or major cause of LBP and are frequently confused with discogenic pain. One of the most prevalent causes of low back pain (LBP) is the Z-joint.
• Although radiculopathy is not the cause of back pain, it is related with several of the primary causes of acute and chronic low back pain (LBP). Lumbosacral radiculopathy is caused by nerve root impingement and/or inflammation, which results in neurologic symptoms in the regions supplied by the afflicted nerve root or roots.
• Spondylolisthesis of the Lumbosacral Spine - Spondylolisthesis is most frequent in the lower lumbar spine. Minor overuse damage, particularly recurrent hyperextension of the lumbar spine, is the cause. If the pars defect is bilateral, it may enable vertebral sliding, most often L5 on S1, resulting in spondylolisthesis.
• Lumbosacral Spondylolysis - The most common causes of Lumbosacral spondylolysis include mechanical forces, which can cause or worsen lumbar spondylolysis. There is also a genetic component. The most typical location is at L5 (85%), however it has been recorded as high as L2. The most prevalent kind of spondylolisthesis is caused by lumbar spondylolysis (lumbar spondylolysis).

 

Treating Discogenic Pain

Medical Management

Minimally invasive therapies offer cost-effectiveness and fewer long-term negative effects for discogenic pain (if possible). The majority of these treatments have yet to be shown effective.

More clinical trials are needed to increase the clinical effectiveness of minimally invasive lumbar discogenic pain therapies. Nonsteroidal anti-inflammatory medications (NSAIDs), physical therapy, rehabilitation, antidepressants, antiepileptics, and acupuncture have all been used to treat low back pain. The efficacy of these therapies for discogenic pain has yet to be determined.

Thermal annular procedures (TAPs) have been developed as a less invasive therapy for this issue. Several procedures were utilized, including intradiscal electrothermal treatment (IDET), radiofrequency annuloplasty, and intradiscal biacuplasty (IDB). However, these therapies are still controversially linked to a lack of proof.

• Intradiscal electrothermal therapy (IDET) - This is a minimally invasive therapeutic strategy that falls between between cautious nonsurgical care and spinal surgery. Patients with modest disc degeneration might still benefit from clinical improvements. It may provide some pain relief to a limited number of people. This treatment appears to provide enough symptom progression without extra problems. It also provides functionally meaningful alleviation in 50% of individuals with persistent discogenic low back pain.
• Radiofrequency annuloplasty - There is minimal evidence supporting the use of radiofrequency annuloplasty. 
• Intradiscal biacuplasty (IDB) - This should be recommended as a strategy of selection for people suffering from persistent discogenic low back pain.

Other treatments are:

• Bi-annular pulsed radiofrequency disc method - The bi-annular pulsed radiofrequency disc method appears to be a safe, minimally invasive treatment option for patients with chronic discogenic low back pain. 
• Intradiscal steroid injections - This method has not been proved to determine long-term benefits. 
• Intradiscal radiofrequency thermocoagulation - No benefits have been found for the intradiscal radiofrequency thermocoagulation. 
• Spinal fusion - The therapeutic improvements found in Kapural et alstudy .'s are the consequence of non-placebo therapy effects provided by IDB, however there is little evidence supporting its usage in other trials. This should be recommended as a strategy of selection for people suffering from persistent discogenic low back pain.

• Ramus communicans block - A obstruction in the ramus communicans can prevent painful information from being sent from the discs to the central nervous system.
• Disc cell transplantation - Although disc cell transplantation is still in its early stages, it has the potential to be effective in the prevention and treatment of discogenic pain. More investigation is required.

 

Conclusion 

Discogenic Intervertebral disc degeneration is a prevalent cause of axial low back pain without radicular symptoms. A history, physical examination, and MRI scans are used to make a diagnosis. NSAIDS, physical therapy, cognitive therapy, and lifestyle changes are common treatments.

If you have back or neck pain that you believe fits this description, you may not always be able to afford to go through a series of testing, referrals, imaging, and diagnosis before you can finally obtain any relief.