Patients with discogenic pain will typically report pain in the midline or the immediate paraspinal region with occasional radiation to the flanks or buttocks. Typically, the pain is worsened with axial loading, sitting, or lumbar flexion and relieved with lumbar extension or lying supine. It is also not uncommon for patients to experience associated stiffness. Given the broad differential diagnosis for non-radicular, axial low back pain, and similarity in clinical features, physical exam maneuvers are relatively poor in accurately diagnosing discogenic pain. Therefore, there are no specific physical tests for diagnosis.

As discogenic pain shares clinical features with other etiologies of axial low back pain, further workup ranging from radiographic imaging to interventional procedures is often necessary. As mentioned previously, disc degeneration can be seen on imaging in asymptomatic individuals, and findings positively correlate with age. Therefore, positive findings on imaging must be taken in the context of the patient’s presentation. Conventional radiographic findings include disc-space narrowing, vacuum disc phenomenon due to accumulation of nitrogen in degenerative fissures, endplate sclerosis, and osteophyte formation. CT can identify these same changes earlier in the course of the disease process. MRI is the modality of choice to evaluate disc degeneration due to superior soft-tissue contrast. High-intensity zone (HIZ) is an MRI finding seen on T2-weighted imaging as a hyperintense signal within the posterior annulus that has been shown to correlate with annulus damage as well as pain.

Additional findings are Modic changes, which are degenerative changes in the vertebral endplates and bone marrow. There are three types of Modic changes based on T1-weighted and T2-weighted characteristics. Type I Modic changes are seen as a low signal in the endplates and adjacent marrow on T1-weighted imaging but hyperintense on T2-weighted imaging (See figure). These changes are highly associated with disc degeneration and pain and have high specificity for positive discography.[9] 

Provocative discography is a fluoroscopically-guided diagnostic procedure involving deliberate administration of contrast into the nucleus pulposus of the suspected painful disc. The pressurized injection of contrast simulates mechanical loading and induces pain. Additionally, the pattern of contrast spread is indicative of the degree of disc disruption. This procedure is only performed when there is a high pretest probability of discogenic pain based on patient presentation and imaging. This is in part due to potentially significant post-procedural complications, including diskitis, dural puncture, disc rupture from contrast overpressurization, and worsening of underlying disc degeneration. It is difficult to define sensitivity and specificity for the procedure as there is no other gold standard for comparison. Due to variability in technique and interpretation, there is no consensus in regards to the false-positive rate. However, systematic review and meta-analysis suggest a rate of about 9.3% per patient.[10] Given these considerations, the procedure should only be performed if it will make a clear difference in management. 

As with other causes of axial low back pain, conservative approach with physical therapy and institution of home exercise is the first step in treatment. Regarding pharmacological therapy, NSAIDs may provide moderate efficacy, but long-term use should be monitored due to the impact on the gastrointestinal and genitourinary systems. Regarding opioids in the treatment of chronic back pain, evidence for efficacy is scant in systematic reviews. Additionally, randomized controlled trials are few. Though opioids appear to have short-term efficacy in treating chronic back pain, the improvements in function are unclear [11]. Furthermore, long-term opioid use is associated with well-known effects such as hyperalgesia, tolerance, and potential addiction and overdose. As a result, the CDC has cautioned against the routine use of opioids in the treatment of chronic low back pain. It has recommended that clinicians carefully reassess evidence of risk and benefit when considering an increase to 50 morphine milligram equivalents (MME) or more per day and avoid increasing daily dosage to 90 MME or more.[12]

There are a number of interventional therapies that are used to target discogenic pain that is unresponsive to conservative management. These include epidural steroid injection, nucleoplasty, intradiscal injection, intradiscal electrothermal therapy (IDET), and biacuplasty. Epidural steroid injection has been shown in a systematic review to have fair efficacy in treating discogenic pain.[13] The underlying mechanism, however, is not entirely clear but may involve a corticosteroid-related reduction in pro-inflammatory mediators. IDET and biacuplasty involve the application of heat to destroy sensory fibers innervating the disc. IDET involves the fluoroscopically-guided placement of an active tip near the area of damage. Biacuplasty creates heat across the posterior annulus using a cooled bipolar radiofrequency device. A systematic review by Helm et al. looking at multiple randomized controlled trials involving these intradiscal thermal therapies concluded level I evidence favoring efficacy of biacuplasty in the treatment of discogenic chronic LBP, whereas IDET showed level III (moderate evidence) of efficacy.[14]

Intradiscal injection with glucocorticoid and stem cell solutions are also proposed treatments. A randomized controlled trial performed by Nguyen et al. demonstrated poor long-term efficacy of discogenic pain treated with intradiscal corticosteroid.[15] Intradiscal biological therapy with platelet-rich plasma (PRP) is an emerging treatment option. PRP is an autologous blood concentrate containing growth factors and cytokines. The PRP concentrate is thought to induce tissue regeneration and repair through anabolic and anti-inflammatory effects. Invitro and animal studies have shown the restoration potential of intervertebral discs. However, there is a dearth of double-blind, randomized controlled trials studying intradiscal PRP, though there are other studies that support its safety and analgesic effects.[16] Additionally, the preparation of the concentrates is highly variable. Therefore, more large-scale randomized controlled studies are needed.

Lastly, surgical fusion also is a proposed treatment for patients who have discogenic pain refractory to conservative and minimally invasive treatments. Currently, there is debate regarding the surgical management of discogenic pain with varying results according to different studies.[17] As a substitute for spinal fusion, artificial disc replacement is another more recent therapy intended to help with pain while also preserving the lumbar spine’s function as a motion segment. This may also help prevent adjacent segment disease typically seen post-fusion. Though further studies are currently needed, a recent meta-analysis showed significant improvement in Oswestry Disability Index, satisfaction, and decrease in reoperation rate compared to fusion.[18] Additionally, as the procedure is performed through the abdomen or retroperitoneum, there is theoretically a decreased risk of muscular dissection compared to posterior fusion, which could result in less postoperative pain.

As discogenic pain is axial, other causes of axial back-pain must be considered. This includes facet arthropathy, paraspinal muscle sprain or strain, ligament sprain or strain, lumbar spondylosis, lumbar spondylolysis, and lumbar spondylolisthesis. Therefore, a detailed history and careful physical exam, along with pertinent imaging, can help to make the correct diagnosis or diagnoses.

Of the patients with chronic low back pain who remain disabled for more than 6 months, less than half return to work. After 2 years, this becomes less likely.[19] For Americans younger than 45 years old, chronic LBP, irrespective of etiology, is the most common cause of disability. Therefore, conservative treatment should begin as soon as possible. Regarding chronic low back pain, poor prognostic factors include emotional distress, ongoing litigation, somatization, and chronic tobacco use.[20][21] Favorable prognostic factors include good social support and symptoms consistent with findings on MRI.

The complications of discogenic pain include significant disability as well as effects on the psychological well-being of patients. There can be a significant increase in stress, depression, and anxiety after the onset of low back pain. In the setting of very progressive degenerative disc disease, the loss of disc height can result in a decrease of the foraminal diameter, resulting in compression of the nerve root and radiculopathy.

A benefit of having the patient engage in physical therapy early includes patient education in managing and preventing worsening of symptoms. Patients can learn about mechanical loading strategies, provided postural education, a walking program, and receive lumbar taping. The McKenzie Method is a comprehensive approach to chronic low back pain that includes both an assessment and an intervention and incorporates the patient’s directional preference.[22] Depending on the underlying pathology, the patient is provided with specific postures and repetitive movements.

Chronic low back pain, inclusive of discogenic etiology, is an interprofessional problem involving primarily physical therapists, primary care physicians, orthopedists, neurosurgeons, and pain medicine specialists. Interprofessional communication must be encouraged through gathering, lecturing, and sharing of recent updates in treatment. Given the societal and economic burden of this disease, all practitioners have a responsibility to address this issue, given the strains on global healthcare costs. 

Furthermore, given the lack of specificity of axial low back pain and often-seen positive imaging in many asymptomatic patients, an emphasis should be made on proper history-taking. This can help prevent unnecessary treatments and risk harm to the patient.