Discogenic low back pain

Overview 
Theory 
Diagnosis 
Management 
Follow up 
Resources 

Discogenic back pain is an extremely complex multifactorial problem that poses a diagnostic and therapeutic challenge for the clinician. A clear understanding of the pathology, patient expectations, and goals of treatment need to be formulated early on in the process.

Patients who are in the early stages of degenerative disk disease (i.e., with early or no degenerative changes) usually respond well to conservative treatment (analgesia, physical therapy, therapeutic needling options) with a multidisciplinary approach. The majority of patients with acute exacerbations of discogenic back pain will improve by 4 weeks.[99] Approximately 90% of patients will have resolution of symptoms within 3 months of onset, with or without treatment.[4] Only a small proportion (5%) of people with an acute episode of low back pain (LBP) develop chronic LBP and related disability.[100]

Referral to a surgeon is recommended when nonsurgical modalities have proved to be ineffective. Successful surgical management is greatly dependent on the identification of the surgical pathology and identification of specific pain generators that may be amenable to surgical treatment.

In an event of acute exacerbation of a preexisting chronic back pain, the clinician should seek out the cause of the acute symptoms. It is imperative to exclude other causes of acute symptoms such as diskitis.

Neurological emergency

A presumed diagnosis of cauda equina syndrome (CES) necessitates an urgent referral to the hospital. CES consists of saddle (perineal) anesthesia, sphincteric dysfunction, bladder retention, and leg weakness. Emergency decompression of the spinal canal within 48 hours after the onset of symptoms is required.

A painful nerve root deficit (motor deficit with pain in the same dermatome) in the presence of identifiable disk compression is amenable to surgery. It should be differentiated from a painless nerve deficit (e.g., a painless foot drop) and from a peripheral nerve lesion.

Pharmacological treatments

Topical or oral analgesia may be considered for the pharmacological management of low back pain.

Topical pain relief

Acute symptoms can also be managed with topical analgesia.[101] Capsaicin depletes the local resources of substance P, which is implicated in the mediation of noxious stimuli.[102] Topical NSAIDs are useful in pain that may be mediated through muscular causes. [ ] Limited local absorption helps to treat symptoms arising from periarticular structures, and systemic absorption delivers the therapeutic agent to intracapsular structures.[103] Plasma NSAID concentration following topical administration is typically <5% of that following oral NSAID administration and is, therefore, less effective. However, use of topical NSAIDs can potentially limit systemic adverse events.[103]

Oral pain relief

Acetaminophen is often used in mild or moderate pain, as it may offer a more favorable safety profile than NSAIDs.[104] However, UK guidelines do not recommend acetaminophen alone as a first line agent for managing low back pain.[64]

Oral NSAIDs are frequently used and are effective for symptomatic relief in patients with acute low back pain.[105] [ ] No specific NSAID has been found to be more effective than any other.[106] NSAIDs should only be used for a limited time (no longer than 3 months). Gastric protection, such as a proton-pump inhibitor, should be considered in patients who are on prolonged NSAID therapy, especially if they are at higher risk for having gastrointestinal bleeding (e.g., older people).[64]

Opioid analgesics may be used judiciously in patients with acute severe, disabling pain that is not controlled (or is unlikely to be controlled) with acetaminophen and/or NSAIDs.[64] A weak opioid can also be considered (with or without acetaminophen) for acute low back pain if NSAIDs are contraindicated, or not tolerated.[64]

Opioid medication should not be used to treat chronic low back pain.[64][107]

Muscle relaxants

Muscle relaxants, such as diazepam, are an option for short-term relief of acute low back pain; however, these need to be used with caution because of a risk of adverse effects (primarily sedation) and dependency.[108]

Antidepressants

Antidepressants are used most commonly for chronic low back pain (LBP). Studies have shown that tricyclic antidepressants produced symptom reduction, whereas selective serotonin-reuptake inhibitors (SSRIs) did not.[109] Amitriptyline is useful in improving sleep quality and dealing with the neuropathic element of pain. Due to a lack of evidence, US guidance does not make a recommendation for the use of amitriptyline for the treatment of lumbar disc herniation with radiculopathy.[62]

SSRIs serotonin-noradrenaline reuptake inhibitors, or tricyclic antidepressants are not recommended for management of low back pain in the UK.[64]

Gabapentin or pregabalin

Some evidence suggests that gabapentin and pregabalin may alleviate pain and improve quality of life in patients with chronic radicular pain, although this is controversial.[110][111][112] Pregabalin appears to have better adherence and better bioavailability than gabapentin.

Gabapentinoids or anticonvulsants are not recommended for management of low back pain in the UK.[64] Guidance from the US does not make any recommendation for or against the use of gabapentin for the treatment of lumbar disc herniation with radiculopathy due to insufficient evidence.[62]

Physical therapy

Remaining active is recommended for the treatment of acute LBP, rather than bed rest.[113][114] Education of patients as employed in back schools, regarding positions of ease, exercise, and correct lifting techniques, has shown improved patient outcomes in both the short and intermediate term.[62][115][116]

Axial symptoms are likely to be muscular and hence influenced by physical therapy. Therapy with strengthening exercises (both for abdominal wall and for lumbar musculature) has demonstrated positive effects in patients with axial pain.[117] However, the timing of exercise is debated, with use of exercise programs being shown to be most effective in subacute (after 2-6 weeks) and chronic disease. A number of exercise regimens have been used. The McKenzie method is a therapist-led system of evaluating and categorizing patients and then prescribing specific exercises.[118] The McKenzie method produced better short-term results than nonspecific, generic guidelines and was equal to the results of the strengthening and stabilization protocols.[118][119]

Spinal manipulation has been shown to be equivalent to physical therapy in the treatment of acute LBP.[120][121]

Use of a variety of interferential systems and stimulators may provide benefit for acute and chronic radicular pain symptoms; however, their use is controversial.[122][123]

The use of bracing as either prevention or treatment of LBP has been shown to be ineffective.[124] Traction has been used for the treatment of LBP in the past. However, more recent studies have shown no evidence of its value in relation to inactive treatment (bed rest).[125][126]

Alternative therapy

Several therapies may be used within the remits on conventional healthcare systems and as alternative therapies.

The use of nonpharmacologic therapies (e..g, acupuncture, acupressure, and yoga) can be considered.[122][127]

Therapeutic needling options

Selective nerve root blocks

Inflammation as a cause of radicular symptoms with a mild or moderate compression can be treated by a selective nerve root block.
This is performed with radiological guidance for the placement of a spinal needle in close proximity to the nerve root. A long-acting local anesthetic with or without a local acting corticosteroid is then infiltrated.

Epidural injection

Radicular pain due to multilevel, bilateral pathology can be efficiently treated by an infiltration of long-acting local anesthetic, with or without a local acting corticosteroid.
Evidence suggests that epidural injections (using caudal, transforaminal and lumbar interlaminar routes) improves short- and/or long-term relief of chronic pain secondary to disk herniation and radiculitis.[62][128][129][130][131][132][133] Reported complications include, rarely, paraplegia related to the foraminal route and associated violation of a radiculomedullary artery.[130][134] The evidence for relief of pain secondary to spinal stenosis, axial pain without disk herniation, and post surgery syndrome was also moderate.
One Cochrane review found that epidural corticosteroid injections reduced leg pain and disability for patients with lumbosacral radicular pain.[135] However, treatment effects were small, mainly evident at short‐term follow‐up, and may not be considered clinically important by patients and clinicians.[135]
The American Academy of Neurology assessed the use of epidural corticosteroid injections to treat patients with radicular lumbosacral pain, they suggest that pain may be improved in the short term (2-6 weeks post injection), but no impact on average impairment of function, on need for surgery, or on long-term pain relief beyond 3 months was demonstrated. Routine use is not recommended for patients with radicular lumbosacral pain.[136]
Can be injected either in the foramen or in the spinal canal. Infiltration in the spinal canal can be achieved by the lumbar route (through the posterior ligaments), the transforaminal route (through the epidural space targeting a specific nerve root) or the caudal route (through the sacral hiatus).[62]
Although epidural steroid injections might provide greater benefit than gabapentin for some outcome measures, the differences are modest and are transient in most cases.[137]
In 2012, an outbreak of fungal infections of the central nervous system was reported in the US in patients who received epidural or paraspinal glucocorticoid injections of preservative-free methylprednisolone acetate prepared by a single compounding pharmacy.[138] Although such cases are extremely rare, it highlights the need for the highest standards in drug preparation and injection if these routes of administration are used.

Facet joint blocks

Facetogenic pain is a well-defined clinical entity. The symptoms include axial back pain and posterior thigh pain (typically to the knee). The infiltration of a long-acting local anesthetic agent with or without a local acting corticosteroid can provide an assessment of the origin of the pain from the facet joints.
The infiltration can either be around the medial branch as it crosses over the superomedial aspect of the transverse process, or it could be intra-articular. The former is a more accurate intervention. The facet joints have a dual-level innervation; hence, the level above should be injected as well.
Spinal injections are not recommended for the management of low back pain in the UK or the US.[64][98]
The Getting it Right First Time (GIRFT) spinal services report recommend that short-term pain relief injections should be replaced with long-term physical and psychological rehabilitation programmes to help patients cope with back pain.[139]

Facet rhizolysis

If axial back pain continues for more than 3 months and the patient had a positive response to a facet block for acute pain, radiofrequency ablation may provide a longer-term effect on facetogenic pain, although its efficacy is unclear.[140][141]

Surgical management

Neural decompression

Decompression of the nerve roots and neural structures is an important consideration as a part of surgical intervention in patients with acute and chronic radicular pain.[62]
Removal of part of the inferior articular process, under cutting of the inferior process, or removal of all of the degenerate facet joints allows for a better subarticular decompression and the removal of one of the potential pain sources.
An indirect decompression can be achieved by placement of interbody grafts to increase the disk height and open up the foramen.

Spinal fusion

Clinical indications for spinal fusion include: failure of conservative treatment, prolonged chronic pain, disability for more than 1 year, and advanced disk degeneration, as identified on magnetic resonance imaging limited to 1 or 2 disk levels.[142][143] However, due to the multifactorial nature of low back pain and the limited and inconsistent success of spinal fusion, indications for surgery vary between countries and surgeons.[144] In the presence of a clear pathology with evident instability (spondylolysis, isthmic spondylolisthesis with instability, facetal arthropathy with a degenerative spondylolisthesis), the response to physical therapy may be noted for a shorter period of time (6 months) before consideration given to surgery.
In cases of radiculopathy, the presence of symptoms longer than 6 months has been associated with poorer clinical outcomes.[145] Similar findings were noted in patients treated for spinal stenosis, with treatment at earlier than 12 months of symptom duration correlating with better clinical outcomes.[146] One systematic review of surgical techniques for the treatment of symptomatic spondylolysis in athletes showed that 84% of the athletes investigated returned to their sporting activities within 5 to 12 months of surgery.[147]
A thorough understanding of the patient's problems, expectations, lifestyle, and any possible functional overlays can be performed by way of several validated scoring systems (ODI, Roland Morris, SF 36, Nottingham Health Profile, pain scores, pain diagrams, Zung/MSPQ). A clinical assessment of Wadell signs of inappropriate behavior is a useful tool prior to any surgical consideration.[148][149] These should be viewed in conjunction with the imaging findings and the presumed pathology causing the symptoms. The ability of the clinician to build in these variables into the decision making for spinal fusion is vital to a good surgical outcome.
The basic goal of spinal fusion is to prevent further segmental motion in a painful lumbar motion segment. Therefore, this procedure is most appropriate for patients with evidence of spinal instability (trauma, tumor, infection, deformity, and intervertebral disk disease). In the presence of degenerative disk disease without significant instability, the application of spinal fusion is based on the perception that preventing any motion across a painful disk or removing the disk altogether and fusing the motion segment will stop the progression of the disease and relieve the pain.[150][151]
Spinal fusion most commonly involves the use of graft to bridge the fused segments. The graft is either placed in the posterolateral gutters or between the vertebral bodies after excising the space and preparing the endplates (with or without structural supports). Bone morphogenetic proteins have been used with a view to improving the fusion rate.
Several techniques that have been developed and advocated for achieving fusion in the lumbar spine, including: the posterolateral fusion (with pedicle screws or not), the posterior lumbar interbody fusion, the transforaminal lumbar interbody fusion, and the anterior lumbar interbody fusion. Generally, the use of instrumentation has been shown to increase the fusion rates but at the cost of increased complication rates, blood loss, and surgical time.[144][152] All fusion techniques reduce pain and disability, with no disadvantage identified to using the less demanding of the surgical techniques.[152][153][154][Figure caption and citation for the preceding image starts]: Spondylolisthesis: flexion/extension viewsFrom the collection of Dr N. Quiraishi [Citation ends].[Figure caption and citation for the preceding image starts]: Preoperative MRI sagittal T2 sequenceFrom the collection of Dr N. Quiraishi [Citation ends].[Figure caption and citation for the preceding image starts]: Intraoperative images showing a gradual reduction of the deformity: L4 to S1 instrumented fusion, transforaminal fusion at L5S1 and bilateral L5 decompressionFrom the collection of Dr N. Quiraishi [Citation ends].[Figure caption and citation for the preceding image starts]: Postoperative radiographsFrom the collection of Dr N. Quiraishi [Citation ends].[Figure caption and citation for the preceding image starts]: Pre- and post-surgical views: a patient presents with back pain and neurogenic claudication with stenosis and degenerative slip at L4-5 and a degenerate disk at L5S1 (left, T2-weighted sagittal MRI); L4-S1 decompression and instrumented fusion and a 2-level transforaminal lumbar interbody fusion was performed (AP radiograph top; lateral, bottom)From the collection of Dr N. Quiraishi [Citation ends].

Artificial disk replacement (ADR)

ADR is another surgical technique, not in routine clinical practice, that involves complete removal of the injured or degenerated disk material and replacement by an artificial disk. [Figure caption and citation for the preceding image starts]: Disk replacement: patient presents with severe back pain, having previously undergone right L5S1 discectomy for a right S1 radiculopathy. Though initially recovered, the right S1 pain recurred after 10 months, with back pain. An MRI scan shows a degenerate L5S1 disk (left, T2-weighted sagittal view). Patient subsequently had a disk replacement (AP radiograph top right, lateral bottom right). The pain in the back and the right leg resolved completelyFrom the collection of Dr N. Quiraishi [Citation ends]. The aim of this device is to restore the normal kinematics of the disk, relieving pain while avoiding instability and protecting adjacent facets from undue degeneration. The principle of replacing the entire disk is based on the success of other, similar prostheses designed and used for other joints (knee and hip replacements). Therefore, the materials that have been used are also similar (polyethylene, chrome, cobalt, titanium).
Indications for the use of ADR include: failure of conservative management; and disabling LBP attributed to degenerative disk disease affecting no more than 2 disks.[155] These indications are similar to those for spinal fusions with some caveats (relatively early involvement of facet joints, lack of gross instability; i.e., spondylolisthesis). Contraindications for the use of ADR include stenosis, facet arthritis, spondylosis or spondylolisthesis, radiculopathy secondary to a herniated disk, sclerosis, osteoporosis, pregnancy, obesity, infection, and fracture.[156] The efficacy and safety of ADR in comparison with fusion surgery have been thoroughly reported in the literature. Although the initial results were encouraging for the use of ADR, more recent studies with longer follow-up showed that the initial benefit in mobility seemed to be less at 12 months, and at 17 years following surgery, mobility was completely absent, resulting in ankylosis.[157][158][159] These findings have generated some caution about the long-term benefits and complications of ADR, especially in terms of preventing ankylosis, and its popularity as a treatment technique has declined.[160][161][162]

Multidisciplinary therapy

Trends in the conservative treatment of LBP encourage a multidisciplinary approach.[163][164] The disciplines usually contain a physical element and also a combination of social, occupational, and psychological components. Multidisciplinary rehabilitation was found to be more effective than simple rehabilitation programs.[163]

Pain clinic

A multidisciplinary clinic comprising a pain specialist (typically, an anesthetist with a special interest in pain management) with provision of additional input from specialist nurse practitioners, physical therapists, psychologists, and pharmacists.
The goal is to streamline medications, provide input on ergonomic issues, and deal with psychological issues, if any.
The pain physician can undertake procedures such as nerve root and epidural infiltrations and facet rhizolysis.

Functional / vocational rehabilitation

This is defined as whatever helps someone with a health problem to stay at, return to, and remain in work. It is an approach, intervention, and service with a focus toward work-focused health care and accommodating work places to working-age adults. Several return to work programs have been trialed with due attention to manual material handling (MMH) advice and assistive devices, although one Cochrane review found moderate quality evidence that such interventions did not reduce back pain, back pain-related disability, or absence from work when compared with no, or alternative, interventions.[165][166] There was also no evidence from randomized controlled trials to support the effectiveness of MMH advice and training, or MMH assistive devices for the treatment of back pain.

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