What is Low Back Pain?

Low back pain explained by Denver, Golden, Aurora, Boulder, Broomfield, Jefferson, and Littleton Colorado’s top pain doctors

Low back pain can be a very debilitating condition. Pain in the lower back, or lumbar region, is relatively common. Estimates indicate that approximately 84% of people over 18 will be subject to one form of lower back pain or another at least once in their lifetimes. Recurrent episodes of low back pain are also widespread. Some reports estimate that up to 78% of low back pain patients are at high risk of a relapse of their condition. The Centers for Disease Control (CDC) reports that low back pain is associated with significant decreases in normal function and detriments in professional and personal life.

Low back pain may also be linked to a negative economic impact. The National Institutes of Health (NIH) have released estimates of a loss to the U.S. of $50 billion per year connected with low back pain. This condition is thought to be the most prominent cause of workday losses and occupational disability. In response to this, low back pain is often the subject of research and treatment development. There has been a significant rise in the number of reports and studies investigating risk factors and improved diagnostic tools for lower back pain in the last decade. Clinical trials of novel and refined treatments for this condition are also increasingly common.

Low Back PainLow back pain may be either chronic or acute in nature. Acute low back pain is defined by a sudden onset and a duration that is usually a number of days to a number of weeks. Chronic low back pain is a condition that lasts longer. An incidence of pain is diagnosed as chronic if it lasts for three months or longer. Experiencing acute lower back pain can increase the risk of developing a chronic case in the future. Chronic conditions are associated with significant debility or lack of function. Approximately 12% of people in the U.S. experience chronic low back pain accompanied by functional disablements. Chronic cases often begin with a low level of pain that escalates gradually into a much more severe condition.

Chronic pain may be divided into two categories: specific and non-specific long-term low back pain. Non-specific chronic low back pain is defined as significant persistent pain not associated with a diagnosis of a concomitant, causative disorder. These are linked to specific cases and include illnesses and conditions such as osteoporosis and tumors in the lumbar region. Some estimates indicate that the total prevalence rate of non-specific chronic low back pain is approximately 23%. This figure implies that a high percentage of the population of 18 years or more are affected by daily lower back pain.

The choice of low back pain treatment is influenced by the causative factors of the individual case in question. This requires adequate diagnosis, often achieved by the physician working with the patient, to find the most likely reason for their condition. This is not aided by the complexity of the lumbar region, which includes the spinal cord, the bones surrounding this, and the muscles and other tissues connected to these. The spinal column is composed of a series of vertebrae (the small spinal bones) that provide a degree of postural and structural support to the skeleton and is the main defense of the spinal cord. Lumbar vertebrae interlock (or form joints) in a way that allows a certain range of motion and flexibility to the spine. They form a canal in which the spinal cord continues its journey along the back from the brain. The intervertebral discs, composed of flexible but resilient tissues, are located between each pair of vertebrae. These act to provide shock absorption, protection, and flexibility to the lumbar spine. Ligaments and muscles are attached to each vertebra in order to provide mobility and strength. Each subcomponent of the lumbar spine is at risk of damage. This may occur as simple mechanical wear over time, as a result of disease or disorder, or more immediately through accident or injury.

The lower back—most often characterized as the region between the last rib and the pelvis—is often subject to sensations of discomfort or pain. Low back pain can, in some cases, spread to other regions of the body, most often the legs. The actual nature of this type of pain may take many forms. Some patients report intense sharp pain in one particular area of the region, while others experience less specific pain that radiates to some or all of the lower back. Levels of pain may also increase and decrease over time. The pain may be recurrent, i.e. fading and then returning in full in a regular pattern, or may increase abruptly at any given moment. Therefore, there may be many discrete types of lower back pain.

On the other hand, many types share some common symptoms. These may include:

  • Strong reactions to pressure or palpitation of the region
  • Sensations of numbness, weakness, or tingling
  • Inflexibility
  • Radiating pain
  • Muscular spasm
  • Cramping

A physician’s assessment of low back pain often begins by obtaining a short but in-depth patient history. This is part of the process of diagnosing the precise source of low back pain. Some consultations may fail to find this cause, however. The physician will take steps to rule out all causes of specific lower back pain (see above). This may include tests for conditions such as spinal disorders and damage to nerve endings. A physician may also detect the probability of risk factors for lower back pain. These are termed “yellow flags,” and may help determine the eventual treatment and rehabilitation plans. Yellow flags associated with low back pain include occupational hazards, depressive symptoms, psychological stress and reactions to pain, pain severity, existing history of low back pain, effects on normal function and motion, and patient descriptions of pain.

There are also red flags, or indicators of serious conditions or damage. These include certain neurological symptoms, general ill health, pain that occurs without movement or other provocation, additional pains in the chest or upper back, use of steroids, skeletal abnormalities, reductions in body weight, and an age outside the usual range (i.e., under 20 years or over 55). These may be symptoms of a serious illness, such as cauda equina syndrome cancer, infectious disease, metastasis, bone fracture, or a disorder causing inflammation. The presence of one or more of these red flags does not automatically indicate such a condition, but a competent physician will often recommend tests to rule them out. A report of one of these risk factors may require referral to another specialist, in case of the rare event of a life-threatening illness.

Causes Of Low Back Pain

Low Back Pain CausesLow back pain is often associated with a range of less serious disorders or damage in this region. These may include:

  • Spinal infections: Low back pain may be associated with an infectious disease that has invaded the spine. This should always be eliminated as a possibility when diagnosing a case, especially if it also presents with fever, long-term drug use, immune system deficiencies, or if the patient has recently undergone an invasive procedure.
  • Bulging disc syndrome: This is a condition in which the intervertebral discs are damaged, causing them to protrude outwards, where they may negatively affect spinal nerves resulting in pain. This is associated with advanced age and is a common source of back pain in this demographic.
  • Spondylolisthesis: This is a form of vertebral dislocation, in which they fall out of place and “slide” over one another. It may fall under the category of nonspecific low back pain, as it is hard to diagnose especially when asymptomatic. Spondylolisthesis is estimated to affect up to 5% of the population.
  • Spinal stenosis: This is caused by compression of the spinal cord or spinal nerves, which is commonly associated with the build-up of scar tissue in the immediate proximity of these. It may also arise as a result of abnormal bone tissue production within vertebrae.
  • Osteoarthritis: This is a condition characterized by progressive autoimmune damage to the cartilage, a protective material within joints that prevents shock or friction within them. Osteoarthritis may also be associated with mechanical or acute damage. If enough cartilage is destroyed by the condition over time, it may result in direct contact between the bones in a joint, which results in pain.
  • Spinal deformities: This is abnormal growth or structuring of the spine, associated with a number of genetic disorders. They may contribute to excessive and noticeable curvature of the spine (e.g., in cases of kyphosis or scoliosis), and generally affect all or many of the vertebrae. Spinal deformities are comparatively rare. Estimates (which are not as up-to-date as they could be) indicate that these conditions affect 0.8% to 1.9% of the population.
  • Fractured vertebrae: These occur in two main forms. The first is vertebral body fracture, in which the bone sustains a number of small fractures that give the appearance of shattered vertebrae. They are thus often referred to as “burst fractures.” Another type of vertebral body fracture is a singular break, called a ‘split’. This type of fracture is associated with accidental damage, such as those occurring in motor vehicle-related accidents. This type of fracture is often not serious, but can cause spinal damage if neglected.
  • Compression fractures: This is the second type of vertebral body fracture. It is strongly associated with degenerative bone conditions such as osteoporosis, and with prolonged corticosteroid intake. A study of 7,000 women of 65 years over four years or more reported that 5% had developed a compression fracture. Unlike vertebral body fractures, these appear as more of an absence of bone in the vertebra(e) affected, which results in a loss of height in the bone and the overall appearance of a collapsed vertebra. Other studies indicate that approximately 0.04% of the adult population requiring consultations for back pain exhibit symptoms associated with compression fractures.

The presence of other factors also determines the risk of the development of low back pain. These risk factors include employment status, pain perception, anxiety, depressive disorder, and gender. A five-year prospective study investigated the influence of certain risk factors on the prevalence of lower back pain. The results suggested that pain perception and psychological issues in relation to chronic pain was associated with poor response to treatment and/or improvements of pain severity at six months into the study, and also again at the end of this investigation.

Treatments For Low Back Pain

Lower back pain has been the subject of many investigative studies and clinical development of many well-regarded, replicated and extensively tested treatments. These therapies and interventions can vary based on the underlying factors associated with each individual case of back pain.

Consultation with a primary care physician, rather than doing nothing and hoping that symptoms go away in time, is recommended if low back pain arises or persists. This is the best option in finding out which treatment is necessary and effective. A physician may also be able to provide educational material about the prevention and management of future back pain. If the pain is less than severe, and does not cause significant debility, the physician may recommend an incremental increase in activity until former levels of function are restored. Some lower back pain research indicates that approximately 90% of patients will respond positively to conventional treatments including physical therapy.

Many low back pain treatments focus on the reduction of debilitating symptoms and a return to normal function. Significant motor and function deficits may act as part of a vicious cycle of this condition. Poor compliance with a treatment regimen is associated with perpetuation of pain symptoms, which in turn, significantly affect the motivation to move about and partake in other normal functions.

As discussed above, lower back pain does not have one specific cause or contributing factor. Many researchers have concluded that a number of factors may interact to determine a level of pain severity and functional decline. Some are psychological factors, such as conscious pain perception and reaction to a diagnosis of a painful condition (sometimes termed “pain acceptance”), that are associated with significant effects on the degree of debility and pain severity. Other psychological conditions (such as “pain catastrophization”) may also influence functional impairments and pain adversity. These effects have become topics of interest in lower back treatment research. Chronic low back pain patients have demonstrated responses to positive reinforcement for treatment compliance and other beneficial activities and for applying pain coping strategies. Targeting negative psychological processes in relation to pain and debility is also associated with a positive impact on these symptoms. This may be achieved by discussion with patients about their negative thoughts and feelings in relation to their condition and probability of its improvement. It is not clear if these effects are of clinical significance, but there is evidence available that indicate a beneficial effect of the confrontation of these factors in the course of treatment. An improved outlook on chronic pain and its management may increase the probability of physical therapy compliance.

Pharmacological Treatments

NSAIDDrug therapy is a conventional first-line treatment for lower back pain. A study of this condition’s treatment in primary care clinics estimated that 4% of patients were prescribed acetaminophen, 12% were prescribed narcotic analgesics, 35% were given muscle relaxants, and 69% non-steroidal anti-inflammatory drugs (NSAIDs). NSAIDs, including naproxen and aspirin, are associated with the control of inflammation, a widely-accepted cause of pain. NSAIDs are some of the most common over-the-counter medications; however, they are associated with risks, including gastrointestinal bleeding, irritation, and ulcers. Therefore, NSAIDs are recommended in short-term courses for acute cases of pain, as the probability of these side-effects increase with high dosages or regular intake over time.

Antidepressants are associated with some reports of effects on pain and have been the subject of some rigorous trials to investigate this. Classic forms of these medications are the tricyclic antidepressants, such as nortriptyline, clomipramine, or doxepin. The pain-relieving effect of these drugs is not fully defined. They are thought to improve pain by increasing availability of norepinephrine and serotonin (molecules called neurotransmitters) between nerve cells (where they facilitate neural signaling). TCAs have been largely replaced as depressive disorder treatments, but are prescribed nowadays for painful conditions. Newer forms of antidepressant drugs are selective serotonin reuptake inhibitors (SSRIs, including fluvoxamine, and citalopram) and serotonin and norepinephrine reuptake inhibitors (SNRIs, e.g. desvenlafaxine, duloxetine, and milnacipran). These are also recommended for low back pain treatment. These drugs are similar in effect to TCAs, but differ in terms of chemical composition and side-effects. SNRIs and SSRIs may be associated with positive effects on chronic lower back pain. This effect may be related to their significant effects on mood, however. Some patients with long-term back pain may develop depressive symptoms in response to this, which can be improved by these medications and thus imply an improvement in pain perception.

Muscle relaxants are another type of drug in use for low back pain. One subdivision of these are the benzodiazepines and non-benzodiazepines. Both of these have similar effects on abnormal muscle spasms that may contribute to lower back pain. Another, which includes drugs such as baclofen and dantrolene, treat uncontrollable rigidity, tightness, and inappropriate movement in affected muscles. Both types of muscle relaxant have shown some efficiency in short-term lower back pain treatment. Anticonvulsants are also associated with treatment of cases of this condition with nerve damage as a main factor. These drugs are associated with increased concentrations of gamma-amino butyric acid (GABA), another neurotransmitter that may be a regulator of pain-signal processing. This may be an emerging application in new pain treatment development.

Capsaicin skin patches are a novel development in pain management increasingly associated with relief from back pain caused by nerve damage. Capsaicin is a molecule derived from chili peppers that can cause a response in the pain receptors in the epidermis. These create burning and itching sensations in the skin it comes into contact with and a subsequent long-lasting decrease in sensitivity. Multiple cutaneous administrations of capsaicin can result in protracted desensitization in the target tissues. This is the basis of capsaicin as a potential analgesic.

Patients with severe chronic lower back pain that is unresponsive to these treatments may be eligible for opioid therapy. These drugs are associated with significant relief from intractable, nonspecific back pain. They act by binding receptors that regulate the pain response. They are, however, associated with risks such as skin reactions, lethargy, mouth dryness, and constipation. Opioids are popularly linked with high risks of tolerance (the progressive resistance to a constant dose over time) and recreational abuse, especially when used over a long period of time.

Interventional Treatments For Low Back Pain

Facet Joint InjectionPain relating to damage or disorder of the vertebrae can be addressed with a range of successful, effective treatments. These include facet joint injections, which are injections of compounds that inhibit pain signaling such as lidocaine, into the vicinity of the nerves controlling the joints between vertebrae. These injections can also be delivered directly into the lumbar facet joints themselves. This may also be done as a diagnostic measure to eliminate the possibility of vertebral joint-related pain.

Other joints that can be targeted by anesthetic injection to treat lower back pain include the sacroiliac joint. This is the juncture of the spine and the pelvic bone. Spinal muscles or ligaments, if implicated in a case of lower back pain, are known as “trigger points.” These points can be directly injected with medication. Trigger point injections are associated with pain relief straight away after this procedure. Epidural steroid injection procedures are another variation on these. In these cases, corticosteroids are injected into the epidural spaces, where spinal nerves are located, of lower back vertebrae. Steroid injections are associated with effective lower back pain relief. Pain reductions immediately after treatment are commonly associated with steroid injections. However, repeat injections over several months or a year may be necessary to elicit maximal effect for some patients. They are associated with medium- to long-term relief from pain. All injection-based therapies incorporate imaging techniques such as fluoroscopy to assist accurate needle placement.

Pain from vertebral fractures in the lower back may be treated by drug therapy in some cases, but many others require invasive restoration. Fractures left to worsen are associated with possible spinal cord or nerve damage. Procedures to correct fractures are vertebroplasties. These are associated with spinal bone healing and pain reduction. They are relatively straightforward and require reduced invasion. The skin above fractured vertebrae is numbed with local anesthetic. A needle is inserted through this, guided by imaging techniques such as MRI. When it is in contact with the vertebra in question, it injects medical-grade acrylic cement to seal the fracture(s).

Kyphoplasty is another version of vertebroplasty. It involves the insertion and inflation of a small medical balloon prior to cement. This provides height and support to the fractures, which aids the injection of acrylic. The main risks of kyphoplasty or vertebroplasty are related to cement leaking out of the intended locations into the spine. This may be associated with inflammation, nerve irritation, and discomfort. Both are also associated with risks of infection and bleeding in the skin over the treated vertebra and headache. In rare cases, inadvertent nerve damage in the spine may cause sensory or motor deficits.

Some cases of lower back pain may be due to prior surgical intervention in this area that has resulted in inadvertent spinal nerve damage. This is associated with significant pain and potential disability. Damage is associated with the development of scar tissue in close enough proximity to nerves to cause chemical (i.e. inflammatory) or mechanical injury. Adhesiolysis (lysis of adhesions or the Racz procedure) is associated with effective removal of scar tissue and subsequent pain relief. This procedure involves the insertion of a catheter into or near the scar tissue (under local anesthetic) to deliver compounds including hyaluronidase. These lyse or destroy the scar tissue and prevent further damage. Adhesiolysis is associated with positive effects on lower back pain associated with failed back surgeries.

Some severe cases of lower back pain may not respond to any of the options outlined above. These may respond to last-resort, unusual methods of pain management. An example of this is another minimally invasive procedure, spinal cord stimulation (SCS). This is associated with effective relief from severe chronic lower back pain linked to nerve damage and failed back surgery. Spinal cord stimulation involves the insertion of thin, wire-like medical implants alongside the spinal nerves thought to conduct the relevant painful signals. They release mild electrical impulses that can override painful signals with ones closer to “non-pain” signals. The implants are attached to leads that connect them to a hand-held controller. The patient may activate spinal cord stimulation themselves to block pain at its onset. The risks of spinal cord stimulation are infection and bleeding at the insertion site. Another adverse effect is the failure of the implants that results in either no impulses or impulses that somehow magnify the pain rather than the opposite. There is also a low incidence of migration, in which implants slip out of the intended location that may be associated with further pain.

Intrathecal pump implants are similar in concept to spinal cord stimulation. In this case, a catheter is inserted near the spinal nerve in question. This is connected to a pump containing a certain volume of anesthetics. Again, this is controlled by an external device, which when activated, delivers a dose to the nerve. Intrathecal pump implants are associated with significant decreases in lower back pain and functional impairments. They are also associated with similar risks to those of spinal cord stimulation.

Alternative Treatment Options For Low Back Pain

Low Back Pain DiagramThe physiological effects of lower back pain may also contribute to its severity. This is supported by observations that stress and tension is associated with negative effects on general health and the capacity to respond to adverse environmental factors. Biofeedback training is a therapy option that focuses on improving these abilities and applying this to the management of pain. This involves training patients to anticipate pain episodes and in techniques that may contribute to the ability to cope with them. In the course of biofeedback, the patient learns aspects of measurements of important vital signs, which include muscle tension (electromyogram (EMG), heart rate (electrocardiogram (ECG)), brain activity (electroencephalogram (EEG)), skin responses (galvanic measurements), and thermal feedback skin thermometer. The effects of pain or tension on these readings will then be observed, often in real time (i.e. the patient is connected to a biofeedback device while experiencing pain). The patient is instructed to apply coping techniques to attempt to return these measures to normal. These techniques are relaxation and stress reduction techniques. This may be associated with a decrease in pain. Biofeedback may be learned initially in a clinic or health center setting, taught by registered technician, and practiced alone in the patient’s home thereafter. This technique has the advantage of being non-invasive and non-reliant on drugs, and is associated with positive results on pain perception in some studies.

Patients with low back pain accompanied by mild functional impairment may be encouraged to try other non-invasive therapies as a first step in treatment. These include chiropractic manipulation, which is often associated with significant pain reductions and positive effects on health in general. This form of therapy involves the applications of specific amounts of manual pressure to joints either beyond or within their normal range of motion. This is associated with incremental movements of a bone or joint back into its normal conformation, in conditions involving mild skeletal problems. Chiropractic manipulation of the lumbar spine carries some risks, including soreness in the area targeted, neurological complications, fatigue, headache, and even consequential discomfort in other, unrelated areas of the body. Some reports indicate that these side effects often arise in the first 24 hours after chiropractic manipulation, and tend to fade in the next 24. There is a lower incidence of more serious risk, including cauda equina syndrome, disc herniation, and motor control problems.

There are also alternative treatments available for lower back pain management. An example of this is acupuncture. This is a technique derived from traditional Chinese practices. Acupuncture is the insertion of thin, sterilized needles into specific body regions. These are termed acupuncture points. Lower back acupuncture may involve points in this and other regions, where needle puncture is thought to also affect lower back pain. The risks of acupuncture include mild skin damage, discomfort, and bleeding. Electroacupuncture is another form of this therapy, in which needles carrying a low electric current are employed. In this case, the side effects may be similar to acupuncture and also include slight skin irritation. The World Health Organization has acknowledged acupuncture as an option with some effect in treating lower back pain and other conditions.

Transcutaneous electrical nerve stimulation (TENS) is another alternative in treating lower back pain. TENS involves the use of pads containing electrodes that emit impulses targeting nerves located under the skin to which they are applied. Some studies report positive results in trials of TENS and lower back pain. This technique requires more in-depth clinical investigation to confirm its effects on this condition, however. TENS is also reported as effective in treating lower back pain in combination with other therapies such as acupuncture.

Another alternative treatment, albeit with a pharmacological component, is the use of Botox injections. This treatment has been reported as having positive effects on pain in conditions such as lower back pain associated with myofascial disorders or damage. Botox is a neurotoxin that can cause significant muscle paralysis. In smaller concentrations, as used in the laboratory or for medical applications, it can inhibit nerve signaling to muscles, which may treat painful spasms. It may also inhibit neurotransmitters involved in the up-regulation of pain signals in general. Several clinical trials have indicated that Botox may achieve significant reductions in pain and functional impairment.

Active release techniques (ART) may be beneficial for patients whose back pain is associated with blunt object-related damage, but not inflammation. ART is the application of controlled manual pressure to soft tissue (e.g. skin or muscle) by a competent accredited technician. At the same time, the patient is asked to engage in some repetitive motions within this area or others in proximity to it. This achieves consistent contraction and flexion of the muscle in these regions. This may slowly reverse damage and return muscle fibers to a normal structure. It may also contribute to a reduction of stiffness, possible inflammation, and pain. There is some evidence that ART may also reduce the incidence of muscle abnormality commonly associated with damage, including tearing, scarring, and fusion.

Conclusion

Lower back pain is a widespread condition that may be associated with any of the structures and tissues that make up the region. This includes the vertebrae, spinal nerves, spinal column, ligaments, and muscles located in the lumbar area. Some estimates indicate that over 80% of people over 18 are at risk of at least one incidence of lower back pain in their lifetimes. This condition has both acute and chronic forms. It is associated with a high incidence of functional and motor impairments that may contribute to decreases in productivity and overall economic losses due to lost or reduced employment. Lower back pain is also linked to increased healthcare burden.

There is no one single etiology of lower back pain. It may be caused by a number of different diseases and disorders. There is also evidence that psychological factors such as pain perception, acceptance, and catastrophization can also influence pain severity and functional decline. Physicians may identify risk factors for future low back pain in certain patients and include options to promote prevention as part of their treatment programs. Many types of lower back pain may be accompanied by other symptoms such as sensitivity to touch or pressure, radiating pain, stiffness, cramping, muscle spasms, and sensations of tingling, numbness, or weakness.

Accurate diagnosis of lower back pain is associated with effective treatment and patient recovery. This may require the request for a patient history and a physical examination. Some specific types of low back pain may be indicative of serious underlying conditions such as tumor metastasis or cauda equina syndrome. Less serious causes of lower back pain, in combination with various possible risk factors, may determine the type of treatment prescribed. These range from low-impact options, such as over-the-counter medications (such as NSAIDSs) or biofeedback, to slightly more invasive treatments, such as facet joint injections or spinal cord stimulation. Other alternative treatments for back pain currently emerging or under evaluation include Botox injections, active release techniques, and acupuncture. Other more established treatments associated with effective relief are corticosteroid injections. Patients with more severe, intransigent forms of lower back pain may be addressed by treatments such as opioids or intrathecal pump implants. Thorough discussions between physicians and patients can help achieve the best probable treatment for lower back pain.

At Pain Doctor our goal is to relieve your low back pain and improve function to increase your quality of life.
Give us a call today at 480-563-6400.

References

  1. Airaksinen O, Brox JI, Cedraschi C, Hildebrandt J, Klaber-Moffett J, Kovacs F. Chapter 4. European guidelines for the management of chronic nonspecific low back pain. Eur Spine J. 2006;15(2 Suppl):192-300.
  2. Birkenmaier C. Should we start treating chronic low back pain with antibiotics rather than with pain medications? Korean J Pain. 2013;26(4):327-335.
  3. Borczuk P. An evidence-based approach to the evaluation and treatment of low back pain in the emergency department. Emerg Med Pract. 2013;15(7):1-23.
  4. Boswell MV, Trescot AM, Datta S, et al. Interventional techniques: Evidence-based practice guidelines in the management of chronic spinal pain. American Society of I Pain Physicians. Pain Physician. 2007;10(1):7-111.
  5. Brosseau L, Milne S, Robinson V, Marchand S, Shea B, Wells G, Tugwell P. Efficacy of the transcutaneous electrical nerve stimulation for the treatment of chronic low back pain: A meta-analysis. Spine. 2002;27(6):596-603.
  6. Campbell P, Foster NE, Thomas E, Dunn KM. Prognostic indicators of low back pain in primary care: Five-year prospective study. J Pain. 2013;14(8):873-883.
  7. Centers for Disease Control (CDC). Morbidity and Mortality Weekly Report. 2001;50:120-125.
  8. Cervera-Irimia J Tome-Bermejo F. Caudal epidural steroid injection in the treatment of chronic discogenic low back pain. Comparative, prospective and randomized study. Rev Esp Cir Ortop Traumatol. 2013;57(5):324-332.
  9. Chan S, Hadjistavropoulos T, Carleton RN, Hadjistavropoulos H. Predicting adjustment to chronic pain in older adults. Can J Behav Sci. 2012;44(3):192-199.
  10. Cohen SP, Bicket MC, Jamison D, Wilkinson I, Rathmell JP. Epidural steroids: A comprehensive, evidence-based review. Reg Anesth Pain Med. 2013;38(3):175-200.
  11. Colhado O, Moura‐Siqueira H, Faleiros Sousa F, et al. Evaluation of low back pain: Comparative study between psychophysical methods. Pain Medicine. 2013;14(9):1307-1315.
  12. Datta S, Manchikanti L, Falco FJ, Calodney AK, Atluri S, Benyamin RM, Buenaventura RM, Cohen SP. Diagnostic utility of selective nerve root blocks in the diagnosis of lumbosacral radicular pain: Systematic review and update of current evidence. Pain Physician. 2013;16(2 Suppl):SE97-124.
  13. Friedman JH, Dighe G. Systematic review of caudal epidural injections in the management of chronic back pain. RI Med J. 2013;96(1):12-6.
  14. Hoffman BM, Papas RK, Chatkoff DK, Kerns RD. Meta-analysis of psychological interventions for chronic low back pain. Health Psychology. 2007;26(1):1-9.
  15. Homola S. Chiropractic: History and overview of theories and methods. Clin Orthop Relat Res. 2006;444:236-42.
  16. Mounce K. Back Pain. Rheumatology. 2002;41:1-5.
  17. Smith HS, Colson J, Sehgal N. An update of evaluation of intravenous sedation on diagnostic spinal injection procedures. Pain Physician. 2013;16(2 Suppl):SE217-28.
  18. Waseem Z, Boulias C, Gordon A, Ismail F, Sheean G, Furlan AD. Botulinum toxin injections for low-back pain and sciatica. Cochrane Database Syst Rev. 2011;19(1):CD008257.
  19. Zhang T, Adatia A, Zarin W, Moitri M, Vijenthira A, Chu R, Thabane L, Kean W. The efficacy of botulinum toxin type A in managing chronic musculoskeletal pain: A systematic review and meta analysis. Inflammopharmacology. 2001;219(1):21-34.
  20. Wertli MM, Eugster R, Held U, Steurer J, Kofmehl R, Weiser S. Catastrophizing – A Prognostic Factor for Outcome in Patients with Low Back Pain – A Systematic Review. The spine journal : official journal of the North American Spine Society. Mar 6 2014. Epub ahead of print.
  21. Fishbain DA, Cole B, Lewis J, Rosomoff HL, Rosomoff RS. What percentage of chronic nonmalignant pain patients exposed to chronic opioid analgesic therapy develop abuse/addiction and/or aberrant drug-related behaviors? A structured evidence-based review. Pain medicine (Malden, Mass.). 2008;9(4):444-459.