MECHANICAL LOW BACK ACHE

MECHANICAL LOW BACK ACHE 

Mechanical low back pain (LBP) remains the second most common symptom-related reason for seeing a physician

Fortunately, the LBP resolves for the vast majority within 2-4 weeks.

For individuals younger than 45 years, mechanical LBP represents the most common cause of disability and is generally associated with a work-related injury.

For individuals older than 45 years, mechanical LBP is the third most common cause of disability, and a careful history and physical examination are vital to evaluation, treatment, and management.

PATHOPHYSIOLOGY

Causes of mechanical low back pain (LBP) generally are attributed to an acute traumatic event, but they may also include cumulative trauma as an etiology.

The severity of an acute traumatic event varies widely, from twisting one's back to being involved in a motor vehicle collision. Mechanical LBP due to cumulative trauma tends to occur more commonly in the workplace.

The pathophysiology of mechanical LBP remains complex and multifaceted.

Multiple anatomic structures and elements of the lumber spine (eg, bones, ligaments, tendons, disks, muscle) are all suspected to have a role. Many of these components of the lumber spine have sensory innervation that can generate nociceptive signals representing responses to tissue-damaging stimuli. Other causes could be neuropathic (eg, sciatica).

Most chronic LBP cases most likely involve mixed nociceptive and neuropathic etiologies.

Biomechanically, the movements of the lumbar spine consist of the cumulative motions of the vertebrae, with 80-90% of the lumbar flexion/extension occurring at the L4-L5 and L5-S1 intervertebral disks.  

The lumbar spine position most at risk for producing LBP is forward flexion (bent forward), rotation (trunk twisted), and attempting to lift a heavy object with out-stretched hands.

Axial loading of short duration is resisted by annular collagen fibers in the disk.

Axial loading of a longer duration creates pressure to the annulus fibrosis and increased pressure to the endplates. If the annulus and endplate are intact, the loading forces can be adequately resisted.

However, compressive muscular forces may combine with the loading forces to increase intradiskal pressure that exceeds the strength of the annular fibers. 

Repetitive, compressive loading of the disks in flexion (eg, lifting) puts the disks at risk for an annular tear and internal disk disruption. Likewise, torsional forces on the disks can produce shear forces that may induce annular tears. 

The contents of the annulus fibrosis (nucleus pulposus) may leak through these tears. Central fibers of the disk are pain free, so early tears may not be painful.

Samples of disk material taken at the time of autopsy reveal that the cross-linked profile of pentosidine, a component of the collagen matrix, declines. This may indicate the presence of increased matrix turnover and tissue remodeling.

In lumbar flexion, the highest strains are recorded within the interspinous and supraspinous ligaments, followed by the intracapsular ligaments and the ligamentum flavum.  

In lumbar extension, the anterior longitudinal ligament experiences the highest strain.

Lateral bending produces the highest strains in the ligaments contralateral to the direction of bending.

Rotation generates the highest strains in the capsular ligaments.

Research since the late 20th century suggests that chemical causes may play a role in the production of mechanical LBP. Components of the nucleus pulposus, most notably the enzyme phospholipase A2 (PLA2), have been identified in surgically removed herniated disk material. This PLA2 may act directly on neural tissue, or it may orchestrate a complex inflammatory response that manifests as LBP.

Glutamate, a neuroexcitatory transmitter, has been identified in degenerated disk proteoglycan and has been found to diffuse to the dorsal root ganglion (DRG) affecting glutamate receptors.

Substance P (pain) is present in afferent neurons, including the DRG, and is released in response to noxious stimuli, such as vibration and mechanical compression of the nerve. Steady, cyclic, or vibratory loading induces laxity and creep in the viscoelastic structures of the spinal elements. This creep does not recover fully in the in vivo cat model, even when rest periods are equal in duration to the loading period.

The concept of a biomechanical degenerative spiral has an appealing quality and is gaining wider acceptance. This concept postulates the breakdown of the annular fibers allows PLA2 and glutamate, and possibly other as-yet unknown compounds, to leak into the epidural space and diffuse to the DRG.

The weakened vertebra and disk segment become more susceptible to vibration and physical overload, resulting in compression of the DRG and stimulating release of substance P.

Substance P, in turn, stimulates histamine and leukotriene release, leading to an altering of nerve impulse transmission. The neurons become sensitized further to mechanical stimulation, possibly causing ischemia, which attracts polymorphonuclear cells and monocytes to areas that facilitate further disk degeneration and produce more pain.

FREQUENCY

The lifetime prevalence of mechanical low back pain (LBP) in the United States is 60-80%. The prevalence of serious mechanical LBP (persisting >2 wk) is 14%. The prevalence of true sciatica (pain radiating down one or both legs) is approximately 2%.

Of all cases of mechanical LBP, 70% are due to lumbar strain or sprain, 10% are due to age-related degenerative changes in disks and facets, 4% are due to herniated disks, 4% are due to osteoporotic compression fractures, and 3% are due to spinal stenosis. All other causes account for less than 1% of cases.

Mechanical LBP is the most common cause of work-related disability in persons younger than 45 years in the United States. 

SEX

The impact of sex on prevalence of low back pain (LBP) has not been established as well as the roles of other risk factors in LBP (eg, previous LBP, age).

A reported 50-90% of women develop symptoms of LBP in the course of pregnancy. Discomfort generally develops in the very early weeks, more commonly in the third trimester.

AGE

Age has been shown to be associated more consistently with mechanical low back pain (LBP) than with sex. The prevalence of LBP during pregnancy appears to increase 5% for every 5 years of patient age.

Sciatica (pain that radiates down one or both legs) is usually reported in persons aged 40-59 years. Women aged 60 years or older also report more low back symptoms.

CLINICAL

HISTORY

• Patients generally present with a history of an inciting event that produced immediate low back pain (LBP). The most commonly reported histories include the following:

  • Lifting and/or twisting while holding a heavy object (eg, box, child, nursing home resident, a package on a conveyor)

  • Operating a machine that vibrates

  • Prolonged sitting (eg, long-distance truck driving, police patrolling)

  • Involvement in a motor vehicle collision

  • Falls

• Commence the history by asking for the patient's age, hand dominance, and occupation. Also ask about the patient's current work status and last day he or she worked. If the back pain is the result of a work-related injury, ask the name of the employer and inquire how long the patient has worked for this particular employer. Sample questions are as follows:

  • When did the current symptoms begin and what were you doing?

  • What and where are your symptoms now? (A pain diagram is helpful for localizing the symptoms. The patient can draw on a figure and give the clinician an idea of the nature of the pain as neuropathic or nociceptive.)

  • Rate the pain on a scale of 0 (none) to 10 (worst imaginable). This is a global pain rating that takes into account physiological and psychological aspects of the LBP.

  • What makes the pain better (eg, sitting, standing, laying, medications, physical therapy)?

  • What makes the pain worse (eg, sitting, standing, laying, medications, physical therapy)?

  • What affect have these symptoms had on sleep, mood, work, activities of daily living, and/or social functioning?

• Use open-ended questions to ascertain the maximum information about the patient's history. Establishing a rapport with the patient is essential to detect serious conditions, provide insights into the patient's concerns and expectations, and to achieve the optimum positive response to treatment.

• In addition to the history of the present illness, the past medical history should be obtained to rule out infections (eg, septic arthritis), congenital abnormalities (eg, dysplasias, juvenile rheumatoid arthritis), metabolic disorders (eg, Paget disease), or previous traumatic causes (eg, athletic participation, military service).

• The review of systems is helpful for relating the current symptoms to any other body parts or systems. Interruption in bowel or bladder function should be a reminder to consider more serious causes of back pain such as a tumor, infection, or fracture. Review of systems also should include a thorough medical history (including history of cancer, arthritis, infection, systemic disease that could increase susceptibility to infection, nocturnal pain, fever, drug use, depression, and symptoms suggestive of metabolic or metastatic disease). Ask for any history of headaches, peptic ulcer disease, prior cancer, or unexplained weight loss.

• Assess for any history of previous treatments, such as the following:

  • Surgery

  • Medications: Obtain as complete a listing as possible, including reasons for discontinuation.

  • Physical therapy

  • Psychiatric or psychological therapy

• Thoroughly screen for anxiety, depression, addiction, somatoform disorders, personality disorders, other prior psychiatric diagnoses, coping styles, and personality traits. Psychosocial factors (eg, depression, hypochondriasis, heavy alcohol consumption, tobacco use, menial work, poor job satisfaction, stressors at home and/or work) may accompany histories involving a work-related injury.

• Assess the patient's vocational history. Look for consistency in the type of work and length of service with each employer since high school or college. Ask how many years the patient has been working for his or her current employer. Some cases have involved patients who have worked less than a week on a new job. Some work-related injuries are reported on a Monday or after a vacation. These are important dates for determining if the LBP was indeed work-related.

• In a work-related LBP case, ask the patient about pending or planned litigation and related expectations.

• Ask the patient what he or she thinks about the cause of the LBP.

• Ask the patient what his or her goals are for the evaluation and treatment.

• If the patient brought imaging study results (eg, plain radiographs, computed tomography [CT] scans, magnetic resonance imaging [MRI] scans), look for imaging evidence of herniated nucleus pulposus, spinal stenosis, or other conditions associated with back pain.  

PHYSICAL

An important part of the physical examination is the general observation of the patient. The patient presents with pain in the low back region and often places his or her whole hand against the skin to indicate a regional pain; however, in some cases the patient may indicate a more precise location.

Realize that much of the physical examination is subjective because a patient-generated response or interpretation to the examiner's questions or maneuvers is required.

For example, sensory findings observed during the physical examination and reported symptoms in response to provocative testing are reliant on the patient's response and, hence, represent a somewhat subjective portion of the physical examination.

A well-performed and well-documented physical examination, with consistent findings from one visit to the next, can yield important information that may be able to stand up to rigorous scrutiny by any involved third parties (eg, insurance company, attorney, workers' compensation judge). These physical examination findings would need to be put into the context of the patient's symptoms and diagnostic test results.

Equipment often used for the examination includes a stethoscope, goniometer, inclinometer, pinwheel or safety pin, tape measure, and reflex hammer.

v  Observe the patient walking into the office or examining room. Observe the patient during the history-gathering portion of the visit for development, nutrition, deformities, and attention to grooming.

v  Measure blood pressure, pulse, respirations, temperature, height, and weight.

v  Inspect the back for signs of asymmetry, lesions, scars, trauma, or previous surgery.

v  Note chest expansion. If it is less than 2.5 cm, this finding can be specific, but not sensitive, for ankylosing spondylitis.

v  Take measurements of the calf circumferences (at midcalf). Differences of less than 2 cm are considered normal variation.

v  Measure lumbar range of motion (ROM) in forward bending while standing (Schober test).

v  The neurologic examination should test 2 muscles and 1 reflex representing each lumbar root to accurately distinguish between focal neuropathy and root problems.

v  Measure leg lengths (anterior superior iliac spine to medial malleolus) if side-to-side discrepancy is suspected.

v  Using the inclinometer, measure forward, backward, and lateral bending. With the goniometer positioned in a horizontal plane over the axial skeleton (ie, over the head), measure trunk rotation.

v  Palpate the entire spine to identify vertebral tenderness that may be a nonspecific finding of fracture or other cause of low back pain (LBP). Note any asymmetry, misalignment, or step-off between vertebral bodies. Remember also to palpate the sacroiliac joints.

v  Test for manual muscle strength in both lower extremities. The Medical Research Council rating is an ordinal scale used for this purpose (0 = absent strength, 1 = trace muscle movement, 2 = poor muscle strength [less than antigravity], 3 = fair muscle strength [antigravity strength through normal arc of motion], 4 = good strength, and 5 = normal strength).

             FUNCTIONAL MUSCLE TESTING 

v  Test for sensation and reflexes using 0-2 ordinal scale for pinprick sensation (0 = no sensation, 1 = diminished sensation, and 2 = normal sensation), and 0-4 ordinal scale to rate reflexes (0 = no reflex, 1 = hyporeflexic, 2 = normal reflex, 3 = hyperreflexic, and 4 = hyperreflexic with clonus).

DERMATOMAL SENSORY AND REFLEX TESTING  

v  Clinical tests for signs of sciatic nerve tension are as follows:

·         Supine straight leg raising (SLR) test - Reproduction of pain caused by elevation of the contralateral limb raises the probability of a disk herniation to 98%. Remember that the SLR test result can be negative in persons with spinal stenosis.

·         Sitting SLR (knee extension) test (for lower roots) - The patient should sit on the table edge with both hips and knees flexed at 90° and extend the knee slowly. This maneuver stretches the nerve roots as much as a moderate degree of supine SLR. The SLR test result, if positive, reproduces symptoms of sciatica with pain that radiates below the knee.

·         The prone SLR test (also called the reverse SLR test or the femoral nerve stretch test) assesses the upper lumbar roots, a less common site of radiculopathy worth remembering.

v  Nonphysiologic testing (Waddell signs) should be performed. The presence of 3 or more positive findings out of the 5 types may be clinically significant in terms of psychosocial issues or poor surgical outcome. Isolated positive signs are of limited value.

·         Nonorganic tenderness consists of the following:

§  Superficial - Skin tenderness to light pinch over a wide area of lumbar surface

§  Non-anatomic - Deep tenderness over a wide area, often extending cephalad to the thoracic spine or caudad to the sacrum

·         Simulation tests give the patient the impression that a particular examination is being conducted, including the following:

§  Axial loading - Vertical loading over the patient's head while he or she is standing, producing LBP

§  Rotation - Back pain when the shoulders and pelvis are rotated passively in the same plane with the feet together

·         Distraction tests indicate a positive finding when the patient's attention is distracted.

§  SLR - Observing an improvement of 30-40° when the patient is distracted, compared with formal testing.

§  Flip test - The patient is seated with the legs dangling over the examination table. Instruct the patient to steady himself or herself by holding the edge of the table. When the affected leg is flipped up quickly, the patient falls back and lets go, placing both hands behind him or her on the table.

·         Regional disturbances that do not correlate with anatomy include the following:

§  Weakness - Cogwheeling (giving way) of many muscle groups upon manual muscle testing of strength

§  Sensory - Diminished light touch or pinprick sensation in a stocking pattern, rather than a dermatomal pattern, in an individual who is not diabetic

§  Nonanatomic sensory loss

·         Overreaction during the examination may be observed in several manifestations (eg, disproportionate verbalization, facial grimacing, muscle tension and tremor, collapsing, sweating). Care must be taken to account for cultural variations.

·         In addition, evaluate the patient's function. Observe ROM and flexibility, ability to dress and undress, and ability to rise from a chair or the examination table.

DIAGNOSIS

LABORATORY STUDIES

• If the history elicits reports of fever, night sweats, and chills that might suggest other causes for the low back pain, then, at a minimum, obtain a CBC count, erythrocyte sedimentation rate, and urinalysis to rule out cancer or infection. Serum and urine electrophoresis studies may help to rule out multiple myeloma at an early stage when radiographic imaging studies appear negative or inconclusive.

IMAGING STUDIES

• The association between symptoms of mechanical low back pain (LBP) and imaging results is weak. Ordering of imaging studies should be limited to patients with clinical findings suggestive of systemic disease (eg, fever, weight loss without explanation, patients older than 50 y, alcohol use, or intravenous drug abuse) or trauma.

• In the absence of any findings from the neurologic examination and no evidence of infection or cancer, imaging studies are not clinically helpful in the first 4 weeks of symptoms. The Quebec Task Force of Spinal Disorders (QTFSD) suggests that early radiographs are necessary only if the patient has neurologic deficits, fever, trauma, age older than 50 years or younger than 20 years, or signs of neoplasm. Anteroposterior and lateral views should be used on plain films unless spondylolysis is suggested, in which case oblique views are needed.

• Persistent mechanical LBP may require additional imaging studies, including CT scanning, discography, and 3-phase bone scanning. Sensitivity refers to the ability of the test or study to show that a disorder is present. Specificity refers to the ability of the test or study to rule in a specific disorder. The higher the number [0 to 1], the more sensitive or specific the test or study.

  • CT scanning has a sensitivity and specificity of 0.92 and 0.88, respectively, for a herniated disk.

  • MRI is superior to CT scanning for detection of many conditions because it presents soft tissue detail and multiple planar points of view; it should be used if infection, cancer, or persistent neurologic deficit is strongly suggested.

  • Diskography has a sensitivity and specificity of 0.83 and 0.78, respectively, for a herniated disk. This test should be interpreted in the context of data on pain reproduction.

  • A 3-phase bone scanning may be helpful if infection, metastatic cancer, or pathological fracture is suggested.

  • Thermography has no known role in the evaluation of mechanical LBP. 

OTHER TESTS

• Electrodiagnostic studies such as electromyography (EMG) and nerve conduction studies (NCS) can be very helpful in the evaluation of neurologic symptoms and/or neurologic deficits seen during the physical examination.

  • In the context of patients with low back pain (LBP) and neurologic symptoms/signs in the lower limb(s), EMG/NCS can objectively assess whether those symptoms/signs are due to lumbosacral radiculopathy versus peripheral polyneuropathy, myopathy, or peripheral nerve entrapment, among other conditions.

  • Further, EMG/NCS can often help identify which specific nerve root is involved in a given radiculopathy, which can be extremely helpful for correlation with any abnormal lumbosacral imaging study results (especially when the MRI shows multilevel abnormalities, while the nerve root compromise may be occurring in only 1 specific level). Identifying the specific nerve root involved can help ensure that any spinal injections or eventual surgery are performed at the appropriate level or site within the lumbar spine.

  • EMG/NCS is considered to have a relatively high degree of sensitivity for detecting radiculopathy, particularly with use of the needle EMG portion of the testing, when performed by an appropriately skilled physician. Further, because a patient is unable to voluntarily influence the appearance of abnormal EMG/NCS findings, the testing can be helpful in providing objective evidence of nerve pathology (or lack of evidence for such nerve pathology) in cases in which symptom magnification or malingering is suspected.

  • Many of the abnormal EMG/NCS findings take a couple of weeks to appear after an acute injury; hence, many electromyographers wait 2-4 weeks before performing the testing.

PROCEDURES

• Selective nerve root blocks and intradiskal injections are 2 diagnostic and therapeutic procedures for identifying the location of a possible pain generator. These interventions depend on the patient's self-report of pain during or after the procedure. Some clinicians videotape the patient's reaction to the injection to correlate the patient's response (subjective) with the physical response (objective).

TREATMENT

PHYSICAL THERAPY

The treatment program for mechanical low back pain (LBP) must have specific functional goals and can be outlined in the following 6 steps:

Ø  Control of pain and the inflammatory process - Pain treatment should be initiated early and efficiently to gain control. Ice, transcutaneous electrical nerve stimulation (TENS), and relative rest may help with controlling the pain and the inflammatory process. Excessive bedrest, however, may be detrimental by leading to lumbar segment motion, loss of muscle strength, and general deconditioning with blunting of motivation.

Ø  Restoration of joint ROM and soft tissue extensibility - Extension exercises may reduce neural tension. Flexion exercises reduce articular weight-bearing stress to the facet joints and stretch the dorsolumbar fascia. The use of ultrasound therapy may improve collagen extensibility.

Ø  Improvement of muscular strength and endurance - Exercise training can begin after the patient has passed successfully through the pain control phase. The key is to attain adequate musculoligamentous control of lumbar spine forces to minimize the risk of repetitive injury to the intervertebral disks, facet joints, and surrounding structures. Start with isometrics, then progress to isotonic exercises with effort directed at concentric strengthening.

Ø  Coordination retraining - Dynamic exercise in a structured training program maximizes coordinated muscle group activities that lead to postural control and the fusion of muscle control with spine stability.

Ø  Improvement of general cardiovascular condition - Patients are encouraged to remain active and to initiate brisk walking programs, aquatic activities, or use of stationary bicycles/stair steppers. These activities can increase endorphin levels, promoting a sense of well-being, and allow the patient to perform at a higher level of function before perceiving pain.

Ø  Maintenance exercise programs - A home program is developed within the tolerance and ability of the patient in order to encourage continued exercise after discharge from physical therapy.

Sertpoyraz et al compared isokinetic and standard exercise programs for chronic low back pain. Pain, mobility, disability, psychological

status, and muscle strength were measured. Forty patients were randomly assigned to a program that took place in an outpatient rehabilitation clinic. No statistically significant difference was found between the 2 programs with regard to their effect in the treatment of low back pain.

The main goal of physical therapy in persons with acute back pain is not to increase strength but to achieve adequate pain control. No benefit has been demonstrated for strengthening exercises in persons with acute back pain.

Exercise should begin with extension exercises in the prone position after lateral trunk shifts and then progress, as tolerated, to prone lying with support.Flexion exercises can be performed only if the patient has no acute dural tension.

The spine should be stabilized using strengthening of segmental muscles followed by the prime movers of the spine (ie, latissimus dorsi, abdominals, erector spinae).

Muscle groups should be strengthened in a neutral position to decrease tension on ligaments and joints; this position allows balanced segmental forces between the disks and the zygapophyseal joints and maximizes functional stability with axial loading.

Physical therapy programs should also include positioning the patient to maximize comfort.

Loosening of the hamstrings, glutei, gastrocnemius/soleus group, tensor fascia latae, quadriceps group, and hip flexors also contributes to reduction of LBP and effective conditioning.

SURGICAL INTERVENTION

Surgical interventions for mechanical low back pain (LBP) are the last choice for treatment.

Better results occur with open excisions compared with percutaneous diskectomies.

OTHER TREATMENT

Evidence-based clinical practices on selected rehabilitation interventions for low back pain (LBP) have focused on the timing of interventions.

• Acute LBP is defined as pain that does not radiate below the knees with current symptoms that have been present 4-6 weeks or less.

• Subacute LBP is defined as pain that does not radiate below the knees with current symptoms that have been present 4-12 weeks from onset.

• Chronic LBP is defined as pain that does not radiate below the knees with current symptoms that have been present greater than 12 weeks.

• The Philadelphia Panel evaluated the literature on the treatment of LBP and assigned Grades of Recommendation based on the clinical importance of the studies, statistical significance of the findings, and the study design. Randomized control trials with statistically significant findings were assigned an A grade. Any study design without clinically significant findings but thought to have been worth performing was assigned a D grade. Grades of Evidence were assigned to the various studies. The highest grades were I for randomized control trials and III for the opinions of respected authorities.

  • For LBP of less than 4 weeks duration, the Philadelphia Panel found poor evidence (grade C) to include or exclude therapeutic exercises, traction, ultrasonography, or TENS. Return to work was strongly encouraged.

  • For LBP of 4-12 weeks duration, the Philadelphia Panel found good evidence for the inclusion of therapeutic exercise and manual traction.

  • For LBP of greater than 12 weeks' duration, the Philadelphia Panel found good evidence for the inclusion of therapeutic exercises, therapeutic ultrasonography, and electromyographic biofeedback. These treatments were positive interventions for achieving adequate pain control, increasing functional activities of daily living, and promoting return to work.

• Evidence-based clinical practice guidelines from the American Pain Society (APS) for patients with chronic low back pain describe the use of interventional diagnostic tests and therapies, surgeries, and interdisciplinary rehabilitation.

  • Practice guidelines for nonradicular pain

    • Interdisciplinary rehabilitation that emphasizes cognitive-behavioral approaches should be considered for patients who fail to respond to usual interventions.

    • Provocative diskography (in which material is injected into a disk nucleus to reproduce the patient's typical pain) is not recommended.

    • Facet joint corticosteroid injection, prolotherapy (stimulation of an inflammatory response through repeated injections of irritant material), and intradiskal corticosteroid injection are not recommended.

    • Degenerative spinal changes and persistent, disabling symptoms should lead to discussion and shared decision-making regarding surgery or interdisciplinary rehabilitation. (The evidence is insufficient to weigh the risks and benefits of vertebral disk replacement in these patients.)

  • Practice guidelines for persistent radiculopathy

    • For patients with herniated disks, the use of epidural steroid injection should be discussed.

    • For patients with herniated disks and disabling leg pain from spinal stenosis, surgical options should be discussed.

    • For patients with persistent pain after surgery, the risks and benefits of spinal cord stimulation should be discussed.

MEDICATION

Pharmacological interventions for the relief of low back pain (LBP) include acetaminophen, nonsteroidal anti-inflammatory drugs (NSAIDs), topical analgesics, muscle relaxants, opioids, corticosteroids, antidepressants, and anticonvulsants.

Acetaminophen remains one of the best first-line treatments of acute LBP. It is generally well tolerated, has few adverse effects or drug reactions with other medications, and is inexpensive. Acetaminophen is as effective as aspirin; however, overdoses can result in fatal hepatic injury. The maximum advised dose is 4 g/d.

NSAIDs are the most frequently prescribed analgesic medications for mechanical LBP worldwide. A review of the Cochrane Controlled Trials Registry found 51 randomized control trials (involving 6057 patients) comparing different NSAIDs for the treatment of acute mechanical LBP.

NSAIDs were found to be effective for short-term symptomatic relief. No specific type was shown to be clearly more effective than the others. Insufficient evidence was found for effective analgesic control in chronic LBP.

NSAIDs augmented with muscle relaxants are a standard medical prescription for LBP in the primary care setting. These agents should be prescribed on a scheduled basis, rather than as needed, for optimal analgesia. Patients on combined NSAIDs and muscle relaxants report reduction of symptoms at 1 week, which is less than when compared with either drug alone. The optimum combination of NSAIDs and muscle relaxants remains to be determined.

Topically applied lidocaine patches (Lidoderm 5% patch) have provided a reduction in pain intensity and pain relief in clinical trials of patients with acute pain.

Opioid medications are mainstays for short-term treatment of severe pain. Their role in the long-term care of patients with mechanical LBP is the subject of intense investigations.

Transdermal opioid (fentanyl) has been shown to compare favorably to oral long-acting opioids. Concerns about drug diversion and abuse continue to cloud the benefits of long-term opioid use for LBP.

Corticosteroids may play a role in the treatment of mechanical LBP with acute radiculopathic features of radiating pain down one or both legs.

Antidepressants are thought to be effective when a component of depression is accompanying the mechanical LBP. Antidepressants may contribute to improving the disruption in sleep that patients frequently mention as a part of the constellation of symptoms resulting from LBP.

The basic mechanism of anticonvulsants is to stabilize neural membranes. This concept has been used to support the use of anticonvulsants for adjunct analgesia suspected to come from neuropathic causes.

Botulinum toxin type A has been investigated for pain relief in several small studies. The toxin temporarily paralyzes the lumbar muscles, which may be creating spasms that contribute to the generation of LBP.

Clinicians have found that long-acting oral opioids can be rotated periodically (eg q6-12mo) to maintain effectiveness. The molecular structures of these compounds may be sufficiently different to opioid receptors to counter the affects of diminished and down-regulation of receptors to chronic opioid exposure.

Pharmaceutical companies are exploring various combinations of NSAIDs/opioids, extended-release formulations, and drug delivery (eg topical, mucosal) in an effort to achieve safe and effective pain control.

ANALGESIC AGENTS

Pain control is essential to quality patient care. Analgesics ensure patient comfort, promote pulmonary toilet, and have sedating properties, which are beneficial for patients who have sustained trauma or have sustained injuries.

ACETAMINOPHEN (Tylenol, Feverall, Tempra)

DOC for pain in patients with documented hypersensitivity to aspirin or NSAIDs, with upper GI disease, or who are taking oral anticoagulants.

Adult: 500-1000 mg PO q4-6h

Pediatric: <12 years: 10-15 mg/kg/dose PO q4-6h prn; not to exceed 2.6 g/d

>12 years: 325-650 mg PO q4h; not to exceed 5 doses in 24 h

Pregnancy

B - Fetal risk not confirmed in studies in humans but has been shown in some studies in animals

Precautions

Hepatotoxicity possible in chronic alcoholism following various dose levels; severe or recurrent pain or high or continued fever may indicate a serious illness; acetaminophen is contained in many OTC products and combined use with these products may result in cumulative doses exceeding recommended maximum dose

NONSTEROIDAL ANTI-INFLAMMATORY DRUGS

Have analgesic, anti-inflammatory, and antipyretic activities.

Mechanism of action is not known, but they may inhibit COX activity and prostaglandin synthesis. Other mechanisms may also exist, such as inhibition of leukotriene synthesis, lysosomal enzyme release, lipoxygenase activity, neutrophil aggregation, and various cell-membrane functions.

ASPIRIN (Anacin, Ascriptin)

Effective in most mechanical LBP cases. Irreversibly inhibits platelet function, leading to prolonged bleeding times.

Adult: 500-1000 mg PO q4-6h

Pregnancy

C - Fetal risk revealed in studies in animals but not established or not studied in humans; may use if benefits outweigh risk to fetus

D - Fetal risk shown in humans; use only if benefits outweigh risk to fetus

Precautions

May cause transient decrease in renal function and aggravate chronic kidney disease; avoid use in patients with severe anemia or history of blood coagulation defects or who are taking anticoagulants

NAPROSYN (Naproxen, Naprelan, Naprosyn)

For relief of mild to moderate pain; inhibits inflammatory reactions and pain by decreasing activity of COX, which results in a decrease of prostaglandin synthesis.

Adult: 500 mg PO initially

250 mg PO q6-8h or 500 mg PO q12h

Pregnancy

C - Fetal risk revealed in studies in animals but not established or not studied in humans; may use if benefits outweigh risk to fetus

D - Fetal risk shown in humans; use only if benefits outweigh risk to fetus

Precautions

Acute renal insufficiency, interstitial nephritis, hyperkalemia, hyponatremia, and renal papillary necrosis may occur; patients with preexisting renal disease or compromised renal perfusion risk acute renal failure; leukopenia occurs rarely, is transient, and usually returns to normal during therapy; persistent leukopenia, granulocytopenia, or thrombocytopenia warrants further evaluation and may require discontinuation of drug

CYCLOOXYGENASE II INHIBITORS

Although increased cost can be a negative factor, the incidence of costly and potentially fatal GI bleeding is clearly less with COX-2 inhibitors than with traditional NSAIDs. Ongoing analysis of cost avoidance of GI bleeds will further define the populations that will find COX-2 inhibitors the most beneficial.

CELECOXIB (Celebrex)

Inhibits primarily COX-2. COX-2 is considered an inducible isoenzyme, induced during pain and inflammatory stimuli. Inhibition of COX-1 may contribute to NSAID GI toxicity. At therapeutic concentrations, COX-1 isoenzyme is not inhibited, thus GI toxicity may be decreased. Seek lowest dose of celecoxib for each patient.

Adult: 100-200 mg PO q12h

Pregnancy

C - Fetal risk revealed in studies in animals but not established or not studied in humans; may use if benefits outweigh risk to fetus

D - Fetal risk shown in humans; use only if benefits outweigh risk to fetus

Precautions

May cause fluid retention and peripheral edema; caution in compromised cardiac function, hypertension, conditions predisposing to fluid retention, severe heart failure, and hyponatremia because may deteriorate circulatory hemodynamics; NSAIDs may mask usual signs of infection; caution in presence of existing controlled infections; evaluate symptoms and signs suggesting liver dysfunction, or in abnormal liver laboratory results

MUSCLE RELAXANTS

Mechanism of action is not fully understood.

CYCLOBENZAPRINE (Flexeril)

Skeletal muscle relaxant that acts centrally and reduces motor activity of tonic somatic origins, influencing alpha and gamma motor neurons.

Structurally related to TCAs and thus carries some of their same liabilities. Given in combination with an NSAID (similar to carisoprodol).

Adult: 10 mg PO tid

Pregnancy

C - Fetal risk revealed in studies in animals but not established or not studied in humans; may use if benefits outweigh risk to fetus

Precautions

Caution in angle-closure glaucoma and urinary hesitance; warn patients not to operate machinery while taking this medication

ORPHENADRINE (Norflex)

While exact mode of action not well understood, has shown clinical effectiveness in muscular injury. Effectiveness may be related to analgesic properties. May have atropinelike effects and analgesic properties.

Adult: 100 mg PO bid

60 mg IV/IM q12h

Pregnancy

C - Fetal risk revealed in studies in animals but not established or not studied in humans; may use if benefits outweigh risk to fetus

Precautions

Caution in cardiac arrhythmias and congestive heart failure

CARISOPRODOL (Soma)

Short-acting medication that may have depressant effects at spinal cord level. Often given in combination with an NSAID.

Adult: 350 mg PO qid

Pregnancy

C - Fetal risk revealed in studies in animals but not established or not studied in humans; may use if benefits outweigh risk to fetus

Precautions

Caution in renal and hepatic impairment

OPIOIDS

Useful only for extremely severe pain. Can be administered by injection.

OXYCODONE (OxyContin)

Indicated for relief of moderate to severe pain.

Adult: 5-10 mg PO q4-6h.