Elastoviscous substances with analgesic effects on joint pain reduce stretch-activated ion channel activity in vitro

Activation by noxious mechanical stimuli of sensory nerve fibres that signal joint pain takes place through stretch-activated ion channels, which open in response to increased membrane tension. It has been suggested that the analgesic effect of hyaluronan solutions used for intra-articular treatment of joint pain in humans are mediated by a reduction of the sensitivity of mechanosensory ion channels of nociceptive nerve terminals. We have investigated whether cross-linked hyaluronan solutions (hylans) of different elastoviscosities modify the response characteristics of stretch-activated ion channels of Xenopus laevis oocytes. Patch-clamp recordings on intact oocytes and in excised membrane patches (outside-out and inside-out configurations) were performed in Barth's solution (control condition) and after exposure to hylans of different elastoviscosities. For mechanical stimulation, monitored suction was applied through the microelectrode and the activity of stretch-activated channels was recorded. The activity of stretch-activated channels was significantly reduced in the presence of high elastoviscous hylan A (0.8% polymer content, molecular weight 6M) and of a mixture of hylan A (90% by weight) and hylan B (10% by weight), 0.9% total polymer content, a clinically used hylan product. In contrast, solutions of hylan A with the same chemical composition but reduced elastoviscosity (0.8% polymer content, molecular weight 96000) were found ineffective. It is concluded that stretch-activated channels have a decreased mechanical sensitivity in the presence of elastoviscous solutions of hylan, but not in the presence of non-elastoviscous solutions of hylan of the same concentration. These data suggest that the analgesic effects of intra-articular injections of elastoviscous solutions of hylans are due to a reduction of the sensitivity to mechanical forces of stretch-activated channels present in the membrane of joint mechanonociceptors.     

<Emphasis Type="Italic">Acid-Sensing Ion Channels</Emphasis> : des canaux ioniques sensibles au pH et aux lipides dans la douleur

Acid-Sensing Ion Channels (ASICs) are excitatory cationic channels expressed all along the pain neuraxis. They mainly carry Na⁺ ions and generate depolarizing currents in neurons following acidification of the extracellular medium. Different ASIC subunits (ASIC1-4) have been identified in mammals, and a functional channel is formed by the association of three of these subunits, leading to homomeric and heteromeric channels. An increasing number of data obtained by combining pharmacological and genetic tools strongly argues for an involvement of ASICs in pain. From a general point of view, pharmacological inhibition of ASICs, at different levels of the nervous system, produces strong analgesic effects in different animal models of pain, whereas injections of compounds able to activate ASICs generate pain behaviors. ASIC1 and ASIC3 participate in nociception and peripheral sensitization of primary sensory neurons, where ASIC3, which is also activated by lipids, seems to play a major role in inflammatory pain, pruritis and pain arising from deep tissues such as muscle and joint. In the central nervous system, ASIC channels made of ASIC1a and ASIC2 subunits are predominant, and their inhibition at spinal and supra-spinal levels induces powerful analgesia in inflammatory and neuropathic pain models. Together, the data summarized in this review illustrate the therapeutical potential of ASIC channels for pain control.     

Developing an integrated care pathway to manage cancer pain across primary,secondary and tertiary care

Throughout the palliative care journey, the patient encounters many different health professionals in a variety of settings so good channels of communication between these professionals is a prerequisite for successful continuity of care (Scottish Partnership Agency for Palliative and Cancer Care (SPA), 1994). Pain control has also long been documented as being ineffective and it has been indicated that pain affects up to 88% of cancer patients in the last year of their life (Addington-Hall and McCarthy, 1995). In order to attempt to resolve these important issues, a joint project was established between primary, secondary and tertiary care in the south sector of Glasgow to establish an integrated care pathway (ICP) for the management of chronic cancer pain. This article discusses how the joint project was successfully established, was instrumental in breaking down existing barriers across the traditional boundaries and developed a uniform system of assessing and managing chronic cancer pain with ICP documentation held in a patient-held record.     

TRPV4 is necessary for trigeminal irritant pain and functions as a cellular formalin receptor

Detection of external irritants by head nociceptor neurons has deep evolutionary roots. Irritant-induced aversive behavior is a popular pain model in laboratory animals. It is used widely in the formalin model, where formaldehyde is injected into the rodent paw, eliciting quantifiable nocifensive behavior that has a direct, tissue-injury-evoked phase, and a subsequent tonic phase caused by neural maladaptation. The formalin model has elucidated many antipain compounds and pain-modulating signaling pathways. We have adopted this model to trigeminally innervated territories in mice. In addition, we examined the involvement of TRPV4 channels in formalin-evoked trigeminal pain behavior because TRPV4 is abundantly expressed in trigeminal ganglion (TG) sensory neurons, and because we have recently defined TRPV4’s role in response to airborne irritants and in a model for temporomandibular joint pain. We found TRPV4 to be important for trigeminal nocifensive behavior evoked by formalin whisker pad injections. This conclusion is supported by studies with Trpv4^−/− mice and TRPV4-specific antagonists. Our results imply TRPV4 in MEK-ERK activation in TG sensory neurons. Furthermore, cellular studies in primary TG neurons and in heterologous TRPV4-expressing cells suggest that TRPV4 can be activated directly by formalin to gate Ca²⁺. Using TRPA1-blocker and Trpa1^−/− mice, we found that both TRP channels co-contribute to the formalin trigeminal pain response. These results imply TRPV4 as an important signaling molecule in irritation-evoked trigeminal pain. TRPV4-antagonistic therapies can therefore be envisioned as novel analgesics, possibly for specific targeting of trigeminal pain disorders, such as migraine, headaches, temporomandibular joint, facial, and dental pain, and irritation of trigeminally innervated surface epithelia.     

Changes in the expression of NaV1.7, NaV1.8 and NaV1.9 in a distinct population of dorsal root ganglia innervating the rat knee joint in a model of chronic inflammatory joint pain

Voltage‐gated sodium channels play an essential role in regulating the excitability of nociceptive primary afferent neurones. In particular the tetrodotoxin‐sensitive (TTX‐S) Na_V1.7 and the tetrodotoxin‐resistant (TTX‐R) Na_V1.8 and Na_V1.9 channels have been suggested to play a role in inflammatory pain. Previous work has revealed acute administration of inflammatory mediators, such as Freund's complete adjuvant (FCA) or carrageenan caused an upregulation in the levels of Na_V1.7 and Na_V1.8 protein in DRG (dorsal root ganglia) tissue up to 4 days post‐insult. In the present study, the expression of Na_V1.7, Na_V1.8 and Na_V1.9 was examined over a 28 day timecourse during a rat model of FCA‐induced chronic inflammatory joint pain. Using the retrograde tracer Fast Blue (FB) and specific Na_V1.7, Na_V1.8 and Na_V1.9 sodium channel antibodies, immunohistochemical staining techniques were used to study sodium channel expression in a distinct population of L3–L5 knee joint afferent DRGs. In the ganglia, counts were made of positively labelled cells in the FB population. The results demonstrate that, following FCA injection, Na_V1.9 expression is upregulated at days 14, 21 and 28 post‐FCA, with Na_V1.7 and Na_V1.8 showing increased channel expression at days 14 and 28. These observations are accompanied by a unilateral joint hypersensitivity in the FCA‐injected knee indicated by a behavioural shift in weight distribution measured using an incapacitance tester. The increased presence of these channels suggests that Na_V1.7, Na_V1.8 and Na_V1.9 play a role, at least in part, in the maintenance of chronic inflammatory pain several weeks after the initial insult.     

Anastrozole-Associated Joint Pain and Other Symptoms in Patients With Breast Cancer

More than a third of breast cancer patients undergoing aromatase inhibitor (AI) treatment report joint pain. We conducted a longitudinal study to characterize the course of AI-induced joint pain and other symptoms and to identify potential predictors for developing these symptoms. Patients were recruited before AI initiation. The Brief Pain Inventory, M. D. Anderson Symptom Inventory, and a joint-pain questionnaire were administered at baseline and then biweekly for 1 year. Analysis included logistic regression, Cox models, and mixed-effects models. Of 47 patients assessed, 16 (34%) reported joint pain at least once. Median time to first report of joint pain was 7 weeks (range, 1–38). Baseline pain was the only predictor for both incidence of joint pain and time to first event. In the first 6 weeks, emergence of joint pain was associated with increase in general pain, fatigue, disturbed sleep, hot flashes, vaginal dryness, and decreased sexual activity. After week 6, having joint pain was associated with increase in general pain and with persistently high fatigue. Having AI-associated joint pain correlated with increase in or persistence of other symptoms likely related to AI therapy. Further research is needed to validate predictors of AI-associated symptoms.PerspectiveWe demonstrate for the first time that AI-induced joint pain associates with development of other symptoms and that pretreatment pain level is a potential, measurable predictor of symptom development during treatment. Because baseline pain is easily assessed with a brief questionnaire, it can be applied clinically with minimal patient burden.     

Evaluation and management of joint pain

The purpose of this article was to provide a review for orthopaedic nurses and nurse practitioners who evaluate, manage, and care for patients with joint pain. Joint pain is a common complaint evaluated by primary care providers. The causation of joint pain is complicated to identify because of an extensive range of differential diagnosis. The history and physical examination are crucial components in evaluating and managing joint pain. The primary care provider uses clinical factors such as patient demographics, presence of inflammation, acute/chronic duration, extra-articular manifestations, pattern of joint involvement, and disease chronology. Many rheumatologic laboratory tests are nonspecific, but aspiration of the joint with synovial fluid analysis may provide diagnostic clues, especially to differentiate infection versus inflammation. Primary care providers utilize both pharmacologic and nonpharmacologic regimens to manage acute and chronic joint pain.     

Pharmacology of modality-specific transient receptor potential vanilloid-1 antagonists that do not alter body temperature

The transient receptor potential vanilloid-1 (TRPV1) channel is involved in the development and maintenance of pain and participates in the regulation of temperature. The channel is activated by diverse agents, including capsaicin, noxious heat (≥ 43°C), acidic pH (< 6), and endogenous lipids including N-arachidonoyl dopamine (NADA). Antagonists that block all modes of TRPV1 activation elicit hyperthermia. To identify efficacious TRPV1 antagonists that do not affect temperature antagonists representing multiple TRPV1 pharmacophores were evaluated at recombinant rat and human TRPV1 channels with Ca(2+) flux assays, and two classes of antagonists were identified based on their differential ability to inhibit acid activation. Although both classes of antagonists completely blocked capsaicin- and NADA-induced activation of TRPV1, select compounds only partially inhibited activation of the channel by protons. Electrophysiology and calcitonin gene-related peptide release studies confirmed the differential pharmacology of these antagonists at native TRPV1 channels in the rat. Comparison of the in vitro pharmacological properties of these TRPV1 antagonists with their in vivo effects on core body temperature confirms and expands earlier observations that acid-sparing TRPV1 antagonists do not significantly increase core body temperature. Although both classes of compounds elicit equivalent analgesia in a rat model of knee joint pain, the acid-sparing antagonist tested is not effective in a mouse model of bone cancer pain.     

Investigation into the neural correlates of emotional augmentation of clinical pain

Although depressive mood is an important psychological determinate of chronic pain, the neural circuitry that mediates its influence on the pain experience is largely unknown. We used functional magnetic resonance imaging (FMRI) to investigate the neurophysiological interactions between depressive symptoms and disease-relevant pain in rheumatoid arthritis (RA) patients. RA is associated with chronic joint pain and swelling, but peripheral joint pathology often does not fully explain the amount of pain a patient experiences. We investigated the neural circuitry that relates joint pain and depressive symptoms and contrasted this with experimental heat pain. We hypothesized that (1) depressive symptoms influence the cerebral processing of provoked joint pain in RA, and (2) the interaction of depressive symptoms with pain processing contributes to the pain RA patients experience on a daily basis. Twenty patients underwent whole brain FMRI during which disease-relevant joint pain was provoked. Depressive symptoms were assessed using the Beck Depression Inventory (BDI). The tender-to-swollen joint ratio (T/S) was assessed as one component of the patients' clinical pain. BDI scores correlated significantly with T/S and medial prefrontal cortex (MPFC) activation during provoked joint pain. The association between BDI scores and T/S was partly mediated by the MPFC activation. Furthermore, the MPFC activation co-varied significantly with the FMRI signal in limbic areas and in areas that process self-relevant information. These results suggest that the MPFC may play an important role in mediating the relationship between depressive symptoms and clinical pain severity in RA, possibly by engaging brain areas important for affective and self-relevant processing.     

The Prevalence of Facet Joint-Related Chronic Neck Pain in Postsurgical and Nonpostsurgical Patients: A Comparative Evaluation

Background: Facet (zygapophysial) joints may be clinically important sources of chronic cervical spinal pain. Previous studies have demonstrated the value and validity of controlled, comparative local anesthetic blocks in the diagnosis of facet joint pain, and reported an overall prevalence of 36% to 67% facet joint involvement in cervical spinal pain. The reports of lumbar facet joint‐involvement in postsurgery syndrome have been shown to be highly variable with prevalence ranging from 8% to 32%. To date, however, the prevalence of postsurgical facet joint‐related pain in the cervical spine has not been evaluated. In light of this, the present retrospective study was conducted to assess and compare the prevalence of chronic postsurgical facet joint cervical spinal pain to nonsurgical, chronic cervical facet joint pain. Methods: Patients presenting with chronic neck pain were studied. The procedures were performed by a single physician in an interventional pain management ambulatory surgery center. The prevalence of cervical facet joint pain in postsurgical patients was assessed and compared to nonsurgical patients. Results: A total of 251 patients (45 postsurgery vs. 206 nonsurgical patients) with chronic persistent neck pain were evaluated using controlled, comparative local anesthetic blocks in accordance with IASP criteria. The prevalence of the cervical facet joint pain and false‐positive rate of single blocks in postsurgical patients were 36% and 50% compared with 39% and 43% in nonsurgical patients. Conclusions: Cervical facet joints are clinically important pain generators in a significant proportion of patients with chronic persistent neck pain after surgical intervention(s). The prevalence of cervical facet joint pain was similar in both postsurgical and nonsurgical patients. ?     

Rôle des canaux calciques de type T dans les douleurs neuropathiques

Pain is a quite frequent complaint accompanying numerous pathologies. Among these pathological cases, numerous neuropathies are retrieved with identified etiologies (chemotherapies, diabetes, surgeries…) and also more diffuse syndromes such as fibromyalgia. More broadly, pain is one of the first consequences of the majority of inherited diseases. Despite its importance for the quality of life, current pain management is limited to drugs that are either old, or with a limited efficacy or that possess a bad benefit/risk ratio. As no new pharmacological concept has led to new analgesics in the last decades, the discovery of new medications is needed, and to this aim the identification of new druggable targets in pain transmission is a first step. Therefore studies of ion channels in pain pathways are extremely active. This is particularly true with ion channels in peripheral sensory neurons in Dorsal Root Ganglia (DRG) known now to express unique sets of these channels. Moreover, both spinal and supra spinal levels are clearly important in pain modulation. Among these ion channels, we and others revealed the important role of low voltage-gated calcium channels in cellular excitability in different steps of the pain pathways. These channels, by being activated nearby resting membrane potential, have biophysical characteristics suited to facilitate action potential generation and rhythmicity. In this review we will present the current knowledge on the role of these channels in the perception and modulation of pain.     

基于膝关节生物力学的膝关节慢性疼痛矫形器研究现状

下肢生物力学因素的改变可导致膝关节内外侧负荷分配的改变,使膝关节一侧的应力增加,是导致膝关节慢性疼痛的主要因素,纠正膝关节异常生物力学已经成为了改善膝关节慢性疼痛的研究热点.本文就引起膝关节疼痛的膝关节生物力学参数及其测量、矫形器对膝关节生物力学的影响进行综述.     

A possible cervical cause of low back pain: pelvic distortion

Objective: to discuss the diagnosis and treatment of pelvic distortion related to cervical spine dysfunction in a patient with low back pain, as well as presenting a theoretical etiology.Clinical features: pelvic distortion is a disorder in which the ilia become counter-rotated on the sacrum. Our clinical experience suggests that it can arise from dysfunction in the cervical spine. It can produce low back pain, as occurred in the presented case. The sacroiliac (SI) joint is often determined to be the primary pain generator, although there may or may not be joint dysfunction detected in this joint. In the presented case the primary pain generator was initially felt to be the T12–L1 joint, as well as trigger points in the iliocostalis muscle. When the pain returned, and normal findings were noted in these structures, the patient was examined for the presence of pelvic distortion. This was found, as was painful joint dysfunction in the cervical spine. It was suspected that the pelvic distortion may have occurred secondary to cervical joint dysfunction.Intervention and outcome: treatment that was limited to manipulative therapy to the cervical spine successfully relieved the low back pain in this case.Conclusion: pelvic distortion secondary to cervical joint dysfunction may be a common cause of low back pain. Further research is needed to identify the prevalence, etiology, mechanism and ideal treatment of pelvic distortion.     

Multiple joint pain and lower extremity disability in middle and old age

Purpose.?To determine whether the extent of multiple-site lower extremity joint pain contributes to disability in middle and old age and describe patterns of severity in site-specific measures amongst those with multiple-site pain.

Method.?Population-based, cross-sectional postal survey. Adults aged 50 years and over registered with three general practices and reporting pain lasting one month or longer in the previous year in at least one hip, knee, or foot were included. Respondents completed a generic measure of physical function and site-specific measures of severity for each relevant joint pain.

Results.?Of 2429 eligible participants, 1801 reported multiple-site lower limb joint pain. Lower limb joint pain count was independently associated with reduced physical function after adjusting for a range of covariates. The severity of pain and disability attributed to each site increased as the number of painful sites increased.

Conclusion.?Many older people with joint pain in the lower limb have more than one joint affected. Generic and site-specific measures of disability both show the same pattern of reduced physical function. Treatment targeted at a single joint may have only a marginal effect on reducing disability in individuals with multiple joint involvement unless treatment is also conferring benefit at other sites.     

Multiple joint pain and lower extremity disability in middle and old age

Purpose. To determine whether the extent of multiple-site lower extremity joint pain contributes to disability in middle and old age and describe patterns of severity in site-specific measures amongst those with multiple-site pain.

Method. Population-based, cross-sectional postal survey. Adults aged 50 years and over registered with three general practices and reporting pain lasting one month or longer in the previous year in at least one hip, knee, or foot were included. Respondents completed a generic measure of physical function and site-specific measures of severity for each relevant joint pain.

Results. Of 2429 eligible participants, 1801 reported multiple-site lower limb joint pain. Lower limb joint pain count was independently associated with reduced physical function after adjusting for a range of covariates. The severity of pain and disability attributed to each site increased as the number of painful sites increased.

Conclusion. Many older people with joint pain in the lower limb have more than one joint affected. Generic and site-specific measures of disability both show the same pattern of reduced physical function. Treatment targeted at a single joint may have only a marginal effect on reducing disability in individuals with multiple joint involvement unless treatment is also conferring benefit at other sites.     

Audit of conservative management of chronic low back pain in a secondary care setting--part I: facet joint and sacroiliac joint interventions

The work of a chronic back pain service in secondary care in the West Midlands is reported. The service offers acupuncture, spinal injection procedures, osteopathy and a range of other interventions for patients whose back pain has not responded to conservative management. This section of the report focuses on injection procedures for lumbar facet joint and sacroiliac joint pain, which have been shown to be the cause of chronic low back pain in 16-40% and 13-19% of patients respectively. Diagnosis relies on the use of intra-articular or sensory nerve block injections with local anaesthetic. Possible treatments following diagnosis include intra-articular corticosteroid, radiofrequency denervation (for facet joint pain) or ligament prolotherapy injections (for sacroiliac joint pain). The results of several hospital audits are reported. At six month follow up, 50% of 38 patients undergoing radiofrequency denervation following diagnostic blocks for facet joint pain had improved by more than 50%, compared to 29% of 34 patients treated with intra-articular corticosteroid injection. Sixty three per cent of 19 patients undergoing prolotherapy following diagnostic block injection for sacroiliac joint pain had improved at six months, compared to 33% of 33 who had intra-articular corticosteroid. Both radiofrequency denervation and sacroiliac prolotherapy showed good long-term outcomes at one year.     

Voltage-gated sodium channels and the molecular pathogenesis of pain: a review

Pain pathways begin with spinal sensory (dorsal root ganglion, DRG) neurons that produce nociceptive signals and convey them centrally. Following injury to the nervous system, DRG neurons can become hyperexcitable, generating spontaneous action potentials or abnormal high-frequency activity that contributes to chronic pain. Because the generation of action potentials in DRG neurons depends on voltage-gated sodium channels, an understanding of the expression and function of these channels in DRG neurons is important for an understanding of pain. Molecular studies have indicated that at least eight distinct voltage-gated sodium channels, sharing a common overall motif but encoded by different genes that endow them with different amino acid sequences, are present within the nervous system. The DRG neurons express six different sodium channels, including several sensory-neuron-specific sodium channels that are not present at significant levels within other parts of the nervous system. Following injury to their axons within peripheral nerve, DRG neurons down-regulate some sodium channel genes, and up-regulate others. As a result, a different repertoire of sodium channels is inserted into the DRG neuron cell membrane following injury, which is a molecular change that is accompanied by changes in physiological properties that contribute to hyperexcitability in these cells. Sodium channel expression is also altered in experimental models of inflammatory pain. The multiplicity of sodium channels, and the dynamic nature of their expression, makes them important targets for pharmacologic manipulation in the search for new therapies for pain.     

The treatment of the sacroiliac joint component to low back pain: a case report.

This case report describes the treatment of a patient who had symptoms and signs suggestive of a sacroiliac joint component of low back pain. The patient developed right-sided low back pain without provocation. He appeared to have sacroiliac joint dysfunction, excessive right hip lateral rotation, and limited right hip medial rotation. The patient's habit of crossing his right leg over his left leg while sitting was believed to have contributed to the excessive lateral hip rotation. After treating the sacroiliac joint and restoring symmetrical hip rotation, the patient no longer complained of low back pain. This case report suggests that asymmetrical hip rotation may contribute to what is often called a sacroiliac joint component of low back pain.     

Pulsed Radiofrequency Treatment of Articular Branches of the Obturator and Femoral Nerves for Management of Hip Joint Pain

▪ Abstract:   Groin and thigh pain are frequently the major symptoms of hip joint pathology. The hip joint is innervated by articular branches of the obturator, femoral, superior gluteal, and sciatic nerves. The nerve responsible for hip joint pain can be determined by a diagnostic nerve block. Radiofrequency ablation of the identified articular branches of the hip was demonstrated to provide relief of hip pain. However, continuous radiofrequency denervation by thermal coagulation carries the potential risk of neuritis. We report on two patients with groin and thigh pain related to hip joint pathology treated with a novel technique for hip pain relief, pulsed radiofrequency treatment (PRF) of articular branches of the obturator and femoral nerves. At the time this case was written, both patients demonstrated at least 50% pain relief 3 to 4 months after the intervention along with improved function (increased ambulation and ability to participate in physical therapy). Our clinical observation suggests that PRF of articular branches of the hip joint may be an alternative treatment for patients with intractable hip pain. ▪     

Are Diagnostic Lumbar Facet Injections Influenced by Pain of Muscular Origin?

Introduction: Nonradicular low back pain can be a difficult entity to accurately diagnose and treat. Facet joints, muscle, ligaments, and fascia have all been reported to be etiologies of acute and chronic low back pain. However, the facet joint as a source of low back pain is controversial. The diagnosis of facet joint pain is made by diagnostic facet joint or median nerve branch injections with a local anesthetic. The purpose of this study was to determine if the results of diagnostic facet joint injections are influenced by the technique used to perform these injections. Methods: Seventy‐five male patients aged 45 years or younger and 18 years or older who were injured while performing heavy work with nonradicular low back pain were included in this study. Diagnostic injection therapy was performed following Institutional Review Board approval and the patient's informed consent. Patients were assigned to one of five groups to receive diagnostic injections in a double‐blinded fashion as follows: Group I: facet joint injection with continuous lidocaine administration from the skin to the facet joint as the needle was advanced; Group II: facet joint injection with saline administration from the skin to the facet joint as the needle was advanced; Group III: median nerve branch injection with a lidocaine advancing needle technique; Group IV: median nerve branch injection with saline advancing needle technique; and Group V: injection of the paraspinous muscles with local anesthetic and steroid following noted areas of pain diagnosed with saline injection and radiopaque contrast. After one week, the patients in Groups I to IV who had no pain relief with facet joint or median nerve block injections subsequently received paraspinous muscle injections, while the patients in Group V who had no long‐term relief with muscle injections were given facet joint injections. The appropriate parametric and nonparametric tests were performed with statistical significance defined as P ≤ 0.05. Results: There were no differences among the groups demographically. The incidence of pain relief was significantly higher in subjects who had a continuous injection of local anesthetic into their musculature than in those individuals who received continuous saline followed by an injection of local anesthetic into their facet joint or median nerve branch. Discussion: The results of this study demonstrated that local anesthetic injections are useful for the diagnosis of nonradicular low back pain but may yield false positive results with respect to lumbar facet pain depending upon the technique utilized.