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14 Articles in Volume 19, Issue #5
Agonism and Antagonism of the Muscles of the Shoulder Joint: An SEMG Approach
Analgesics of the Future: The Potential of IV Formulations for Post-Op Treatment of Pain
Blood Biomarkers Show Promise for Precision Pain Management
Can I Call Myself a “Pain Specialist?”
Cases in Urine Drug Monitoring Interpretation: How to Stay in Control (Part 2)
Fear-Avoidance and Chronic Pain: Helping Patients Stuck in the Mouse Trap
How to Avoid Patient Alienation When Discussing Stress
Managing Phantom Limb Pain with Medication
Nerve Blocks Lead to Improved Quality of Life
Sacroiliac Joint Dysfunction: New Methods in Evaluation and Management
SCS Therapy in a Patient with Advanced Bilateral Kienbocks
Thoracic Epidural Abscess with Cord Compression Following a High-Frequency SCS Trial
What is the evidence to support clonidine as an adjuvant analgesic?
What’s In A Name? In This Case, That Which We Call Addiction Is Not Dependence

Nerve Blocks Lead to Improved Quality of Life

A population cross-sectional study in a community pain practice.
Pages 31-36,45

It is well known that chronic pain affects physical, sensory/perceptual, cognitive, emotional, and social levels, all of which make improvement in a patient's quality of life (QoL) – often described as pain reduction and increased functionality1 – a key goal in pain management. To accomplish this goal, however, clinicians face multiple challenges, including:

  • How to treat the pain without adversely affecting the patient’s life or ability to work
  • How to quantify the efficacy of a drug or treatment other than subjectively
  • How to help all those with chronic pain when each patient’s pain is experienced differently.

The scope of this paper will examine these questions from the perspective of interventional pain medicine, using nerve blocks as an example of improving chronic pain. An observational research approach is utilized.

Current Gaps in Research and Therapies

RCTs

There is a lack of high-quality evidence for the impact on areas such as QoL enhancement with randomized controlled trials (RCTs) or supporting meta-analyses.2 This gap may be due, in part, to a general lack of resources being dedicated to pain research and drug development.3 Benson and Hartz outlined several advantages of observational studies over RCTs, including lower costs, greater timeliness, and a broader range of patients.4 They also argued that, in most cases, estimates of treatment effects from observational studies and RCTs were similar. Concato, et al, came to a similar conclusion after evaluating various types of clinical research, noticing that observational studies had not only remarkably similar results to those of RCTs, but that well-designed observational studies did not overestimate the magnitude of the effects of treatment as compared to RCTs on the same topic.5 Bogduk further noted that well designed, properly conducted observational studies may offer a reasonable alternative to RCTs in studying the efficacy of interventional pain medicine procedures.6

The authors believe that evidence-based pain medicine, therefore, needs to move beyond RCTs and to utilize other forms of verification acceptable under the evidence-based rubric (ie, observational studies or single case reports)7 to frame necessary questions and future research.

In the study, 94% of patients considered nerve blocks to be "effective." (Source: 123RF)

Minor Interventional Therapies

A multimodal approach to managing chronic pain is considered to be the optimal approach. Modes of therapy may include pharmacotherapy, interventional therapies (eg, anesthetic nerve blocks, spinal cord stimulation), complementary therapies (eg, massage/supplemental therapy), lifestyle modifications (eg, weight loss, diet), physical medicine and rehabilitation (eg, exercise, physical/occupational therapy, assistive devices), and psychological therapy (eg, psychotherapy, mindfulness). With recent research showing a lack of pain reduction from basic alternative therapies (such as cognitive behavioral therapy, complementary or integrative approaches), the need for better chronic pain therapies is warranted.8,9

There is a growing body of evidence demonstrating the value of major interventions (ie, spine procedures and stimulators),7 yet the ongoing use of peripheral nerve blocks as treatment of chronic non-cancer pain has not been studied in-depth. One common interventional treatment used to manage chronic pain is anesthetic nerve blocks as previous work shows these blocks may reduce both acute and chronic pain.10 While primarily used to manage chronic pain in the neck, back, face, and associated with headaches, nerve blocks have been used to manage pain in other areas inadequately managed with other modes of treatment.11,13 Researchers have also found significant improvements in levels of depression and anxiety as compared to those not receiving nerve blocks.12,13 Despite strong evidence supporting their use in early intervention, many physicians continue to use nerve blocks to help manage chronic pain only as a last resort when other medications and approaches have failed.

In the scope of this paper, the primary research question was whether the patients receiving regular anesthetic nerve blocks considered them to be a reasonable and effective modality to include as part of a multimodal approach to managing severe chronic non-cancer pain. Our objective was to evaluate the effectiveness and efficacy of these blocks (with reference to management) while also reviewing and adding to the current literature on interventional chronic pain medicine. As there are a small number of studies specifically addressing the efficacy of ongoing interventional chronic pain treatment using anesthetic nerve blocks,12,13 it was felt that our study might provide useful background in support of the need for future research. Therefore, our study attempted to observe:

  • the percentage of pain relief experienced after injection relative to pre-nerve block pain levels
  • duration of pain reduction following nerve blocks (based on anatomic region)
  • interval between nerve blocks received
  • how nerve blocks affected mood, overall function, and patient satisfaction.

These questions were addressed using a questionnaire-based, cross-sectional study abiding by the Strengthening the Reporting of Observational Studies in Epidemiology (STROBE) guidelines.14

Methods 

Population

Patients were selected based on their attendance to the community pain clinic (Jacobs Pain Centre [JPC], Markham, Ontario, Canada). JPC conforms to the International Association for the Study of Pain (IASP) definition of a community based pain clinic15 and has been certified to provide interventional procedures under the out-of-hospital premises inspection program (OHPIP) by the College of Physicians and Surgeons of Ontario (CPSO).16 Patients are seen for initial consultation by referral. Referrals for evaluation are made by primary care providers and specialists, including neurologists, rheumatologists, orthopedic surgeons, neurosurgeons, and anesthetists. The catchment area for referred patients extends throughout southern Ontario with the majority coming from the greater Toronto area. All physicians practicing at JPC have met the requirements for the change of scope of practice set out by the CPSO guidelines for pain management.17

Inclusion Criteria

Patients undergoing treatment for chronic pain at JPC and who had received treatment for a period greater than 3 months were included in the study. Informed consent was obtained and confirmed by the treating physician. All patients were made aware that their personal information would be kept confidential and that they were free to refuse participation.

Study Design and Timeframe

This cross-sectional study, which took place over a three-month period between March 12, 2014 and June 15, 2014, looked at a large population of people living with chronic pain in Ontario at a single time point using a questionnaire; in effect, this was a quality improvement project. The questionnaire was developed by compiling components of the visual analog scale (VAS) pain score. The methodology, questionnaire, consent process, and documentation were reviewed and approved by the executive committee at JPC. All patients presenting for treatment during that time were invited to be part of the study.

Data Collection

Patients were asked to complete the survey provided and return it to the physician. Only when the survey was not completed or not filled out properly did an attending physician assist. All completed surveys were collected and stored until the study period concluded. Only one questionnaire per patient was accepted. When multiple surveys were completed by the same patient (ie, multiple appointments during the three-month study period), only results from the most recent (last completed) survey were used. The questionnaire included the following questions:

  • Did the patient take any medications for pain management? Was the medication sufficient for their pain?
  • What was the location/effectiveness of nerve blocks?
  • What was the percentage of pain reduction based on location of their nerve blocks?
  • What length of time did the nerve blocks remain effective?
  • How often did they receive nerve blocks?
  • Did the patient have pain relief accompanied by better functionality?
  • Did the patient have pain relief accompanied by improved moods?
  • What other treatments were used for their chronic pain?

All quantitative variables were given in a format that gave patients a range of options. Percentages were given to evaluate reduction of pain, and time-scale was given to evaluate how long nerve blocks remained effective and how often the patient received them. Figure 1 depicts a sample survey.

Analysis

The study compared descriptive count data based on patient responses. To manage bias, the following adaptations were integrated:

  • It was written for easy understanding and completion.
  • All patients part of JPC were included in the study, with the exception of patients who were treated for less than three months, to reduce selection bias.
  • Surveys were filled out at the time of presentation and receiving of nerve block injection to reduce recall bias.
  • Patients were asked about pain relief and efficacy of nerve blocks currently and since they were last seen (prospective thought process).
  • As large a sample size as possible was used to reduce confounding variables.

Results

A total of 358 (n = 358) patients completed the survey. Of the 358 patients, 340 (95%) were receiving pharmacotherapy for management of their chronic pain, and 294 (82%) were also receiving nerve blocks in addition to pharmacotherapy. Patients also reported using physiotherapy (61%); massage therapy (56%); chiropractic care (50%); and acupuncture (43%) as part of their chronic pain management regimen, often at different locations beyond the JPC clinic.

Data were sorted based upon anatomic location of chronic pain. Of the 294 patients who received nerve blocks regularly, 91 (31%) received nerve blocks for head pain/headaches; 196 (67%) for neck pain; 249 (85%) for lumbar/sacral pain; 29 (10%) for face pain; and 100 (34%) for pain in other anatomic regions. Totals exceed 100% as many patients were treated for pain in multiple anatomic regions. The following improvements in pain were reported after nerve blocks were given (see also Figures 2A-B):

  • head pain: administered to 91 patients; 76 (83.5%) reported a reduction of pain ≥ 50%.
  • neck pain: administered to 196; 155 (79%) reported a reduction of pain 50%.
  • back pain: administered to 249 patients; 183 (73.5%) reported reduction of pain 50%.
  • facial pain; administered to 29 patients; 24 patients (83%) reported reduction of pain 50%.

Figure 2A. Proportion of patients who reported that they received nerve blocks for facial pain, head pain, neck/cervical pain, lumbar/sacral pain, and other areas, including shoulder thoracic pain.

Figure 2B. Proportion of surveyed patients who felt the effectiveness of the nerve blocks reduced their pain by greater than or equal to 50%.

Question 5 asked patients to rate their impression of the effectiveness of the nerve blocks received. Of the 294 patients that received blocks: 158 patients (54%) rated the nerve blocks as “effective” and 118 patients (40%) rated them as “very effective.” In total, 276 patients (94%) reported the nerve blocks to be either “effective” or “very effective” for management of their chronic pain (see Figure 2C).

Figure 2C. Proportion of patients who felt the nerve block were “not effective,” “effective,” or “very effective” in reducing their pain overall.

Patients were also asked to quantify the duration of effectiveness of the nerve blocks they received. Of the 294 patients receiving nerve blocks (see also Figure 2D):

  • 109 (37%) reported the duration of benefit to be ≥ 3 weeks.
  • 100 (34%) reported the duration of benefit to be ≤ 2 weeks
  • 85 (29%) reported the duration of benefit to be 2 to 3 weeks

Figure 2D. Patients’ average effect time of pain relief after receiving a nerve block.

Patients at the JPC that received nerve blocks reported how often they received this treatment:

  • 23 (7.8%) reported receiving nerve blocks weekly
  • 90 (31%) received nerve blocks every 2 weeks
  • 53 (18%) every 3 weeks
  • 74 (25%) every 4 weeks
  • 53 (18%) received nerve blocks at intervals greater than 4 weeks.

In the final part of the questionnaire, patients treated with nerve blocks were asked to share their impression regarding pain relief, level of functioning, and overall mood. Of the 294 patients receiving nerve blocks:

  • 260 (88.4%) reported that the blocks resulted in a significant reduction in their pain
  • 237 patients (80.6%) reported that the blocks significantly contributed to increased functionality
  • 166 patients (56.5%) reported that the blocks significantly contributed to improvements in their mood.

Discussion

Potential Weaknesses

The authors submit that several weaknesses may be present in the cross-sectional study, namely:

  • the inability of the study to track pain relief over time
  • subjectivity in pain relief based on patients’ feelings at the time of the survey
  • likelihood that this clinic (JPC) may not be representative of an entire chronic pain population
  • difficulty for some patients to complete the survey independently
  • issue of physician/primary caregiver involvement in the study with potential influence on patient
    participation/response
  • limited generalizability to all patients with similar clinical problems. This patient population concluded that they benefited from this treatment more so than any other treatments they sought out.

Features of this observational design (uncontrolled, pre-post comparison) preclude the establishment of a definite causal relationship between administration of the nerve blocks and the reported pain relief. Experimental (or possibly quasi-experimental) designs are necessary to achieve that end. However, a number of factors are at least consistent with a causal relationship between the nerve block and the reported pain reduction. First, it is highly consistent with current conceptualizations of pain signals transmission from sites of origin to higher neural pain centers. Second, patients had no external incentive to report amelioration of pain. Third, the study protocol meticulously avoided any suggestion of the result, and there was no “cultural” (ie, media) information suggesting these results to the treated patients. Finally, despite individual differences in pain responses documented in the literature to all interventions, general consistency and absence of reports of increased pain with nerve blocks suggest that a fundamental mechanism across pain types and individuals appears to underlie the analgesic effects of nerve blocks for chronic pain.

Potential Strengths

The authors also submit that several strengths may be present in the cross-sectional study, namely:

  • most patients approached agreed to participate, suggesting a high degree of engagement in their treatment process and with the care team
  • a simple “pragmatic” approach was used to assess impact and satisfaction
  • the study was carried out in a community clinic that may be considered representative of the pain care offered in the province of Ontario
  • treatments offered and evaluated were not complex and are readily available in a community practice.

The Reimbursement Issue

There are two main areas of controversy concerning the practice of offering local anesthetic nerve blocks for care of patients with chronic pain. First is the short duration of the expected effect of local anesthetic injections. Second is the potential fiscal conflict as interventional treatments are relatively well compensated through procedural codes in Ontario compared to simple visits or counseling sessions. Thus, fiscal interests may drive the decision to offer such care and availability. Further complicating the matter is that there are few, if any, RCTs evaluating these particular practices, leaving no body of evidence with which to inform the discussion.

On the other hand, pharmaceuticals are also of short duration and must be taken repeatedly under minimal supervision, avoiding repeated physician visits. The cost of pharmaceutical care is not trivial, and many pharmacological agents tend to be aimed at reducing symptoms rather than changing the disease process.

There is also variability across the country in physician reimbursement for interventional pain care, whether in the office or more specialized settings. payors are often concerned that changes observed in practice patterns represent fiscally driven physician decisions rather than a move toward optimal care.

Optimal interdisciplinary treatments have been identified but are frequently not available within provincial healthcare systems and are not universally effective. The lack of available evidence for treatments such as nerve blocks complicates care delivery as payors may decline reimbursement for treatments for which there is little published evidence, despite significant uptake by clinicians and specific patient populations.

Return to the Study and Questions Addressed

Our review attempted to provide, through an inexpensive observational study, a commentary on the value of nerve blocks to the patients receiving them. This paper further aims to help provide an estimate of the impact of treatment and could inform a study protocol. It represents care being delivered in a community setting, not in a secondary or tertiary care center. At the time of this writing, 1.6% of Canadian Institutes of Health Research (CIHR) research budget allocation was devoted to studies of pain and its treatment.18

Many of the questions addressed in this study may be of particular interest to provincial and federal health ministries. Pain patient registries, such as those proposed at a national level in Canada through the auspices of the CIHR Strategies for Patient-Oriented Research Supported Chronic Pain Network, may help to address similar questions.19 Bogduk argued the “adoption of well-designed observational studies is an economically realistic, and achievable, means of bringing evidence to bear on behalf of the patients who suffer pain. Unless this is carried out, under the current academic nihilism that has been applied to interventional pain medicine, soon no patient with pain will be able to get any form of treatment.”6 With this level of uncertainty in the field of chronic pain treatment, the authors believe our study, utilizing the STROBE guidelines,18 addresses a gap in knowledge in the current literature. We further believe this is the largest study to date on peripheral nerve blocks for chronic pain.

This study was able to quantify the levels of pain reduction experienced by chronic pain sufferers by asking what their pain levels were prior to and after injection of the nerve block. We believe a reduction in pain of 50% to be significant for numerous reasons. In the Canadian Guideline for Opioids for Chronic Non-Cancer Pain,17 a 1-cm (10-cm scale) reduction on the VAS was identified as a significant treatment effect.20 Farrar, et al, examined the clinical importance of pain reduction and increased functionality and concluded that any pain reduction felt by the patient was significant.21 Martin, et al, concluded that when quantifying pain reduction, a balance of specificity and sensitivity was found at reductions of 50% or greater.22 We observed that anesthetic nerve block injections were not only “effective” or better in 94% of this study population, but that pain was reduced significantly in more than 70% of those receiving the blocks.

Overall, local anesthetic nerve block injections may offer pain relief, increased functioning, and have a positive effect on anxiety and depression in the short term. The therapeutic effect, however, far outlasts the expected effect of the anesthetic itself, allowing many patients, including those included herein, to experience pain relief for greater periods of time. The mechanisms of this effect are currently unknown, but there are many possibilities consistent with this clinical finding. Chronic pain is associated with peripheral and central sensitization, and injection therapy with local anesthetic may alter this sensitization. Staud reported that lidocaine injections in patients with fibromyalgia syndrome decreased pain thresholds compared to saline injections.23 In fact, any intervention that changes excitability of the peripheral or central nervous system may ultimately affect the mechanisms of central sensitization.

In this context, local anesthetic injections may enhance these effects by decreasing peripheral nerve excitability. Based on this potential mechanism of action, increasing injection therapy with local anesthetic might be associated with greater effects.24 We were also able to show that the pain reduction experienced by patients was accompanied by an increase in quality of life.

Conclusion

Ninety-four percent (94%) of patients included in this questionnaire-based study considered nerve blocks to be “effective” or better as part of their overall pain management. Patients also reported improved levels of functioning and mood leading to increased patient satisfaction, QoL, and ability to return to work. Overall, RCTs and meta-analyses help to increase medical knowledge on populations and help clinicians to implement useful treatments, but observational studies also allow providers to critically look at treatments on an individual and real-world level. Clinicians are encouraged to utilize all types of studies to allow better care of all chronic pain sufferers. The challenge for healthcare payors is structuring a system that supports use of multiple modalities while identifying and selecting them appropriately.

Last updated on: August 2, 2019
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