Evaluation of neurolytic blocks using phenol and cryogenic block in the management of chronic pain.

This study compared the use of phenol and cryogenic blocks for neurolysis in 28 patients. Patients were assigned randomly to receive peripheral nerve blocks with either phenol or cryoanalgesia. Significantly more patients in the phenol group received 20% or greater relief at 2, 12, and 24 wk than patients in the cryogenic group. Only 27% of patients received significant relief, however, indicating that neurolytic blocks were not particularly effective even though local anesthetic blocks produced significant but temporary pain relief.

Diagnostic epidural opioid technique.

Diagnostic epidural blocks were performed on 27 chronic pain patients sequentially using saline, fentanyl, and lidocaine solution. The patients were divided into one of four groups based on their response to the epidural solutions: placebo response group--pain relief with placebo solutions; fentanyl response group--pain relief with epidural fentanyl; lidocaine response group (LRG)--pain relief with lidocaine but not fentanyl; and no response group--no pain relief with any of the solutions used. The four groups were compared on the basis of age, sex, site of pain, duration of pain, narcotic use, pain assessment index, and workmen's compensation claims. The comparisons resulted in the conclusion that LRG patients had a much longer average duration of pain than the other groups. On the basis of the information gathered, it was theorized that, despite their response to epidural lidocaine, LRG patients may actually be a group of operant pain patients. Their failure to receive analgesia from epidural fentanyl may be a learned response such that they associate any sensory input from the affected area as painful. If follow-up studies support these findings, then the diagnostic opioid technique may be a more sensitive tool in diagnosing chronic pain.

Studies of the Modified Somatic Perceptions Questionnaire (MSPQ) in patients with back pain. Psychometric and predictive properties.

The Modified Somatic Perceptions Questionnaire (MSPQ) was designed to measure heightened somatic awareness among patients with chronic pain. It was hoped that this questionnaire would help predict therapeutic responses for back pain patients. The reliability, validity, and predictive characteristics of this scale were tested among 97 patients with chronic low-back pain enrolled in a clinical trial of transcutaneous nerve stimulation and stretching exercises. Internal consistency was good (alpha = 0.78), and correlations with the Zung depression scale and certain MMPI scales were significant. Correlations with a baseline functional scale (the Sickness Impact Profile) were stronger than those with the MMPI. Unfortunately, the MSPQ did not correlate with functional outcomes, and was only weakly associated with pain outcomes. Thus, the MSPQ appears to be reliable and valid, but the somatic perceptions it measures may have little relation to patient outcomes.

Long-term outcomes and costs of an integrated rehabilitation program for chronic knee pain: a pragmatic, cluster randomized, controlled trial.

OBJECTIVE: Chronic joint pain is a major cause of pain and disability. Exercise and self-management have short-term benefits, but few studies follow participants for more than 6 months. We investigated the long-term (up to 30 months) clinical and cost effectiveness of a rehabilitation program combining self-management and exercise: Enabling Self-Management and Coping of Arthritic Knee Pain Through Exercise (ESCAPE-knee pain). METHODS: In this pragmatic, cluster randomized, controlled trial, 418 people with chronic knee pain (recruited from 54 primary care surgeries) were randomized to usual care (pragmatic control) or the ESCAPE-knee pain program. The primary outcome was physical function (Western Ontario and McMaster Universities Osteoarthritis Index [WOMAC] function), with a clinically meaningful improvement in physical function defined as a ≥15% change from baseline. Secondary outcomes included pain, psychosocial and physiologic variables, costs, and cost effectiveness. RESULTS: Compared to usual care, ESCAPE-knee pain participants had large initial improvements in function (mean difference in WOMAC function -5.5; 95% confidence interval [95% CI] -7.8, -3.2). These improvements declined over time, but 30 months after completing the program, ESCAPE-knee pain participants still had better physical function (difference in WOMAC function -2.8; 95% CI -5.3, -0.2); lower community-based health care costs (£-47; 95% CI £-94, £-7), medication costs (£-16; 95% CI £-29, £-3), and total health and social care costs (£-1,118; 95% CI £-2,566, £-221); and a high probability (80-100%) of being cost effective. CONCLUSION: Clinical and cost benefits of ESCAPE-knee pain were still evident 30 months after completing the program. ESCAPE-knee pain is a more effective and efficient model of care that could substantially improve the health, well-being, and independence of many people, while reducing health care costs.

Clinical effectiveness of a rehabilitation program integrating exercise, self-management, and active coping strategies for chronic knee pain: a cluster randomized trial.

OBJECTIVE: Chronic knee pain is a major cause of disability and health care expenditure, but there are concerns about efficacy, cost, and side effects associated with usual primary care. Conservative rehabilitation may offer a safe, effective, affordable alternative. We compared the effectiveness of a rehabilitation program integrating exercise, self-management, and active coping strategies (Enabling Self-management and Coping with Arthritic Knee Pain through Exercise [ESCAPE-knee pain]) with usual primary care in improving functioning in persons with chronic knee pain. METHODS: We conducted a single-blind, pragmatic, cluster randomized controlled trial. Participants age >/=50 years, reporting knee pain for >6 months, were recruited from 54 inner-city primary care practices. Primary care practices were randomized to continued usual primary care (i.e., whatever intervention a participant's primary care physician deemed appropriate), usual primary care plus the rehabilitation program delivered to individual participants, or usual primary care plus the rehabilitation program delivered to groups of 8 participants. The primary outcome was self-reported functioning (Western Ontario and McMaster Universities Osteoarthritis Index physical functioning [WOMAC-func]) 6 months after completing rehabilitation. RESULTS: A total of 418 participants were recruited; 76 (18%) withdrew, only 5 (1%) due to adverse events. Rehabilitated participants had better functioning than participants continuing usual primary care (-3.33 difference in WOMAC-func score; 95% confidence interval [95% CI] -5.88, -0.78; P = 0.01). Improvements were similar whether participants received individual rehabilitation (-3.53; 95% CI -6.52, -0.55) or group rehabilitation (-3.16; 95% CI -6.55, -0.12). CONCLUSION: ESCAPE-knee pain provides a safe, relatively brief intervention for chronic knee pain that is equally effective whether delivered to individuals or groups of participants.

Economic evaluation of a rehabilitation program integrating exercise, self-management, and active coping strategies for chronic knee pain.

OBJECTIVE: To conduct an economic evaluation of the Enabling Self-Management and Coping with Arthritic Knee Pain through Exercise (ESCAPE-knee pain) program. METHODS: Alongside a clinical trial, we estimated the costs of usual primary care and participation in ESCAPE-knee pain delivered to individuals (Indiv-rehab) or groups of 8 participants (Grp-rehab). Information on resource use and informal care received was collected during face-to-face interviews. Cost-effectiveness and cost-utility were assessed from between-group differences in costs, function (primary clinical outcome), and quality-adjusted life years (QALYs). Cost-effectiveness acceptability curves were constructed to represent uncertainty around cost-effectiveness. RESULTS: Rehabilitation (regardless of whether Indiv-rehab or Grp-rehab) cost 224 pounds (95% confidence interval [95% CI] 184 pounds, 262 pounds) more per person than usual primary care. The probability of rehabilitation being more cost-effective than usual primary care was 90% if decision makers were willing to pay 1,900 pounds for improvements in functioning. Indiv-rehab cost 314 pounds/person and Grp-rehab 125 pounds/person. Indiv-rehab cost 189 pounds (95% CI 168 pounds, 208 pounds) more per person than Grp-rehab. The probability of Indiv-rehab being more cost-effective than Grp-rehab increased as willingness to pay (WTP) increased, reaching 50% probability at WTP 5,500 pounds. The lack of differences in QALYs across the arms led to lower probabilities of cost-effectiveness based on this outcome. CONCLUSION: Provision of ESCAPE-knee pain had small cost implications, but it was more likely to be cost-effective in improving function than usual primary care. Group rehabilitation reduces costs without compromising clinical effectiveness, increasing probability of cost-effectiveness.

Practical instrumentation and common sources of error.

A thorough comprehension of electrodiagnostic equipment is essential to consistently obtain accurate and reproducible data. Unreliable waveform latencies or morphologies may result from inappropriate filter settings, sensitivity comparisons, sweep speeds, interelectrode separation, cathode/anode reversals and stimulus artifact. A low frequency filter with too high a frequency limit may decrease amplitude, shorten peak latency, decrease the negative spike duration, add a phase and increase total waveform duration. A high frequency filter with too low a cut-off may decrease amplitude and prolong onset and peak latencies. Increasing the amplifier's sensitivity may shorten the onset latency of a response. Sweep speeds that are too slow may omit phases, turns or entire potentials when using digital equipment. If the interelectrode separation is inadequate, waveform morphology and amplitude can be altered. Reversing cathode and anode placement affects latency and velocity determinations. Stimulus artifact may obscure a response and its reduction must be understood. Comparing latencies and amplitudes at different instrument settings is never appropriate and can lead to serious errors and misdiagnoses. A naive approach to instrumentation, therefore, is indefensible.

The influence of compensation on recovery from low back pain.

The influence of financial compensation on recovery is one of the most controversial issues in the treatment of low back pain. In this review the authors include psychological aspects of compensation and the effects of compensation on injury rate, injury duration, and rehabilitation outcomes.

The influence of prophylactic orthoses on abdominal strength and low back injury in the workplace.

This study was designed to determine the effect of multimodal intervention and the prevention of back injury, and to evaluate the adverse side effects of using a lumbosacral corset in the workplace. Subjects were 90 male warehouse workers randomly selected from over 800 employees at a grocery distribution center. Subjects were assigned to three groups: true controls, no back school, no brace orthoses; back school only; and back school plus wearing a custom molded lumbosacral orthosis. Comparisons of pre-testing and 6-month follow-up post-testing for abdominal strength, cognitive data, work injury incidence and productivity and use of health care services were evaluated. Controls and training-only group showed no changes in strength productivity or lost time. Orthoses and training-group showed no changes in strength productivity or accident rate; however, they showed substantially less lost time. This study supports the concept of using education and prophylactic bracing to prevent back injury and reduce time loss. It appears that the use of intermittent prophylactic bracing has no adverse affects on abdominal muscle strength and may contribute to decreased lost time from work injuries.

Electrophysiologic evaluation of the facial nerve in Bell's palsy. A review.

Facial nerve paralysis is the most common mononeuropathy and idiopathic facial paralysis (Bell's palsy) the most common seventh nerve disease electromyographers may be asked to evaluate. The electrophysiologic method of choice to assess the facial nerve is side-to-side evoked amplitude comparison with the affected side expressed as a percentage of the nonaffected side. This examination should be performed on days 3, 5, 7, 9, 11 and 13 after onset of paralysis. If the percentage of surviving axons falls below 10% within the first 14 days, an incomplete recovery is suggested. Electromyography may assist in prognosticating a functional return, determining neural conduction across the site of injury and following reinervation in the recovery period. The persistence or early return of an absent R1 component of the blink reflex may qualitatively suggest a satisfactory functional outcome in facial paralysis. Supramaximally exciting the facial nerve at the stylomastoid foramen and comparing the clinical response on the affected and nonaffected side, maximum stimulation test, can also predict eventual seventh nerve return. Observing a minimal twitch, utilizing the nerve excitability test or measuring the facial nerve latency have yielded poor correlations with functional return and are of limited usefulness in the prognostication of acute facial palsies. Trigeminal somatosensory evoked potentials can be employed to evaluate the status of the trigeminal nerve as approximately 50% of patients with Bell's palsy also have lesions involving the fifth nerve. Side-to-side amplitude comparison and electromyography are the two most valuable electrophysiologic methods of assessing facial nerve functioning.

The premotor potential.

A small waveform precedes the compound muscle action potential evoked from the thenar eminence with median nerve stimulation with high amplifier gains. This potential is believed to emanate from fibers destined to innervate the volar aspect of the first digit. It has been suggested recently that the source of the premotor potential is the palmar cutaneous branch of the median nerve. In this study, the palmar cutaneous branch of the median nerve was blocked at the wrist. A localized zone of anesthesia was observed over the proximal midpalm, not the thenar eminence, and the premotor response remained unchanged as did a midpalmar potential. The median nerve was then blocked at the base of the thenar eminence; only then did the premotor potential disappear. The palmar cutaneous branch of the median nerve innervates only a small portion of the medial aspect of the thenar eminence and does not produce the thenar premotor potential. Additionally, because of the close proximity of the main median nerve to its palmar cutaneous branch, volume conduction of stimuli and responses precludes an electrophysiologic technique which exclusively localizes the palmar cutaneous branch of the median nerve.

Normative model for cold pressor test.

The cold pressor test elicits an emotional/motivational pain experience from the immersion of a limb in cold water. It has been widely used to evaluate (experimental and chronic) pain. However, normative models for quantification and comparison for pain tolerance have not previously been established. This study developed a normative mathematical model for pain tolerance using the cold pressor test with over 600 subjects. Norms for age, sex, and ethnic group were calculated. In addition, chronic pain patients were compared with pain-free patients to determine normative differences in response. The results indicate that at any given age Anglo-Saxon males have the longest tolerance time followed by non-Anglo-Saxon males, Anglo-Saxon females, and finally non-Anglo-Saxon females. There is a consistent decrease in tolerance time as the male age increases and minimal change in tolerance time as the female age increases. Chronic pain patients exhibited the same type of pain response pattern as healthy volunteers when corrected for age, sex, and ethnocultural subgroup.

Global core recommendations for a musculoskeletal undergraduate curriculum.

OBJECTIVE: To develop core recommendations for the learning outcomes of an undergraduate curriculum in musculoskeletal conditions for any parts of the globe. METHODS: Recommendations were developed by wide consultation with experts in orthopaedics, rheumatology, osteoporosis, and rehabilitation from all parts of the world who had interest and experience in these specialties, with the support of international and national societies. All possible knowledge, skills, and attitudes that might be of relevance to musculoskeletal conditions were initially considered and then reduced to those considered essential for all doctors. RESULTS: The recommendations focus on (a) basic skills to assess and diagnose musculoskeletal problems; (b) the competency to assess specific common or urgent musculoskeletal problems; (c) the theoretical background of the conditions and their management; and (d) the core knowledge necessary to support diagnosis and management, including basic sciences. At the end of the course, all students should be able to differentiate normal from abnormal locomotor symptoms in a patient, determine the relevant investigations and interpret the results, formulate a limited differential diagnosis, recognise the impact of the problem on the individual patient, and make an appropriate management plan. CONCLUSIONS: The recommendations set global standards for the minimum level of competence in managing patients with musculoskeletal problems. They define what all doctors should know when graduating from medical school, regardless of further specialisation. They are intended to form the basis of a curriculum for a musculoskeletal course and can be adapted for any medical school in any country throughout the world.

Analgesic effectiveness of D-phenylalanine in chronic pain patients.

Enkephalins are a biochemical pathway for endogenous analgesia. A number of compounds inhibit degradation of enkephalins within the body. One of these compounds, D-phenylalanine (DPA), has been shown to increase the pain threshold in animals. It is hypothesized that this naloxone reversible analgesia is induced by DPA blockage of enkephalin degradation by the enzyme carboxypeptidase A. Preliminary studies of chronic pain patients have shown a response rate to DPA from 32% to 75%. This study was a double-blind crossover evaluation of a randomized parallel design to determine the efficacy of DPA in 30 subjects with chronic pain from varied etiology which was unrelieved by multiple therapeutic interventions. Each patient received a stabilized therapeutic regimen during this study consisting of four weeks of either DPA 250 mg or lactose (placebo) orally four times a day. After four weeks the DPA and placebo groups were crossed over for an additional four weeks of treatment. Pain was quantified using a visual analog pain scale and a cold pressor test. Data from the pain questionnaires revealed more pain relief on DPA reported by 25% of the patients, more pain relief on placebo reported by 22% of the patients, and no difference in pain relief reported by 53% of the patients. Lowest pain level of the visual analog scale was reported by 47% of the patients on DPA and 53% on placebo. There appears to be no significant analgesic effect from D-phenylalanine in chronic pain patients when compared to placebo.

Prognostic variability among chronic pain patients: implications for study design, interpretation, and reporting.

Chronic pain patients share many characteristics, but there is important prognostic variability among them. By selecting for certain characteristics, different recruitment methods and entry criteria for clinical or research programs may influence the likelihood of success regardless of treatment efficacy. This was demonstrated when subjects (n = 55) were recruited through lay publicity for a clinical trial of therapy for chronic back pain. In comparison to routine pain clinic patients (n=61), subjects in the clinical trial were better educated, were more often employed, had more favorable personality profiles, and were less likely to have had surgery or narcotic use (all p less than 0.004). Pain relief was significantly better for clinical trial subjects, apparently due to baseline prognostic differences rather than uniquely efficacious therapy. We conclude that chronic pain patients vary in prognostically important ways; that recruitment methods and criteria strongly influence these characteristics; and that greater attention to these details is needed when interpreting and reporting clinical research.

A controlled trial of transcutaneous electrical nerve stimulation (TENS) and exercise for chronic low back pain.

A number of treatments are widely prescribed for chronic back pain, but few have been rigorously evaluated. We examined the effectiveness of transcutaneous electrical nerve stimulation (TENS), a program of stretching exercises, or a combination of both for low back pain. Patients with chronic low back pain (median duration, 4.1 years) were randomly assigned to receive daily treatment with TENS (n = 36), sham TENS (n = 36), TENS plus a program of exercises (n = 37), or sham TENS plus exercises (n = 36). After one month no clinically or statistically significant treatment effect of TENS was found on any of 11 indicators of outcome measuring pain, function, and back flexion; there was no interactive effect of TENS with exercise. Overall improvement in pain indicators was 47 percent with TENS and 42 percent with sham TENS (P not significant). The 95 percent confidence intervals for group differences excluded a major clinical benefit of TENS for most outcomes. By contrast, after one month patients in the exercise groups had significant improvement in self-rated pain scores, reduction in the frequency of pain, and greater levels of activity as compared with patients in the groups that did not exercise. The mean reported improvement in pain scores was 52 percent in the exercise groups and 37 percent in the nonexercise groups (P = 0.02). Two months after the active intervention, however, most patients had discontinued the exercises, and the initial improvements were gone. We conclude that for patients with chronic low back pain, treatment with TENS is no more effective than treatment with a placebo, and TENS adds no apparent benefit to that of exercise alone.

Can trials of physical treatments be blinded? The example of transcutaneous electrical nerve stimulation for chronic pain.

Therapeutic trials often attempt to "blind" patient and investigator to the true nature of treatments received, reducing the influences of conscious or subconscious prejudices. In drug trials, this is accomplished with placebo tablets, but blinding in trials of physical treatments is more problematic. This issue arose in a clinical trial of transcutaneous electrical nerve stimulation (TENS) for patients with chronic low back pain. Several study design features were incorporated to promote blinding: use of sham TENS units visually identical with real units, exclusion of potential subjects with previous TENS experience, avoidance of a crossover design and use of identical visit frequency, instructions and modifications in electrode placement. Subjects were asked not to discuss treatments with the clinicians who performed outcome assessments. Both patients and clinicians were asked to guess actual treatment assignments at the trial's end. Every patient in the true TENS group believed the unit was functioning properly, but the degree of certainty varied. In the sham TENS group, 84% also believed they had functioning units, but their certainty was significantly less than in the active treatment group. Differences in patient perceptions did not affect compliance, as the two groups had similar dropout rates, appointment compliance, days of TENS use and daily duration of TENS use. Clinicians guessed treatments correctly 61% of the time (as opposed to 50% expected by chance), again suggesting partial success in blinding. These efforts at blinding may partly explain the negative trial results for TENS efficacy. We conclude that complete blinding is difficult to achieve because of sensory difference in treatment and unintended communication between patient and examiner.(ABSTRACT TRUNCATED AT 250 WORDS)