Patient Presentations in a Community Pain Clinic after COVID-19 Infection or Vaccination: A Case-Series Approach

OBJECTIVES

Early case report studies and anecdotes from patients, medical colleagues, and social media suggest that patients may present to chronic pain clinics with a number of complaints post COVID-19 infection or vaccination. The aim of this study is to systematically report on a consecutive series of chronic pain patients seen in a community-based pain clinic, who acquired symptoms after COVID-19 infection or vaccination.

METHODS

This retrospective cross-sectional descriptive study identified all patients seen at the clinic over a 4-month period (January-April 2022) with persistent symptoms after COVID-19 infection, vaccination, or both. Information was collected on sex, gender, age, details of vaccination, new pains, or exacerbation of old pain plus the development of novel symptoms.

RESULTS

The study identified 21 community dwellers (17 females and 4 males; F/M 4.25/1; age range 22-79 years; mean age 46.3 years), with symptoms attributed to COVID-19 infection or vaccination. Several patients suffered exacerbation of previous pains or developed novel pains, as well as high levels of anxiety and mood disorders. A review of the existing literature provides support for the spectrum of symptoms displayed by the study group.

CONCLUSIONS

Information collected in this study will add to the body of COVID-19-related literature and assist particularly community practitioners in recognizing and managing these conditions.

Diagnosis and conservative management of sural neuropathy: a case report

Nerve entrapments in the lower extremity are rare and can be difficult to diagnose. Here we describe a Canadian Armed Forces veteran with left posterior-lateral calf pain. The patient's condition was previously misdiagnosed as a left-sided mid-substance Achilles tendinosis, which subsequently led to mismanagement, persistent pain and severe functional limitations. After performing a thorough evaluation, we diagnosed the patient with chronic left-sided sural neuropathy secondary to entrapment within the gastrocnemius fascia. The patient's physical symptoms abated completely with chiropractic care, while overall disability improved substantially after taking part in an interdisciplinary pain program. The objectives of this case report are to describe a challenging differential diagnosis of sural neuropathy, and present conservative whole-person management options according to the patient's needs and goals.

Comparison of Older and Younger Patients Referred to a Non-interventional Community Pain Clinic in the Greater Toronto Area (GTA)

AIM

To compare demographic and pain characteristics of older (≥ 65) vs younger (< 65) chronic non-cancer pain patients referred to a community pain clinic in the Greater Toronto Area (GTA), Ontario, Canada.

METHODS

This is a retrospective study of 644 consecutive new patients with pain seen during 2016-2017 (older group n = 126; younger group n = 518). Demographic characteristics, Brief Pain Inventory pain ratings, and diagnosis were obtained using retrospective chart review. Patients were classified into group I (pure biomedical pathology), group II (mixed biomedical causes and psychological factors) and group III (no detectable physical pathology but psychological factors were considered important).

RESULTS

Older patients comprised 19.6% of the overall population (higher than the average GTA older population). Regarding older vs younger group, male/female ratio was 1:1.3 vs 1:1.7 respectively, while 71% of the older patients were foreign born vs 37% of the younger group (p < 0.001). Low back was the most prevalent pain site for both groups; 70% of the older patients were classified as group I vs 35% of the younger patients (p < 0.0001), and only 6% as group III (vs 18% of the younger population, p < 0.05).

CONCLUSION

The study points to considerable differences between younger and older patients with pain with the latter presenting with significant biomedical pathology but lesser psychopathology. The results are comparable to those obtained from a university pain clinic as well as a rural Northern Ontario clinic. Implications of the study for planning of pain care are discussed.

Evolution of a chronic pain management program in a Northwestern Ontario community: from structural elements to practical application

Background

Chronic pain is a highly prevalent health problem especially in rural regions. There is a dearth of comprehensive pain management programs particularly in rural areas.

Aim

The objectives of this paper are to describe the evolution of an interprofessional chronic pain team employing a patient-centered model of care with a biopsychosocial approach, and health services metrics.

Method

This descriptive case study approach includes an overview of the Chronic Pain Management Program (CPMP) services at St. Joseph Care Group in Thunder Bay, NW Ontario; the process involved in the development of an interprofessional chronic pain team employing a patient-centered model of care with a biopsychosocial approach; and metrics of the program’s operations.

Results

Established in 1998, CPMP has evolved to become inter-professional, providing consultations and management, with partial funding by the Ontario Ministry of Health and Long term Care that has allowed expansion of services. The CPMP currently provides three distinct program streams as follows: a) Intensive 6-week, four half-days/week, outpatient program that offers an interdisciplinary team approach in groups and individual format; b) PACE-IT (Pain Assessment Collaborative Education Inter-professional Therapy), 8-week long, half-day/ week, interprofessional treatment program, in person; and c) Individual format for one-on-one services for patients not fitting in either the 6-Week or PACE-IT programs. In addition, Additional services provide virtual consultations and didactic videoteleconference sessions on opioid stewardship and pain management to health providers. Health services outcomes, research, and educational opportunities across the Northwestern Ontario Region, challenges and future needs are discussed.

Conclusion

The CPMP’s model of care can serve as a foundation for expert chronic pain care delivery across rural Canada, and as template for similar institutionally-based and publicly funded pain clinics.

Long term outcomes of chronic pain patients attending a publicly funded community-based interdisciplinary pain program in the Greater Toronto area: results of a practice-based audit

Background

Chronic pain management multi/interdisciplinary programs attempt to address all elements of the biopsychosocial model. The primary objective of this retrospective study (based on practice-based audit) was to determine the effectiveness of a patient-centered, comprehensive and intense interdisciplinary pain management program in a publicly funded community-based pain clinic in the Greater Toronto Area.

Method

This retrospective longitudinal study was conducted on 218 carefully selected sequential chronic pain patients, with 158 completing a 3–4-month interdisciplinary program between January 2016 and December 2018. Data collected upon exit, at 6 months and 12 months post-discharge included demographic information, pain characteristics, emotional/functional status obtained by validated instruments and global impression of change (GIC). Additionally, social health outcomes (return to work or school) were retrieved through retrospective chart review. Means of pre-and post-program variables were compared to assess changes of each patient’s “journey”.

Results

Physical and mental/ emotional health outcomes at exit, 6 months and 12 months post-discharge, showed initial and sustained, statistically and clinically significant improvement from pre-treatment levels, with GIC (much/very much improved) reported as 77%, 58% and 76%, respectively. Additionally, a substantial positive change in social health outcomes was noted particularly in patients on disability (29%), part time workers gaining full time employment (55%), and students (71%) who improved their level of schooling.

Conclusion

The study showed that careful patient selection in a community-based publicly funded interdisciplinary pain management program can produce significant improvement in pain, physical, mental/emotional health and social function, with sustained long-term outcomes.

Demographics, Pain Characteristics and Diagnostic Classification Profile of Chronic Non-Cancer Pain Patients Attending a Canadian University-Affiliated Community Pain Clinic

INTRODUCTION

Little information exists regarding the characteristics of patients with chronic non-cancer pain (CNCP) attending Canadian pain clinics. The study describes the demographics, pain characteristics and the diagnostic classification profile of such patients attending a university-affiliated community-based pain clinic in the Greater Toronto Area.

METHODS

Retrospective descriptive study based on 644 unique consecutive CNCP patients assessed between January 2016 and December 2017.

RESULTS

The female/male ratio was 1.6:1; 80% were younger than 65 years; 43% held some form of employment (full-time, part-time or self employment); median pain duration was 3 years; car accidents and medical conditions accounted for 28 and 27% of pain onset, respectively; 34% had four or more distinct areas of pain; and low back pain (LBP) was the most prevalent site (66%), but was the sole site of pain in less than a third of these patients. Age was positively associated with LBP prevalence. Self-reported health service utilization (visits to the emergency room, pain physician or psychologist) increased with patient psychopathology. Cannabis was used by 15% of the cohort and opioids by 34.5%, with only one in six opioid users exceeding 90 mg of morphine equivalent dose per day. Comparison of our data to three previously published studies from other Canadian pain clinics demonstrated both similarities and substantial differences between the populations.

CONCLUSION

Our study highlights regional differences between CNCP population phenotypes. Recognition of biomedical, psychological and socio-environmental factors affecting pain should be considered for patient stratification and rational approaches to treatment, as "one size treatment does not fit all".

From (Ontario Ministry of Health and Long-Term Care) policy to implementation: A retrospective look at a community-based patient-centered model of care for chronic pain

Background: Chronic pain is one of the most widely recognized, disabling, and expensive health problems in Canada. Interdisciplinary multimodal pain management is effective in helping chronic pain patients lessen symptoms and reclaim functionality, but most patients lack access to such treatments.

Aim: The aim of this study was to describe the development and implementation of a publicly funded and patient-centered model of care in the community.

Methods: The study was set in the Pain & Wellness Centre (PWC) in Vaughan, the only community-based chronic pain clinic in Ontario funded by the Ontario Ministry of Health and Long-Term Care (MOHLTC) as a demonstration project of a template for similar future community clinics. The study is descriptive, including a brief review of the Ontario comprehensive pain strategy framework and an overview of the PWC and the process involved in the development of an interdisciplinary pain program (IDP), based on the biopsychosocial model of chronic pain management.

Results: During a 2.5-year period, the PWC has offered 1055 new patient medical consultations and 1921 follow-up visits and admitted 242 patients in the IDP program (demonstrating significant success in patient outcomes at the 3-month exit from the program). It established robust outcomes research, organized educational programs for pain trainees, and cultivated a collaborative relationship with the Toronto Academic Pain Medicine (TAPMI) network and the community at large.

Conclusions: This demonstration program has shown the feasibility and applicability of the principles of the MOHLTC comprehensive pain strategy, providing an effective, evidence-based, and accountable approach to chronic pain diagnosis and management in the community.

Evidence-based guideline for neuropathic pain interventional treatments: spinal cord stimulation, intravenous infusions, epidural injections and nerve blocks

BACKGROUND

The Special Interest Group of the Canadian Pain Society has produced consensus-based guidelines for the pharmacological management of neuropathic pain. The society aimed to generate an additional guideline for other forms of neuropathic pain treatments.

OBJECTIVE

To develop evidence-based recommendations for neuropathic pain interventional treatments.

METHODS

A task force was created and engaged the Institute of Health Economics in Edmonton, Alberta, to survey the literature pertaining to multiple treatments. Sufficient literature existed on four interventions only: spinal cord stimulation; epidural injections; intravenous infusions; and nerve blocks. A comprehensive search was conducted for systematic reviews, randomized controlled trials and evidence-based clinical practice guidelines; a critical review was generated on each topic. A modified United States Preventive Services Task Force tool was used for quality rating and grading of recommendations.

RESULTS

Investigators reviewed four studies of spinal cord stimulation, 19 studies of intravenous infusions, 14 studies of epidural injections and 16 studies of nerve blocks that met the inclusion criteria. The task force chairs rated the quality of evidence and graded the recommendations. Feedback was solicited from the members of the task force.

CONCLUSION

There is sufficient evidence to support recommendations for some of these interventions for selected neuropathic pain conditions. This evidence is, at best, moderate and is often limited or conflicting. Pain practitioners are encouraged to explore evidence-based treatment options before considering unproven treatments. Full disclosure of risks and benefits of the available options is necessary for shared decision making and informed consent.

Sympathectomy for neuropathic pain

BACKGROUND

Neuropathic pain is defined as pain initiated or caused by a primary lesion or dysfunction in the nervous system. Some examples of this condition are phantom limb pain, post-stroke pain and complex regional pain syndrome type I (reflex sympathetic dystrophy) and type II (causalgia). Treatment options include drugs, physical treatments, surgery and psychological interventions. The concept that many neuropathic pain syndromes, particularly RSD and causalgia are "sympathetically maintained pains" has historically led to attempts to temporarily or permanently interrupt the sympathetic nervous system. Chemical sympathectomies use alcohol or phenol injections to destroy the sympathetic chain, but this effect is temporary until regeneration of the sympathetic chain occurs. Surgical ablation can be performed by open removal or electrocoagulation of the sympathetic chain, or minimally invasive procedures using stereotactic thermal or laser interruption.

OBJECTIVES

The review aimed to assess the effects of both chemical and surgical sympathectomy for neuropathic pain. Secondary objectives were to compare the effects of sympathectomy with no treatment, placebo or conventional treatment, and to evaluate whether the technique of sympathectomy influences the outcomes of the procedure.

SEARCH STRATEGY

We searched MEDLINE and EMBASE up to February 2003 and the latest issue of the Cochrane Library (Issue 1, 2003). We screened references in the retrieved articles, literature reviews and book chapters. We also contacted experts in the field of neuropathic pain.

SELECTION CRITERIA

Clinical trials and observational studies assessing the effects of sympathectomy (surgical or chemical) for neuropathic pain of both central or peripheral origin were included.

DATA COLLECTION AND ANALYSIS

Two reviewers applied the selection criteria to titles and abstracts. Full articles of potentially eligible trials were obtained and the same reviewers applied the inclusion criteria to the studies. The methodological quality of the studies was evaluated. The studies were also evaluated for clinical relevance according to a classification developed by our group. Statistical pooling was not possible due to heterogeneity of data; instead a narrative description of each included study was performed.

MAIN RESULTS

We included four studies. One randomized trial comparing radiofrequency sympatholysis with phenol sympathectomy was rated as low methodological quality and it showed that radiofrequency sympatholysis does not offer advantage over phenol techniques. However, a modified technique produced sympatholysis comparable to that produced by 6% phenol, with less incidence of post-sympathectomy neuralgia.

REVIEWER'S CONCLUSIONS

The practice of surgical and chemical sympathectomy is based on poor quality evidence, uncontrolled studies and personal experience. Furthermore, complications of the procedure may be significant, in terms of both worsening the pain or producing a new pain syndrome; and abnormal forms of sweating (compensatory hyperhidrosis and pathological gustatory sweating). Therefore, more clinical trials of sympathectomy are required to establish the overall effectiveness and potential risks of this procedure.

Dissociation between cutaneous and deep sensibility in central post-stroke pain (CPSP)

We present three cases of central post-stroke pain after right hemorrhagic or ischemic stroke associated with severe impairment of cutaneous sensibility but preservation of stimulus-evoked pain from periosteum. This is the first such report of dissociation of cutaneous- from deep-tissue sensibility loss.

Gabapentin for neuropathic pain: systematic review of controlled and uncontrolled literature

OBJECTIVE

To assess the efficacy/effectiveness and side effects of gabapentin for the treatment of neuropathic pain.

DESIGN

Systematic review of the literature.

METHODS

Extensive search of several electronic databases located both controlled and uncontrolled studies. Efficacy was assessed through meta-analysis of randomized controlled trials (RCTs), whereas the effectiveness of gabapentin in uncontrolled studies was assessed via a novel system of dichotomous classification of "bad" versus "good" results.

FINDINGS

Thirty-five papers involving 727 patients with multiple neuropathic pain conditions met the inclusion criteria. The meta-analysis of the 2 high-quality, placebo-controlled RCTs showed positive effect of gabapentin in diabetic neuropathy and post-herpetic neuralgia. The addition of 2 low-quality, placebo-controlled RCTs did not alter the magnitude or direction of observed effect. The uncontrolled studies demonstrated positive effect on pain in different neuropathic syndromes, as well as benefit on different types of neuropathic pain; highest dose administered and rate-of-dose escalation showed wide variability between prescribers. Fewer and less severe side effects were reported in the uncontrolled studies.

CONCLUSIONS

Gabapentin seems to be effective in multiple painful neuropathic conditions. The variable prescribing patterns of the uncontrolled studies raise the suspicion that effectiveness may be reduced if one limits administration of the drug to very low doses, whereas rapid dose escalation may be associated with increased central nervous system side effects. Well-designed controlled trials may provide insight into differential symptom sensitivity to the drug.

Chemical sympathectomy for neuropathic pain: does it work? Case report and systematic literature review

OBJECTIVE

To determine if chemical sympathectomy successfully reduces limb neuropathic pain.

DESIGN

Systematic literature review of the effectiveness of phenol or alcohol sympathectomy for extremity neuropathic pain.

PATIENT

A 29-year-old female with complex regional pain syndrome of both lower extremities after back surgery who was submitted to bilateral lumbar chemical sympathectomy.

SEARCH STRATEGY

The Cochrane Database of Systematic Reviews, the Cochrane Controlled Trials Register, Medline, and EMBASE were systematically searched.

OUTCOME MEASURES

(1) For the patient in question: spontaneous pain, allodynia, pinprick hyperalgesia, pressure evoked pain; (2) For the literature review: meaningful versus nonmeaningful pain relief based on degree and duration (>2 weeks) of pain relief.

RESULTS

(1) The case reported experienced partial temporary relief of pain primarily related to selective modulation of allodynia, but not deep pain or pinprick hyperalgesia; (2) 44% of 66 patients in 13 studies that met the authors' inclusion criteria experienced meaningful pain relief. Whereas 19% experienced no meaningful relief, for the remaining 37% of the patients no conclusions regarding duration and degree of relief could be drawn due to poor reporting of outcomes.

CONCLUSIONS

Based on the case reported and systematic literature review, chemical sympathectomy seems to have at best a temporary effect, limited to cutaneous allodynia. Despite the popularity of chemical sympatholysis, only few patients and poorly defined outcomes are reported in the literature, substantiating the need for well-designed studies on the effectiveness of the procedure.

Unexplainable nondermatomal somatosensory deficits in patients with chronic nonmalignant pain in the context of litigation/compensation: a role for involvement of central factors?

OBJECTIVE

To address the prevalence and characteristics of nondermatomal somatosensory deficits (NDSD) in subjects with chronic pain in the context of compensation/litigation.

METHODS

Data were collected via standardized history, examination, and patient- as well as physician-drawn body maps in a consecutive series of 194 subjects seen for the purpose of an independent medical examination.

RESULTS

Forty-nine subjects (25.3%) with primarily widespread pain (often diagnosed as fibromyalgia) presented with hemisensory or quadrotomal deficits to pinprick and other cutaneous stimuli on the side of lateralized pain or worse pain. The NDSD limbs often had impairment of vibration sense (not infrequently associated with "forehead vibration split"), reduced strength, dexterity or movement, and extreme sensitivity to superficial skin palpation or profound insensitivity to deep pain. Spatial, temporal, qualitative, and evolutionary patterns of NDSD emerged associated with cognitive/affective symptoms. NDSD subjects were more often born outside Canada, more likely to be injured at work, present with abnormal pain behavior, and have negative investigations.

CONCLUSION

NDSD are a prevalent problem associated with chronic pain. Future research should explore the prevalence of NDSD in other pain populations, the role of personality and related factors, and the underlying biological substrate of these deficits.

Neuropathic pain syndrome as an occult manifestation of injury of the spinal cord after surgical repair of aortic coarctation

Injury to the spinal cord injury with paraplegia, is a rare complication of surgical repair of aortic coarctation recognized immediately post-operatively. We present the case of a 41-year-old male undergoing surgery for restenosis at the site of a repair. Intra-operatively, he suffered inadvertent injury to an intercostal arterial branch during isolation of the aorta below the graft. Over the following months, he developed unusual symptoms involving the legs and genitourinary tract which, only after extensive investigations, were attributed to ischemic damage to the spinal cord related to the surgery. We suspect that similar syndromes reflecting injury to the spinal cord injury may be unrecognized following surgical repair of coarctation.

Chronic pain in a family of 6 in the context of litigation

We describe a family of 6 (2 parents and 4 children), evaluated 6 and 8 years after a minor car accident for chronic pain. A near identical complex of multiple physical, constitutional, and psychological symptoms were shared by all family members, all of whom bore the diagnosis of fibromyalgia. The case was brought to court after nearly a decade of symptomatology and extensive use of the health care system. The minor compensation awarded was consumed ultimately by legal fees. Psychosocial/personality issues and iatrogenic and medico-legal contributions in the evolution and resolution of the legal claim are discussed.

Anterior intercostal nerve damage after coronary artery bypass graft surgery with use of internal thoracic artery graft

BACKGROUND

The prevalence of intercostal nerve damage associated with coronary artery bypass graft-internal thoracic (mammary) artery surgery is unknown.

METHODS

A total of 37 consecutive patients with coronary artery bypass graft surgery (all with left internal thoracic artery graft) who were attending a cardiac-related exercise program underwent a thorough examination. Nerve damage was considered to be "definite" in the presence of two consistent and well-demarcated sensory abnormalities over the anterior chest wall within the T1 to T6 anterior intercostal nerve territory, and was considered "possible" in the presence of one such abnormality.

RESULTS

Definite nerve damage was detected in 73% of the subjects, and possible nerve damage was found in another 11% at the site of internal thoracic artery harvesting. Protracted postoperative pain or unpleasant sensations, usually subsiding by 4 months, were reported by recollection by 81% of the subjects. Overall, the prevalence of persistent pain in those with definite nerve damage 5 to 28 months after surgery was 15%.

CONCLUSIONS

Intercostal nerve damage seems to occur in three-quarters of all patients undergoing coronary artery bypass graft-internal thoracic artery surgery. A significant minority may continue to experience bothersome chronic chest wall pain.

Are We Paying a High Price for Surgical Sympathectomy? A Systematic Literature Review of Late Complications

The purpose of this article was to systematically review the literature in order to assess (1) the current indications for surgical sympathectomy and (2) the incidence of late complications collectively and per indication. All types of upper or lower limb surgical sympathectomies are included. An extensive search strategy looked for controlled trials and observational studies or case series with an english abstract. Out of 1,024 abstracts from MEDLINE and 221 from EMBASE, 135 articles reporting on 22,458 patients and 42,061 procedures (up to april 1998) fulfilled the inclusion criteria. Weighted means were used to control for heterogeneity of data. No controlled trials were found. The main indication was primary hyperhidrosis in 84.3% of the patients. Compensatory hyperhidrosis occurred in 52.3%, gustatory sweating in 32.3%, phantom sweating in 38.6%, and horner's syndrome in 2.4% of patients, respectively, with cervicodorsal sympathectomy, more often after open approach. Neuropathic complications (after cervicodorsal and lumbar sympathectomy) occurred in 11.9% of all patients. Compensatory hyperhidrosis occurred 3 times more often if the indication was palmar hyperhidrosis instead of neuropathic pain (52.3% versus 18.2%), whereas neuropathic complications occurred 3 times more often if the treatment was for neuropathic pain instead of palmar hyperhidrosis (25.2% versus 9.8%). Surgical sympathectomy, irrespective of approach, is accompanied by several potentially disabling complications. Detailed informed consent is recommended when surgical sympathectomy is contemplated.

Drug interactions in human neuropathic pain pharmacotherapy

Current practice predicates the use of multiple drug combinations in the treatment of neuropathic pain. These combinations may be required because of multiple pain symptoms directly arising from neuropathic pathology, other symptoms attributable to the chronicity and severity of the patient's pain or conditions unrelated to their pain. A fear exists that combination drug use or the addition of a new drug to a therapeutic regimen may lead to increased drug toxicity or decreased efficacy. Many of the drug interactions of significance to neuropathic pain physicians involve the cytochromes P450 2D6 and 3A3/4 isoenzymes. Drug interactions should be more predictable based on the knowledge of which compounds induce, inhibit or are metabolized by specific cytochrome P450 enzymes. Mechanisms of induction or inhibition of biotransformation via the P450 hepatic enzyme system are discussed and various inducers, inhibitors and substrates relating to neuropathic pain pharmacotherapy are listed.

Hematuria-loin pain syndrome: its existence as a discrete clinicopathological entity cannot be supported

OBJECTIVE

To (a) review existing literature and current concepts on Hematuria-Loin Pain Syndrome (HLPS) and (b) to describe seven cases of this syndrome.

PATIENTS AND SETTING

Seven HLPS patients seen over a period of 8 years by the pain and nephrology services of the Toronto Hospital, Toronto, Ontario, Canada.

METHODS AND RESULTS

Retrospective analysis was performed. All patients were remarkable for the variability of clinical presentation, pain characteristics, and dissociation of pain and hematuria occurrence. Routine renal investigations revealed different benign kidney pathologies in 5 of 7 patients. All patients, however, displayed variable combinations of personality factors, drug seeking behaviour, psychopathology, and presence of significant psychosocial stressors. Four cases were managed conservatively with antidepressants, anxiolytics, and supportive counseling and did very well despite persistent hematuria in two.

CONCLUSIONS

HLPS does not constitute a distinct clinicopathological entity. In a minority of cases only underlying kidney pathology is related to pain, and in many cases psychosocial stressors and underlying psychopathology may play a significant role in the reported disabling pain. A concerted medical/psychological approach is advocated.

Effect of intravenous sodium amytal on cutaneous limb temperatures and sympathetic skin responses in normal subjects and pain patients with and without Complex Regional Pain Syndromes (type I and II). I

This study examined the effects of intravenous administration of sodium amytal (SA), a medium action barbiturate, on cutaneous limb temperatures and sympathetic skin responses (SSR) to electrical stimulation. Eight normal volunteers and 13 patients with musculoskeletal pain, somatoform pain disorders or nerve/root injury (with findings strictly limited to the distribution of the distribution of the involved nerve) were compared to 15 patients with Complex Regional Pain syndromes (one of whom had documented nerve injury). The Complex Regional Pain Syndromes (CRPS) patients were characterized by the presence of severe diffuse limb pain and extraterritorial sensory, sudomotor and vasomotor abnormalities (i.e., not confined to the site of injury or the distribution of the injured nerve). The CRPS patients were different from the normal controls and the non-CRPS patients in their tendency to warm significantly many of their limbs (not just the symptomatic ones). SSR were reduced or lost in a few limbs only in all three groups, irrespective of the increase or decrease of limb temperature and the side of symptoms. We argue that the enhanced thermogenic effect of SA in CRPS patients is due to generalized central changes of thermoregulatory control specifically in this group.

Effect of intravenous sodium amytal on cutaneous sensory abnormalities, spontaneous pain and algometric pain pressure thresholds in neuropathic pain patients: a placebo-controlled study. II

This study investigated the behaviour exhibited by 17 neuropathic pain patients (almost half of whom had documented neurological injury) with diffuse pain and extraterritorial sensory, sudomotor and vasomotor abnormalities, under the influence of intravenous administration of saline-controlled sodium amytal (SA), a medium action barbiturate. After SA (but not after normal saline) infusion, there was a dramatic and selective reduction of allodynia (touch-evoked pain) in all patients displaying this phenomenon, while pin prick and cold hypo- or hyperalgesia, as well as algometric pressure thresholds of the symptomatic limb (as a measurement of deep pain) were minimally changed in most patients. Spontaneous subjective pain was reduced substantially but not totally. The patients were able (once allodynia was eliminated) to recognize a deep-seated pain of which they were unaware before, evoked by firm but gentle palpation of the limb. Sympathetic blocks and A-fibre ischemic blocks in several patients and spinal stimulation in one patient produced effects identical to those observed during SA administration. The deep pain component was maintained despite elimination of allodynia even under stages of sleep induced by SA, at which time the patients would withdraw only the symptomatic limb upon firm but gentle palpation. We argue that neuropathic pain patients have two separate pain components, a cutaneous one (touch-evoked pain or allodynia) mediated by large fibres as a product of central sensitization, and a deep pain component mediated via nociceptors, which can be easily discriminated during systemic administration of SA.

Persistent neuropsychological deficits following whiplash: evidence for chronic mild traumatic brain injury?

OBJECTIVE

To investigate claims of neuropsychological evidence for acquired brain damage (axonal degeneration) in chronic whiplash.

DESIGN

Fifteen whiplash patients (Whiplash) were compared with 10 patients who had documented moderate-to-severe head injury (Mod-Sev), and with 24 patients who had chronic pain syndrome (CPS) and no history of head injury on two tests of mental efficiency considered highly sensitive to and specific for the subtle effects of brain trauma. All 3 groups, assessed 4 years after onset in a teaching hospital setting were matched for age, education, and IQ. Exclusion criteria included narcotics/benzo-diazepines or (suspected) malingering. Subjective ratings of depression and pain were collected as well as objective indices of outcome (return to work/school).

MEASURES

Neuropsychological test scores were subjected to ANOVA followed by regression analysis regarding the possible effects of age, IQ, pain, and mood ratings.

RESULTS

No differences between the Whiplash, Mod-Sev, or CPS groups on the neuropsychological tests emerged. IQ was strongly related to mental efficiency. Counterintuitively, Mod-Sev patients complained of less depression and pain than did Whiplash or CPS patients (where no differences were seen) and displayed a better outcome. Finally, although results from 3 of the original 18 patients in the Whiplash group were later discarded for malingering, no malingering was detected in the 2 other groups.

CONCLUSIONS

The theory of neuronal degeneration in the etiology of whiplash-related cognitive complaints was not supported, nor was the specificity of neuropsychological tests in detecting the subtle effects of brain trauma.

Compulsive targeted self-injurious behaviour in humans with neuropathic pain: a counterpart of animal autotomy? Four case reports and literature review

Four cases of compulsive self-injurious behaviour (SIB) with variable degrees of tissue damage targeted to the painful body part are reported in humans with neuropathic pain. Review of human literature revealed several cases, primarily after central nervous system (CNS) lesions, during which non-psychotic verbally communicating humans (mostly with intact mental status) target specifically the painful part which is usually analgesic or hypoalgesic. In few instances, however, the involved part is not only sentient but also hyperalgesic in part or as a whole. The act is characterized by uncontrollable urge and compulsion, aggravated under conditions of stress, isolation, confusion or depression, and occasionally occurring in patients with personality disorders, ongoing drug abuse and pre-existing compulsive habits (i.e., habitual nail biting or picking). It fails to be deterred by the appearance of the injured part, social mores or even the experience of pain. Successful treatment of underlying painful dysesthesiae with specific medications, neurostimulation or surgery has resulted in marked improvement of dysesthesiae accompanied by wound healing in several cases. The four presented cases and the human literature experience provide evidence that compulsive targeted SIB in humans with neuropathic pain and painful dysesthesiae is consistent with the concept that animal autotomy may result from chronic neuropathic pain after experimental peripheral or CNS lesions.

Thoracic outlet syndrome after motor vehicle accidents in a Canadian pain clinic population

OBJECTIVE

To record symptoms and signs, operative findings, and long-term outcome in operated and nonoperated patients with the diagnosis of thoracic outlet syndrome after a motor vehicle accident.

DESIGN

Descriptive prospective study.

SETTING

Pain clinic population in the Toronto Hospital (Western Division), Toronto, Ontario, Canada.

PATIENTS

Thirty-two patients diagnosed as having thoracic outlet syndrome after injuries sustained in a car accident (based on specific symptoms and signs as well as exclusion of other disorders generating brachialgia).

INTERVENTIONS

Conservative management versus transaxillary or supraclavicular exploration of the thoracic outlet.

OUTCOME MEASURES

Pain/symptom relief.

RESULTS

Most patients presented with pain and paresthesiae, but conspicuous discoloration of the symptomatic extremity was seen in 41%. Osseous anomalies were seen in 22% of the patients in simple neck x-rays. Vascular studies were abnormal in 24% of tested patients. During transaxillary first rib resection in 15 patients, 87% were found to have musculotendinous and less often osseous anomalies compromising primarily the lower trunk of the brachial plexus. Long-term follow up demonstrated very good pain relief (based on patients' estimates) only in 47% of the operated patients and 20% of the conservatively treated patients. Reoperation was necessary in six cases through a supraclavicular decompression with only one patient experiencing substantial improvement with long-term follow-up. The difficulties in diagnosis as well as reasons for failures of conservative and surgical management are discussed, and the authors' current protocol for diagnosis and management is presented.

Profile of Caucasian women with possible genetic predisposition to reflex sympathetic dystrophy: a pilot study

OBJECTIVES

To test possible human lymphocyte antigen (HLA) associations in subjects with reflex sympathetic dystrophy (RSD), and to determine correlation of HLA associations to treatment outcomes.

DESIGN

Identification of class I (HLA-A, B, C) and class II (HLA-DR and DQ) (MHC) antigens by well-defined reagents in patients with RSD.

SETTING AND PATIENTS

The HLA analysis was performed on 15 Caucasian women attending a university pain clinic and diagnosed with RSD on the basis of strict inclusion and exclusion criteria.

OUTCOME MEASURES

Resistance to treatment was defined on the basis of lack of response to conservative management, failure to experience long-term symptom relief after sympathetic blocks, recurrence of pain after sympathectomy, need for palliative treatment, and degree of residual disability at the end of all treatments.

RESULTS

A twofold increase of A3, B7, and DR2(15) MHC antigens was observed in the study population compared to control frequencies. Eighty (five of six) of DR2(15)-positive patients proved to be resistant to treatment.

CONCLUSIONS

The results of this pilot study are the first to suggest a possible genetic diathesis in RSD patients with poor treatment outcome. If this finding can be confirmed in larger studies, strictly defined RSD could constitute the third neuroimmune disorder (besides multiple sclerosis and narcolepsy) associated with DR2(15). Gene(s) conferring susceptibility to RSD may be present within or near the MHC region of the short arm of chromosome 6. Due to the small size of our study group it is imperative that larger studies be done in RSD patients employing strict diagnostic criteria to confirm or refute our original observations.

Effect of surgical sympathectomy on arterial blood flow in reflex sympathetic dystrophy: Doppler US assessment

PURPOSE

To assess duplex Doppler ultrasound (US) in providing objective, reproducible measurements of blood flow in patients with reflex sympathetic dystrophy (RSD) who underwent surgical sympathectomy.

MATERIALS AND METHODS

Findings in eight adult patients with RSD who were evaluated with arterial duplex Doppler US after surgical sympathetectomy were retrospectively reviewed. Pulsatility index (PI) and waveform characteristics were compared to clinical findings (temperature and sudomotor state) in sympathectomized limbs.

RESULTS

Warm and dry limbs yielded a consistently low PI (usually less than 2) and biphasic waveform. Cold and clammy limbs, which indicated failed sympathectomy, produced a high PI (usually greater than 4) and triphasic waveform. The Doppler waveform promptly reverted with the return of sympathetic tone in patients who had clinical relapse.

CONCLUSION

Duplex Doppler US may be useful for objective follow-up of RSD patients after sympathectomy.

Alterations of the three-phase bone scan after sympathectomy

OBJECTIVE

To evaluate alterations of the three-phase bone scan (TPBS) in patients with the clinical diagnosis of reflex sympathetic dystrophy (RSD) before and after surgical or chemical sympathectomy.

DESIGN

The TPBS was done after i.v. administration of 99technetium dimethylphosphonate. Scans were read by one blinded and one nonblinded reviewer (as to site of symptoms and procedure), using a visual grading system devised in our institution. Since there were no statistically significant differences between the two examiners' scores for blood flow, pool, and delayed phases, all scores were averaged and used for comparison before and after sympathectomy.

SUBJECTS

Ten women and four men with RSD were observed with 17 TPBSs before and 30 TPBSs after surgical (n = 6) or chemical (n = 8) sympathectomy.

RESULTS

All three phases of TPBS were significantly enhanced after sympathectomy in 11 of 14 patients in a pattern indistinguishable from that very commonly reported in florid RSD. The increased uptake occurred within 24 h after the procedure, normalized as early as 3 months in some scans, and remained abnormal in some patients in the 12-month follow-up period. In total, only 33% of all sympathectomies performed led to long-term symptom relief.

CONCLUSIONS

The data demonstrated that alterations in TPBS after sympathectomy are identical to those reported in early RSD and these alterations bear no relationship to the success of sympathectomy regarding pain relief. The mechanisms underlying alterations of TPBS as well as the potential mechanisms of sympathectomy failures are discussed.

Intermittent claudication caused by compression of tibial vessels as a result of calf muscle hypertrophy: case report

We present a case with findings suggestive of popliteal artery entrapment in a patient with intermittent claudication and localized muscle hypertrophy in the calf muscles after removal of a herniated disk. Angiography failed to demonstrate popliteal artery entrapment but instead revealed compression of the tibial vessels caused by calf muscle hypertrophy. The concept of muscle hypertrophy caused by denervation is also discussed.

Transient migratory osteoporosis: a variant of reflex sympathetic dystrophy? Report of 3 cases and literature review

Three cases of transient migratory osteoporosis treated with sympathetic blocks are described. Review of the literature in conjunction with the presentation and treatment of these 3 cases led to the formulation of a hypothesis of a common mechanism (mediated through the sympathetic nervous system) responsible for the profound osteoporosis and pain of reflex sympathetic dystrophy and transient migratory osteoporosis. Arguments are presented supporting transient migratory osteoporosis as a variant of the classical reflex sympathetic dystrophy.

Alterations in group Ia projections to motoneurons following spinal lesions in humans

1. The hypothesis that the exaggerated tendon jerks and stretch reflexes that follow chronic spinal cord lesions in humans result from alterations in transmission from group I muscle afferents to motoneurons was tested by making observations on nine normal subjects and 25 patients with spinal cord lesions. All the patients had increased tendon jerks, one-third of them had both increased tendon jerks and increased, velocity-dependent stretch reflexes (i.e.g spasticity). 2. Changes in the firing probability of single, voluntary-activated soleus or tibialis anterior motor units during stimulation of the muscle nerve below the threshold of the alpha-motoneuron axons were used to derive the characteristics of the postsynaptic potentials produced by group I volleys in single motoneurons. Paired stimuli were used to test how multiple volleys in group I muscle afferents were transmitted to motoneurons. 3. Stimulation of the posterior tibial nerve produced a short-latency period of increased firing probability representing the homonymous composite Ia excitatory postsynaptic potential (EPSP) in all soleus motoneurons tested. There was no detectable alteration in the magnitude, duration, or profile of the short-latency facilitation in the patients with spinal lesions when compared with normal subjects. 4. In patients with traumatic spinal cord lesions less than 8 wk in duration the magnitude of the facilitation representing the composite Ia EPSP was significantly larger than normal, although only one out of the four patients in this group had spasticity. 5. In the patients with the greatest spasticity, group I volleys produced a second period of facilitation 11-15 ms after the facilitation representing the composite Ia EPSP. This is presumed to represent enhanced transmission through polysynaptic pathways from group I afferents to motoneurons. 6. In normal subjects the facilitation of motoneurons produced by the second of two group I volleys is greater 5 and 10 ms after the first volley and less 20, 30, and 50 ms after the first volley. These changes involve at least two factors: 1) changes in excitability of peripheral nerves and 2) changes in transmission at the Ia-motoneuron synapse. 7. In patients with spinal lesions the facilitation produced by the second of two muscle-afferent volleys was less depressed at the 30-ms interstimulus interval. 8. Thus two separate abnormalities have been uncovered in human subjects with chronic spinal lesions: 1) a change in the transmission of multiple volleys from muscle afferents to motoneurons and 2) an increase in transmission through polysynaptic pathways from Ia afferents to motoneurons. Both could contribute to the increased tendon jerks and exaggerated stretch reflexes.

Chest wall pain after aortocoronary bypass surgery using internal mammary artery graft: a new pain syndrome?

During an 18-month period 11 patients were seen at the Toronto Western Hospital Pain Clinic 4 months to 5 years after internal mammary artery (IMA) bypass with a specific cluster of chest wall symptoms and signs confined to the site of IMA graft harvesting. Sympathetic ganglia blocks produced dramatic but temporary relief of symptoms in two of the most severely affected patients. In two other patients seen quite early after surgery, use of transcutaneous electrical stimulation produced considerable and permanent decrease of symptoms within 3 weeks. Such a chronic pain syndrome has not been previously reported in the literature. We postulate that IMA bypass surgery may be associated with a specific pain syndrome. This syndrome may arise from injury to the anterior branches of the intercostal nerves at the site of graft harvesting. Possible neurophysiologic mechanisms are discussed.

The evaluation of "spasticity"

Lesions of the upper motor neuron cause: 1. Alterations in segmental reflex activity. For example increased tendon jerks and velocity dependent stretch reflexes ("spasticity"), clonus, the clasp knife response, release of flexion reflexes and extensor plantar reflexes. 2. Impaired ability to activate motoneurons rapidly and selectively. Voluntary movements may also be restrained by co-contraction of antagonists muscles, by segmental reflexes (enhanced during voluntary effort) or by contractures. A combination of these factors may impair overall functional ability. Segmental reflexes, voluntary power and overall functional abilities can be assessed using clinical scoring systems. Recordings of muscle length, tension and EMG offer more objective measures of reflex and voluntary activity and of overall functions such as locomotion, and can separate weakness from co-contraction, spasticity from contracture. Methods are now available for exploring individual (transmitter specific) segmental reflex pathways and descending pathways in man. Lesions of the upper motor neuron are complicated by secondary changes in segmental neurons. Segmental reflex activity and muscle mechanics depend on the immediate past history of events. These factors must be taken into account.

Postsynaptic potentials in motoneurons caused by spinal cord stimulation in humans

Epidural spinal cord stimulation (SCS) causes facilitation and/or inhibition of spinal motoneurons many segments below the level of the cathode. On the assumption that a spinal cord pathway is activated by the cathode the conduction velocity of the fiber system responsible for the facilitation of soleus motoneurons was estimated to be between 21.5 and 27 m/sec. It is clear that SCS in man can generate postsynaptic potentials in spinal neurons and thus is capable of modifying transmission in spinal segmental pathways.