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1.  A Novel Tool for the Assessment of Pain: Validation in Low Back Pain 
PLoS Medicine  2009;6(4):e1000047.
Joachim Scholz and colleagues develop and validate an assessment tool that distinguishes between radicular and axial low back pain.
Adequate pain assessment is critical for evaluating the efficacy of analgesic treatment in clinical practice and during the development of new therapies. Yet the currently used scores of global pain intensity fail to reflect the diversity of pain manifestations and the complexity of underlying biological mechanisms. We have developed a tool for a standardized assessment of pain-related symptoms and signs that differentiates pain phenotypes independent of etiology.
Methods and Findings
Using a structured interview (16 questions) and a standardized bedside examination (23 tests), we prospectively assessed symptoms and signs in 130 patients with peripheral neuropathic pain caused by diabetic polyneuropathy, postherpetic neuralgia, or radicular low back pain (LBP), and in 57 patients with non-neuropathic (axial) LBP. A hierarchical cluster analysis revealed distinct association patterns of symptoms and signs (pain subtypes) that characterized six subgroups of patients with neuropathic pain and two subgroups of patients with non-neuropathic pain. Using a classification tree analysis, we identified the most discriminatory assessment items for the identification of pain subtypes. We combined these six interview questions and ten physical tests in a pain assessment tool that we named Standardized Evaluation of Pain (StEP). We validated StEP for the distinction between radicular and axial LBP in an independent group of 137 patients. StEP identified patients with radicular pain with high sensitivity (92%; 95% confidence interval [CI] 83%–97%) and specificity (97%; 95% CI 89%–100%). The diagnostic accuracy of StEP exceeded that of a dedicated screening tool for neuropathic pain and spinal magnetic resonance imaging. In addition, we were able to reproduce subtypes of radicular and axial LBP, underscoring the utility of StEP for discerning distinct constellations of symptoms and signs.
We present a novel method of identifying pain subtypes that we believe reflect underlying pain mechanisms. We demonstrate that this new approach to pain assessment helps separate radicular from axial back pain. Beyond diagnostic utility, a standardized differentiation of pain subtypes that is independent of disease etiology may offer a unique opportunity to improve targeted analgesic treatment.
Editors' Summary
Pain, although unpleasant, is essential for survival. Whenever the body is damaged, nerve cells detecting the injury send an electrical message via the spinal cord to the brain and, as a result, action is taken to prevent further damage. Usually pain is short-lived, but sometimes it continues for weeks, months, or years. Long-lasting (chronic) pain can be caused by an ongoing, often inflammatory condition (for example, arthritis) or by damage to the nervous system itself—experts call this “neuropathic” pain. Damage to the brain or spinal cord causes central neuropathic pain; damage to the nerves that convey information from distant parts of the body to the spinal cord causes peripheral neuropathic pain. One example of peripheral neuropathic pain is “radicular” low back pain (also called sciatica). This is pain that radiates from the back into the legs. By contrast, axial back pain (the most common type of low back pain) is confined to the lower back and is non-neuropathic.
Why Was This Study Done?
Chronic pain is very common—nearly 10% of American adults have frequent back pain, for example—and there are many treatments for it, including rest, regulated exercise (physical therapy), pain-killing drugs (analgesics), and surgery. However, the best treatment for any individual depends on the exact nature of their pain, so it is important to assess their pain carefully before starting treatment. This is usually done by scoring overall pain intensity, but this assessment does not reflect the characteristics of the pain (for example, whether it occurs spontaneously or in response to external stimuli) or the complex biological processes involved in pain generation. An assessment designed to take such factors into account might improve treatment outcomes and could be useful in the development of new therapies. In this study, the researchers develop and test a new, standardized tool for the assessment of chronic pain that, by examining many symptoms and signs, aims to distinguish between pain subtypes.
What Did the Researchers Do and Find?
One hundred thirty patients with several types of peripheral neuropathic pain and 57 patients with non-neuropathic (axial) low back pain completed a structured interview of 16 questions and a standardized bedside examination of 23 tests. Patients were asked, for example, to choose words that described their pain from a list provided by the researchers and to grade the intensity of particular aspects of their pain from zero (no pain) to ten (the maximum imaginable pain). Bedside tests included measurements of responses to light touch, pinprick, and vibration—chronic pain often alters responses to harmless stimuli. Using “hierarchical cluster analysis,” the researchers identified six subgroups of patients with neuropathic pain and two subgroups of patients with non-neuropathic pain based on the patterns of symptoms and signs revealed by the interviews and physical tests. They then used “classification tree analysis” to identify the six questions and ten physical tests that discriminated best between pain subtypes and combined these items into a tool for a Standardized Evaluation of Pain (StEP). Finally, the researchers asked whether StEP, which took 10–15 minutes, could identify patients with radicular back pain and discriminate them from those with axial back pain in an independent group of 137 patients with chronic low back pain. StEP, they report, accurately diagnosed these two conditions and was well accepted by the patients.
What Do These Findings Mean?
These findings indicate that a standardized assessment of pain-related signs and symptoms can provide a simple, quick diagnostic procedure that distinguishes between radicular (neuropathic) and axial (non-neuropathic) low back pain. This distinction is crucial because these types of back pain are best treated in different ways. In addition, the findings suggest that it might be possible to identify additional pain subtypes using StEP. Because these subtypes may represent conditions in which different pain mechanisms are acting, classifying patients in this way might eventually enable physicians to tailor treatments for chronic pain to the specific needs of individual patients rather than, as at present, largely guessing which of the available treatments is likely to work best.
Additional Information
Please access these Web sites via the online version of this summary at
This study is further discussed in a PLoS Medicine Perspective by Giorgio Cruccu and and Andrea Truini
The US National Institute of Neurological Disorders and Stroke provides a primer on pain in English and Spanish
In its 2006 report on the health status of the US, the National Center for Health Statistics provides a special feature on the epidemiology of pain, including back pain
The Pain Treatment Topics Web site is a resource, sponsored partly by associations and manufacturers, that provides information on all aspects of pain and its treatment for health care professionals and their patients
Medline Plus provides a brief description of pain and of back pain and links to further information on both topics (in English and Spanish)
The MedlinePlus Medical Encyclopedia also has a page on low back pain (in English and Spanish)
PMCID: PMC2661253  PMID: 19360087
2.  Glutamate-evoked jaw muscle pain as a model of persistent myofascial TMD pain? 
Archives of oral biology  2008;53(7):666-676.
Compare pain-related measures and psychosocial variables between glutamate-evoked jaw muscle pain in healthy subjects (HS) and patients with persistent myofascial temporomandibular disorder (TMD) pain.
47 female HS and 10 female patients with persistent myofascial TMD pain participated. The HS received an injection of glutamate into the masseter muscle to model persistent myofascial TMD pain. Participants filled out a coping strategies questionnaire (CSQ), the symptom checklist 90 (SCL-90) and McGill Pain Questionnaire (MPQ). Pain intensity was assessed on an electronic visual analog scale (VAS). Pain-drawing areas, Numerical Rating Scale (NRS) scores of unpleasantness, pressure pain thresholds (PPT) and tolerance (PPTOL) were measured. Unpaired t-tests and correlation tests were used for analyses.
The groups were significantly different when comparing the CSQ scores of control, decrease, diverting attention, increase of behavioral activities and somatization. The peak VAS pain, NRS of unpleasantness and MPQ scores were not significantly different between groups, but PPT and PPTOL were significantly lower in the TMD patients. Significant positive correlations were found in the TMD patients between peak VAS pain and CSQ catastrophizing score and SCL-90 somatization. The scores of PPTs and PPTOLs, in patients showed positive correlations with CSQ reinterpreting pain sensations scores and PPTs correlated with CSQ praying/hoping scores.
Glutamate-evoked pain responses in HS and persistent myofascial TMD pain have similar sensory-discriminative and affective-unpleasantness components but differ in psycho-social features. This study suggests that experimental designs based on glutamate injection into muscle can provide an appropriate model for elucidating persistent myofascial pain conditions.
PMCID: PMC2491493  PMID: 18313028
Orofacial pain; temporomandibular disorders; muscle pain; glutamate; trigeminal physiology; coping strategies questionnaire; catastrophizing; experimental muscle pain model
3.  An open-label, long-term study examining the safety and tolerability of pregabalin in Japanese patients with central neuropathic pain 
Journal of Pain Research  2014;7:439-447.
Studies of pregabalin for the treatment of central neuropathic pain have been limited to double-blind trials of 4–17 weeks in duration. The purpose of this study was to assess the long-term safety and tolerability of pregabalin in Japanese patients with central neuropathic pain. The efficacy of pregabalin was also assessed as a secondary measure.
Patients and methods
This was a 53-week, multicenter, open-label trial of pregabalin (150–600 mg/day) in Japanese patients with central neuropathic pain due to spinal cord injury, multiple sclerosis, or cerebral stroke.
A total of 103 patients received pregabalin (post-stroke =60; spinal cord injury =38; and multiple sclerosis =5). A majority of patients (87.4%) experienced one or more treatment-related adverse events, most commonly somnolence, weight gain, dizziness, or peripheral edema. The adverse event profile was similar to that seen in other indications of pregabalin. Most treatment-related adverse events were mild (89.1%) or moderate (9.2%) in intensity. Pregabalin treatment improved total score, sensory pain, affective pain, visual analog scale (VAS), and present pain intensity scores on the Short-Form McGill Pain Questionnaire (SF-MPQ) and ten-item modified Brief Pain Inventory (mBPI-10) total score at endpoint compared with baseline. Improvements in SF-MPQ VAS and mBPI-10 total scores were evident in all patient subpopulations. Mean changes from baseline in SF-MPQ VAS and mBPI-10 scores at endpoint were −20.1 and −1.4, respectively.
These findings demonstrate that pregabalin is generally well tolerated and provides sustained efficacy over a 53-week treatment period in patients with chronic central neuropathic pain.
PMCID: PMC4122555  PMID: 25114584
clinical trial; spinal cord injury; multiple sclerosis; cerebral stroke
4.  Pain in Portuguese Patients with Multiple Sclerosis 
Early reports often ignored pain as an important symptom in multiple sclerosis (MS). Pain prevalence figures in MS from European countries other than Portugal range between 40 and 65%. To our knowledge there is no published data in English on pain in MS in Portugal. We describe the demographic and clinical characteristics, with an emphasis on pain, of 85 MS patients followed-up in a Portuguese hospital, contributing to pain epidemiology in MS. Patients were interviewed sequentially after their regular appointments at the MS clinic; patients with pain completed The Brief Pain Inventory and The McGill Pain Questionnaire (MPQ). The prevalence of pain found was 34%. Headache and back pain were the most common anatomical sites described, followed by upper and lower limbs. Intensity of pain in an 11-point scale was, for the maximum pain intensity 6.7 ± 1.8, for the minimum pain intensity 2.2 ± 2.0, for the mean pain intensity 4.5 ± 1.5, and for the actual pain intensity 2.4 ± 2.9. Pain interfered significantly with general activity, mood, work, social relations, and enjoyment of life. All MS patients with pain employed words from both the sensory and affective categories of the MPQ to describe it. Patient pain descriptions’ included the word “hot-burning” in 59% of the cases, common in the report of central pain, but neuropathic pain medications were only used by 10% of them. Pain is an important symptom in Portuguese patients with MS, not only because of the high prevalence found, concordant with other European countries, but also because of its interference with quality-of-life.
PMCID: PMC3071492  PMID: 21503136
multiple sclerosis; pain; quality-of-life; epidemiology; Europe
5.  Chronic pain associated with the Chikungunya Fever: long lasting burden of an acute illness 
Chikungunya virus (CHIKV) is responsible for major epidemics worldwide. Autochthonous cases were recently reported in several European countries. Acute infection is thought to be monophasic. However reports on chronic pain related to CHIKV infection have been made. In particular, the fact that many of these patients do not respond well to usual analgesics suggests that the nature of chronic pain may be not only nociceptive but also neuropathic. Neuropathic pain syndromes require specific treatment and the identification of neuropathic characteristics (NC) in a pain syndrome is a major step towards pain control.
We carried out a cross-sectional study at the end of the major two-wave outbreak lasting 17 months in Réunion Island. We assessed pain in 106 patients seeking general practitioners with confirmed infection with the CHIK virus, and evaluated its impact on quality of life (QoL).
The mean intensity of pain on the visual-analogical scale (VAS) was 5.8 ± 2.1, and its mean duration was 89 ± 2 days. Fifty-six patients fulfilled the definition of chronic pain. Pain had NC in 18.9% according to the DN4 questionnaire. Conversely, about two thirds (65%) of patients with NC had chronic pain. The average pain intensity was similar between patients with or without NC (6.0 ± 1.7 vs 6.1 ± 2.0). However, the total score of the Short Form-McGill Pain Questionnaire (SF-MPQ)(15.5 ± 5.2 vs 11.6 ± 5.2; p < 0.01) and both the affective (18.8 ± 6.2 vs 13.4 ± 6.7; p < 0.01) and sensory subscores (34.3 ± 10.7 vs 25.0 ± 9.9; p < 0.01) were significantly higher in patients with NC. The mean pain interference in life activities calculated from the Brief Pain Inventory (BPI) was significantly higher in patients with chronic pain than in patients without it (6.8 ± 1.9 vs 5.9 ± 1.9, p < 0.05). This score was also significantly higher in patients with NC than in those without such a feature (7.2 ± 1.5 vs 6.1 ± 1.9, p < 0.05).
There exists a specific chronic pain condition associated to CHIKV. Pain with NC seems to be associated with more aggressive clinical picture, more intense impact in QoL and more challenging pharmacological treatment.
PMCID: PMC2833164  PMID: 20170492
6.  Pain Quality Predicts Lidocaine Analgesia among Patients with Suspected Neuropathic Pain 
Pain medicine (Malden, Mass.)  2010;11(4):617-621.
Oral sodium channel blockers have shown mixed results in randomized controlled trials despite the known importance of sodium channels in generating pain. We hypothesized that differing baseline pain qualities (e.g. “stabbing” vs “dull”) might define specific subgroups responsive to intravenous (IV) lidocaine—a potent sodium channel blocker.
A prospective cohort study of 71 patient with chronic pain suspected of being neuropathic were recruited between January 2003 and July 2007 and underwent lidocaine infusions at Stanford University Hospital in a single-blind nonrandomized fashion. Baseline sensory pain qualities were measured with the Short-Form McGill Pain Questionnaire (SF-MPQ). Pain intensity was measured with a visual analog scale (VAS).
Factor analysis demonstrated two underlying pain quality factors among SF-MPQ sensory items: a heavy pain and a stabbing pain. Baseline heavy pain quality, but not stabbing quality predicted subsequent relief of pain intensity in response to lidocaine. In contrast, these factors did not predict divergent analgesic responses to placebo infusions. In response to each 1 mcg/mL increase in lidocaine plasma level, patients with high heavy pain quality drop their VAS 0.24 (95% CI 0.05–0.43) more points than those with low heavy pain quality (P < 0.013).
“Heavy” pain quality may indentify patients with enhanced lidocaine responsiveness. Pain quality may identify subgroups among patients with suspected neuropathic pain responsive to IV lidocaine. Further investigation is warranted to validate and extend these findings.
PMCID: PMC2913605  PMID: 20210867
Lidocaine; Pain; Neuropathic Pain; Pain Quality; Sodium Channel Blockade; Intravenous Lidocaine; McGill Pain Questionnaire; Factor Analysis
7.  Short-Term Change of Handgrip Strength After Trigger Point Injection in Women With Muscular Pain in the Upper Extremities 
Annals of Rehabilitation Medicine  2014;38(2):241-248.
To determine overall handgrip strength (HGS), we assessed the short-term change of HGS after trigger point injection (TPI) in women with muscular pain in the upper extremities by comparison with established pain scales.
The study enrolled 50 female patients (FMS with MPS group: 29 patients with combined fibromyalgia [FMS] and myofascial pain syndrome [MPS]; MPS group: 21 patients with MPS) who presented with muscular pain in the upper extremities at Konyang University Hospital. In addition, a total of 9 healthy women (control group) were prospectively enrolled in the study. We surveyed the three groups using the following established pain scales: the Fibromyalgia Impact Questionnaire (FIQ), the 36-Item Short Form Health Survey (SF-36), and the Short Form McGill Pain Questionnaire (MPQ). HGS was measured in both hands of study participants using a handgrip dynamometer. We performed TPI (0.5% lidocaine, total 10 mL, injected at the pain site of upper extremities). After 20 minutes, we remeasured the patient's HGS and MPQ score.
ANOVA analysis was conducted among groups. Based on Tukey multiple comparison test, the majority of FIQ and SF-36 subscales, total FIQ and SF-36 scores, MPQ and HGS were significantly different between FMS with MPS and the other groups. There was no statistically significant difference between MPS and control groups. Higher HGS was positively associated with enhanced physical function, negatively associated with total FIQ and MPQ scores, and positively associated with the total SF-36 score calculated using Spearman correlation. Post-TPI MPQ decreased and HGS increased. In patient groups, a negative correlation was found between MPQ and HGS.
The HGS test might potentially be a complementary tool in assessing the short-term treatment effects of women with muscular pain in the upper extremities.
PMCID: PMC4026611  PMID: 24855619
Fibromyalgia; Hand strength; Trigger point injection
8.  Pain characteristic differences between subacute and chronic back pain 
Back pain is commonly classified based on duration. There is currently limited information regarding differences in the clinical features of back pain between these duration-based groupings. Here, we compared the pain characteristics of patients with subacute (SBP; pain 6–16 weeks, n = 40) and chronic back pain (CBP; pain ≥ 1year, n = 37) recruited from the general population. CBP patients reported significantly higher pain intensity on the Visual Analogue Scale (VAS) compared to SBP patients. Based on this finding, we investigated group differences and their dependence on VAS for the Beck Depression Inventory (BDI), sensory and affective dimensions of the McGill Pain Questionnaire (MPQ-S and MPQ-A), Neuropathic Pain Scale (NPS) and the variability of spontaneous pain. Correction for VAS abolished significant group differences on the MPQ-S, MPQ-A and NPS. Only a significant difference in the variability of spontaneous pain was independent of VAS. Finally, whereas SBP patients displayed a higher incidence of unilateral pain radiating down the legs/buttocks, there was a shift towards more bilateral pain in CBP patients. In summary, SBP and CBP groups differ on three independent parameters: VAS ratings, pain location and temporal dynamics of spontaneous pain.
PMCID: PMC3130842  PMID: 21497139
Low Back Pain; Chronic Back Pain (CBP); Subacute Back Pain (SBP); Pain Intensity; Visual Analogue Scale (VAS); McGill Pain Questionnaire (MPQ); Fractal Dimension
9.  Pain-QuILT: Clinical Feasibility of a Web-Based Visual Pain Assessment Tool in Adults With Chronic Pain 
Chronic pain is a prevalent and debilitating problem. Accurate and timely pain assessment is critical to pain management. In particular, pain needs to be consistently tracked over time in order to gauge the effectiveness of different treatments. In current clinical practice, paper-based questionnaires are the norm for pain assessment. However, these methods are not conducive to capturing or tracking the complex sensations of chronic pain. Pain-QuILT (previously called the Iconic Pain Assessment Tool) is a Web-based tool for the visual self-report and tracking of pain (quality, intensity, location, tracker) in the form of time-stamped records. It has been iteratively developed and evaluated in adolescents and adults with chronic pain, including usability testing and content validation. Clinical feasibility is an important stepping-stone toward widespread implementation of a new tool. Our group has demonstrated Pain-QuILT clinical feasibility in the context of a pediatric chronic pain clinic. We sought to extend these findings by evaluating Pain-QuILT clinical feasibility from the perspective of adults with chronic pain, in comparison with standard paper-based methods (McGill Pain Questionnaire [MPQ] and Brief Pain Inventory [BPI]).
The goal of our study was to assess Pain-QuILT for (1) ease of use, (2) time for completion, (3) patient preferences, and (4) to explore the patterns of self-reported pain across the Pain-QuILT, MPQ, and BPI.
Participants were recruited during a scheduled follow-up visit at a hospital-affiliated pain management and physical rehabilitation clinic in southwestern Ontario. Participants self-reported their current pain using the Pain-QuILT, MPQ, and BPI (randomized order). A semistructured interview format was used to capture participant preferences for pain self-report.
The sample consisted of 50 adults (54% female, 27/50) with a mean age of 50 years. Pain-QuILT was rated as significantly easier to use than both the MPQ and BPI (P<.01) and was also associated with the fewest difficulties in completion. On average, the time to complete each tool was less than 5 minutes. A majority of participants (58%, 29/50) preferred Pain-QuILT for reporting their pain over alternate methods (16%, 8/50 for MPQ; 14%, 7/50 for BPI; 12%, 6/50 for “other”). The most commonly chosen pain descriptors on MPQ were matched with Pain-QuILT across 91% of categories. There was a moderate-to-high correlation between Pain-QuILT and BPI scores for pain intensity (r=.70, P<.01).
The results of this clinical feasibility study in adults with chronic pain are consistent with our previously published pediatric findings. Specifically, data indicate that Pain-QuILT is (1) easy to use, (2) quick to complete, (3) preferred by a majority of patients, and (4) correlated as expected with validated pain measures. As a digital, patient-friendly method of assessing and tracking pain, we conclude that Pain-QuILT has potential to add significant value as one standard component of chronic pain management.
PMCID: PMC4034112  PMID: 24819478
chronic pain; assessment tool; Internet; clinical feasibility
Predictive validity of each word from the McGill Pain Questionnaire (MPQ) has not been investigated independent of pain etiology. The purpose of this study was to explore differences in the words used to describe nociceptive and neuropathic pain. Patients with lung cancer (N = 123) selected words from the 78 MPQ pain quality descriptors and indicated the corresponding pain site for each word. Using only the MPQ pain location and the disease and treatment data abstracted from medical records, each pain site was classified as nociceptive, neuropathic (etiology). Pain etiology and quality descriptors were tested for proportional differences. Of the 457 pain sites, 343 were classified as nociceptive (75%), 114 as neuropathic (25%). Lacerating, stinging, terrifying and suffocating were selected for a significantly larger proportion of nociceptive sites whereas throbbing, aching, numb, tender, punishing, pulling, tugging, pricking, punishing, miserable, and nagging were selected for a larger proportion of neuropathic sites. Interestingly, several pain quality descriptors (burning, shooting, flashing, tingling, itching, and cold) previously associated with neuropathic pain did not distinguish between neuropathic and nociceptive pain etiologies in this lung cancer sample. Infrequent selection of most MPQ words and lack of neurological exam data in the categorizing scheme are possible explanation for inconsistency with previous literature. Prospective investigations are needed to validate pain quality descriptors for nociceptive and neuropathic types of pain.
PMCID: PMC3682837  PMID: 11728793
Classification of Pain; Lung Neoplasms; Pain Quality Descriptors; Human
11.  Somatosensory Profiles but Not Numbers of Somatosensory Abnormalities of Neuropathic Pain Patients Correspond with Neuropathic Pain Grading 
PLoS ONE  2012;7(8):e43526.
Due to the lack of a specific diagnostic tool for neuropathic pain, a grading system to categorize pain as ‘definite’, ‘probable’, ‘possible’ and ‘unlikely’ neuropathic was proposed. Somatosensory abnormalities are common in neuropathic pain and it has been suggested that a greater number of abnormalities would be present in patients with ‘probable’ and ‘definite’ grades. To test this hypothesis, we investigated the presence of somatosensory abnormalities by means of Quantitative Sensory Testing (QST) in patients with a clinical diagnosis of neuropathic pain and correlated the number of sensory abnormalities and sensory profiles to the different grades. Of patients who were clinically diagnosed with neuropathic pain, only 60% were graded as ‘definite’ or ‘probable’, while 40% were graded as ‘possible’ or ‘unlikely’ neuropathic pain. Apparently, there is a mismatch between a clinical neuropathic pain diagnosis and neuropathic pain grading. Contrary to the expectation, patients with ‘probable’ and ‘definite’ grades did not have a greater number of abnormalities. Instead, similar numbers of somatosensory abnormalities were identified for each grade. The profiles of sensory signs in ‘definite’ and ‘probable’ neuropathic pain were not significantly different, but different from the ‘unlikely’ grade. This latter difference could be attributed to differences in the prevalence of patients with a mixture of sensory gain and loss and with sensory loss only. The grading system allows a separation of neuropathic and non-neuropathic pain based on profiles but not on the total number of sensory abnormalities. Our findings indicate that patient selection based on grading of neuropathic pain may provide advantages in selecting homogenous groups for clinical research.
PMCID: PMC3425512  PMID: 22927981
12.  Gender differences in pain characteristics of chronic stable angina and perceived physical limitation in patients with coronary artery disease 
Pain  2003;101(0):45-53.
Chronic stable angina pectoris, the chest pain associated with reversible myocardial ischemia has detrimental effects on health-related quality of life, particularly in women. The limited research on gender differences in chronic stable angina suggests that angina may be experienced differently in women and that women report greater functional disability related to angina symptoms. No studies have examined gender differences in chronic stable angina from a multidimensional pain perspective or have included reliable and valid measures of pain that would facilitate comparing chronic angina patients with other chronic pain populations. The purpose of this descriptive study was to examine gender differences in characteristics of chronic stable angina using the short-form McGill pain questionnaire (SF-MPQ) and to explore relationships among these pain characteristics and perceived limitation in performing physical activities in patients with coronary artery disease (CAD) (physical limitation subscale of the Seattle angina questionnaire). One hundred and twenty-eight subjects (30.5% women) with stable CAD and angina pectoris documented by a cardiologist completed study questionnaires in an outpatient cardiology clinic. Results of the study suggest that men and women with chronic stable angina had more similarities than differences in chest pain characteristics. No significant gender differences were demonstrated in total sensory or affective intensity scores, the present pain intensity index, or the number of pain words chosen. However, women did report significantly greater pain intensity on the SF-MPQ visual analogue scale. Women were also significantly more likely to describe their chronic angina as ‘hot-burning’ and ‘tender’ and to have greater intensity of pain for these two descriptors. Despite the similarities in pain characteristics, women reported greater physical limitation related to anginal pain. The variables of social status and years diagnosed with CAD significantly interacted with gender in predicting physical limitation suggesting that gender-specific models of physical limitation in angina patients need to be explored. To our knowledge, this is one of the first studies that has assessed chronic anginal pain using a reliable and valid generic pain instrument. More research is needed to better understand the nature of gender differences in functional limitation secondary to anginal pain and the physiologic, cognitive-perceptual and psychosocial mechanisms that lead to angina-related functional disability.
PMCID: PMC4310562  PMID: 12507699
McGill pain questionnaire – short form; Gender differences; Physical functional limitation; Quality of life
13.  Pain in castration-resistant prostate cancer with bone metastases: a qualitative study 
Bone metastases are a common painful and debilitating consequence of castration-resistant prostate cancer (CPRC). Bone pain may predict patients' prognosis and there is a need to further explore CRPC patients' experiences of bone pain in the overall context of disease pathology. Due to the subjective nature of pain, assessments of pain severity, onset and progression are reliant on patient assessment. Patient reported outcome (PRO) measures, therefore, are commonly used as key endpoints for evaluating the efficacy of CRPC treatments. Evidence of the content validity of leading PRO measures of pain severity used in CRPC clinical trials is, however, limited.
To document patients' experience of CRPC symptoms including pain, and their impact on health-related quality of life (HRQL), semi-structured in-depth qualitative interviews were conducted with 17 patients with CRPC and bone metastases. The content validity of the Present Pain Intensity (PPI) scale from the McGill Pain Questionnaire (MPQ), and the 'Average Pain' and 'Worst Pain' items of the Brief Pain Inventory Short-Form (BPI-SF) was also assessed.
Patients with CRPC and bone metastases present with a constellation of symptoms that can have a profound effect on HRQL. For patients in this study, bone pain was the most prominent and debilitating symptom associated with their condition. Bone pain was chronic and, despite being generally well-managed by analgesic medication, instances of breakthrough cancer pain (BTcP) were common. Cognitive debriefing of the selected PRO measures of pain severity highlighted difficulties among patients in understanding the verbal response scale (VRS) of the MPQ PPI scale. There were also some inconsistencies in the way in which the BPI-SF 'Average Pain' item was interpreted by patients. In contrast, the BPI-SF 'Worst Pain' item was well understood and interpreted consistently among patients.
Study findings support the importance of PRO measures of pain severity as key endpoints for evaluating the efficacy of treatments for CRPC, particularly for patients with bone metastases where episodes of BTcP are common. Qualitative evidence from CRPC patients supports the content validity of the BPI-SF ''Worst Pain' item and promotes use of this item for measuring pain severity in this population.
PMCID: PMC3222603  PMID: 21992720
14.  Neuropathic pain and use of PainDETECT in patients with fibromyalgia: a cohort study 
BMC Neurology  2013;13:21.
Fibromyalgia has a plethorae of symptoms, which can be confusing and even misleading. Accurate evaluation is necessary when patients with fibromyalgia are treated. Different types of instruments are available for the clinicians to supplement evaluation. Our objective was to study the applicability of the PainDETECT instrument to screen neuropathic pain in patients with fibromyalgia.
158 patients with primary fibromyalgia underwent a neurological examination including bedside sensory testing. They also fulfilled four questionnaires: PainDETECT, Beck depression inventory IA (BDI IA), Fibromyalgia Impact Questionnaire (FIQ) and a self-made questionnaire regarding present pain and pain relieving methods of the patients. The results of the clinical evaluation and questionnaires were then compared.
Clinically verified neuropathic pain was diagnosed in 53/158 [34% (95% Cl: 26 to 41)] patients. The ROC curve achieved a maximum Youden´s index at score of 17 when sensitivity was 0.79 (95% Cl: 0.66 to 0.89) and specificity 0.53 (95% Cl: 0.43 to 0.63). The PainDETECT total score (OR: 1.14 95% Cl: 1.06 to 1.22), FM as the worst current pain (OR: 0.31; 95% 0.16 to 0.62), body mass index (BMI) (OR: 1.05; 95% Cl: 1.00 to 1.11) and the intensity of current pain (OR: 1.20; 95% Cl: 1.01 to 1.41) were significantly associated with the presence of neuropathic pain in univariate analyses.
This study highlights the importance of thorough clinical examination. The Neuropathic pain screening tool PainDETECT is not as useful in patients with fibromyalgia as in patients with uncompromised central pain control.
PMCID: PMC3582578  PMID: 23409793
15.  Neuropathic and nociceptive pain in head and neck cancer patients receiving radiation therapy 
Head & Neck Oncology  2009;1:26.
Pain is common in head and neck cancer (HNC) patients and may be attributed to the malignancy and/or cancer treatment. Pain mechanisms and patient report of pain in HNC are expected to include both nociceptive and neuropathic components. The purpose of this study was to assess the trajectory of orofacial and other pain during and following treatment, using patient reports of neuropathic pain and nociceptive pain and pain impact.
124 consecutive HNC patients receiving radiation therapy (RT) (95 men, 29 women; mean age: 54.7 ± 12.3 years) participated in a patient-reported outcome (PRO) assessment. Patients completed the McGill Pain Questionnaire three times during therapy and 3 months following study entry.
The majority of patients related their pain to the tumor and/or cancer treatment. Whereas 59% reported their pain to be less severe than they expected, 29% were not satisfied with their level of pain despite pain management during cancer therapy. Worst pain was 3.0 ± 1.3 on a 0- to 5-point verbal descriptor scale. Pain intensity was present at entry, highest at 2-week follow-up, declining towards the end of treatment and persisting at 3-month follow-up. The most common neuropathic pain descriptors chosen were aching (20%) and burning (27%); nociceptive words chosen were dull (22%), sore (32%), tender (35%), and throbbing (23%), and affective/evaluative descriptors were tiring (25%) and annoying (41%). 57% of patients reported continuous pain, and combined continuous and intermittent pain was reported by 79% of patients.
This study provides evidence that patients with HNC experience nociceptive and neuropathic pain during RT despite ongoing pain management. The affective and evaluative descriptors chosen for head and neck pain indicate considerable impact on quality of life even with low to moderate levels of pain intensity. These findings suggest that clinicians should consider contemporary management for both nociceptive and neuropathic pain in head and neck cancer patients.
PMCID: PMC2717963  PMID: 19594943
16.  Effect of optically modified polyethylene terephthalate fiber socks on chronic foot pain 
Increasing experimental and clinical evidence suggests that illumination of the skin with relatively low intensity light may lead to therapeutic results such as reduced pain or improved wound healing. The goal of this study was to evaluate prospectively whether socks made from polyethylene terephthalate (PET) incorporating optically active particles (Celliant™) ameliorates chronic foot pain resulting from diabetic neuropathy or other disorders. Such optically modified fiber is thought to modify the illumination of the skin in the visible and infrared portions of the spectrum, and consequently reduce pain.
A double-blind, randomized trial with 55 subjects (38 men, 17 women) enrolled (average age 59.7 ± 11.9 years), 26 with diabetic neuropathy and 29 with other pain etiologies. Subjects twice completed the Visual Analogue Scale (VAS), Brief Pain Inventory (BPI), McGill Pain Questionnaire (MPQ), and SF-36 a week apart (W1+2) before receiving either control or Celliant™ socks. The same questionnaires were answered again one and two weeks (W3+4) later. The questionnaires provided nine scores for analyzing pain reduction: one VAS score, two BPI scores, five MPQ scores, and the bodily pain score on the SF-36. Mean W1+2 and W3+4 scores were compared to measure pain reduction.
More pain reduction was reported by Celliant™ subjects for 8 of the 9 pain questions employed, with a significant (p = 0.043) difference between controls and Celliant™ for McGill question III. In neuropathic subjects, Celliant™ caused more pain reduction in 6 of the 9 questions, but not significantly. In non-neuropathic subjects 8 of 9 questions showed more pain reduction with the Celliant™ socks.
Socks with optically modified PET (Celliant™) appear to have a beneficial impact on chronic foot pain. The mechanism could be related to the effects seen with illumination of tissues with visible and infrared light.
Trial Registration NCT00458497
PMCID: PMC2680395  PMID: 19386127
17.  Sensory profile and its impact on quality of life in patients with painful diabetic polyneuropathy 
Painful diabetic polyneuropathy (PDN) is common and causes significant disability. The sensory profile in each patient is different and affects quality of life.
To describe the demographic, details of sensory profile and its impact on quality of life in patients with PDN.
Settings and Design:
A cross-sectional survey in patients with PDN who were treated in a University Hospital.
Materials and Methods:
They were interviewed with standard questionnaires, which included neuropathic pain scale (NPS), a short-form McGill Pain Questionnaire (SF-MPQ) and a short form-36 quality of life survey (SF-36).
Statistical Analysis Used:
Descriptive statistics were used in demographic data. Student's t test was used to analyze continuous data. Multiple comparisons for proportions and correlations were made using Fisher Exact test and Pearson's coefficient of correlation, respectively.
Thirty three patients were included in this study. In NPS, sharp pain was the most common symptom and itching was the least common. Almost all patients had more than one type of pain. The mean VAS was 53 mm. In SFMPQ, the sensory score, affective score and the present pain score fell in the moderate range. In SF-36, physical functioning was the most affected and social function was the least affected.
PDN significantly affects patients’ quality of life, especially physical function and role limitation due to a physical problem. Almost all patients have many types of pain and sharp pain is the most common.
PMCID: PMC3821410  PMID: 24250157
Pain; polyneuropathy; quality of life; sensory profile; type 2 diabetes
18.  Prevalence of myofascial pain in general internal medicine practice. 
Western Journal of Medicine  1989;151(2):157-160.
Myofascial pain is a regional pain syndrome characterized in part by a trigger point in a taut band of skeletal muscle and its associated referred pain. We examined a series of 172 patients presenting to a university primary care general internal medicine practice. Of 54 patients whose reason for a visit included pain, 16 (30%) satisfied criteria for a clinical diagnosis of myofascial pain. These patients were similar in age and sex to other patients with pain, and the frequency of pain as a primary complaint was similar for myofascial pain as compared with other reasons for pain. The usual intensity of myofascial pain as assessed by a visual analog scale was high, comparable to or possibly greater than pain due to other causes. Patients with upper body pain were more likely to have myofascial pain than patients with pain located elsewhere. Physicians rarely recognized the myofascial pain syndrome. Commonly applied therapies for myofascial pain provided substantial abrupt reduction in pain intensity. The prevalence and severity of myofascial pain in this university internal medicine setting suggest that regional myofascial pain may be an important cause of pain complaints in the practice of general internal medicine.
PMCID: PMC1026905  PMID: 2788962
19.  Evaluation of the Psychometric Properties of the Revised Short-Form McGill Pain Questionnaire (SF-MPQ-2) 
The recently revised version of the Short-Form McGill Pain Questionnaire (SF-MPQ-2) was created to assess both neuropathic and non-neuropathic pain. The current study extends prior research by testing the reliability and validity of the SF-MPQ-2 in a sample of U.S. veteran patients with a range of chronic pain diagnoses. Participants (N = 186) completed the SF-MPQ-2, a sociodemographic questionnaire, the Structured Clinical Interview for the DSM-IV, and self-report pain and psychiatric measures. Pain diagnoses were extracted from the electronic medical record. The SF-MPQ-2 total and scale scores demonstrated good to excellent internal consistency. Convergent and discriminant validity were supported, and SF-MPQ-2 total and scale scores increased with number of pain diagnoses and pain severity. Confirmatory factor analyses indicated a four-factor model fit the data better than a single-factor model. However, high intercorrelations among the four latent constructs were observed, and a 2nd-order global pain construct also emerged. Overall, the SF-MPQ-2 demonstrated excellent reliability and validity in a sample of U.S. veteran patients with chronic neuropathic and non-neuropathic pain. Future psychometric studies of the SF-MPQ-2 should employ longitudinal data to evaluate the ability of scale scores to uniquely predict clinical and health service outcomes.
PMCID: PMC3513374  PMID: 23182230
Chronic Pain; McGill Pain Questionnaire; Psychometric; Reliability; Validity
20.  Myofascial pain in patients waitlisted for total knee arthroplasty 
Knee pain is one of the major sources of pain and disability in developed countries, particularly in aging populations, and is the primary indication for total knee arthroplasty (TKA) in patients with osteoarthritis (OA).
To determine the presence of myofascial pain in OA patients waitlisted for TKA and to determine whether their knee pain may be alleviated by trigger point injections.
Following ethics approval, 25 participants were recruited from the wait list for elective unilateral primary TKA at the study centre. After providing informed consent, all participants were examined for the presence of active trigger points in the muscles surrounding the knee and received trigger point injections of bupivacaine. Assessments and trigger point injections were implemented on the first visit and at subsequent visits on weeks 1, 2, 4 and 8. Outcome measures included the Timed Up and Go test, Brief Pain Inventory, Centre for Epidemiologic Studies Depression Scale, State-Trait Anxiety Inventory and Short-Form McGill Pain Questionnaire.
Myofascial trigger points were identified in all participants. Trigger point injections significantly reduced pain intensity and pain interference, and improved mobility. All participants had trigger points identified in medial muscles, most commonly in the head of the gastrocnemius muscle. An acute reduction in pain and improved functionality was observed immediately following intervention, and persisted over the eight-week course of the investigation.
All patients had trigger points in the vastus and gastrocnemius muscles, and 92% of patients experienced significant pain relief with trigger point injections at the first visit, indicating that a significant proportion of the OA knee pain was myofascial in origin. Further investigation is warranted to determine the prevalence of myofascial pain and whether treatment delays or prevents TKA.
PMCID: PMC3465092  PMID: 23061082
Myofascial pain; Osteoarthritis; Pain assessment; Total knee replacement; Trigger point
21.  Guidelines in the management of diabetic nerve pain: clinical utility of pregabalin 
Diabetic peripheral neuropathy is a common complication of diabetes. It presents as a variety of syndromes for which there is no universally accepted unique classification. Sensorimotor polyneuropathy is the most common type, affecting about 30% of diabetic patients in hospital care and 25% of those in the community. Pain is the reason for 40% of patient visits in a primary care setting, and about 20% of these have had pain for greater than 6 months. Chronic pain may be nociceptive, which occurs as a result of disease or damage to tissue with no abnormality in the nervous system. In contrast, neuropathic pain is defined as “pain arising as a direct consequence of a lesion or disease affecting the somatosensory system.” Persistent neuropathic pain interferes significantly with quality of life, impairing sleep and recreation; it also significantly impacts emotional well-being, and is associated with depression, anxiety, and noncompliance with treatment. Painful diabetic peripheral neuropathy is a difficult-to-manage clinical problem, and patients with this condition are more apt to seek medical attention than those with other types of diabetic neuropathy. Early recognition of psychological problems is critical to the management of pain, and physicians need to go beyond the management of pain per se if they are to achieve success. This evidence-based review of the assessment of the patient with pain in diabetes addresses the state-of-the-art management of pain, recognizing all the conditions that produce pain in diabetes and the evidence in support of a variety of treatments currently available. A search of the full Medline database for the last 10 years was conducted in August 2012 using the terms painful diabetic peripheral neuropathy, painful diabetic peripheral polyneuropathy, painful diabetic neuropathy and pain in diabetes. In addition, recent reviews addressing this issue were adopted as necessary. In particular, reports from the American Academy of Neurology and the Toronto Consensus Panel on Diabetic Neuropathy were included. Unfortunately, the results of evidence-based studies do not necessarily take into account the presence of comorbidities, the cost of treatment, or the role of third-party payers in decision-making. Thus, this review attempts to give a more balanced view of the management of pain in the diabetic patient with neuropathy and in particular the role of pregabalin.
PMCID: PMC3587397  PMID: 23467255
diabetes mellitus; painful neuropathy; pain; treatment; pregabalin
22.  Confirmatory factor analysis of the Korean version of the short-form McGill pain questionnaire with chronic pain patients: a comparison of alternative models 
The Short Form of the McGill Pain Questionnaire (SF-MPQ) is the most widely used assessment of the quality and intensity of pain. In previous validation studies, the factor structure of the SF-MPQ varied widely from various two-factor structures to a five-factor structure, although research on the SF-MPQ quite consistently supports its two-factor structure (i.e., sensory and affective) across different countries and languages. In Korea, the results of exploratory factor analysis of a Korea version of SF-MPQ (KSF-MPQ) showed 2-factor structure consisting of ‘sensory’ and ‘affective’ excluding two items such as splitting and heavy. As an attempt to further validate the KSF-MPQ, the purpose of this study was to confirm whether the KSF-MPQ model is an appropriate model for chronic pain patients in Korea by comparing several alternative models of the SF-MPQ.
A total of 150 chronic pain patients seeking treatment in Seoul, Korea, participated and completed the KSF-MPQ. Confirmatory factor analysis was conducted to evaluate the adequacy of the KSF-MPQ model and several alternative models. The results indicated that the adjusted KSF-MPQ model showed the best fit to the data among the models in chronic pain patients in Korea.
The results showed the KSF-MPQ is cross-culturally equivalent to the original questionnaire. Thus, the KSF-MPQ is valid measurement for assessing the quality and intensity of pain to chronic pain patients and may be helpful in clinical and research settings in Korea.
PMCID: PMC4326205
Short-form McGill pain questionnaire; Chronic pain; Korean; Confirmatory factor analysis
23.  Neuropathic sensory symptoms: association with pain and psychological factors 
A large number of population-based studies of chronic pain have considered neuropathic sensory symptoms to be associated with a high level of pain intensity and negative affectivity. The present study examines the question of whether this association previously found in non-selected samples of chronic pain patients can also be found in chronic pain patients with underlying pathology of neuropathic sensory symptoms.
Neuropathic sensory symptoms in 306 patients with chronic pain diagnosed as typical neuropathic pain, radiculopathy, fibromyalgia, or nociceptive back pain were assessed using the Pain DETECT Questionnaire. Two separate cluster analyses were performed to identify subgroups of patients with different levels of self-reported neuropathic sensory symptoms and, furthermore, to identify subgroups of patients with distinct patterns of neuropathic sensory symptoms (adjusted for individual response bias regarding specific symptoms).
ANOVA (analysis of variance) results in typical neuropathic pain, radiculopathy, and fibromyalgia showed no significant differences between the three levels of neuropathic sensory symptoms regarding pain intensity, pain chronicity, pain catastrophizing, pain acceptance, and depressive symptoms. However, in nociceptive back pain patients, significant differences were found for all variables except pain chronicity. When controlling for the response bias of patients in ratings of symptoms, none of the patterns of neuropathic sensory symptoms were associated with pain and psychological factors.
Neuropathic sensory symptoms are not closely associated with higher levels of pain intensity and cognitive-emotional evaluations in chronic pain patients with underlying pathology of neuropathic sensory symptoms. The findings are discussed in term of differential response bias in patients with versus without verified neuropathic sensory symptoms by clinical examination, medical tests, or underlying pathology of disease. Our results lend support to the importance of using adjusted scores, thereby eliminating the response bias, when investigating self-reported neuropathic symptoms by patients.
PMCID: PMC4038419  PMID: 24899808
self-reported neuropathic sensory symptoms; pain-related features; response bias
24.  Longlasting antalgic effects of daily sessions of repetitive transcranial magnetic stimulation in central and peripheral neuropathic pain 
Background and objective: A single session of repetitive transcranial magnetic stimulation (rTMS) over motor cortex had been reported to produce short term relief of some types of chronic pain. The present study investigated whether five consecutive days of rTMS would lead to longer lasting pain relief in unilateral chronic intractable neuropathic pain.
Patients and methods: Forty eight patients with therapy resistant chronic unilateral pain syndromes (24 each with trigeminal neuralgia (TGN) and post-stroke pain syndrome (PSP)) participated. Fourteen from each group received 10 minutes real rTMS over the hand area of motor cortex (20 Hz, 10x10 s trains, intensity 80% of motor threshold) every day for five consecutive days. The remaining patients received sham stimulation. Pain was assessed using a visual analogue scale (VAS) and the Leeds assessment of neuropathic symptoms and signs (LANSS) scale, before, after the first, fourth, and fifth sessions, and two weeks after the last session.
Results: No significant differences were found in basal pain ratings between patients receiving real- and sham-rTMS. However, a two factor ANOVA revealed a significant "± TMS" x "time" interaction indicating that real and sham rTMS had different effects on the VAS and LANSS scales. Post hoc testing showed that in both groups of patients, real-rTMS led to a greater improvement in scales than sham-rTMS, evident even two weeks after the end of the treatment. No patient experienced adverse effects.
Conclusion: These results confirm that five daily sessions of rTMS over motor cortex can produce longlasting pain relief in patients with TGN or PSP.
PMCID: PMC1739662  PMID: 15897507
25.  Characteristics of Neuropathic Pain in Patients With Spinal Cord Injury 
Annals of Rehabilitation Medicine  2014;38(3):327-334.
To characterize neuropathic pain in patients with spinal cord injury (SCI) according to classification used in the study by Baron et al. (Baron classification), a classification of neuropathic pain based on the mechanism. To also compare the patterns of neuropathic pain in SCI patients with those in patients with other etiologies and to determine the differences in patterns of neuropathic pain between the etiologies.
This was a descriptive cross-sectional study. We used the Baron classification to investigate the characteristics of neuropathic pain in SCI. Sixty-one SCI patients with neuropathic pain (The Leeds assessment of neuropathic symptoms and signs score ≥12) were enrolled in this study between November 2012 and August 2013, after excluding patients <20 of age, patients with visual analog scale (VAS) score <3, pregnant patients, and patients with systemic disease or pain other than neuropathic pain.
The most common pain characteristic was pricking pain followed by electrical pain and numbness. The mean VAS score of at-level neuropathic pain was 7.51 and that of below-level neuropathic pain was 6.83. All of the patients suffered from rest pain, but 18 (54.6%) patients with at-level neuropathic pain and 20 (50.0%) patients with below-level neuropathic pain suffered from evoked pain. There was no significant difference in between at-level and below-level neuropathic pains.
The result was quite different from the characteristics of post-herpetic neuralgia, but it was similar to the characteristics of diabetic neuropathy as shown in the study by Baron et al., which means that sensory nerve deafferentation may be the most common pathophysiologic mechanism of neuropathic pain after SCI. Since in our study, we included short and discrete symptoms and signs based on diverse mechanisms, our results could be helpful for determining further evaluation and treatment.
PMCID: PMC4092172  PMID: 25024955
Neuralgia; Spinal cord injuries; Classification

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