Using screening tools to identify neuropathic pain.
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Health Status Indicators↗
Biomedical subjects
Troels Staehelin Jensen
Publications and source records attributed to Troels Staehelin Jensen.
Differential effect of intravenous S-ketamine and fentanyl on atypical odontalgia and capsaicin-evoked pain.
Atypical odontalgia (AO) is an intraoral pain condition of currently unknown mechanisms. In 10 AO patients and 10 matched healthy controls, we examined the effect of intravenous infusion of an N-methyl-D-aspartate (NMDA) receptor antagonist S-ketamine and a mu-opioid agonist fentanyl on spontaneous AO pain and on an acute intraoral nociceptive input evoked by topical application of capsaicin. The drugs were administered in a randomized, placebo-controlled, cross-over manner. Furthermore, measures of intraoral sensitivity to mechanical and thermal quantitative sensory testing (QST) including temporal summation were compared between groups and sides. Both drugs failed to produce an analgesic effect on spontaneous AO pain, but fentanyl effectively reduced capsaicin-evoked pain. AO patients showed increased sensitivity to capsaicin and heat pain, but no significant differences in cold and mechanical sensitivity compared with healthy controls. No side-to-side differences in QST measures were found in AO patients. The present study demonstrates that AO is unlikely to be primarily due to a persistent afferent barrage from the peripheral region. Furthermore, in contrast to studies on various neuropathic pain conditions, fentanyl and S-ketamine in the present doses failed to attenuate AO pain.
Adult↗
[Pain and genetics].
Genetic factors can explain a significant amount of the variance in the perception of pain, sensitivity to painful stimuli and development of chronic pain. Twin studies, association studies and linkage analysis have located DNA sequences and SNPs that may be involved in the regulation of pain. Individual genes have an influence on the reaction to experimental painful stimuli, and certain genes are probably involved in painful clinical conditions. Optimal pain control and counselling of patients may be achievable through research into the genetic mechanisms involved in pain.
Catechol O-Methyltransferase↗
[Pain and depression].
Pain and depression are often associated. The frequency of pain complaints in depressed patients is 13-100%. In general, depressed patients have a higher pain threshold than do controls, but lower and unchanged thresholds have also been observed. The frequency of depression in chronic pain patients is 1.5-100%. Pain etiology, short education, marital status, gender, psychiatric family history and unemployment are risk factors for depression. Possible mechanisms underlying the pathophysiology of depression and pain could be involvement of the monoamines (5-HT and NA) and the HPA axis.
Central Nervous System↗
[Chronic postoperative pain].
Chronic pain constitutes a major health care and social problem. Around 20% of adults in a number of Western countries suffer from severe to moderate chronic pain that seriously affects their quality of life. That chronic pain may be an adverse outcome of surgery has been overlooked so far, but new studies suggest that chronic pain even after minor surgery is far more frequent than previously assumed. This article presents epidemiological, clinical and pathophysiological aspects of chronic postoperative pain and offers suggestions for pain management and prophylaxis.
Adult↗
Phantom limb pain: a case of maladaptive CNS plasticity?
Phantom pain refers to pain in a body part that has been amputated or deafferented. It has often been viewed as a type of mental disorder or has been assumed to stem from pathological alterations in the region of the amputation stump. In the past decade, evidence has accumulated that phantom pain might be a phenomenon of the CNS that is related to plastic changes at several levels of the neuraxis and especially the cortex. Here, we discuss the evidence for putative pathophysiological mechanisms with an emphasis on central, and in particular cortical, changes. We cite both animal and human studies and derive suggestions for innovative interventions aimed at alleviating phantom pain.
Adaptation, Physiological↗
Long-lasting mechanical sensitization following third molar surgery.
AIMS: To investigate the degree and duration of neuronal hyperexcitability due to local inflammatory trauma after surgical removal of an impacted mandibular third molar. METHODS: A total of 32 healthy men (16 patients, 16 control subjects) underwent quantitative sensory tests (QST) at baseline (preoperatively) and 2, 7, and 30 days following surgical removal of a mandibular third molar. Thermal and mechanical QST was applied to the extraoral and intraoral regions as well as to the dominant forearm. RESULTS: Detection thresholds for thermal and mechanical stimuli did not change over time in patients and control subjects, but pain thresholds (thermal, pressure, electrical) in the control group increased significantly. Patients showed significantly decreased pain pressure thresholds and pressure pain tolerance (P < .05 for both) on the operated side and absence of adaptation to the tests for up to 30 days postoperatively. CONCLUSION: These results indicate that even a minor surgical procedure in the orofacial region may be sufficient to evoke hyperexcitability in an area adjacent to the surgical wound for up to 30 days. The decreased adaptive capacity in the patient group also suggests the involvement of central pain-regulatory mechanisms in response to the surgical trauma.
Adult↗
Increased pain sensitivity to intraoral capsaicin in patients with atypical odontalgia.
AIMS: To use 2 well-characterized stimuli, the intraoral capsaicin model and the "nociceptive-specific" electrode, to compare superficial nociceptive function between patients with atypical odontalgia (AO) and matched healthy controls. Furthermore, the authors aimed to describe the sensitivity, specificity, and positive predictive values (PPV) of the techniques if group differences could be established. METHODS: Thirty-eight patients with AO and 27 matched healthy controls participated in this study. Thirty microliters of 5% capsaicin was applied to the gingiva on the left and right sides of all participants as a pain-provocation test. The participants scored the capsaicin-evoked pain continuously on a 0-to-10 visual analog scale (VAS). Furthermore, individual electrical sensory and pain thresholds to stimulation with a "nociceptive-specific" electrode on the facial skin above the infraorbital or mental nerve were determined. RESULTS: AO patients had higher VAS pain scores for capsaicin application than healthy controls (ANOVA: F > 4.88; P < .029). No differences between the painful sides and the nonpainful sides of the patients were found (ANOVA: F < 1.26; P > .262). No main effects of group or stimulation side on the electrical sensory and pain thresholds were detected (ANOVA: F < 0.309; P > .579). Sensitivity was 0.51; specificity, 0.81; and PPV, 0.77 when a VAS value of > or = 8 for capsaicin-evoked pain was used. CONCLUSION: AO patients show increased sensitivity to intraoral capsaicin but normal sensitivity to "nociceptive-specific" electrical stimulation of the face in an area proximal to the painful site. The use of the intraoral pain-provocation test with capsaicin as a possible adjunct to the diagnostic workup is hampered by the only moderately good sensitivity and specificity.
Analysis of Variance↗
Acute pain increases heart rate: differential mechanisms during rest and mental stress.
The main aim was to investigate if acutely stressed subjects have abnormal heart rate variability responses to acute pain. Efferent cardiac autonomic activity was assessed by analyzing RR interval variation in 26 male volunteers. Heart rate variability was measured as mean and standard deviation of normal RR intervals (mean RR, SDNN) and by power spectral analysis where high frequency (HF) and low frequency (LF) power were used as indexes of vagal function and of sympatho-vagal interaction, respectively. Coefficient of component variance in the LF and HF bands (CCV-LF, CCV-HF) was estimated to adjust for possible influences of different mean RR levels on power amplitude. Subjects received painful and non-painful sural nerve stimulations during rest, during attention to pain, and during mental stress. Our results show that pain significantly decreased mean RR and increased LF power and CCV-LF during rest and during attention to pain. SDNN, HF power, and total power were not affected by pain. During mental stress, pain significantly decreased mean RR but failed to affect other heart rate variability parameters. We conclude that acute pain induced efferent cardiac sympathetic activation during rest and during attention to pain as LF power and CCV-LF increased without alterations of pure vagal heart rate variability measures. During mental stress, pain inhibited mean RR without changing heart rate variability measures suggesting that pain does not increase efferent cardiac sympathetic activity during mental stress. Pain induced decrease of mean RR during mental stress may be caused by the release of catecholamines into the systemic circulation.
Acoustic Stimulation↗
[Effect of the synthetic cannabinoid dronabinol on central pain in patients with multiple sclerosis--secondary publication].
Cannabinoids reduce allodynia/hyperalgesia in animal pain models, but few clinical studies evaluated the analgesic action in humans. We aimed to evaluate the effect of delta-9-tetrahydrocannabinol (dronabinol) on central pain in MS patients. Twenty-four MS patients participated in a double-blind placebo-controlled crossover trial. Dronabinol reduced the spontaneous pain intensity significantly compared with placebo (4.0 (2.3-6.0) vs. 5.0 (4.0-6.4), median (25th-75th percentiles), p = 0.02). Though dronabinol's analgesic effect is modest, its use should be evaluated considering the general difficulty in treating central pain.
Administration, Oral↗
[Questions to the Drug Committee about administration of Lyrica].
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Anticonvulsants↗
Effects of evoked pain on the electromyogram and compound muscle action potential of the brachial biceps muscle.
Muscle pain is often accompanied by a feeling of muscle fatigue and weakness. We examined the effect of experimental muscle pain on the electromyogram (EMG) during maximal voluntary contraction (MVC), and on the compound muscle action potential (CMAP) of the brachial biceps muscle. Twenty-one healthy subjects were injected intramuscularly with 0.1 ml/30 microg of the vanilloid receptor agonist (capsaicin) or 0.2 ml of 5% hypertonic saline. A Teflon-coated cannulated EMG needle was used to record the EMG interference pattern (IP) at MVC. The CMAP of the brachial biceps muscle was obtained by stimulation of the musculocutaneous nerve at the axilla using surface electrodes. Amplitude, mean frequency of the power spectrum, and turns/s of the interference pattern were reduced after pain induced by capsaicin or hypertonic saline. Latency, amplitude, and area-under-curve of the CMAP did not change after injection of either substance. Acute stimulation of muscle nociceptors thus produced a fatiguelike change in the interference pattern during MVC, possibly due to a decrease in motoneuron firing rate and increased muscle fatigability.
Action Potentials↗
Sensory function and quality of life in patients with multiple sclerosis and pain.
Central neuropathic pain is well known in multiple sclerosis (MS), but the underlying mechanisms are unclear. In the present study we studied sensory function in MS patients with pain, MS patients without pain and healthy subjects in order to clarify the role of sensory abnormalities in pain. Fifty MS patients with pain were randomly recruited from a previous epidemiological MS study in Aarhus County, Denmark. Age and gender stratified MS patients without pain (N=50) and healthy subjects (N=50) served as controls. Patients with pain underwent a structured pain interview. Sensory function was examined by bedside and quantitative sensory testing. Quality of life was assessed using the health-related quality of life questionnaire, SF-36. Patients with pain had lower pressure pain threshold than pain-free patients (260 kPa vs. 322 (median), P=0.02) otherwise quantitative sensory testing was similar. Pain patients more frequently had cold allodynia (9/50 vs. 0/50, P=0.003) and abnormal temporal summation (10/48 vs. 3/49, P=0.03). Fifty-eight percent had central pain. Central pain patients did not differ from musculoskeletal pain patients in quantitative sensory testing, but allodynia was more common in MS patients with central pain. Pain patients scored lower in all dimensions of SF-36 compared with pain-free patients and healthy subjects. The results suggest that pain in MS is central in more than half of the patients and is associated with mechanical or thermal hyperalgesia.
Adult↗
Blink reflexes in patients with atypical odontalgia.
AIMS: To use the human blink reflex (BR) to explore possible neuropathic pain mechanisms in patients with atypical odontalgia (AO). METHODS: In 13 AO patients, the BR was elicited using a concentric electrode and recorded bilaterally with surface electromyographic (EMG) electrodes on both orbicularis oculi muscles. Electrical stimuli were applied to the skin above branches of the V1, V2, and V3 nerves and to the V branch contralateral to the painful branch. Sensory and pain thresholds were determined. The BR examination of the painful V branch was repeated during a capsaicin pain-provocation test. The data were analyzed with nonparametric statistics. RESULTS: The BR responses (R2 and R3) evoked by stimulation of V3 were significantly smaller than the BR responses evoked by stimulation of V1 and V2 (P < .004). There were no differences in BR (R2 or R3) between the painful and nonpainful sides (P > .569), and the BR (R2 and R3) was not significantly modulated by experimental pain (P > .080). The sensory thresholds were significantly lower on the painful side compared to the nonpainful side (P = .014). The pain thresholds were not different between sides (P > .910). CONCLUSION: No major differences between the V nociceptive pathways on the right and left sides were found in a relatively small group of AO patients. Future studies that compare BRs in AO patients and healthy volunteers are needed to provide further knowledge on the pain mechanisms in AO.
Adult↗
Reduced cold pressor pain tolerance in non-recovered whiplash patients: a 1-year prospective study.
UNLABELLED: Whiplash injury and chronic whiplash syndrome represent major health problems in certain western communities, pain being the main symptom. Sensitization of the nociceptive system may play a role for non-recovery after whiplash injury. AIMS: This study examined if tolerance to endure pain stimuli may predict outcome in whiplash injury. In a prospective fashion, 141 acute whiplash patients exposed to rear-end car collision (WAD grade 1-3) and 40 ankle-injured controls were followed and exposed to a cold pressor test, respectively, 1 week, 1, 3, 6 and 12 months after the injury. VAS score of pain and discomfort was obtained before, during and after immersion of the dominant hand into cold water for 2 min. The McGill Pain Questionnaire showed that ankle-injured controls had higher initial pain scores than the corresponding whiplash group, while whiplash-injured subjects had higher scores at 6 months; pain scores being similar at other time points. No difference was found in cold pressor pain between recovered whiplash patients and ankle-injured subjects. Non-recovery was only encountered in whiplash injury. Eleven non-recovered whiplash patients (defined as: handicap after 1 year) showed reduced time to peak pain from 1 week to 3 months (P<0.001), 6 months (P<0.01), but not 12 months after the injury. A larger pain area was seen in non-recovered vs. recovered whiplash-injured subjects during the entire observation period (P<0.001). Non-recovery after whiplash was associated with initially reduced cold pressor pain endurance and increased peak pain, suggesting that dysfunction of central pain modulating control systems plays a role in chronic pain after acute whiplash injury.
Accidents, Traffic↗
Evoked pain in the motor endplate region of the brachial biceps muscle: an experimental study.
Spontaneous electrical activity, interpreted as motor endplate activity, has been reported at muscle trigger points. This study examined whether the motor endplate region, identified by electromyography, is more sensitive to noxious stimuli than other muscle sites. We induced pain in the brachial biceps muscles of 21 healthy subjects by injecting capsaicin (30 microg/0.1 ml) and NaCl (5%/0.2 ml) in the motor endplate region and at electrically silent muscle sites. Needle and evoked pain were measured by a visual analogue scale (VAS) (0-10) and the short form of the McGill Pain Questionnaire. The needle pain in the motor endplate region differed both in intensity and quality from that at other sites. The maximal pain after NaCl 5% was higher, and the VAS area-under-the-curve for NaCl 5% and capsaicin were larger, in the motor endplate region than in other sites. A higher density of muscle nociceptors in the vicinity of the motor endplate region may account for the observed differences in pain. These findings may have clinical implications for the treatment of musculoskeletal pain conditions.
Adult↗
Symptoms and signs in patients with suspected neuropathic pain.
The study sought to determine if symptoms and signs cluster differentially in groups of patients with increasing evidence of neuropathic pain (NP). We prospectively looked at symptoms and signs in 214 patients with suspected chronic NP of moderate to severe intensity. According to a set of clinical criteria the patients were a priori classified as having the so-called 'Definite NP' (n = 91), 'Possible NP' (n = 71), or 'Unlikely NP' (n = 52). A recording of symptoms including pain descriptors, intensity of five categories of pain, Short Form McGill Pain Questionnaire, and Major Depression Inventory were done. Sensory tests including repetitive pinprick stimulation, examination for cold-evoked pain by an acetone drop and brush-evoked pain were carried out in the maximal pain area and in a control area. High intensity of superficial ongoing pain, and touch or cold provoked pain was associated with chronic pain classified as definite or possible neuropathic. Intensity of deep ongoing pain, and 'paroxysms' was similar in the three groups. Brush-evoked pain was more frequent in definite NP. The McGill Pain Questionnaire and the used pain descriptors could not distinguish between the three clinical categories. Although certain symptoms (touch or cold provoked pain) and signs (brush-evoked allodynia) are more prominent in patients with definite or possible NP, we found considerable overlap with the clinical presentation of patients with unlikely NP.
Adult↗
Differential effects of peripheral ketamine and lidocaine on skin flux and hyperalgesia induced by intradermal capsaicin in humans.
The capsaicin-induced flux in the primary and secondary hyperalgesic area after pretreating the capsaicin injection site with local ketamine, lidocaine or saline 10 min prior to injection was examined in this study. Twelve healthy volunteers participated in two randomized, double-blinded, placebo-controlled, cross-over experiments. In the first experiment, the skin on the volar forearm was pretreated with s.c. ketamine or saline, 10 min prior to capsaicin injection. Flux was recorded before and continuously after the injection of capsaicin in the primary and secondary hyperalgesic area. Spontaneous pain, evoked pain and areas of hyperalgesia were measured. In the second experiment, a similar capsaicin test was carried out 10 min after pretreating the skin with s.c. lidocaine or saline. Ketamine reduced flux significantly both in the primary and secondary hyperalgesic area. Lidocaine reduced flux significantly in the primary hyperalgesic area. No effect was observed on flux in the secondary hyperalgesic area. Only lidocaine reduced spontaneous pain, evoked pain and areas of hyperalgesia, whereas ketamine had no effect. Our results suggest that there is no simple and close relation between vascular and sensory reactions to pharmacological manipulation following intradermal capsaicin injection. We propose distinct mechanisms for local lidocaine and ketamine based on the differential effects of local lidocaine and ketamine on flux and pain.
Administration, Cutaneous↗