The effects of non-painful transcutaneous electrical nerve stimulation on cutaneous pain threshold and muscular reflexes in normal men and in subjects with chronic pain

In healthy subjects and in subjects with chronic myofascial pain of one lower limb, the following was measured in both lower limbs: (i) sequential Hoffman (H) reflex, (ii) sequential Achilles tendon (T) reflex, (iii) cutaneous pain threshold determined with electrical stimuli, before, during and after transcutaneous electrical nerve stimulation (TENS).In healthy subjects no significant differences were observed between the pain thresholds of the two limbs. During and after TENS, changes of the reflexes were related to the pain thresholds.In the pathological subjects a significant difference of pain threshold was present between the affected limb and the contralateral one. An important difference between healthy and pathological subjects is not the quality but the quantity of the changes induced by TENS, in the sense that the levels of inhibition and facilitation of the reflexes are more evident in patients with pain. Indeed, TENS induces a reset of sensory and of motor system and a parallel long lasting effect both on sensory and on muscular function, with concomitant pain relief in the pathological subjects.     

Assessment of small and large fiber function in long-term type 1 (insulin-dependent) diabetic patients with and without painful neuropathy

Twelve neural function tests (thermal discrimination thresholds, pain perception thresholds to heat and cold stimuli, vibration perception thresholds, and motor and sensory nerve conduction velocities) were assessed in the lower and upper extremities of 60 long-term type 1 diabetic patients. Thirty patients were asymptomatic (group 1) and 30 patients had painful neuropathy (group 2), predominantly originating in the distal lower limbs (group 2a; n = 20) or in the distal upper limbs (group 2b; n = 10). There were no significant differences between the groups with regard to age, duration of diabetes or glycemic control. Eleven of the 12 functions tested (6 in lower and upper limbs, respectively) were significantly diminished in both groups of diabetics as compared to age-matched control subjects. Group 2a had significant impairment in 5 of 6 parameters of the lower limbs, while in group 2b only 1 of 6 functions of the upper limbs was diminished. In the whole diabetic group, the most frequent abnormality was an elevated threshold for thermal sensation in the foot. Significant correlations between small and large fiber abnormalities were observed predominantly in the foot. Selective affection of small or large fiber functions showed different patterns in the arms and in the legs. In the upper extremities selective impairment in nerve conduction was predominant, while in the lower extremities it was thermal sensation. These findings suggest that both generalized and selective small or large fiber affection may occur in long-term type 1 diabetic patients. Dysfunction of both modalities is more severe in the lower limbs, when painful symptoms have developed in this region.     

Lateralisation of pain in cluster headache

In 27 patients with cluster headache a careful sensory examination of the entire body was performed. The exam included: the measurement of sensory thresholds with mechanical and electrical stimuli, the assessment of cutaneous and deep hyperalgesia and the ischaemic test of the upper limbs with limbs at rest. In most patients a lateralisation of the findings was observed: cutaneous and deep hyperalgesia were prevalent in the side of cluster headache attacks. The results indicate that in cluster headache, as in other pain syndromes, a lateralisation may be induced throughout the body, probably by phenomena of facilitation in the central nervous system and by activation of reflex arcs.     

Local and remote effects of hypnotic suggestions of analgesia

The present study was designed to further characterize hypnotic analgesia and particularly to examine whether the effects are due to a selective alteration of pain perception and are organized somatotopically. Thirty-two healthy volunteers participated in this study. Thermal detection thresholds for warmth and cool stimuli and heat pain thresholds were measured at both the upper and lower left limbs by means of a thermotest. Measurements were performed before, during and after a hypnotic session during which the subjects were administered a French adaptation of the Stanford Hypnotic Susceptibility Scale and then standardized suggestions of analgesia limited to the left foot. Heat pain thresholds were significantly increased at both the lower and upper limbs. Changes at the foot were positively correlated with the hypnotic susceptibility score, while, unexpectedly, changes at the hand were negatively correlated with the susceptibility score. Mean detection thresholds for warmth and cool stimuli were also altered at both the lower and upper limbs during hypnosis, but these modifications were correlated neither with susceptibility nor with the changes in heat pain threshold. These results indicate that hypnotic suggestions can selectively and somatotopically alter pain sensation in highly susceptible subjects. It is also suggested, however, that suggestions of analgesia can induce selective alterations of pain perception in poorly susceptible subjects, although these effects did not appear to be localized 'appropriately'.     

Changes in somatic sensitivity during transcutaneous electrical analgesia.

Patients with chronic pain in one limb, who experienced pain reduction with transcutaneous neurostimulation, were examined for sensory perception in that limb before and during electrical analgesia. Contralateral limbs and normal subjects served as controls. Sensory stimuli were quantified, a range of stimuli were presented and data were analyzed according to sensory decision theory. Results showed that, compared to controls, painful limbs show considerable impairment in sensory sensitivity. With transcutaneous neurostimulation, however, sensitivity is improved towards normal, whereas electrical stimulation slightly impairs perception in normal limbs. These results suggest that electrical analgesia involves both peripheral small-fiber blockade and large-fiber stimulation; the latter is more noticeable in the normal limb, but the former effect is predominant when pain reduction occurs in a painful limb.     

正确肢体摆放预防脑卒中后患者肩痛的临床观察

目的 探讨正确的肢体摆放对脑卒中后患者肩痛的预防作用.方法 选择41例上肢运动功能障碍、无感觉障碍、无肩痛的脑卒中患者随机分为对照组20例和观察组21例.2组均进行神经内科常规治疗和肢体被动活动、肢体按摩.观察组在此基础上进行正确的肢体摆放.2个月后,评定2组患者肩关节前屈最大正常活动范围时有无疼痛并进行比较.结果 治疗后2个月时,肩痛发生率对照组为65.0%,观察组为19.0%,χ2=8.91,P＜0.01.2组比较,差异有统计学意义.结论 正确的肢体摆放对脑卒中后患者肩痛有预防作用.     

Functional abnormalities of the cervical cord and lower medulla and their effect on pain: observations in chronic pain patients with incidental mild Chiari I malformation and moderate to severe cervical cord compression

OBJECTIVE: Abnormalities of central sensory processing may play a role in the pathogenesis of chronic pain. The Chiari I malformation is a congenital hindbrain anomaly characterized by protrusion of the cerebellar tonsils into the upper cervical canal, with variable effects on the lower brain stem and cervical cord. The purpose of this study was to compare sensory function and pain among patients with chronic pain who had these disorders incidentally diagnosed, to assess the effect on pain in these patients in comparison with those without central nervous system disease. DESIGN: Retrospective study in which pain, mood, and sensory function in 32 patients with chronic pain who had mild Chiari I malformation were compared with that in 53 patients with chronic pain who had moderate to severe compression of the cervical spinal cord and 52 patients with chronic pain who had no apparent central nervous system disorder. Data had been collected previously as part of standard clinical assessments, including clinical neurological examinations, quantitative sensory testing, pain drawings, and psychometric testing with the Symptom Checklist 90. PATIENTS: All subjects were patients of a hospital-based pain management practice who had been accepted for treatment over a 5-year period. RESULTS: Both the Chiari I and cervical compression groups had long tract signs evident on clinical neurological examination. Quantitative sensory testing indicated elevations in the trigeminal territory among patients with Chiari I malformation and on the neck, hands, and feet in both the Chiari I and cervical compression groups. The extent of pain and mood disturbance was greatest in the Chiari I group and least in the group with no central nervous system disorder. Complex regional pain syndrome, fibromyalgia, and temporal mandibular joint disorder were more common among the Chiari I malformation group than among the other groups. CONCLUSIONS: Quantitative sensory analysis indicates sensory dysfunction associated with Chiari I malformation and cervical cord compression. The pattern of sensory abnormality is consistent with medullary dysfunction among the patients with Chiari I malformation and cervical cord dysfunction among cord compression patients. There were differences in the types and extent of pain and the associated disorders of mood observed among the cohorts defined above. These differences may be partly due to the presence and location of central sensory dysfunction.     

脑卒中后肩关节半脱位对偏瘫侧上肢周围神经电生理特征的影响

目的:探讨脑卒中后肩关节半脱位对偏瘫侧上肢周围神经电生理参数的影响。方法:纳入20例脑卒中伴肩关节半脱位的患者,分别对患者双上肢肩胛上神经、腋神经、肌皮神经、桡神经、正中神经、尺神经的运动神经传导及桡神经、正中神经、尺神经的感觉神经传导进行评估,并对偏瘫上肢冈上肌、三角肌、肱二头肌、伸指总肌、拇短展肌和小指展肌进行静息...     

早期康复训练对急性脑梗塞患者肢体功能恢复影响

目的:探讨早期康复训练对急性脑梗塞患者肢体功能恢复的影响。方法:康复组采用药物与系统的康复训练相结合的方法,对照组采用单纯的药物治疗。第28天评价效果。结果:康复组上肢肌力和持匙进餐、扶拐行走等日常生活活动能力的恢复优于对照组(P<0.05),下肢肌力的恢复2组无显著差异。结论:早期康复训练能促进急性脑梗塞患者肢体功能的恢复,减少并发症,提高治疗效果。     

Neural processing of sensory and emotional-communicative information associated with the perception of vicarious pain

The specific neural processes underlying vicarious pain perception are not fully understood. In this functional imaging study, 20 participants viewed pain-evoking or neutral images displaying either sensory or emotional-communicative information. The pain images displayed nociceptive agents applied to the hand or the foot (sensory information) or facial expressions of pain (emotional-communicative information) and were matched with their neutral counterparts. Combining pain-evoking and neutral images showed that body limbs elicited greater activity in sensory motor regions, whereas midline frontal and parietal cortices and the amygdala responded more strongly to faces. The pain-evoking images elicited greater activity than their neutral counterparts in the bilateral inferior frontal gyrus (IFG), the left inferior parietal lobule (IPL) and the bilateral extrastriate body area. However, greater pain-related activity was observed in the rostral IPL when images depicted a hand or foot compared to a facial expression of pain, suggesting a more specific involvement in the coding of somato-motor information. Posterior probability maps enabling Bayesian inferences further showed that the anterior IFG (BA 45 and 47) was the only region showing no intrinsic probability of activation by the neutral images, consistent with a role in the extraction of the meaning of pain-related visual cues. Finally, inter-individual empathy traits correlated with responses in the supracallosal mid/anterior cingulate cortex and the anterior insula when pain-evoking images of body limbs or facial expressions were presented, suggesting that these regions regulated the observer's affective-motivational response independent from the channels from which vicarious pain is perceived.     

On the origin of sensory impairment and altered pain perception in Prader–Willi syndrome: A neurophysiological study

Introduction: High pain threshold is a supportive diagnosis criterion for Prader–Willi syndrome (PWS), but its pathogenesis is poorly understood. In this study we investigate sensory pathways in PWS, in order to evaluate peripheral or central involvement in altered sensory perception. Methods: 14 adult PWS patients, 10 obese non‐diabetic people and 10 age‐matched controls underwent: (a) motor/sensory nerve conduction velocities at the upper and lower limbs; (b) palmar/plantar sympathetic skin response; (c) somatosensory evoked potentials from upper/lower limbs; (d) quantitative sensory testing to measure sensory threshold for vibration, warm and cold sensation, heat and cold‐induced pain and (e) blood sample analysis to evaluate glucose and insulin levels and to calculate the quantitative insulin‐sensitivity check index (QUICKI). Results: Electroneurographic examination, sympathetic skin response and somatosensory evoked potentials were all within normal ranges. In the PWS group, thermal and pain thresholds but not vibratory were significantly higher than in healthy and obese people (p<0.05). Sensory threshold did not correlate with BMI nor with QUICKI. Conclusions: Our data suggest that altered perception in PWS does not seem attributable to a peripheral nerve derangement due to metabolic factors or obesity. Impairment of the small nociceptive neurons of dorsal root ganglia or involvement of hypothalamic region may not be excluded.     

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.     

Functional electrical therapy for hemiparesis alleviates disability and enhances neuroplasticity

Impaired motor and sensory function is common in the upper limb in humans after cerebrovascular stroke and it often remains as a permanent disability. Functional electrical stimulation therapy is known to enhance the motor function of the paretic hand; however, the mechanism of this enhancement is not known. We studied whether neural plasticity has a role in this therapy-induced enhancement of the hand motor function in 20 hemiparetic subjects with chronic stroke (age 53 ± 6 years; 7 females and 13 males; 10 with cerebral infarction and 10 with cerebral haemorrhage; and time since incident 2.4 ± 2.0 years). These subjects were randomized to functional electrical therapy or conventional physiotherapy group. Both groups received upper limb treatment (twice daily sessions) for two weeks. Behavioral hand motor function and neurophysiologic transcranial magnetic stimulation (TMS) tests were applied before and after the treatment and at 6-months follow-up. TMS is useful in assessing excitability changes in the primary motor cortex. Faster corticospinal conduction and newly found muscular responses were observed in the paretic upper limb in the functional electrical therapy group but not in the conventional therapy group after the intervention. Behaviourally, faster movement times were observed in the functional electrical therapy group but not in the conventionally treated group. Despite the small number of heterogeneous subjects, functional exercise augmented with individualized electrical therapy of the paretic upper limb may enhance neuroplasticity, observed as corticospinal facilitation, in chronic stroke subjects, along with moderate improvements in the voluntary motor control of the affected limb.     

A型肉毒素局部注射对脑卒中后痉挛性上肢功能障碍的影响

目的评估A型肉毒毒素(BTX-A)局部注射对脑卒中后痉挛性腕及手功能障碍的影响。方法 36例患者于治疗前及治疗后1周、4周、8周和12周应用改良Ashworth量表(MAS)、Carroll上肢功能试验(UEFT)、肢体静息位置、疼痛视觉模拟评分(VAS)、改良Barthel指数(MBI)、上肢3个运动任务(清洗偏瘫侧的手掌、剪患侧手指甲、将患侧的手臂伸进袖子)中遇到的困难进行评估。结果治疗后,MAS、VAS、UEFT评分和3个上肢任务完成情况均有改善(P<0.05),改善于注射后1周出现,并至少维持12周。MBI与治疗前比较无显著性差异(P>0.05)。结论 BTX-A局部注射可以改善脑卒中后痉挛性上肢功能障碍,减轻疼痛。     

Deficits of Movement Accuracy and Proprioceptive Sense in the Ipsi-lesional Upper Limb of Patients with Hemiparetic Stroke

[Purpose] Previous studies have reported on motor deficits in the ipsilateral upper limbs (UL) of a damaged brain hemisphere in motor tasks. However, little is known about sensory deficits on the ipsilateral side. Therefore, we investigated whether both motor and sensory function of the ipsilateral UL are affected in patients with stroke. [Subjects and Methods] Fifty patients with unilateral stroke and 40 age- and sex- matched normal subjects participated in this study. Subjects were evaluated on performance of a tracking task for motor function, and by the joint reposition test for integrity of proprioceptive sense in the ipsilateral UL. [Result] The comparison of the stroke group and the control group showed significant differences in performance of the tracking task and the joint reposition test. The accuracy index for the tracking task showed significant correlation with the error score for the joint reposition test in the stroke group. [Conclusion] These results suggest that the ipsilateral UL of stroke patients has impairment in sensory function which is related to proprioceptive sense, along with motor deficits. Therefore, we think that the difficulty stroke patients experience with motor tasks for the ipsilateral UL is induced by diminished integrity of sensorimotor function due to both sensory and motor deficits.Key words: Visuomotor coordination, Proprioceptive sense, Motor deficits     

Thermographic evaluation of the painful shoulder in the hemiplegic patient

In this study, we investigated the applicability of thermography as a technique for evaluating the painful postcerebrovascular accident (CVA) shoulder in hemiplegic patients. A thermographic series was taken of the upper extremities and upper trunk of 27 female subjects. The four groups we evaluated were nonhemiplegic subjects (n = 9), post-CVA subjects with recovered function (n = 6), hemiplegic subjects with upper extremity motor impairment (n = 6), and hemiplegic subjects with both motor impairment and ipsilateral shoulder pain (n = 6). The data revealed a normal thermographic series in 8 of the 9 nonhemiplegic subjects, but only in 1 of the 18 post-CVA subjects. The majority of the abnormal thermographic series of post-CVA subjects showed a 1 degree to 5 degree C coolness on the involved side. No consistent thermographic patterns emerged that could be related to the severity or location of pain. Further studies are needed to evaluate the efficacy of thermography as a means of determining the relationship between ipsilateral post-CVA coolness and hemiplegic shoulder pain.     

Capsaicin evoked pain and allodynia in post-herpetic neuralgia

The hypothesis that the pain and allodynia associated with post-herpetic neuralgia (PHN) is maintained by a combination of input from preserved primary afferent nociceptors and sensitization of central pain transmitting neurons was examined in 17 subjects with PHN. Pain, allodynia, thermal sensory function, cutaneous innervation, and response to controlled application of 0.075% capsaicin were measured. Compared to mirror-image skin, applying capsaicin on a 9 cm(2) area of PHN skin significantly increased overall PHN pain and allodynia in 11 of 17 subjects. These 'capsaicin responders' were characterized by higher average daily pain, higher allodynia ratings, and relatively preserved sensory function at baseline compared to the non-responders. In three of the 'capsaicin responders' the area of allodynia expanded into previously non-allodynic and non-painful skin that had normal sensory function and cutaneous innervation. These observations support the hypothesis that allodynia in some PHN patients is a form of chronic secondary hyperalgesia maintained by input from intact and possibly 'irritable' primary afferent nociceptors to a sensitized CNS.     

Anger and pain sensitivity in chronic low back pain patients and pain-free controls: the role of endogenous opioids

The experience of anger (i.e. trait anger) and anger management style (i.e. anger-in, anger-out) are related to sensitivity to acute and chronic pain stimuli, although underlying mechanisms are unknown. This study tested whether anger variables are associated with impaired endogenous opioid antinociceptive activity, and whether these relationships differed between chronic pain patients and healthy normals. Forty-three chronic low back pain (LBP) sufferers and 45 pain-free normals received opioid blockade (8 mg naloxone i.v.) or placebo blockade (saline) in randomized, counterbalanced order in separate sessions. During each session, subjects participated in a 1-min finger pressure pain task followed by an ischemic forearm pain task (maximum duration 5 min), providing pain intensity ratings during and immediately following each task. As a measure of opioid antinociceptive function, drug effects were derived by subtracting placebo from blockade condition pain ratings. Multivariate general linear model analyses indicated that anger-out, but not anger-in, had significant main effects on both finger pressure drug effects (P < 0.05) and ischemic task drug effects (P < 0.05). As hypothesized, high anger-out scores were associated with an absence of opioid analgesia during the acute pain tasks; low anger-out scores were associated with effective opioid analgesia. A similar non-significant trend was noted for trait anger on finger pressure drug effects (P < 0.06). Anger-out x LBP/normal interactions were non-significant, suggesting that links between anger-out and drug effects were similar for patients and normals. Controlling for depression did not eliminate the significant relationship between anger-out and drug effects. Findings suggest that anger-in and anger-out affect pain sensitivity through different mechanisms: only the effects of anger-out may be mediated by endogenous opioid dysfunction.     

Migrainous corpalgia: body pain and allodynia associated with migraine attacks

Cephalic and extracephalic allodynia are recognized as a common sign of sensory sensitization during migraine episodes. However, the occurrence of body pain in migraine has not been thoroughly explored. Here we report three patients presenting with spontaneous body pain in association with migraine attacks. A 41-year-old woman experienced face and limb pain along with migraine headaches; it started before, during or after headache, was usually ipsilateral to head pain, and could last from minutes to days. A 39-year-old woman had pain in her right limbs, back and neck for 30–60 min prior to right-sided migraine headaches. A 30-year-old woman perceived pain in her left upper limb for 24–48 h prior to left-sided migraine headaches. All patients had allodynia to mechanical stimuli over the painful areas. Spontaneous body pain may be associated with migraine attacks. Together with allodynia, this might be a consequence of central sensitization.