Liesbeth Daenen

Exercise, Not to Exercise, or How to Exercise in Patients With Chronic Pain? Applying Science to Practice

Background:Exercise is an effective treatment strategy in various chronic musculoskeletal pain disorders, including chronic neck pain, osteoarthritis, headache, fibromyalgia and chronic low back pain. Although exercise can benefit those with chronic pain (CP), some patients (eg, those with fibromyalgia, myalgic encephalomyelitis/chronic fatigue syndrome and chronic whiplash associated disorders) encounter exercise as a pain inducing stimulus and report symptom flares due to exercise. Objectives:This paper focuses on the clinical benefits and detrimental effects of exercise in patients with CP. It summarizes the positive and negative effects of exercise therapy in migraine and tension-type headache and provides an overview of the scientific evidence of dysfunctional endogenous analgesia during exercise in patients with certain types of CP. Further, the paper explains the relationship between exercise and recovery highlighting the need to address recovery strategies as well as exercise regimes in the rehabilitation of these patients. The characteristics, demands and strategies of adequate recovery to compensate stress from exercise and return to homeostatic balance will be described. Methods:narrative review. Results:Exercise is shown to be effective in the treatment of chronic tension-type headache and migraine. Aerobic exercise is the best option in migraine prophylaxis, whereas specific neck and shoulder exercises is a better choice in treating chronic tension-type headache. Besides the consensus that exercise therapy is beneficial in the treatment of CP, the lack of endogenous analgesia in some CP disorders should not be ignored. Clinicians should account for this when treating CP patients. Furthermore, optimizing the balance between exercise and recovery is of crucial merit in order to avoid stress-related detrimental effects and achieve optimal functioning in patients with CP. Conclusion:Exercise therapy has found to be beneficial in CP, but it should be appropriately and individually tailored with emphasis on prevention of symptom flares and applying adequate recovery strategies.

Nociception Affects Motor Output: A Review on Sensory-motor Interaction With Focus on Clinical Implications

ObjectivesResearch has provided us with an increased understanding of nociception-motor interaction. Nociception-motor interaction is most often processed without conscious thoughts. Hence, in many cases neither patients nor clinicians are aware of the interaction. It is aimed at reviewing the scientific literature on nociception-motor interaction, with emphasis on clinical implications. MethodsNarrative review. ResultsChronic nociceptive stimuli result in cortical relay of the motor output in humans, and a reduced activity of the painful muscle. Nociception-induced motor inhibition might prevent effective motor retraining. In addition, the sympathetic nervous system responds to chronic nociception with enhanced sympathetic activation. Not only motor and sympathetic output pathways are affected by nociceptive input, afferent pathways (proprioception, somatosensory processing) are influenced by tonic muscle nociception as well. DiscussionThe clinical consequence of the shift in thinking is to stop trying to restore normal motor control in case of chronic nociception. Activation of central nociceptive inhibitory mechanisms, by decreasing nociceptive input, might address nociception-motor interactions.

Dysfunctional pain inhibition in patients with chronic whiplash-associated disorders: an experimental study

Inefficient endogenous pain inhibition, in particular impaired conditioned pain modulation (CPM), may disturb central pain processing in patients with chronic whiplash-associated disorders (WAD). Previous studies revealed that abnormal central pain processing is responsible for a wide range of symptoms in patients with chronic WAD. Hence, the present study aimed at examining the functioning of descending pain inhibitory pathways, and in particular CPM, in patients with chronic WAD. Thirty-five patients with chronic WAD and 31 healthy controls were subjected to an experiment evaluating CPM. CPM was induced by an inflated occlusion cuff and evaluated by comparing temporal summation (TS) of pressure pain prior to and during cuff inflation. Temporal summation was provoked by means of 10 consecutive pressure pulses at upper and lower limb location. Pain intensity of first, fifth, and 10th pressure pulse was rated. During heterotopic noxious conditioning stimulation, TS of pressure pain was significantly depleted among healthy controls. In contrast, TS was quite similar prior to and during cuff inflation in chronic WAD, providing evidence for dysfunctional CPM in patients with chronic WAD. The present study demonstrates a lack of endogenous pain inhibitory pathways, and in particularly CPM, in patients with chronic WAD, and hence provides additional evidence for the presence of central sensitization in chronic WAD.

Sensorimotor incongruence exacerbates symptoms in patients with chronic whiplash associated disorders: an experimental study

OBJECTIVES Incongruence between sensory feedback and motor output may serve as an ongoing source of nociception inside the CNS, and hence may contribute to the development of chronic whiplash associated disorder (WAD). It has been demonstrated that sensorimotor incongruence exacerbates symptoms and provokes additional sensations in patients with chronic pain. This study aimed to evaluate whether a visually mediated incongruence between motor output and sensory input aggravates symptoms and triggers additional sensations in patients with chronic WAD. METHODS Thirty-five patients with chronic WAD and 31 healthy controls were subjected to a coordination test. They performed congruent and incongruent arm movements while viewing a whiteboard or mirror. RESULTS All patients with chronic WAD (n = 35) reported sensory changes such as increased pain, tightness, loss of control, dizziness or feelings of peculiarity at some stage of the test protocol. No significant differences in frequency and intensity of sensory changes were found between the various test stages (P > 0.05). In the healthy control group, 18 (58%) subjects reported sensory changes at some stage of the test protocol, with the highest number during the incongruent mirror stage (n = 17), corresponding to the highest level of sensorimotor incongruence. The pattern of reported sensory changes during the congruent and incongruent stages was significantly different between both groups (P < 0.05). CONCLUSION This study demonstrates an exacerbation of symptoms and/or additional sensory changes due to reducing or disturbing the visual input during action, indicating altered sensorimotor central nervous processing and altered perception of distorted visual feedback in chronic WAD.

Motor Control and Low Back Pain in Dancers

Professional dancers suffer a high incidence of injuries, especially to the spine and lower extremities. There is a lack of experimental research addressing low back pain (LBP) in dancers. The aim of this study is to compare lumbopelvic motor control, muscle extensibility and sacroiliac joint pain between dancers with and without a history of LBP. 40 pre-professional dancers (mean age of 20.3 years) underwent a clinical test battery, consisting of an evaluation of lumbopelvic motor control, muscle extensibility, generalized joint hypermobility, and sacroiliac joint pain provocation tests. Also self-reported measurements and standardized questionnaires were used. 41% of the dancers suffered from LBP during at least 2 consecutive days in the previous year. Only one dancer suffered from sacroiliac joint pain. Compared to dancers without a history of LBP, dancers with a history of LBP showed poorer lumbopelvic motor control (p<0.05). No differences in muscle extensibility or joint hypermobility were observed between dancers (p>0.05). Despite their young age, pre-professional dancers suffer from LBP frequently. Sacroiliac joint pain, generalized joint hypermobility or muscle extensibility appears unrelated to LBP in dancers. Motor control is decreased in those with a history of LBP. Further research should examine whether motor control is etiologically involved in LBP in dancers.

Sensorimotor incongruence triggers sensory disturbances in professional violinists: an experimental study

OBJECTIVES Professional violinists are at increased risk of developing disabling symptoms, such as tightness, stiffness, cramps, swelling and numbness in the upper limbs. In the majority of the symptoms, a demonstrable nociceptive aetiology cannot be defined. It has been suggested that a conflict between sensory input and motor intention can generate sensory disturbances. The purpose of this study was (i) to examine whether a sensorimotor conflict triggers sensory changes in professional violinists and (ii) to determine whether a conflict between motor intention and sensory feedback contributes to pathological symptoms in professional violinists. METHOD Twenty students following a professional master education in violin performed a coordination task simulating sensorimotor incongruence. Sensory changes were reported and rated after each stage of the protocol. RESULTS Twelve (60%) violinists reported sensory changes at some stage in the test protocol. The maximum number of reports of sensory changes occurred when the subjects moved their arms incongruently viewing the mirror (i.e. the stage of the protocol with the highest level of sensorimotor conflict). During performance of the coordination task viewing the mirror, a significant difference in sensory changes between violinists with and without baseline symptoms was revealed (P = 0.012 and P = 0.025). CONCLUSION Violinists with baseline symptoms may have a reduced threshold for sensorimotor incongruence. A conflict between the efferent motor output and the afferent sensorimotor input may play a role in symptoms without a discernible or local nociceptive aetiology in violinists. Further research is required.

Cervical motor dysfunction and its predictive value for long-term recovery in patients with acute whiplash-associated disorders: a systematic review

OBJECTIVE To study the presence of cervical motor dysfunctions in acute whiplash-associated disorders, evaluate their course and assess their predictive value for long-term recovery. DESIGN Systematic literature review. METHODS PubMed and Web of Science databases were used to select studies of the presence of cervical motor dysfunctions within the acute stage (< 6 weeks) after whiplash trauma and/or their predictive value for the development of chronic whiplash-associated disorders. RESULTS The presence of cervical motor dysfunctions in the acute stage after whiplash trauma was investigated in 4 cohorts. The course of cervical motor dysfunctions in whiplash-associated disorders was examined in 4 cohorts, and the predictive value on outcome 1 year post-whiplash trauma was assessed in 3 cohorts. Reduced cervical mobility, disturbed kinaesthesia, and altered muscle activity were found in the acute stage, and these persisted over time in the moderate/severe group. The predictive value of examining the presence of cervical motor dysfunctions was doubtful. The course and predictive value of initial reduced cervical mobility was inconsistent. CONCLUSION Cervical motor dysfunctions are present soon after whiplash trauma persisting in those with moderate/severe symptoms. However, these dysfunctions have limited predictive value, and hence may not explain the complex clinical picture of whiplash-associated disorders. This systematic review highlights the need for differentiating between patients with acute whiplash-associated disorders taking into account the biopsychological framework.

Recruitment bias in chronic pain research: whiplash as a model

In science findings which cannot be extrapolated to other settings are of little value. Recruitment methods vary widely across chronic whiplash studies, but it remains unclear whether this generates recruitment bias. The present study aimed to examine whether the recruitment method accounts for differences in health status, social support, and personality traits in patients with chronic whiplash-associated disorders (WAD). Two different recruitment methods were compared: recruiting patients through a local whiplash patient support group (group 1) and local hospital emergency department (group 2). The participants (n = 118) filled in a set of questionnaires: the Neck Disability Index, Medical Outcome Study Short-Form General Health Survey, Anamnestic Comparative Self-Assessment measure of overall well-being, Symptom Checklist-90, Dutch Personality Questionnaire, and the Social Support List. The recruitment method (either through the local emergency department or patient support group) accounted for the differences in insufficiency, somatization, disability, quality of life, self-satisfaction, and dominance (all p values <.01). The recruitment methods generated chronic WAD patients comparable for psychoneurotism, social support, self-sufficiency, (social) inadequacy, rigidity, and resentment (p > .01). The recruitment of chronic WAD patients solely through patient support groups generates bias with respect to the various aspects of health status and personality, but not social support. In order to enhance the external validity of study findings, chronic WAD studies should combine a variety of recruitment procedures.

Management of chronic sensitization, from drugs to physical therapy

Over the past decades, scientific understanding of unexplained chronic pain disorders has increased substantially. Several chronic musculoskeletal pain disorders may be explained by alterations in central nervous system processing. More specifically, the responsiveness of central neurons to input from unimodal and polymodal receptors is augmented, resulting in a pathophysiological state corresponding to central sensitization, characterized by generalized or widespread hypersensitivity. Central sensitization encompasses altered sensory processing in the brain, impaired functioning of top-down anti-nociceptive mechanisms, and (over)activation of top-down and bottom-up pain facilitatory pathways which augment nociceptive transmission. Importantly, a different ‘pain signature’ arises in the brain of those with chronic musculoskeletal pain and central sensitization. Given the increasing evidence supporting the clinical significance of central sensitization in those in a wide variety of disorders, including chronic whiplash associated disorders, chronic tension-type headache and migraine among others, the awareness is growing that desensitising the central nervous system should be a treatment target in these patients. Besides pharmacological options, rehabilitation (consisting of pain physiology education, stress management and exercise therapy) and neurotechnology options (e.g. Transcranial magnetic stimulation, TENS, virtual reality) offer interesting perspectives.

Lower Resting State Heart Rate Variability Relates to High Pain Catastrophizing in Patients with Chronic Whiplash‐Associated Disorders and Healthy Controls

Vagally mediated heart rate variability (vmHRV) is widely respected as a psychophysiological measure of emotion regulation capacity and serves as a readily available index of executive brain areas that exert an inhibitory influence on subcortical structures. Pain catastrophizing (PC) is conceptualized as the tendency to misinterpret and exaggerate pain‐related situations that may be threatening. Chronic pain patients show lower vmHRV and higher PC. Previously, no study has investigated the association of PC and vmHRV. We examined the association of PC and vmHRV in a sample of patients with chronic whiplash‐associated disorders (WAD, n = 30) and healthy controls (n = 31). Patients with WAD showed lower vmHRV, indexed by high‐frequency HRV (effect size, Cohens d = 0.442), and greater PC (d = 0.815). Zero‐order and partial correlations controlling for age and sex revealed that vmHRV and PC are inversely related. The results provide evidence for a psychophysiological mechanism underlying PC, in particular in chronic pain patients.