ABSTRACT Whiplash associated disorders (WAD) is one of the most debated musculoskeletal conditions. Sensory disturbances including hypersensitive responses to mechanical, thermal and electrical stimulation have been consistently shown to be a feature of both the acute and chronic stages of the whiplash condition. More importantly, such dysfunctions have also been found to be associated with higher risk of poor functional recovery. It is apparent that better understanding of the sensory disturbances in WAD is needed in order to elucidate mechanisms underlying the pain and disability of this recalcitrant condition and to facilitate the development of more effective management strategies. Comprehensive Quantitative Sensory Testing (QST) combining sensory detection and pain threshold measures is proving to be a valuable tool to advance the classification and illuminating the underlying mechanisms of an array of musculoskeletal pain disorders but such protocol has never been undertaken in a WAD cohort. In order to fill this gap in knowledge, the series of studies in the thesis aimed to utilize comprehensive QST to investigate the presence of somatosensory dysfunction in chronic WAD and to compare the somatosensory profile of WAD to cervical radiculopathy and idiopathic (non-traumatic) neck pain. Once a better understanding of the potential underlying mechanisms in chronic WAD was established, the research then focused on documenting the presence of such somatosensory disturbances soon after whiplash injury and its temporal development over a 6 months period. The results have provided a number of significant insights into some of the potential underlying mechanisms of the somatosensory dysfunction in WAD as well as other neck pain conditions of different aetiology. It is clear that generalised sensory hypoaesthesia coexisted with sensory hypersensitivity in chronic WAD and a combination of pain and detection measures best discriminated patients with WAD and controls. Similar sensory presentation was also found in patients with cervical radiculopathy but not in idiopathic neck pain patients. This finding indicates that different mechanisms underlie various musculoskeletal conditions with disordered central processes contributing to a greater degree in some conditions. Patients with whiplash and those with cervical radiculopthy may share similar underlying pain mechanisms involving the central nervous system and the discrepant findings in the idiopathic neck pain group may be due to the magnitude of nociceptive input required to induce/maintain altered central adaptive changes. Another important observation from the studies was that sensory hypoaesthesia was present in the majority of patients with whiplash injury in the acute stage. However, it persisted only in individuals who initially reported higher levels of pain and disability levels and sign of hypersensitivity. It was this group of individuals who predominantly developed persistent symptoms at six months post injury. The longitudinal findings indicate that such sensory impairments can be identified very early on and treatment interventions directed at these sensory disturbances (both sensory hypersensitivity and hypoaesthesia) should aim to reduce the nociceptive input and this may improve recovery post whiplash injury. The findings in this thesis demonstrated the clear association between sensory hypersensitivity and other sensory disturbances and their potential influence on recovery. Furthermore, the heterogeneity of the whiplash condition highlighted the importance of the early identification of “low-risk and “high-risk” patients in order to assist the clinicians to make clinical decisions on the best management approach. It cannot be overemphasised that the early assessment of whiplash injured patients should aim to identify features associated with poor recovery and a better classification system will be an important step. Implications for assessment and management of whiplash are vital in the acute stage of injury and may well go some way toward preventing the transition to chronicity, particularly in those with a more complex clinical presentation involving somatosensory disturbances. Further research directions have also been identified in order to improvement management of this complex clinical condition.

O envelhecimento humano resulta em anormalidades que podem comprometer a autonomia e a qualidade de vida da pessoa idosa, e a perda de sensibilidade está entre elas. A percepção sensitiva orofacial depende da interação de diversas modalidades, e no processo de transdução a saliva tem um papel importante. Este estudo teve como objetivo investigar os limiares de sensibilidade somestésica, gustativa, olfativa, e o fluxo salivar em indivíduos de diferentes faixas etárias e de acordo com o sexo. Foram avaliados 126 voluntários saudáveis (65 mulheres). Os participantes foram divididos em cinco grupos de acordo com a idade: 18 a 25 anos, 26 a 40 anos, 41 a 60 anos, 61 a 80 anos e acima de 80 anos. Foram utilizados instrumentos para a avaliação sensitiva superficial (dor, tato - IITC Woodland Hills, EUA; frio, calor - MSA II e vibratórios - Somedic, Suécia) aplicados em pontos distintos da face, dentes (sensibilidade elétrica - Pulpotest) e à distância (mãos e pernas) além de substâncias diluídas em diferentes concentrações para as sensibilidades gustativa (doce - glicose, salgado - cloreto de sódio, azedo - ácido cítrico e amargo - uréia) e olfativa (isopropanol em diferentes concentrações). O fluxo salivar também foi mensurado. Os limiares sensitivos tácteis, vibratórios, ao frio, ao calor, doloroso de profundidade, gustativos (doce; salgado; azedo) e olfativos foram maiores e o fluxo salivar foi menor após os 61 anos quando comparados aos grupos mais jovens. Na comparação entre os sexos, as mulheres apresentaram os seguintes limiares menores do que os homens: gustativos (doce; salgado; azedo e amargo), olfativo, calor e dolorosos (superfície e profundidade). Conclui-se que a idade e o sexo influenciam na sensibilidade dos indivíduos / The aging process results in abnormalities that can affect the autonomy and quality of life of the elderly and the loss of sensitivity is one of them. The orofacial sensory perception depends on an interaction among sensory modalities and saliva plays a role in the transduction of oral sensations. The aim of this study was to investigate the gustative, olfactory and somesthetic sensory thresholds and salivary flow in subjects divided according to the ages and according to sexes. One hundred twenty six (126) healthy individuals were evaluated (65 women). The age groups were: 18 to 25 years, 26 to 40 years, 41 to 60 years, 61 to 80 years and above 80 years. The following instruments were used for the quantitative sensory testing: IITC Woodland Hills, USA for the superficial tactile and pain thresholds; Quantitative sensory testing MSA II, Somedic, Sweden for cold and warm thresholds, Somedic Vibrometer, Sweden for vibration thresholds, Pulpotest for electric sensitivity of the teeth. The tests were performed at the face and in hands and legs. The gustative and olfactory thresholds were assessed with the following substances in several concentrations: -glucose (sweet), sodium chlorate (salty), citric acid (sour), urea (bitter) and isopropanol (olfaction). The salivary flow was also measured with an electronic balanceTactile, vibratory, cold, warm, superficial pain, gustative (sweet; salty; sour) and olfactory thresholds were higher after 61 years and the salivary flow was lower after 61 years than the younger age groups. Comparing the sexes, women had lower gustative (sweet; salty; sour and bitter), olfactory, warm and pain (superficial and deep) thresholds than men. In conclusion, ages and sex may have an influence in sensory perception of subjects

Pain and movement are intimately connected and nearly universal human experiences. However, our understanding of the extent, significance, and mechanisms of pain-movement relationships is limited. While pain is a normal, protective response to injury and potentially harmful stimuli, prolonged or dysfunctional neuromuscular adaptions in response to pain can contribute to a variety of pain conditions. Alternatively, movement (in the form of global physical activity, individual exercise programs, and/or specific motor learning/functional tasks) is often prescribed to help decrease pain and improve function. While attempts have been made to show an effect of movement on pain or to better understand altered movement strategies in response to pain, much of the research has been limited to animal models or to those with specific persistent or chronic pain conditions limiting generalizability and interpretability. Therefore, this research sought to advance current understanding of the relationships between physical activity and normal variability in centrally- and peripherally-mediated pain in healthy adults. Additionally, we sought to characterize changes in reflexive motor responses in the upper extremity to an endogenous, naturally-occurring, long-lasting acute muscle pain. The results of these investigations indicate that greater, self-reported intense (i.e. vigorous) and leisure activity are more strongly associated with decreased pain sensitivity than is pain modulation or measured activity (via accelerometry). Future research is needed to determine directionality of these relationships. Further, reflexive motor responses to endogenous, acute muscle pain in the upper extremity were not significantly altered indicating that changes in pain-related, movement strategies may be more strongly influenced by supraspinal adaptations. These results may have value in improving understanding of pain-related, movement sequelae and directing future research in this area.

No description available.

BACKGROUND: Chronic low back pain (CLBP) is the leading cause of disability in the United States. People suffering from CLBP often have multiple comorbidities including depression, anxiety, and substance use disorder (SUD). Although the opioid epidemic has intensified the search for new treatment options, both pharmacological and other, opioids still remain the most common treatment for chronic pain. Long-term opioid therapy (LTOT) has been shown to lead to opioid-induced hyperalgesia (OIH), an increased sensitivity to painful stimuli. It remains unclear, however, the extent to which reductions in opioid dose impact OIH. METHODS: This is a longitudinal cohort study whose primary aim is to determine how changes in opioid doses are associated with changes in psychosocial and quantitative sensory testing (QST) variables. Participants were 24 adults with CLBP being treated with LTOT and visits were conducted on a monthly basis for six months. All 24 participants were included in the analysis of demographic and psychosocial variables (disability, anxiety, depression, opioid misuse, pain severity, pain interference, and catastrophizing). A subset of 13 participants were included in the analysis of QST variables. RESULTS: We found that pressure pain thresholds at the thumb and the trapezius, and heat pain threshold significantly (p < 0.05) improved between visit 1 and visit 6. We also found that a decrease in morphine equivalent doses (MED) is correlated (coefficient > 0.2) with improvements in punctuate probe rating, pain pressure at the thumb, and maximum cold ratings. DISCUSSION: Our results show that reductions in opioid dose are associated with reduced pain sensitivity, even while the psychosocial variables studied (including subjective pain score, depression, and anxiety) remain stable.

BACKGROUND AND AIMS: Globally, chronic low back pain (CLBP) affects 70-80% of adults at some point in their lives and current treatments are widely unsuccessful in relieving pain. Understanding the underlying neurophysiological (e.g., descending pain inhibition) and biobehavioral (e.g., stress) processes contributing to chronic pain in patients with CLBP is needed for the development of novel treatments. Previous studies have shown that acute stress can impact pain sensitivity and that childhood trauma may predispose a person to CLBP, but the mechanisms underlying this impact are unknown. Conditioned Pain Modulation (CPM) is a psychophysical paradigm used in research to assess descending pain modulatory pathways, which are thought to be impaired in patients with CLBP as well as in those with childhood trauma. The overlap of conditions has not been explored. The current study explored the impact of childhood trauma on the CPM response within a sample of patients with CLBP being treated at a tertiary pain clinic. CLBP patients exposed to an acute stress paradigm were expected to shower higher pain sensitivity, with acute stress significantly interacting with a history of childhood trauma as a factor leading to the higher pain sensitivity. METHODS: 46 Participants with CLBP (n=46, mean age=49 years, 55.3% female) recruited from a pain treatment service completed a Quantitative Sensory Testing (QST) and CPM before and after an acute psychological stressor. Participants were randomized to a control (n=25) or an acute-stress (n=21) condition. The acute-stress condition included the Stroop Color Word Task (SCWT) and a mental arithmetic task prior to completing the QST protocol a second time. The control participants did not undergo any additional stressors and completed the QST protocol a second time after a 20-minute break. Participants’ CPM response was measured by the average change in pressure pain threshold (PPT) from baseline to the conditioning stimulus (non-dominant hand in ice-water bath). A “Good CPM response” was defined as a CPM effect above 100, indicating that the pain threshold increased when exposed to the conditioning stimulus. To examine the impact of childhood trauma on pain sensitivity, participants completed a Childhood Traumatic Events Scale (CTES) to assess the presence and severity of six types of trauma (death, parental upheaval, sexual, violence, illness or injury, other upheaval) during childhood. The CTES was scored as a continuous variable by calculating the sum the trauma severity for all six trauma types. RESULTS: A large majority of the sample (94% of participants) showed an increase in pain threshold during hand immersion in ice water, which was contrary to our hypothesis based on prior research done on other chronic pain conditions and CLBP. Participants exposed to an acute stressor had an impaired CPM effect compared to those that were not exposed to an acute stressor, however there was no difference between groups (p=0.277). A history of childhood traumatic events did not correlate significantly with an impaired baseline CPM or a change in CPM effect when exposed to an acute stressor. CONCLUSION: The current study used novel QST modalities, including CPM, to analyze the interaction between acute and chronic stress on pain sensitivity. Ultimately, this study found that exposure to an acute stressor had a negative effect on CPM, indicating that when under experimental stress participants were more sensitive to pain compared to when they were not under stress, although the findings were not statistically significant. These findings should be further investigated to expand the understanding of the neurophysiological mechanisms underlying CLBP and to potentially provide novel treatment modalities for patients with CLBP.

No description available.

L'objectif de notre travail était dans un premier temps d'étudier les liens entre l'altération des fibres nerveuses de petit diamètre et la présence de douleurs chez des patients ayant une neuropathie périphérique. Notre deuxième objectif était d'évaluer la pertinence de certaines techniques neurophysiologiques pour mettre en évidence l'atteinte de ces petites fibres nerveuses. Notre première étude réalisée sur une large cohorte de patients présentant divers types de neuropathie a montré, grâce à une étude quantifiée de la sensibilité, qu'il n'y avait pas de corrélation entre la perte ou perte de fonction des fibres nerveuses de petit diamètre et la présence de douleurs. Ceci a été confirmé par notre deuxième étude portant sur une population plus homogène de patients ayant une neuropathie amyloïde familiale et étudiés avec une batterie neurophysiologique plus large. Ainsi, les douleurs neuropathiques des patients présentant une neuropathie périphérique sont probablement dues à la combinaison de facteurs d'hyperexcitabilité périphérique et de sensibilisation centrale et non directement liée à la perte en petites fibres. Il reste cependant pertinent de développer des techniques objectives d'exploration de ces petites fibres notamment dans un but de diagnostic clinique. Notre troisième étude a montré que certaines méthodes neurophysiologiques étaient particulièrement sensibles dans ce cadre en prenant pour exemple la détection d'anomalies précoces d'atteinte des petites fibres au cours de la neuropathie amyloïde familiale. Une batterie de tests comprenant l'enregistrement des potentiels évoqués laser, la mesure du seuil de détection du chaud et de la conductance cutanée, s'est avérée être la combinaison la plus pertinente, comme l'a montré notre quatrième étude sur une grande cohorte de patients susceptibles de présenter une neuropathie des petites fibres. / The aim of our work was initially to study the relationship between alterations in small diameter nerve fibers and the presence of pain in patients with peripheral neuropathy. Our second objective was to assess the relevance of some neurophysiological tests to characterize these alterations in small nerve fibers. Our first study of a large cohort of patients with various types of neuropathy showed, using quantitative sensory testing, that there was no correlation between the loss or loss of function of small nerve fibers and the presence of pain. This was confirmed by our second study focused on a more homogeneous population of patients with familial amyloid neuropathy and studied with a larger neurophysiological battery. Thus, neuropathic pain in patients with peripheral neuropathy is probably due to a combination of factors of peripheral hyperexcitability and central sensitization and not directly related to the loss of small nerve fibers. However, it remains relevant to develop techniques of objective investigation of these small nerve fibers for a purpose of clinical diagnosis. Our third study showed that some neurophysiological methods were particularly sensitive in this context, taking the example of the detection of early alteration of small nerve fibers in familial amyloid neuropathy. A battery of tests, including laser evoked potential recording, warm detection threshold and electrochemical skin conductance measurement, proved to be the most appropriate combination for this diagnostic purpose, as shown by our fourth study on a large cohort of patients likely to have a small fiber neuropathy.

<p>In a prospective randomised double-blind study eighty patients with MRI verified lumbar disc herniation and corresponding clinical findings underwent microscopic disc removal. The patients were peroperatively given systemic and local corticosteroids or placebo, and followed for 2 years. The hospital stay and time to return to full-time work was significantly shorter in the treatment group. Pain measured as worst pain during the last week was also lower in the corticosteroid group. The results indicate that peroperative treatment with corticosteroids reduces pain and improves the functional outcome in patients operated for lumbar disc herniations.</p><p>To evaluate whether thermal quantitative sensory testing (QST) is applicable in the study of sensory dysfunction in lumbar disc herniations 66 patients with disc herniations underwent thermal QST. We found that thermal QST reflects sensory dysfunction in patients with lumbar disc herniations. However, thermal QST seems to have a poor predictive value for identifying the anatomic location of a herniated lumbar disc.</p><p>Quantitative sensory testing (QST) was used to detect damage to the myelinated A-delta fibres (cold sense) and the unmyelinated C-fibres (warmth sense). Corticosteroids combined with surgery in lumbar disc surgery improved the normalisation for the warmth disturbance compared to the control group. </p><p>A prospective analysis was performed on the predictive value of preoperatively determined lumbar lordosis and flexion for pain and disability in patients treated by microscopic lumbar disc surgery. Preoperative hyperlordosis correlated to more pain postoperatively (p=0.004). In patients with hypoflexion there was an association between hyperlordosis and moderate or severe pain postoperatively (p<0.001). The same outcomes were found for DRI. The stiff and straight back indicates a good outcome of lumbar disc surgery concerning pain and disability. </p>

In a prospective randomised double-blind study eighty patients with MRI verified lumbar disc herniation and corresponding clinical findings underwent microscopic disc removal. The patients were peroperatively given systemic and local corticosteroids or placebo, and followed for 2 years. The hospital stay and time to return to full-time work was significantly shorter in the treatment group. Pain measured as worst pain during the last week was also lower in the corticosteroid group. The results indicate that peroperative treatment with corticosteroids reduces pain and improves the functional outcome in patients operated for lumbar disc herniations. To evaluate whether thermal quantitative sensory testing (QST) is applicable in the study of sensory dysfunction in lumbar disc herniations 66 patients with disc herniations underwent thermal QST. We found that thermal QST reflects sensory dysfunction in patients with lumbar disc herniations. However, thermal QST seems to have a poor predictive value for identifying the anatomic location of a herniated lumbar disc. Quantitative sensory testing (QST) was used to detect damage to the myelinated A-delta fibres (cold sense) and the unmyelinated C-fibres (warmth sense). Corticosteroids combined with surgery in lumbar disc surgery improved the normalisation for the warmth disturbance compared to the control group. A prospective analysis was performed on the predictive value of preoperatively determined lumbar lordosis and flexion for pain and disability in patients treated by microscopic lumbar disc surgery. Preoperative hyperlordosis correlated to more pain postoperatively (p=0.004). In patients with hypoflexion there was an association between hyperlordosis and moderate or severe pain postoperatively (p&lt;0.001). The same outcomes were found for DRI. The stiff and straight back indicates a good outcome of lumbar disc surgery concerning pain and disability.