Utilisation d'une rétroaction virtuelle altérée pour évaluer les représentations du corps en présence ou en absence de douleur
|Advisor:||Mercier, Catherine; McCabe, Candy|
|Abstract:||Introduction: Approximately 20% of the Canadian adults suffer from chronic pain in spite of the available pharmacological approaches. Thus, it is important to develop complementary therapeutic approaches in rehabilitation and to understand the underlying mechanisms involved in the maintenance of pain. One hypothesis that has been put forward to explain the persistence of pain postulates that pain is the consequence of a discordance between the motor efferences and the sensory feedback arising from one’s actions (defined as a sensorimotor conflict), just as the sensation of nausea in motion sickness arises from a conflict between visual, proprioceptive and vestibular information. Such sensorimotor conflicts in the presence of pain could be caused by alterations in body representations and motor control. Studies using experimental sensorimotor conflicts show that people with pain are more sensitive to the presence of conflicts (as demonstrated by an increase in painful sensations and other sensory disturbances), what could contribute to a vicious circle maintaining and aggravating pain. However, the reason why people with pain are more sensitive to sensorimotor conflicts remains unclear. Therefore, the main objective of the study was to assess the clinical and sensorimotor characteristics explaining higher sensitivity to sensorimotor conflicts in the presence of pain. The main hypothesis was that increased malleability of body representations in the presence of pain explains increased sensitivity to sensorimotor conflicts. Methods: Sensorimotor conflicts have been created using a mirror (Chapter III, N=140 participants, either healthy or with fibromyalgia, or complex regional pain syndrome (CRPS) or arthritis) or a robotic device combined with a 2D virtual reality interface (KINARM) (Chapter IV, N=30 healthy participants with or without experimental pain; Chapter V, N=20 healthy participants). Two types of disturbances were assessed: 1) sensory disturbances (measured with a questionnaire) and 2) motor disturbances (mediolateral drift and amplitude variation). The KINARM was also used to assess various body representations in participants with or without chronic pain (Chapter VI: N=26 participants, healthy or with a CRPS). Clinical outcomes were assessed with questionnaires. Results: Only some sensory disturbances induced by sensorimotor conflicts were increased in the presence of chronic (Chapter III) and acute (Chapter IV) pain, and were mainly related to pain intensity (Chapter III). The other clinical characteristics (pathology origin, duration of pain, anxious and depressive symptoms) contributed very little to the increase in sensitivity to sensorimotor conflicts in the presence of pain (Chapter III). Contrary to sensory disturbances, motor disturbances induced by sensorimotor conflicts were not influenced by the presence of acute pain (Chapter IV). Moreover, a conflict between vision and motor efferences (during active movements) induces higher sensory disturbances than a conflict between vision and proprioception (passive movements, Chapter V). Finally, kinesthesia (senses of limb position and movement) was altered in people with CRPS compared to healthy participants, but was not related to the subjective perception of the painful limb (Chapter VI). Conclusions: The presence of pain (acute or chronic) decreases the detection threshold of sensorimotor conflicts and contributes to maintain a conflict situation. This vicious circle of pain worsening is explained more by an alteration of body perception than by a perturbation in sensorimotor integration. These results support the multiple body representations theory suggesting a dissociation between the body image and the body schema. Contrary to the body image which is altered in the presence of acute and chronic pain, the body schema is altered only in the presence of chronic pain. In clinical practice, it would be relevant to assess and treat the alterations of body image and body schema separately. In research, it would be necessary to explore the underlying mechanisms of this dissociation.|
|Document Type:||Thèse de doctorat|
|Open Access Date:||5 December 2018|
|Collection:||Thèses et mémoires|
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