[Mindfulness meditation in somatic medicine. A management tool for physical and psychological pain]. / Applications de la méditation de pleine conscience dans différents secteurs de médecine somatique. Un outil de gestion de la douleur physique et morale.

Mindfulness meditation is a mind-body approach that helps to cope with psychological or physical symptoms such as pain. To date, this approach is still not widely available to patients in our French-speaking somatic clinical settings, despite its scientific validation. This article describes three mindfulness meditation programs delivered at Lausanne University Hospital (CHUV) to people living with HIV, cancer or chronic pain. It highlights the issues related to the involvement of participants in these programs as well as those related to their implementation in a Swiss somatic, teaching French-speaking hospital.

La méditation de pleine conscience est une approche corps-esprit qui permet de faire face à des symptômes psychiques ou physiques tels que la douleur. À ce jour, malgré sa validation scientifique, cette approche reste peu accessible pour les patient-e-s dans nos contextes cliniques somatiques romands. Cet article décrit trois programmes de méditation de pleine conscience délivrés au sein du CHUV (Lausanne), à des personnes qui vivent avec un VIH, un cancer ou une douleur chronique. Il met en lumière les enjeux liés à l'engagement des participant-e-s dans ces programmes mais aussi ceux en lien avec leur implémentation dans un contexte hospitalier somatique romand.

The disappearing hand: vestibular stimulation does not improve hand localisation.

BACKGROUND: Bodily self-consciousness depends on the coherent integration of sensory information. In addition to visual and somatosensory information processing, vestibular contributions have been proposed and investigated. Vestibular information seems especially important for self-location, but remains difficult to study. METHODS: This randomised controlled experiment used the MIRAGE multisensory illusion box to induce a conflict between the visually- and proprioceptively-encoded position of one hand. Over time, the perceived location of the hand slowly shifts, due to the fact that proprioceptive input is progressively weighted more heavily than the visual input. We hypothesised that left cold caloric vestibular stimulation (CVS) augments this shift in hand localisation. RESULTS: The results from 24 healthy participants do not support our hypothesis: CVS had no effect on the estimations with which the perceived position of the hand shifted from the visually- to the proprioceptively-encoded position. Participants were more likely to report that their hand was 'no longer there' after CVS. Taken together, neither the physical nor the subjective data provide evidence for vestibular enhanced self-location.

Canal-otolith interactions alter the perception of self-motion direction.

Few studies have investigated the perception of vestibular stimuli when they occur in sequences. Here, three experiments (ntotal = 33) are presented that focus on intravestibular motion sequences and the underlying perceptual decision-making process. Natural vestibular stimulation (yaw rotation or translation) was used to investigate the discrimination process of the direction of a subsequent spatially congruent or incongruent translation or rotation. The few existing studies focusing on unimodal motion sequences have uncovered self-motion aftereffects, similar to the visual motion aftereffect, possibly due to altered processing of sensory stimuli. An alternative hypothesis predicts a shift of spatial attention due to the cue motion influencing perception of the subsequent motion stimulus. The results show that participants systematically misjudged the direction of motion stimuli well above the detection threshold if the direction of the preceding cue motion stimulus was congruent with the direction of the target (a motion aftereffect). Hierarchical drift diffusion models were used to analyze the data. The results suggest that altered perceptual decision-making and the resulting misperceptions are likely to originate in altered processing of sensory vestibular information.

Defensive reflexes in people with pain - a biomarker of the need to protect? A meta-analytical systematic review.

Upregulation of defensive reflexes such as the nociceptive flexion reflex (NFR) has been attributed to sensitisation of peripheral and spinal nociceptors and is often considered biomarkers of pain. Experimental modulation of defensive reflexes raises the possibility that they might be better conceptualised as markers of descending cognitive control. Despite strongly held views on both sides and several narrative reviews, there has been no attempt to evaluate the evidence in a systematic manner. We undertook a meta-analytical systematic review of the extant English-language literature from inception. Thirty-six studies satisfied our a priori criteria. Seventeen were included in the meta-analysis. Reflexive threshold was lower in people with clinical pain than it was in pain-free controls, but reflex size, latency, and duration were unaffected. The pattern of difference was not consistent with sensitisation of nociceptive neurones, as these changes were not isolated to the affected body part but was more consistent with top-down cognitive control reflective of heightened protection of body tissue. The pattern of modulation is dependent on potentially complex evaluative mechanisms. We offer recommendations for future investigations and suggest that defensive reflex threshold may reflect a biomarker of a broader psychological construct related to bodily protection, rather than sensitisation of primary nociceptors, spinal nociceptors, or pain.

Can screening instruments accurately determine poor outcome risk in adults with recent onset low back pain? A systematic review and meta-analysis.

BACKGROUND: Delivering efficient and effective healthcare is crucial for a condition as burdensome as low back pain (LBP). Stratified care strategies may be worthwhile, but rely on early and accurate patient screening using a valid and reliable instrument. The purpose of this study was to evaluate the performance of LBP screening instruments for determining risk of poor outcome in adults with LBP of less than 3 months duration. METHODS: Medline, Embase, CINAHL, PsycINFO, PEDro, Web of Science, SciVerse SCOPUS, and Cochrane Central Register of Controlled Trials were searched from June 2014 to March 2016. Prospective cohort studies involving patients with acute and subacute LBP were included. Studies administered a prognostic screening instrument at inception and reported outcomes at least 12 weeks after screening. Two independent reviewers extracted relevant data using a standardised spreadsheet. We defined poor outcome for pain to be ≥ 3 on an 11-point numeric rating scale and poor outcome for disability to be scores of ≥ 30% disabled (on the study authors' chosen disability outcome measure). RESULTS: We identified 18 eligible studies investigating seven instruments. Five studies investigated the STarT Back Tool: performance for discriminating pain outcomes at follow-up was 'non-informative' (pooled AUC = 0.59 (0.55-0.63), n = 1153) and 'acceptable' for discriminating disability outcomes (pooled AUC = 0.74 (0.66-0.82), n = 821). Seven studies investigated the Orebro Musculoskeletal Pain Screening Questionnaire: performance was 'poor' for discriminating pain outcomes (pooled AUC = 0.69 (0.62-0.76), n = 360), 'acceptable' for disability outcomes (pooled AUC = 0.75 (0.69-0.82), n = 512), and 'excellent' for absenteeism outcomes (pooled AUC = 0.83 (0.75-0.90), n = 243). Two studies investigated the Vermont Disability Prediction Questionnaire and four further instruments were investigated in single studies only. CONCLUSIONS: LBP screening instruments administered in primary care perform poorly at assigning higher risk scores to individuals who develop chronic pain than to those who do not. Risks of a poor disability outcome and prolonged absenteeism are likely to be estimated with greater accuracy. It is important that clinicians who use screening tools to obtain prognostic information consider the potential for misclassification of patient risk and its consequences for care decisions based on screening. However, it needs to be acknowledged that the outcomes on which we evaluated these screening instruments in some cases had a different threshold, outcome, and time period than those they were designed to predict. SYSTEMATIC REVIEW REGISTRATION: PROSPERO international prospective register of systematic reviews registration number CRD42015015778 .

The effect of repeated laser stimuli to ink-marked skin on skin temperature-recommendations for a safe experimental protocol in humans.

Background. Nd:YAP laser is widely used to investigate the nociceptive and pain systems, generating perpetual and laser-evoked neurophysiological responses. A major procedural concern for the use of Nd:YAP laser stimuli in experimental research is the risk of skin damage. The absorption of Nd:YAP laser stimuli is greater in darker skin, or in pale skin that has been darkened with ink, prompting some ethics boards to refuse approval to experimenters wishing to track stimulus location by marking the skin with ink. Some research questions, however, require laser stimuli to be delivered at particular locations or within particular zones, a requirement that is very difficult to achieve if marking the skin is not possible. We thoroughly searched the literature for experimental evidence and protocol recommendations for safe delivery of Nd:YAP laser stimuli over marked skin, but found nothing. Methods. We designed an experimental protocol to define safe parameters for the use of Nd:YAP laser stimuli over skin that has been marked with black dots, and used thermal imaging to assess the safety of the procedure at the forearm and the back. Results. Using thermal imaging and repeated laser stimulation to ink-marked skin, we demonstrated that skin temperature did not increase progressively across the course of the experiment, and that the small change in temperature seen at the forearm was reversed during the rest periods between blocks. Furthermore, no participant experienced skin damage due to the procedure. Conclusion. This protocol offers parameters for safe, confident and effective experimentation using repeated Nd:YAP laser on skin marked with ink, thus paving the way for investigations that depend on it.

The Moving History of Vestibular Stimulation as a Therapeutic Intervention.

Although the discovery and understanding of the function of the vestibular system date back only to the 19th century, strategies that involve vestibular stimulation were used long before to calm, soothe and even cure people. While such stimulation was classically achieved with various motion devices, like Cox's chair or Hallaran's swing, the development of caloric and galvanic vestibular stimulation has opened up new possibilities in the 20th century. With the increasing knowledge and recognition of vestibular contributions to various perceptual, motor, cognitive, and emotional processes, vestibular stimulation has been suggested as a powerful and non-invasive treatment for a range of psychiatric, neurological and neurodevelopmental conditions. Yet, the therapeutic interventions were, and still are, often not hypothesis-driven as broader theories remain scarce and underlying neurophysiological mechanisms are often vague. We aim to critically review the literature on vestibular stimulation as a form of therapy in various selected disorders and present its successes, expectations, and drawbacks from a historical perspective.

Self-motion direction discrimination in the visually impaired.

Despite the close interrelation between vestibular and visual processing (e.g., vestibulo-ocular reflex), surprisingly little is known about vestibular function in visually impaired people. In this study, we investigated thresholds of passive whole-body motion discrimination (leftward vs. rightward) in nine visually impaired participants and nine age-matched sighted controls. Participants were rotated in yaw, tilted in roll, and translated along the interaural axis at two different frequencies (0.33 and 2 Hz) by means of a motion platform. Superior performance of visually impaired participants was found in the 0.33 Hz roll tilt condition. No differences were observed in the other motion conditions. Roll tilts stimulate the semicircular canals and otoliths simultaneously. The results could thus reflect a specific improvement in canal-otolith integration in the visually impaired and are consistent with the compensatory hypothesis, which implies that the visually impaired are able to compensate the absence of visual input.

Motor imagery training improves precision of an upper limb movement in patients with hemiparesis.

BACKGROUND: In healthy participants, beneficial effects of motor imagery training on movement execution have been shown for precision, strength, and speed. In the clinical context, it is still debated whether motor imagery provides an effective rehabilitation technique in patients with motor deficits. OBJECTIVE: To compare the effectiveness of two different types of movement training: motor imagery vs. motor execution. METHODS: Twenty-five patients with hemiparesis were assigned to one of two training groups: the imagery or the execution-training group. Both groups completed a baseline test before they received six training sessions, each of which was followed by a test session. Using a novel and precisely quantifiable test, we assessed how accurately patients performed an upper limb movement. RESULTS: Both training groups improved performance over the six test sessions but the improvement was significantly larger in the imagery group. That is, the imagery group was able to perform more precise movements than the execution group after the sixth training session while there was no difference at the beginning of the training. CONCLUSIONS: The results provide evidence for the benefit of motor imagery training in patients with hemiparesis and thus suggest the integration of cognitive training in conventional physiotherapy practice.

Spatial cognition, body representation and affective processes: the role of vestibular information beyond ocular reflexes and control of posture.

A growing number of studies in humans demonstrate the involvement of vestibular information in tasks that are seemingly remote from well-known functions such as space constancy or postural control. In this review article we point out three emerging streams of research highlighting the importance of vestibular input: (1) Spatial Cognition: Modulation of vestibular signals can induce specific changes in spatial cognitive tasks like mental imagery and the processing of numbers. This has been shown in studies manipulating body orientation (changing the input from the otoliths), body rotation (changing the input from the semicircular canals), in clinical findings with vestibular patients, and in studies carried out in microgravity. There is also an effect in the reverse direction; top-down processes can affect perception of vestibular stimuli. (2) Body Representation: Numerous studies demonstrate that vestibular stimulation changes the representation of body parts, and sensitivity to tactile input or pain. Thus, the vestibular system plays an integral role in multisensory coordination of body representation. (3) Affective Processes and Disorders: Studies in psychiatric patients and patients with a vestibular disorder report a high comorbidity of vestibular dysfunctions and psychiatric symptoms. Recent studies investigated the beneficial effect of vestibular stimulation on psychiatric disorders, and how vestibular input can change mood and affect. These three emerging streams of research in vestibular science are-at least in part-associated with different neuronal core mechanisms. Spatial transformations draw on parietal areas, body representation is associated with somatosensory areas, and affective processes involve insular and cingulate cortices, all of which receive vestibular input. Even though a wide range of different vestibular cortical projection areas has been ascertained, their functionality still is scarcely understood.

Moving along the mental number line: Interactions between whole-body motion and numerical cognition.

Active head turns to the left and right have recently been shown to influence numerical cognition by shifting attention along the mental number line. In the present study, we found that passive whole-body motion influences numerical cognition. In a random-number generation task (Experiment 1), leftward and downward displacement of participants facilitated small number generation, whereas rightward and upward displacement facilitated the generation of large numbers. Influences of leftward and rightward motion were also found for the processing of auditorily presented numbers in a magnitude-judgment task (Experiment 2). Additionally, we investigated the reverse effect of the number-space association (Experiment 3). Participants were displaced leftward or rightward and asked to detect motion direction as fast as possible while small or large numbers were auditorily presented. When motion detection was difficult, leftward motion was detected faster when hearing small number and rightward motion when hearing large number. We provide new evidence that bottom-up vestibular activation is sufficient to interact with the higher-order spatial representation underlying numerical cognition. The results show that action planning or motor activity is not necessary to influence spatial attention. Moreover, our results suggest that self-motion perception and numerical cognition can mutually influence each other.

Mental transformation abilities in patients with unilateral and bilateral vestibular loss.

Vestibular information helps to establish a reliable gravitational frame of reference and contributes to the adequate perception of the location of one's own body in space. This information is likely to be required in spatial cognitive tasks. Indeed, previous studies suggest that the processing of vestibular information is involved in mental transformation tasks in healthy participants. In this study, we investigate whether patients with bilateral or unilateral vestibular loss show impaired ability to mentally transform images of bodies and body parts compared to a healthy, age-matched control group. An egocentric and an object-based mental transformation task were used. Moreover, spatial perception was assessed using a computerized version of the subjective visual vertical and the rod and frame test. Participants with bilateral vestibular loss showed impaired performance in mental transformation, especially in egocentric mental transformation, compared to participants with unilateral vestibular lesions and the control group. Performance of participants with unilateral vestibular lesions and the control group are comparable, and no differences were found between right- and left-sided labyrinthectomized patients. A control task showed no differences between the three groups. The findings from this study substantiate that central vestibular processes are involved in imagined spatial body transformations; but interestingly, only participants with bilateral vestibular loss are affected, whereas unilateral vestibular loss does not lead to a decline in spatial imagery.

Effects of microgravity on cognition: The case of mental imagery.

Human cognitive performance is an important factor for the successful and safe outcome of commercial and non-commercial manned space missions. This article aims to provide a systematic review of studies investigating the effects of microgravity on the cognitive abilities of parabolic or space flight participants due to the absence of the gravito-inertial force. We will focus on mental imagery: one of the best studied cognitive functions. Mental imagery is closely connected to perception and motor behavior. It aids important processes such as perceptual anticipation, problem solving and motor simulation, all of which are critical for space travel. Thirteen studies were identified and classified into the following topics: spatial representations, mental image transformations and motor imagery. While research on spatial representation and mental image transformation continues to grow and specific differences in cognitive functioning between 1 g and 0 g have been observed, motor imagery has thus far received little attention.

Vestibular thresholds for yaw rotation about an earth-vertical axis as a function of frequency.

Perceptual direction detection thresholds for yaw rotation about an earth-vertical axis were measured at seven frequencies (0.05, 0.1, 0.2, 0.5, 1, 2, and 5 Hz) in seven subjects in the dark. Motion stimuli consisted of single cycles of sinusoidal acceleration and were generated by a motion platform. An adaptive two-alternative categorical forced-choice procedure was used. The subjects had to indicate by button presses whether they perceived yaw rotation to the left or to the right. Thresholds were measured using a 3-down, 1-up staircase paradigm. Mean yaw rotation velocity thresholds were 2.8 deg s(-1) for 0.05 Hz, 2.5 deg s(-1) for 0.1 Hz, 1.7 deg s(-1) for 0.2 Hz, 0.7 deg s(-1) for 0.5 Hz, 0.6 deg s(-1) for 1 Hz, 0.4 deg s(-1) for 2 Hz, and 0.6 deg s(-1) for 5 Hz. The results show that motion thresholds increase at 0.2 Hz and below and plateau at 0.5 Hz and above. Increasing velocity thresholds at lower frequencies qualitatively mimic the high-pass characteristics of the semicircular canals, since the increase at 0.2 Hz and below would be consistent with decreased gain/sensitivity observed in the VOR at lower frequencies. In fact, the measured dynamics are consistent with a high pass filter having a threshold plateau of 0.71 deg s(-1) and a cut-off frequency of 0.23 Hz, which corresponds to a time constant of approximately 0.70 s. These findings provide no evidence for an influence of velocity storage on perceptual yaw rotation thresholds.

Mental own-body and body-part transformations in microgravity.

The aim of this experiment was to investigate the influence of gravity on the cognitive ability to mentally transform images of bodies or body parts. A total of eight participants were tested in two separate parabolic flight missions. In the main experiment, participants had to make a discrimination judgement (left or right) about pictures of a human figure with one arm outstretched, and pictures of a body part (hand). The stimuli appeared in varying views and orientations. Response times and error rates were measured. In microgravity, the participants showed increased response times overall as well as increased error rates when compared to 1 g for both types of stimuli. Thus, a task that requires the mental transformation of one's own body or body parts becomes more difficult during microgravity. This is in contrast to previous studies showing no effect of microgravity on the mental rotation of abstract 3D objects and to our follow-up case study in which participants applied an object-based mental rotation strategy. Moreover, the analysis of response times suggests that in microgravity body-part stimuli are affected more strongly than body figures.