The barriers and facilitators to satisfaction with botulinum neurotoxin treatment in people with cervical dystonia: a systematic review.

BACKGROUND: Cervical dystonia (CD) is an isolated, focal, idiopathic dystonia affecting the neck and upper back. CD is usually treated by botulinum neurotoxin (BoNT) injections into the dystonic muscles; however, about 20% of people will discontinue BoNT therapy. This systematic review aimed to determine the barriers to satisfaction and facilitators that could improve satisfaction with BoNT therapy for people with CD. METHODS: A database search for journal articles investigating satisfaction with BoNT treatment in CD identified seven qualitative studies and one randomised controlled trial. Results were grouped into "direct" and "indirect" barriers and facilitators. RESULTS: The most reported direct barrier to satisfaction with BoNT was treatment non-response, reported by up to 66% of participants. Other direct barriers included negative side effects, early wearing-off of treatment effect and inexperience of the treating physician. Indirect barriers included limited accessibility to treatment (including cost) and personal choice. Direct facilitators of satisfaction with BoNT included relief of symptoms and flexible re-treatment intervals. Indirect facilitators included easy accessibility to treatment. CONCLUSIONS: Despite BoNT having a discontinuation rate of only 20%, it appears a much greater proportion of people with CD are dissatisfied with this treatment. As BoNT is currently the main treatment offered to people with CD, efforts to improve treatment response rates, reduce side effects and make treatment more flexible and readily available should be adopted to improve the quality of life for people with CD.

Can Transcranial Direct Current Stimulation Enhance Poststroke Motor Recovery? Development of a Theoretical Patient-Tailored Model.

New treatments that can facilitate neural repair and reduce persistent impairments have significant value in promoting recovery following stroke. One technique that has gained interest is transcranial direct current stimulation (tDCS) as early research suggested it could enhance plasticity and enable greater behavioral recovery. However, several studies have now identified substantial intersubject variability in response to tDCS and clinical trials revealed insufficient evidence of treatment effectiveness. A possible explanation for the varied and negative findings is that the physiologic model of stroke recovery that researchers have used to guide the application of tDCS-based treatments in stroke is overly simplistic and does not account for stroke heterogeneity or known determinants that affect the tDCS response. Here, we propose that tDCS could have a more clearly beneficial role in enhancing stroke recovery if greater consideration is given to individualizing treatment. By critically reviewing the proposed mechanisms of tDCS, stroke physiology across the recovery continuum, and known determinants of tDCS response, we propose a new, theoretical, patient-tailored approach to delivering tDCS after stroke. The proposed model includes a step-by-step principled selection strategy for identifying optimal neuromodulation targets and outlines key areas for further investigation. Tailoring tDCS treatment to individual neuroanatomy and physiology is likely our best chance at producing robust and meaningful clinical benefit for people with stroke and would therefore accelerate opportunities for clinical translation.

The Effect of the COVID-19 Pandemic Movement Restrictions on Self-Reported Physical Activity and Health in New Zealand: A Cross-Sectional Survey.

This study describes self-reported physical activity (PA), motivation to exercise, physical and mental health and feelings towards PA during the March-May 2020 COVID-19 lockdown in New Zealand. Adults over the age of 18 years (n = 238; 80.2% female) completed the International Physical Activity Questionnaire (IPAQ), the Behavioural Regulation in Exercise Questionnaire 3, the Short Form-36 and open-ended questions about PA through an anonymous online survey. Regular exercise was undertaken by 85% of respondents prior to lockdown, but only 49.8% were able to maintain their usual level of PA. Although respondents were considered sufficiently physically active from the IPAQ, 51.5% reported not being able to maintain their usual level of PA primarily due to the closure of their gym facilities. Sixty percent of respondents reported that PA had a positive effect on their overall wellbeing. When asked to specify which aspects of wellbeing were affected, the effect on mental health was reported the most while the effect on body image or fitness was reported the least. Strategies to increase or maintain engagement in physical activity during lockdowns should be encouraged to promote positive mental health during the COVID-19 pandemic.

Cortical neurophysiology of primary isolated dystonia and non-dystonic adults: A meta-analysis.

Transcranial magnetic stimulation (TMS) is a non-invasive method to assess neurophysiology of the primary motor cortex in humans. Dystonia is a poorly understood neurological movement disorder, often presenting in an idiopathic, isolated form across different parts of the body. The neurophysiological profile of isolated dystonia compared to healthy adults remains unclear. We conducted a systematic review with meta-analysis of neurophysiologic TMS measures in people with isolated dystonia to provide a synthesized understanding of cortical neurophysiology associated with isolated dystonia. We performed a systematic database search and data were extracted independently by the two authors. Separate meta-analyses were performed for TMS measures of: motor threshold, corticomotor excitability, short interval intracortical inhibition, cortical silent period, intracortical facilitation and afferent-induced inhibition. Standardized mean differences were calculated using a random effects model to determine overall effect sizes and confidence intervals. Heterogeneity was explored using dystonia type subgroup analysis. The search resulted in 78 studies meeting inclusion criteria, of these 57 studies reported data in participants with focal hand dystonia, cervical dystonia, blepharospasm or spasmodic dysphonia, and were included in at least one meta-analysis. The cortical silent period, short-interval intracortical inhibition and afferent-induced inhibition was found to be reduced in isolated dystonia compared to controls. Reduced GABAergic-mediated inhibition in the primary motor cortex in idiopathic isolated dystonia's suggest interventions targeted to aberrant cortical disinhibition could provide a novel treatment. Future meta-analyses require neurophysiology studies to use homogeneous cohorts of isolated dystonia participants, publish raw data values, and record electromyographic responses from dystonic musculature where possible.

Neurorehabilitation in dystonia: a holistic perspective.

Rehabilitation for isolated forms of dystonia, such as cervical or focal hand dystonia, is usually targeted towards the affected body part and focuses on sensorimotor control and motor retraining of affected muscles. Recent evidence, has revealed people who live with dystonia experience a range of functional and non-motor deficits that reduce engagement in daily activities and health-related quality of life, which should be addressed with therapeutic interventions. These findings support the need for a holistic approach to the rehabilitation of dystonia, where assessment and treatments involve non-motor signs and symptoms, and not just the dystonic body part. Most studies have investigated Cervical Dystonia, and in this population, it is evident there is reduced postural control and walking speed, high fear of falling and actual falls, visual compensation for the impaired neck posture, and a myriad of non-motor symptoms including pain, fatigue, sleep disorders and anxiety and depression. In other populations of dystonia, there is also emerging evidence of falls and reduced vision-related quality of life, along with the inability to participate in physical activity due to worsening of dystonic symptoms during or after exercise. A holistic approach to dystonia would support the management of a wide range of symptoms and signs, that if properly addressed could meaningfully reduce disability and improve quality of life in people living with dystonia.

Neck rotation modulates motor-evoked potential duration of proximal muscle cortical representations in healthy adults.

Transcranial magnetic stimulation (TMS) produces motor-evoked potentials (MEP) used to infer changes in corticomotor excitability. In humans, neck rotation can probe reticulospinal input on corticomotor output. This study investigated the effect of neck rotation on MEP duration in a proximal and distal upper limb muscle and compared responses between rest and preactivation. Single-pulse TMS to motor cortex was used to evoke MEPs at two stimulus intensities in 18 healthy adults (20-40 years). Surface electromyography recorded MEPs from the non-dominant biceps brachii (BB) and first dorsal interosseous (FDI). Participants were seated with the target muscle at rest or 10% preactivated, and head rotated ipsilateral, contralateral, or in neutral position. The primary outcome was MEP tail, defined as the mean difference in MEP duration between active and rest trials. Secondary outcomes were MEP duration and amplitude. MEP tail was modulated by neck rotation in the proximal BB (P = 0.03) but not distal FDI (P > 0.19), with shorter duration during ipsilateral or contralateral rotation relative to neutral. In a neutral neck position, MEP duration was prolonged by muscle preactivation and higher TMS intensities in the FDI and BB (P < 0.03). Neck rotation attenuated the prolongation of MEP duration during preactivation in the BB, but not the FDI. Neck rotation had no effect on MEP amplitude for either muscle (P > 0.05). Modulation of the late portion of the MEP by rotation of the neck could indicate subcortical projections to alpha-motoneuron pools are stronger in proximal than distal upper limb muscles. These findings may have relevance for using MEP duration as a neural biomarker in neurological diseases.

The Effect of Exercise-Based Cardiac Rehabilitation on Objectively Measured Physical Activity and Sedentary Behavior: A Systematic Review and Meta-analysis.

Objective: Adequate physical activity following cardiac rehabilitation (CR) is required to reduce secondary cardiovascular disease risk. The aim of this review and meta-analysis was to determine the effect of exercise-based CR on objectively measured physical activity (PA) and sedentary behavior (SB) comparing pre- to postintervention, pre- to postchange compared to a control group, and in a longer term follow-up. Methods: Five databases were searched (PubMed, MEDLINE [OVID], Scopus, SPORTDiscus, and CINAHL) from inception to January 2019. Two reviewers screened and selected 15 studies involving 1434 participants. Data were synthesized descriptively and by meta-analyses. Results: CR resulted in an improvement in activity behaviors compared with preintervention levels (standardized mean difference [SMD] 0.50, 95% CI 0.25-0.55, P < .0001). CR resulted in a greater improvement in activity behaviors in the intervention compared with the control group (SMD 0.25, 95% CI 0.02-0.49, P = .04). Increased PA was maintained (SMD 0.32, 95% CI 0.22-0.41, P < .0001). Eight out of 15 studies showed an improvement in PA outcomes while 7 reported that objectively measured PA did not change immediately following the intervention compared to preintervention levels and/or compared with the control group. Of the 7 studies that reported changes in SB, 4 observed a reduction following CR while 3 reported no change. Conclusion: Participation in exercise-based CR programs is effective in improving PA and SB. However, our descriptive synthesis indicates that only half the studies were successful in improving activity behaviors following exercise-based CR. Standard guidelines for the assessment of activity behaviors following CR would be valuable in understanding of the effects of CR on long-term activity participation.

A survey of falls in people with dystonia.

OBJECTIVE: Dystonia is a chronic and sometimes progressive neurological disorder causing abnormalities in movement and function. We conducted a preliminary survey to investigate whether people with dystonia experience falls and to identify contributing factors to falls in this population. METHODS: An online survey of people with dystonia was conducted in November 2015. Respondents were asked to complete demographic information, three questionnaires (the Falls Self-Efficacy Scale International [FES-I], the Activities-based Balance Confidence Scale [ABC] and the Functional Disability Questionnaire [FDQ]), and to report any falls sustained during the previous 6 months. RESULTS: Thirty-nine percent of the 122 respondents reported falling in the previous 6 months and 65% of fallers were diagnosed with dystonia not affecting the lower limbs. Fallers reported lower falls self-efficacy and balance confidence with higher functional disability. Both falling scales correlated with self-reported functional disability. Linear regression analysis for falls prediction revealed the variables FES-I and FDQ accounted for almost 30% of the falls in this dystonia population. CONCLUSION: This survey indicates that fear of falling and balance confidence are impaired in people with dystonia, possibly impacting on function and falls. Further investigation into balance, function and falls in this population is required.

Reduced vision-related quality of life in people living with dystonia.

Purpose: Dystonia is a neurological movement disorder with negative impact on function and quality of life. It is currently unclear whether vision-related quality of life is affected. The aim of this study was to determine whether vision-related quality of life is reduced by dystonia.Materials and methods: A vision-related quality of life questionnaire was delivered online to probe visual function in people living with dystonia. Scores for each of six domains were compared to normative data of 819 healthy participants using one sample t-tests. Respondents were divided into two groups based on whether they had botulinum toxin injections and compared using independent samples t-tests.Results: There were 42 completed responses. There was a difference from norm for two domains; ocular symptoms (t(41) = 2.31, p = 0.026) and role performance (t(41) = 2.85, p = 0.007). There was variation in responses for all six domains. No difference in scores for the botulinum toxin injection group was found for either domain (both p > 0.74).Conclusions: Some people with dystonia experience reduced vision-related quality of life, which has potential to contribute to their disability. Health professionals should be aware of vision-related issues when managing people with dystonia and consider appropriate rehabilitative interventions to reduce disability and enhance quality of life.Implications for rehabilitationDystonia is a neurological movement disorder resulting in abnormal postures and movements.Vision-related quality of life is reduced by dystonia which may contribute to disability and reduced function.Strategies to improve vision-related quality of life should be included in rehabilitation programmes for people living with dystonia.

Physical Activity, Sedentary Behavior, and Barriers to Exercise in People Living With Dystonia.

Background: Dystonia is a neurological movement disorder that presents as sustained or intermittent involuntary muscle contractions causing abnormal postures and movements. Knowledge of dystonia is mostly at the impairment level with minimal understanding of activity and participation limitations. Physical activity (PA) is an important aspect of neurological disease management, with wide-ranging benefits for overall health and quality of life. No studies have quantified PA and sedentary behavior (SB), nor explored barriers to being physically active in people with dystonia. Methods: Participants diagnosed with any form of dystonia completed a mixed-methods anonymous online survey on activity behaviors. The International Physical Activity Questionnaire (IPAQ) and Adult Sedentary Behavior Questionnaire (SBQ) assessed self-reported PA and SB. Barriers to exercise engagement were investigated according to the five-factor social-ecological framework and dystonia-specific questions regarding the impact of exercise on symptoms were included. Results: Two-hundred and sixty-three participants consented to the study (mean (SD) age = 55 (13) years, 76% Female). A large proportion of respondents (40%) reported living with cervical dystonia (CD). Overall, the median (IQR) time spent in walking, moderate, and vigorous activity was 60 (0-120), 120 (15-300), and 0 (0-13) min/day, respectively. SB time during weekdays was 285.0 (157.5-465.0) min/day and 345.0 (195.0-502.5) min/day on weekends. Fifty-five percent of participants were dissatisfied with their current level of PA and 75% reported dystonia had decreased their level of PA. Fifty-seven percent found their symptoms were worsened during exercise though the after-effects on symptoms varied. Fatigue, motor symptoms, pain, and poor balance were commonly cited limiting factors. Qualitative and quantitative data indicated difficulties with more vigorous intensity activity. The common barriers to engagement were personal and governmental factors, such as physical impairments, lack of funding and lack of trained exercise professionals. Conclusion: While more than half of respondents indicated they were not satisfied with their current level of PA, and exercise primarily worsened their dystonia symptoms, most participants were meeting the minimum guidelines. Future studies should incorporate robust objective methods of PA and SB measurement and explore the causal mechanisms underpinning exercise-induced aggravation of dystonic symptoms to further enhance life participation of people living with dystonia.

Consensus Paper: Experimental Neurostimulation of the Cerebellum.

The cerebellum is best known for its role in controlling motor behaviors. However, recent work supports the view that it also influences non-motor behaviors. The contribution of the cerebellum towards different brain functions is underscored by its involvement in a diverse and increasing number of neurological and neuropsychiatric conditions including ataxia, dystonia, essential tremor, Parkinson's disease (PD), epilepsy, stroke, multiple sclerosis, autism spectrum disorders, dyslexia, attention deficit hyperactivity disorder (ADHD), and schizophrenia. Although there are no cures for these conditions, cerebellar stimulation is quickly gaining attention for symptomatic alleviation, as cerebellar circuitry has arisen as a promising target for invasive and non-invasive neuromodulation. This consensus paper brings together experts from the fields of neurophysiology, neurology, and neurosurgery to discuss recent efforts in using the cerebellum as a therapeutic intervention. We report on the most advanced techniques for manipulating cerebellar circuits in humans and animal models and define key hurdles and questions for moving forward.

Visual compensation in cervical dystonia.

Introduction: Visual-spatial processing can be affected in people with cervical dystonia (CD). These impairments have almost exclusively been observed in laboratory studies, but the impact of visuo-spatial impairments on daily activities is unclear. Here, we investigated how people living with CD visually explore the environment. Method: 21 participants (10 patients and 11 controls) walked a designated course searching for targets while their eye movements were tracked by the means of eye tracking glasses. In addition, all participants performed an extensive battery of spatial neglect tests. Results: People with CD visually compensated for their lateral head position. That is, they made more eye movements towards the side opposite their lateral head position. No evidence for or against spatial asymmetries were detected in a range of behavioral measures (target detection, standard neglect battery tests) on a group level. Yet, single patients showed a neglect-like pattern. One patient with a right torticollis failed to detect most left-sided targets when walking. Conclusion: In general, participants seem to adequately compensate for the deviated head posture when judging spatial stimuli. However, the insufficient spatial exploration in one patient with a valid driving license should raise awareness in clinicians to potential visuo-spatial problems in people living with CD. An interesting question arising from our findings is whether people with CD and marked visuo-spatial deficits would benefit from scanning training, as is employed in stroke rehabilitation.

Investigating the mechanisms of acupuncture on neural excitability in healthy adults.

Acupuncture is gaining interest as a potential treatment modality for various neurological conditions. Yet, the underlying mechanisms and efficacy on brain function are not well understood. Therefore, this study investigated the previously proposed hypothesis that acupuncture suppresses motor cortex excitability using transcranial magnetic stimulation (TMS) in healthy adults. The study was randomised, sham-controlled, and double-blinded. Single and paired-pulse TMS was delivered before, during, immediately after, and 30 min after removal of the needle. Acupuncture to the right Hegu acupoint (LI-4) of the hand was delivered by an experienced acupuncturist using standardised manipulations. A disposable (0.22×30 mm, Hwato) needle was used for verum stimulation (penetrating) and a Park retractable needle for sham (nonpenetrating). The peak-to-peak amplitude of TMS-induced motor-evoked potentials was recorded from two intrinsic hand muscles. Needling sensations were quantified using the Massachusett's acupuncture sensation scale. Participant needling sensations were not different between verum or sham acupuncture (P>0.54). Corticomotor excitability, intracortical inhibition, and intracortical facilitation were not modulated by verum or sham acupuncture during, immediately after, or 30 min after, recorded from a local or distant hand muscle to the needling site (all P>0.075). Contrary to previous studies, manual acupuncture did not affect motor cortex excitability in healthy adults. Because of the increasing popularity of acupuncture therapy, further research using patient populations should be considered.

Systematic Review of Rehabilitation in Focal Dystonias: Classification and Recommendations.

BACKGROUND: Rehabilitation interventions are rarely utilized as an alternative or adjunct therapy for focal dystonias. Reasons for limited utilization are unknown, but lack of conclusive evidence of effectiveness is likely a crucial factor. METHODS AND FINDINGS: The purpose of this systematic review was to determine the level of evidence for rehabilitation interventions in focal dystonias. Rehabilitation interventions were classified based upon the underlying theoretical basis of different approaches, and the strength of evidence for each category was evaluated to identify gaps in the field. Prospective studies using rehabilitation methods in cervical, hand, and foot dystonia were reviewed. The key elements of treatments tested were identified and studies were grouped into six categories based on the theoretical basis of the intervention: (1) movement practice, (2) training with constraint, (3) sensory reorganization, (4) normalization of muscle activity with external techniques, (5) neuromodulation with training, and (6) compensatory strategies. Quality of the body of evidence ranged from very low-to-low according to the grades of recommendation, assessment, development, and evaluation (GRADE). Despite inconclusive evidence for these rehabilitation approaches, data suggest that intensive movement practice and neuromodulation combined with motor training should be further explored. CONCLUSIONS: This systematic review presents a novel approach to classify studies of rehabilitation in focal dystonias based on the theoretical basis of intervention. The proposed classification system will move toward a unified theoretical understanding of rehabilitation interventions in dystonia. Moreover, it will help provide recommendations for clinical applications and future investigations.

Impairments of balance, stepping reactions and gait in people with cervical dystonia.

BACKGROUND: Impaired balance is common in neurological disorders. Cervical dystonia is a neurological movement disorder affecting the neck. The effect of this aberrant head posture on physical function is unknown. OBJECTIVES: To compare balance, mobility, gait and stepping reactions between ten people with cervical dystonia and ten control adults. METHODS: Spatiotemporal gait parameters and walking speed were assessed using a computerised walkway. Step length and time, time in double support and gait variability were calculated, then normalised to gait speed. Centre of pressure path length was assessed with eyes open and eyes closed to calculate a Romberg Quotient. Simple and choice reaction times were measured using customised apparatus while mobility was assessed by the timed up and go. Cervical spine range of motion was measured using a head mounted goniometer. Self-reported scales included Falls Self Efficacy Scale and Dystonia Discomfort Scale. RESULTS: There was a difference between groups for most outcome measures. The timed up-and-go and walking speed was slower (both P<0.005) and the Romberg Quotient lower (P=0.046) in cervical dystonia. People with cervical dystonia had lower falls self-efficacy (P=0.0002). Reduced cervical range of motion was correlated with balance, stepping reaction time and mobility (all P<0.05). Timed up and go was positively associated with stepping reaction time (P<0.01). Dystonia discomfort did not impact function. CONCLUSIONS: People with cervical dystonia displayed deficits in balance, gait and stepping reactions, and expressed higher fear of falling. Studies to further elucidate functional limitations and their impact on activity and participation in daily life are required.

Reorganization of the primary motor cortex following lower-limb amputation for vascular disease: a pre-post-amputation comparison.

PURPOSE: This study compared bilateral corticomotor and intracortical excitability of the primary motor cortex (M1), pre- and post-unilateral transtibial amputation. METHOD: Three males aged 45, 55, and 48 years respectively who were scheduled for elective amputation and thirteen (10 male, 3 female) healthy control participants aged 58.9 (SD 9.8) were recruited. Transcranial magnetic stimulation assessed corticomotor and intracortical excitability of M1 bilaterally. Neurophysiological assessments were performed 10 (SD 7) days prior to surgery and again at 10 (SD 3) days following surgery. Data were analyzed descriptively and objectively compared to 95% confidence intervals from control data. RESULTS: Prior to amputation, all three patients demonstrated stronger short-latency intracortical inhibition evoked from M1 ipsilateral to the affected limb and reduced long-latency intracortical inhibition evoked from M1 contralateral to the affected limb compared to control subjects. Following amputation, short-latency intracortical inhibition was reduced in both M1s and long-latency intracortical inhibition was reduced for the ipsilateral M1. Single-pulse motor evoked potential amplitude and motor thresholds were similar pre-to-post amputation. CONCLUSIONS: Modulation of intracortical excitability shortly following amputation indicates that the cortical environment may be optimized for reorganization in the acute post-amputation period which might be significant for learning to support prosthetic mobility. Implications for Rehabilitation Amputation of a lower-limb is associated with extensive reorganization at the level of the cortex. Reorganization occurs in the acute post-amputation period implying a favorable cortical environment for recovery. Rehabilitation or brain interventions may target the acute pre-prosthetic post-amputation period to optimize recovery.

Cerebellar Intermittent Theta-Burst Stimulation and Motor Control Training in Individuals with Cervical Dystonia.

BACKGROUND: There is emerging evidence that cervical dystonia is a neural network disorder with the cerebellum as a key node. The cerebellum may provide a target for neuromodulation as a therapeutic intervention in cervical dystonia. OBJECTIVE: This study aimed to assess effects of intermittent theta-burst stimulation of the cerebellum on dystonia symptoms, quality of life, hand motor dexterity and cortical neurophysiology using transcranial magnetic stimulation. METHODS: Sixteen participants with cervical dystonia were randomised into real or sham stimulation groups. Cerebellar neuromodulation was combined with motor training for the neck and an implicit learning task. The intervention was delivered over 10 working days. Outcome measures included dystonia severity and pain, quality of life, hand dexterity, and motor-evoked potentials and cortical silent periods recorded from upper trapezius muscles. Assessments were taken at baseline and after 5 and 10 days, with quality of life also measured 4 and 12 weeks later. RESULTS: Intermittent theta-burst stimulation improved dystonia severity (Day 5, -5.44 points; p = 0.012; Day 10, -4.6 points; p = 0.025), however, effect sizes were small. Quality of life also improved (Day 5, -10.6 points, p = 0.012; Day 10, -8.6 points, p = 0.036; Week 4, -12.5 points, p = 0.036; Week 12, -12.4 points, p = 0.025), with medium or large effect sizes. There was a reduction in time to complete the pegboard task pre to post intervention (both p < 0.008). Cortical neurophysiology was unchanged by cerebellar neuromodulation. CONCLUSION: Intermittent theta-burst stimulation of the cerebellum may improve cervical dystonia symptoms, upper limb motor control and quality of life. The mechanism likely involves promoting neuroplasticity in the cerebellum although the neurophysiology remains to be elucidated. Cerebellar neuromodulation may have potential as a novel treatment intervention for cervical dystonia, although larger confirmatory studies are required.

Variation in left posterior parietal-motor cortex interhemispheric facilitation following right parietal continuous theta-burst stimulation in healthy adults.

Spatial neglect is modeled on an imbalance of interhemispheric inhibition (IHI); however evidence is emerging that it may not explain neglect in all cases. The aim of this study was to investigate the IHI imbalance model of visual neglect in healthy adults, using paired pulse transcranial magnetic stimulation to probe excitability of projections from posterior parietal cortex (PPC) to contralateral primary motor cortex (M1) bilaterally. Motor-evoked potentials (MEPs) were recorded from the first dorsal interossei and facilitation was determined as ratio of conditioned to non-conditioned MEP amplitude. A laterality index reflecting the balance of excitability between the two hemispheres was calculated. A temporal order judgment task (TOJ) assessed visual attention. Continuous theta-burst stimulation was used to transiently suppress right parietal cortex activity and the effect on laterality and judgment task measured, along with associations between baseline and post stimulation measures. Stimulation had conflicting results on laterality, with most participants demonstrating an effect in the negative direction with no decrement in the TOJ task. Correlation analysis suggests a strong association between laterality direction and degree of facilitation of left PPC-to right M1 following stimulation (r=.902), with larger MEP facilitation at baseline demonstrating greater reduction (r=-.908). Findings indicate there was relative balance between the cortices at baseline but right PPC suppression did not evoke left PPC facilitation in most participants, contrary to the IHI imbalance model. Left M1 facilitation prior to stimulation may predict an individual's response to continuous theta-burst stimulation of right PPC.

The relationship between knowledge of pain neurophysiology and fear avoidance in people with chronic pain: A point in time, observational study.

Chronic pain is prevalent in the western world; however fear of pain often has a greater impact than the degree of initial injury. The aim of this study was to explore the relationship between knowledge of the neurophysiology of pain and fear avoidance in individuals diagnosed with chronic pain. Twenty-nine people with chronic musculoskeletal pain were recruited and completed questionnaires to determine their understanding of pain neurophysiology and the degree of their fear avoidance beliefs. There was an inverse relationship between knowledge of pain neurophysiology and the level of fear avoidance. Patients with higher pain knowledge reported less fear avoidance and lower perceived disability due to pain. There was no relationship with the educational level or compensable status for either variable. The findings suggest that fear avoidance is positively influenced by neurophysiology of pain education, so that a higher level of pain knowledge is associated with less activity-related fear. The clinical implication is that reducing fear avoidance/kinesiophobia using neurophysiology of pain education in people with chronic pain may provide an effective strategy to help manage fear avoidance and related disability in the chronic pain population in order to improve treatment outcomes.

Anodal Cerebellar Direct Current Stimulation Reduces Facilitation of Propriospinal Neurons in Healthy Humans.

BACKGROUND: Coordinated muscle synergies in the human upper limb are controlled, in part, by a neural distribution network located in the cervical spinal cord, known as the cervical propriospinal system. Studies in the cat and non-human primate indicate the cerebellum is indirectly connected to this system via output pathways to the brainstem. Therefore, the cerebellum may indirectly modulate excitability of putative propriospinal neurons (PNs) in humans during upper limb coordination tasks. OBJECTIVE/HYPOTHESIS: This study aimed to test whether anodal direct current stimulation (DCS) of the cerebellum modulates PNs and upper limb coordination in healthy adults. The hypothesis was that cerebellar anodal DCS would reduce descending facilitation of PNs and improve upper limb coordination. METHODS: Transcranial magnetic stimulation (TMS), paired with peripheral nerve stimulation, probed activity in facilitatory and inhibitory descending projections to PNs following an established protocol. Coordination was tested using a pursuit rotor task performed by the non-dominant (ipsilateral) hand. Anodal and sham DCS were delivered over the cerebellum ipsilateral to the non-dominant hand in separate experimental sessions. Anodal DCS was applied to a control site lateral to the vertex in a third session. Twelve right-handed healthy adults participated. RESULTS: Pairing TMS with sub-threshold peripheral nerve stimulation facilitated motor evoked potentials at intensities just above threshold in accordance with the protocol. Anodal cerebellar DCS reduced facilitation without influencing inhibition, but the reduction in facilitation was not associated with performance of the pursuit rotor task. CONCLUSIONS: The results of this study indicate dissociated indirect control over cervical PNs by the cerebellum in humans. Anodal DCS of the cerebellum reduced excitability in the facilitatory descending pathway with no effect on the inhibitory pathway to cervical PNs. The reduction in PN excitability is likely secondary to modulation of primary motor cortex or brainstem nuclei, and identifies a neuroanatomical pathway for the cerebellum to assist in coordination of upper limb muscle synergies in humans.