To stimulate or not to stimulate? A rapid systematic review of repetitive sensory stimulation for the upper-limb following stroke

Abstract: Background: Repetitive sensory stimulation (RSS) is a therapeutic approach which involves repeated electrical stimulation of the skin’s surface to improve function. This rapid systematic review aimed to describe the current evidence for repetitive sensory stimulation (RSS) in rehabilitation of the upper-limb for people who have had a stroke. Main text: Methods: Relevant studies were identified in a systematic search of electronic databases and hand-searching in February 2020. The findings of included studies were synthesized to describe: the safety of RSS, in whom and when after stroke it has been used, the doses used and its effectiveness. Results: Eight studies were included. No serious adverse events were reported. The majority of studies used RSS in participants with mild or moderate impairments and in the chronic stage after stroke. Four studies used RSS in a single treatment session, reporting significant improvements in strength and hand function. Findings from longitudinal studies showed few significant differences between control and experimental groups. Meta-analysis was not possible due to the heterogeneity of included studies. Conclusions: This review suggests that there is insufficient evidence to support the use of RSS for the upper-limb after stroke in clinical practice. However, this review highlights several clear research priorities including establishing the mechanism and in whom RSS may work, its safety and optimal treatment parameters to improve function of the upper-limb after stroke

Pallido-putaminal connectivity predicts outcomes of deep brain stimulation for cervical dystonia

Cervical dystonia is a non-degenerative movement disorder characterised by dysfunction of both motor and sensory cortico-basal ganglia networks. Deep brain stimulation targeted to the internal pallidum (GPi) is an established treatment, but its specific mechanisms remain elusive, and response to therapy is highly variable. Modulation of key dysfunctional networks via axonal connections is likely important. Fifteen patients underwent pre-operative diffusion-MRI acquisitions and then progressed to bilateral DBS targeting the posterior GPi. Severity of disease was assessed pre-operatively and later at follow-up. Scans were used to generate tractography-derived connectivity estimates between the bilateral regions of stimulation and relevant structures. Connectivity to the putamen correlated with clinical improvement, and a series of cortical connectivity-based putaminal parcellations identified the primary motor (M1) putamen as the key node (r = 0.70, p = 0.004). A regression model with this connectivity and electrode coordinates explained 68% of variance in outcomes (r = 0.83, p = 0.001), with both as significant explanatory variables. We conclude that modulation of the M1 putamen—posterior GPi limb of the cortico-basal ganglia loop is characteristic of successful DBS treatment of cervical dystonia. Pre-operative diffusion imaging contains additional information that predicts outcomes, implying utility for patient selection and/or individualised targeting

Deep brain stimulation of the nucleus accumbens in severe enduring anorexia nervosa: a pilot study

Introduction: Anorexia nervosa is one of the most debilitating psychiatric disorders, becoming severe and enduring in a third of cases; with few effective treatments. Deep brain stimulation is a reversible, adjustable neurosurgical procedure that has been gaining ground in psychiatry as a treatment for depression and obsessive compulsive disorder, yet few studies have investigated anorexia nervosa. Abnormal eating behaviour and the compulsive pursuit of thinness in anorexia nervosa is, in part, a consequence of dysfunction in reward circuitry and the nucleus accumbens is central to reward processing. Methods: Phase 1 prospective open-label pilot study of seven individuals with severe enduring anorexia nervosa. Electrodes were implanted bilaterally into the nucleus accumbens with stimulation at the anterior limb of the internal capsule using rechargeable implantable pulse generators. The protocol of 15 months included 12 months of deep brain stimulation incorporating two consecutive, randomized blind on-off fortnights 9 months after stimulation onset. The primary objectives were to investigate safety and feasibility, together with changes in eating disorder psychopathology. Results: Feasibility and safety was demonstrated with no serious adverse events due to deep brain stimulation. Three patients were responded to treatment (defined as >35% reduction in Eating Disorders Examination (EDE) score at 12 months) and four patients were non-responders. Responders had a statistically significant mean reduction in EDE scores (50.3% reduction; 95% CI 2.6% to 98.2%), Clinical Impairment Assessment (45.6% reduction; 95% CI 7.4% to 83.7%). Responders also had a statistically significant mean reduction in Hamilton Depression Scale, Hamilton Anxiety Scale and Snaith-Hamilton pleasure scale. There were no statistically significant changes in Body Mass Index, Yale-Brown-Cornell Eating Disorder Scale, Yale-Brown Obsessive-Compulsive Scale and World Health Organisation Quality of Life Psychological subscale. Conclusions: Selected patients with severe enduring anorexia nervosa can benefit from deep brain stimulation to the nucleus accumbens. In this small study, the three responders had comorbid obsessive compulsive disorder which predated anorexia nervosa diagnosis. Future studies should aim to further elucidate predictors of outcome. Clinical Trial Registration: The study is registered with www.ClinicalTrials.gov, https://clinicaltrials.gov/ct2/show/NCT01924598, 22 July, 2013. It has full ethical and HRA approval (Project ID 128658)

Pallido-putaminal connectivity predicts outcomes of deep brain stimulation for cervical dystonia

Cervical dystonia is a non-degenerative movement disorder characterised by dysfunction of both motor and sensory cortico-basal ganglia networks. Deep brain stimulation targeted to the internal pallidum (GPi) is an established treatment, but its specific mechanisms remain elusive, and response to therapy is highly variable. Modulation of key dysfunctional networks via axonal connections is likely important. Fifteen patients underwent pre-operative diffusion-MRI acquisitions and then progressed to bilateral DBS targeting the posterior GPi. Severity of disease was assessed pre-operatively and later at follow-up. Scans were used to generate tractography-derived connectivity estimates between the bilateral regions of stimulation and relevant structures. Connectivity to the putamen correlated with clinical improvement, and a series of cortical connectivity-based putaminal parcellations identified the primary motor (M1) putamen as the key node (r = 0.70, p = 0.004). A regression model with this connectivity and electrode coordinates explained 68% of variance in outcomes (r = 0.83, p = 0.001), with both as significant explanatory variables. We conclude that modulation of the M1 putamen—posterior GPi limb of the cortico-basal ganglia loop is characteristic of successful DBS treatment of cervical dystonia. Pre-operative diffusion imaging contains additional information that predicts outcomes, implying utility for patient selection and/or individualised targeting