Non-invasive brain stimulation techniques for chronic pain. A report of a Cochrane systematic review and meta-analysis.

BACKGROUND: Non-invasive brain stimulation techniques aim to induce an electrical stimulation of the brain in an attempt to reduce chronic pain by directly altering brain activity. They include repetitive transcranial magnetic stimulation (rTMS), cranial electrotherapy stimulation (CES) and transcranial direct current stimulation (tDCS). AIM: To evaluate the efficacy of non-invasive brain stimulation techniques in chronic pain. DESIGN: A Cochrane systematic review with meta-analyses. METHODS: We employed a comprehensive search strategy. Randomised and quasi-randomised studies of rTMS, CES or tDCS were included if they employed a sham stimulation control group, recruited patients over the age of 18 with pain of three months duration or more and measured pain as a primary outcome. Where possible we entered data into meta-analyses. RESULTS: We included 33 trials in the review (19 rTMS, eight CES and six tDCS). Only one study was judged as being at low risk of bias. Studies of rTMS demonstrated significant heterogeneity. Pre-specified subgroup analyses suggest that low-frequency stimulation is ineffective. A short-term effect on pain of active high-frequency stimulation of the motor cortex in single-dose studies was suggested (standardised mean difference (SMD) -0.40, 95% confidence interval (CI) -0.26 to -0.54, P < 0.00001). This equates to a 15% (95% CI 10% to 20%) reduction in pain which does not clearly exceed the pre-established criteria for a minimally clinically important difference (> 15%). For CES (four studies, 133 participants) no statistically significant difference was found between active stimulation and sham. Analysis of tDCS studies (five studies, 83 people) demonstrated significant heterogeneity and did not find a significant difference between active and sham stimulation. Pre-specified subgroup analysis of tDCS applied to the motor cortex suggested superiority of active stimulation over sham (SMD -0.59, 95% CI -1.10 to -0.08). Non-invasive brain stimulation appears to be associated with minor and transient side effects. CONCLUSION: Single doses of high-frequency rTMS of the motor cortex may have small short-term effects on chronic pain. The effects do not clearly exceed the predetermined threshold of minimal clinical significance. Low-frequency rTMS is not effective in the treatment of chronic pain. There is insufficient evidence from which to draw firm conclusions regarding the efficacy of CES or tDCS. The available evidence suggests that tDCS applied to the motor cortex may have short-term effects on chronic pain and that CES may be ineffective. There is a need for further, rigorously designed studies of all types of stimulation.

A clinical model for the assessment of posture and balance in people with stroke.

PURPOSE: The lack of models to define and describe rehabilitation processes have often been identified as limiting research and the development of clinical practice. This study describes the development of a clinical model to address a key aspect of stroke physiotherapy--the assessment of posture and balance. METHOD: Twenty seven experienced neurological physiotherapists (PT) in six focus groups were used. Participants were shown photographs of a typical stroke patient in sitting and standing positions and were asked 'What would you note if you were assessing the posture and balance of this patient?' Answers were displayed on flip charts to allow immediate feedback about the accuracy and completeness of data. Thematic content analysis was then used. RESULTS: A complex reasoning process emerged to answer three main questions: What can the patient do? How does s/he do it? Why does s/he do it that way? To answer these questions physiotherapists established balance disability (by observing the patient's ability to perform a series of increasingly demanding balance tasks), identified postural and movement impairments (by observing alignment and movement of body segments relative to each other and to the expected norm for that patient) and assessed muscle activity (by observation and palpation). CONCLUSIONS: Focus groups have been used to elicit a clinical model for the assessment of posture and balance, the content of which will be used to inform a new outcome measure.