Search Strategy and Selection Criteria
Literature for this review was identified from a PubMed search (http://www.ncbi.nlm.nih.gov/pubmed/) from 1 January 2014 up to 4 April 2015 with the search term 'deep brain stimulation'. This search yielded 1365 records, which was reduced to 714 after excluding papers not focused on movement disorders. Our personal files and the bibliography of retrieved studies were also accessed. The final list of references was selected by including papers considered to be of specific relevance, prioritizing publications of the last 3 years.
In addition, we reviewed registered trials that have been submitted to the US NIH database (https://clinicaltrials.gov) including items published with the search term 'deep brain stimulation' and with no time limit. This search yielded 325 trials, which was then reduced to 274 after excluding items focused on other stimulation techniques. The final list of 120 trials was selected by prioritizing active trials (ongoing and/or enrolling patients) focusing on movement disorders.