Deep Brain Stimulation for Dystonia in the Netherlands: A Delphi Study to Develop National Consensus.

Background: Predicting outcome for individuals with dystonia undergoing treatment with deep brain stimulation (DBS) remains challenging. This is further complicated by a lack of uniform screening, follow-up, and heterogeneous outcome measures. This study aims to achieve consensus on a national level among experts in the field to develop an agreed set of outcome measures and introduce more uniformity in the process of preoperative screening and follow-up. Methods: A modified Delphi process was conducted among experts in the field of DBS for dystonia. The process consisted of an inventory round, followed by two rounds of Delphi questionnaires, closing with a digital consensus meeting. Experts rated the importance of items within several categories: ((non-)motor symptoms, selection criteria, follow-up, DBS-related aspects, involved care providers). A threshold of 70% was maintained as consensus criterium. Results: After the first two rounds, consensus was reached on 40/59 items (adult DBS), and 47/61 items (pediatric DBS). The remaining items were rephrased into 28 statements (13 adult DBS, 13 pediatric DBS, and 2 concerning both) and voted on during a final consensus meeting. There, 23/28 statements (11 adult, 11 pediatric, 1 both) reached consensus. Overall, after three rounds, on most items consensus was reached. Discussion: In this Delphi study, a high level of consensus among national experts was achieved on outcome measures and the process of screening and follow-up in DBS for dystonia for adults and children. The results present national consensus and offer an excellent start for collaborative international studies on best practice for DBS in dystonia.