Abstract
BACKGROUND: Isolated dystonia is a disabling movement disorder for which neuromodulation represents a key therapeutic option in medically refractory cases. Deep brain stimulation (DBS) of the globus pallidus internus (GPi) is the current standard target, while subthalamic nucleus (STN) stimulation and non-invasive techniques such as repetitive transcranial magnetic stimulation (rTMS) and transcranial direct current stimulation (tDCS) have been investigated as alternative or adjunctive approaches. OBJECTIVES: To systematically evaluate the efficacy and safety of invasive and non-invasive neuromodulation techniques for motor symptom improvement in adults with isolated dystonia. METHODS: A systematic search of PubMed, Embase and Cochrane Library (January 2007–December 2020) was conducted according to PRISMA guidelines. Randomized and non-randomized clinical studies assessing motor outcomes after GPi-DBS, STN-DBS, rTMS or tDCS were included. Risk of bias was assessed using design-specific tools. RESULTS: Twelve studies met the inclusion criteria. GPi-DBS provided consistent and sustained motor improvement across dystonia phenotypes with an acceptable safety profile. STN-DBS showed comparable efficacy in selected cohorts, with faster early clinical response and lower energy consumption, although the lack of prospective head-to-head trials prevents definitive conclusions. Non-invasive techniques (rTMS and tDCS) yielded modest but clinically meaningful benefits, particularly when combined with structured rehabilitation. Study heterogeneity precluded quantitative synthesis. CONCLUSIONS: Neuromodulation is an effective and safe treatment for isolated dystonia. GPi-DBS remains the best-supported approach, STN-DBS a promising option in selected patients, and non-invasive techniques a potential adjunct. Prospective comparative trials and standardized, phenotype-driven strategies are still needed.