Low-frequency quadruple target transcranial magnetic stimulation for severe levodopa-induced dyskinesia in Parkinson's disease. A single case report

<h2>Abstract</h2> Levodopa-induced dyskinesias (LID) are a common and debilitating complication in patients with advanced Parkinson's disease (PD), significantly impairing quality of life. While single-target transcranial magnetic stimulation (TMS) has shown limited efficacy, multitarget approaches tailored to patient-specific symptomatology remain unexplored. Objective: This case report describes the development and application of a novel low-frequency multitarget TMS protocol designed to address severe, refractory LID in a PD patient. Methods: A 77-year-old male with advanced PD (Modified Hoehn and Yahr Stage 4) and debilitating LID underwent a personalized TMS protocol. The treatment involved 20 sessions over two weeks, targeting six cortical regions through four stimulation sites, with sequential low-frequency stimulation. Symptomatology was assessed using the Dyskinesia Diary, the Abnormal Involuntary Movement Scale (AIMS), and subjective improvement scales. Results: Dyskinesias decreased significantly, from an average of 8–10 h per day to 2 h daily during treatment, and were further reduced to 0–1 h daily following a levodopa dose adjustment. Improvements persisted for up to six weeks post-treatment. The AIMS score improved from 23 (baseline) to 2 (post-treatment). Non-motor symptoms, including mood and speech articulation, also showed marked improvement. The patient reported mild, transient post-treatment rigidity and bradykinesia, which resolved with levodopa adjustments. Conclusion: This case demonstrates the potential efficacy of a multitarget low-frequency TMS protocol in managing severe LID, highlighting its role as a non-invasive alternative for patients unsuitable for deep brain stimulation (DBS). However, the findings are limited by the single-patient design, the absence of a control group, and the relatively short follow-up period. These limitations underscore the need for larger studies with sham-controlled designs and extended follow-ups to validate this approach and explore its long-term outcomes.