Objective: To assess long term benefit of multiple source current steering in two dystonic patients with GPi-DBS.

Background: GPi-DBS proved to be safe and effective in treating selected cases of disabling dystonia.The degree of control of the electric current delivered to the neural tissue is important for optimization of the therapy.We used a novel DBS system capable of multiple source current steering to assess its possible extra benefit.

Methods: This case report is in accordance with Declaration of Helsinki.Patient 1 is a 20 years old male with severely disabling primary generalized dystonia (PGD).He had severe dysarthria, dysphagia and was dependent for all activities of daily living. Patient 2 is a 45 years old male with disabling PGD involving mainly trunk,with a severely impaired gait,sitting and supine positions. Bilateral GPi-DBS implant was performed,employing an eight contacts lead per hemisphere and a rechargeable pulse generator.


Results: Patient 1 scored 76 on the Unified Dystonia Rating Scale (UDRS), 91 on the Fahn Marsden Scale (FMRS) part 1 and 25 on part 2, pre-DBS. He improved by 32%, 34% and 8% 16 weeks post-DBS and by 68%,75% and 52% respectively 48 months post-DBS. Patient 2 scored 25 on UDRS, 34 on BMFS part 1 and 11 on part 2, pre-DBS. He improved by 96%, 94% and 91% respectively 16 weeks post-DBS. This remained stable until 42 months post-DBS. Best monopolar stimulation was used in both patients. Variable combinations of multipolar fractionalized current stimulation of two, three and four adjacent contacts were tried in 16 sessions with 1 week intervals in patient 1, with no further clinical improvement. This was tried in 8 sessions in patient 2 without obtaining superior results than monopolar stimulation. No adverse events related to the therapy occurred.


Conclusions: Current steering showed no extra benefit in any of our 2 patients. Nonetheless, we suggest larger studies to be done in dystonic patients to investigate possible benefits of current steering on symptoms control. The system showed to be safe and clinically effective in the long term. No hardware problems or recharge issues were reported. To our knowledge, patient 1 is the first dystonia case described treated with this DBS system.

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MDS Abstracts - https://www.mdsabstracts.org/abstract/two-patients-with-dystonia-treated-with-internal-globus-pallidus-deep-brain-stimulation-gpi-dbs-using-a-multiple-independent-source-current-controlled-systemlong-term-resultsa-case-report%e2%80%a8/