Comparison of the Efficacy of Double Monopolar Versus Interleaving Stimulation Modes for Pallidal Deep Brain Stimulation
Condition: Primary Dystonia
MeSH terms: Dystonia; Dystonic Disorders
Study type: Interventional

Summary: 
      The aim of the study is to compare the efficacy and the safety profile of the newly
      introduced interleaving stimulation mode to those of the standard double monopolar
      stimulation mode during pallidal deep brain stimulation of primary generalized or segmental
      dystonia.
    

Detailed description: 
      Background:

      For the treatment of drug-refractory dystonia, bilateral pallidal deep brain stimulation
      (GPi-DBS) is proven to be an efficient option. On average, 40-55% improvement on dystonia
      rating scales (DRS) could be achieved according to the results of multicenter trials lasting
      for years. However, a considerable portion (10-25%) of the patients experience minimal
      alleviation despite of good electrode placement. These patients can be regarded as
      non-responders to GPi-DBS defined as having either limited improvement (< 25% on DRS) or
      worsening. Besides adjusting the amplitude, frequency or pulse-width of stimulation, one can
      change the electrode configuration from the commonly applied single monopolar stimulation
      mode (one contact on the electrode is negative) to either double monopolar stimulation (two
      -usually adjacent- negative contacts on the electrode are stimulated with same amplitude and
      pulse-width values) or bipolar stimulation mode (one contact on the electrode is positive) in
      case of unsatisfactory outcomes. Although these techniques had been utilized in multicenter
      trials, non-responsiveness to GPi-DBS did occur. Recently the investigators have reported in
      the Movement Disorders that the newly introduced interleaving stimulation mode was superior
      to single or double monopolar stimulation in four patients who had initially (6-12 months
      after implantation) limited response to GPi DBS.

      Aims of the study:

      To systematically compare the efficacy and the side-effect profile of double monopolar
      stimulation mode to those of interleaving stimulation mode in a prospective, randomized,
      double-blind, and cross-over study.

      Methods:

      The investigators would enroll 20-25 patients with drug refractory segmental or generalized
      primary dystonia undergoing bilateral GPi-DBS implantation within a 2-3 year time frame. The
      inclusion and exclusion criteria would follow those of the study of Kupsch et al.
    

Intervention name(s): Interleaving stimulation mode (Medtronic); Double monopolar stimulation mode (Medtronic)
Intervention type(s): Device; Device
Intervention description(s): Interleaving stimulation mode with constant frequency (125 Hz) and pulse-width (120us)parameters 'Interleavingr stimulation mode (Medtronic)'; Double monopolar stimulation mode with constant frequency (125 Hz) and pulse-width (120us)parameters 'Double monopolar stimulation mode (Medtronic)'
Other intervention name(s): Medtronic Activa RC Interleaving Stimulation Mode; Medtronic Activa RC Double Monopolar Stimulation Mode
Allocation: Randomized
Intervention model: Crossover Assignment
Masking: Quadruple (Participant, Care Provider, Investigator, Outcomes Assessor)
Primary purpose: Treatment
Keywords: dystonia; pallidal stimulation; deep brain stimulation; deep brain stimulation of GPi; GPi; interleaving stimulation