Novel Stimulation Patterns for the Treatment of Dystonia
Condition: Dystonia; Cervical Dystonia
MeSH terms: Dystonia; Dystonic Disorders; Torticollis
Study type: Observational

Summary: 
      Deep brain stimulation (DBS) is an effective surgical therapy for select Dystonia patients
      who are refractory to medications or who have generalized symptoms (e.g. patients with
      Early-Onset Primary Dystonia(DYT1) mutations and other dystonia subtypes). DBS patients
      typically experience significant improvement in disabling symptoms; however, detailed
      programming is always required, and stimulation-induced side effects commonly emerge.
      Clinicians may empirically vary voltage, pulse width, frequency and also the active contacts
      on the DBS lead to achieve observed optimal benefits.

      The majority of DBS patients undergo repeat surgeries to replace the implantable pulse
      generator (IPG) every 2.5 to 5 years. It has been demonstrated that, in dystonia patients,
      that higher settings are required for adequate symptomatic control, and that neurostimulators
      have a considerably shorter life when compared to neurostimulators from patients with
      essential tremor or Parkinson's disease. Additionally, several smaller studies have suggested
      that alternative pulse stimulation properties and pulse shape modifications can lower IPG
      battery consumption.

      Newer patterns of stimulation (regularity of pulses and shapes of pulses) have not been
      widely tested in clinical practice, and are not part of the current FDA device labeling.
      Novel patterns of stimulation do however, have the potential to improve symptoms, reduce side
      effects, and to preserve the neurostimulator life.

      The current research proposal will prospectively study biphasic pulse stimulation paradigms
      and its effects on dystonic symptoms. The investigators aim to demonstrate that we can tailor
      DBS settings to address dystonia symptoms, improve the safety profile, characterize distinct
      clinical advantages, and carefully document the safety and neurostimulator battery
      consumption profile for biphasic stimulation.
    

Detailed description: 
      In this research study, different stimulation patterns on the DBS device will be tried for
      effectiveness against current symptoms. There will be two different stimulation patterns that
      will be performed and can occur at different clinic dates. Each of the stimulation patterns
      will have times varying between 2-3 hours per stage. One part of the study will deliver
      stimulation in a continuous manner, while the other part of the study will deliver
      stimulation based upon responses obtained from changes in brain wave patterns. These
      procedures can be performed while in the clinic for regular programming visits or at
      different visits. The current DBS setting will be recorded and at the end of the session the
      setting will be reset to back to the previous settings. The participant will have the option
      of participating in both or just one part.

      During the visit, the participant will be analyzed for tremor and slowness by using the
      Trigno wireless Electromyography (EMG) and the Kinesia system. The system includes a unit
      composed of two modules: a wrist module, which is the size of an I-Pod and will be attached
      to the wrist over a comfortable wristband, and a sensor module, which will be placed over the
      index finger.

      The entire visit will be videotaped and UDRS (Unified Dystonia Disease Rating Scale) and
      BFMDRS (Burke-Fahn-Marsden Dystonia Rating Scale) scores will be evaluated by two scorers.
      Pre-DBS "off" and "on" scores will also be taken.
    

Intervention name(s): Biphasic DBS stimulation; Unified Dystonia Rating Scale; Burke-Fahn- Marsden scale
Intervention type(s): Device; Other; Other
Intervention description(s): The following protocol will be followed for each subject. In between, baseline and novel stimulation settings there will be a 30-minute washout period with DBS in the off state.
Current best/optimized DBS setting (considered "baseline")
DBS off for 30 minutes
Biphasic pulse stimulation mode (immediate assessment)
Biphasic pulse stimulation mode (assessment at 1h)
Biphasic pulse stimulation mode (assessment at 2h); Neurologist use the UDRS to determine the severity and duration of dystonia on 14 body areas.; Neurologist use the BFMDRS to rate the severity of dystonia in 9 regions of the body.
Other intervention name(s): UDRS; BFMDRS
Observational model: Case-Only
Time perspective: Prospective
Sampling method: Non-Probability Sample
Study population: 
        This is a preliminary pilot investigation that will utilize a within subjects study design
        and will screen 10 generalized dystonia and screen 10 cervical dystonia patients.
      
Keywords: Deep brain stimulation; DBS; Dystonia; DYT1