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.
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.
- Diagnosis of primary generalized dystonia or cervical dystonia
- Bilaterally implanted globus pallidus interus(GPi) DBS.
- Minimum of 6 months of chronic stimulation
- Greater than 60 days on stable DBS settings
- Does not have DBS for dystonia or cervical dystonia