Comparison of Constant Current to Constant Voltage Stimulation in Subthalamic Deep Brain Stimulation for Parkinson's Disease

March 17, 2015 updated by: Israel Zvi, Hadassah Medical Organization

Comparison of Constant Current to Constant Voltage Stimulation in Subthalamic DBS for Parkinson's Disease

HYPOTHESIS: Constant current stimulation for STN DBS will allow better and more stable control of Parkinson's disease symptoms than constant voltage stimulation.

Subthalamic nucleus (STN) deep brain stimulation (DBS) is an established therapy for advanced Parkinson's disease (PD). Two types of implantable pulse generators (IPGs) are available, differing on whether voltage or electrical current is controlled. Constant current IPGs provide a specific electrical current and will automatically adjust the voltage depending on the impedance, while the current applied by constant voltage IPGs will depend on the tissue impedance that may change over time. No study has compared the clinical differences of these two electronic modalities.

Study Overview

Status

Completed

Conditions

Intervention / Treatment

Detailed Description

Deep brain stimulation (DBS) is an established therapy for neurological and psychiatric disorders, being one of the most important therapies in functional neurosurgery to date. Class I evidence shows that subthalamic nucleus stimulation (STN) for Parkinson's disease (PD) is more effective than the best medical therapy (1,2). Globus pallidus internus stimulation for primary dystonia has an improvement rate of up to 70%(4) and is considered the main surgical treatment for this pathology. Symptom improvement in essential tremor is well documented. Pain, epilepsy, psychiatric disorders such as Tourette syndrome, obsessive - compulsive disorder and depression are promising applications of DBS. Obesity, memory improvement, aggressiveness, drug addiction, minimal conscious state and hypertension are areas of continuing investigation as potential applications of DBS.

The clinical effects of DBS result from the delivery of electrical charge to brain tissue. The way this electrical charge is delivered depends on the electronics of implantable pulse generators (IPGs). IPGs apply pulses of electrical stimulation in which voltage or current increases from zero to a maximum value for a period of time (order of tens of microseconds) and then returns to zero.

There are two types IPGs , differing on whether voltage or electrical current is controlled (3).

  1. Constant - voltage IPGs: in this type of IPG there is control over the maximum voltage associated with each pulse. The maximum current will vary depending on the impedance. A specific voltage is programmed. The amount of electrical current delivered with a constant voltage depends on the impedance of the tissue and the electrodes. Thus, the voltage will not indicate how much electrical current is given; the resistance will determine this parameter.
  2. Constant - current IPGs: provide a specific electrical current and will automatically adjust the voltage depending on the impedance. The strength of stimulation will remain the same regardless of changes in the impedance. The difference in impedances on each electrode and the intersubject variability in impedances will not alter the electrical current by modifying the voltage.

Until fairly recently, only constant voltage IPG's have been available for use. A newer generation of IPG's have been available for more than a year that can provide either constant voltage or constant current according to physician and patient preference. There is no evidence yet to support the preferential use of one modality over the other.

IMPORTANCE OF THE STUDY Following DBS electrode implantation, the impedances within the same patient can vary widely. Surgical implantation changes tissue impedance, being usually higher immediately after surgery. In this case the patient will require higher electrical currents. After the initial tissue reaction subsides, the reduction of impedance will generate an increase of the charge density. For this reason it is commonplace to wait at least 2 weeks after electrode implantation before programming the IPG.

Furthermore, different contacts on the same DBS lead can have widely varying impedances. Effects or side effects associated with stimulation of one electrode contact often cannot be applied to a different contact on the same DBS lead in the same patient because the impedances may differ.

The range of impedances that can be measured will depend on the choice of voltage. In some patients, the voltage used therapeutically may not be enough to allow an accurate measure of the impedances, causing confusion regarding the structural and electrical integrity of the IPG.

For all the above mentioned factors, the clinical results in patients with constant - voltage IPGs will depend on the experience of the operator to deal with the different aspects related to tissue and electrode impedances to achieve the desired current. The electronic properties of constant - current IPGs allows the system to make voltage adjustments in order to maintain the desired current and the subsequent clinical effect. This has been the theoretical background for the development of constant current IPG's; whether or not this theory is true in practice is the subject of this study.

Study Type

Interventional

Enrollment (Actual)

8

Phase

  • Not Applicable

Contacts and Locations

This section provides the contact details for those conducting the study, and information on where this study is being conducted.

Study Locations

  • Israel
      • Jerusalem, Israel, 91120
        • Hadassah University Hospital

Participation Criteria

Researchers look for people who fit a certain description, called eligibility criteria. Some examples of these criteria are a person's general health condition or prior treatments.

Eligibility Criteria

Ages Eligible for Study

26 years to 76 years (Adult, Older Adult)

Accepts Healthy Volunteers

No

Genders Eligible for Study

All

Description

Inclusion Criteria:

  • Idiopathic Parkinson's disease
  • Subthalamic Deep Brain Stimulation Surgery

Exclusion Criteria:

  • Any patient not meeting the inclusion criteria

Study Plan

This section provides details of the study plan, including how the study is designed and what the study is measuring.

How is the study designed?

Design Details

  • Primary Purpose: Treatment
  • Allocation: Randomized
  • Interventional Model: Crossover Assignment
  • Masking: Double

Arms and Interventions

Participant Group / Arm
Intervention / Treatment
Experimental: Deep Brain Stimulation
Device: Deep Brain Stimulation (Medtronic, Activa PC)
Following subthalamic nucleus deep brain stimulation patients will be randomized to receive either constant current or constant voltage stimulation and subsequently "crossed over" to receive the other type of stimulation
Other Names:
  • Medtronic
  • Activa PC

What is the study measuring?

Primary Outcome Measures

Outcome Measure
Measure Description
Time Frame
Impact of constant current on motor effects of STN DBS
Time Frame: 1 month
To assess any clinical impact of changing the electronic modality of IPGs from constant - voltage to constant - current in patients with advanced PD after STN stimulation in terms of motor examination according to the Unified Parkinson's Disease Rating Scale (UPDRS) III.
1 month

Secondary Outcome Measures

Outcome Measure
Measure Description
Time Frame
Impact of constant current on psychocognitive affective status
Time Frame: 1 month
To assess the clinical impact of changing the electronic modality of IPGs from constant - voltage to constant - current in patients with advance PD after STN in terms of cognitive function, behavior, mood, quality of life and emotional processing according to the UPDRS I, UPDRS II, Hamilton Rating Scale for Depression (HAM-D17), Beck Depression Inventory (BDI), Clinical Global Inventory (CGI), Parkinson's disease questionnaire (PDQ-39), Addenbrooke's Cognitive Examination (ACE), Frontal Assessment Battery (FAB) and Hebrew version of the Montreal Affective Voices paradigm.
1 month

Collaborators and Investigators

This is where you will find people and organizations involved with this study.

Sponsor

Hadassah Medical Organization

Investigators

  • Study Director: Zvi Israel, MBBS, Hadassah Medical Organization

Study record dates

These dates track the progress of study record and summary results submissions to ClinicalTrials.gov. Study records and reported results are reviewed by the National Library of Medicine (NLM) to make sure they meet specific quality control standards before being posted on the public website.

Study Major Dates

Study Start

September 1, 2011

Primary Completion (Actual)

March 1, 2012

Study Completion (Actual)

March 1, 2012

Study Registration Dates

First Submitted

August 23, 2011

First Submitted That Met QC Criteria

August 25, 2011

First Posted (Estimate)

August 26, 2011

Study Record Updates

Last Update Posted (Estimate)

March 18, 2015

Last Update Submitted That Met QC Criteria

March 17, 2015

Last Verified

March 1, 2015

More Information

Terms related to this study

Keywords

Additional Relevant MeSH Terms

Other Study ID Numbers

  • 386150-HMO-CTIL

This information was retrieved directly from the website clinicaltrials.gov without any changes. If you have any requests to change, remove or update your study details, please contact register@clinicaltrials.gov. As soon as a change is implemented on clinicaltrials.gov, this will be updated automatically on our website as well.

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