Efficacy and Safety of Deep Brain Stimulation (DBS) of the Pallidal (GPi) in Patients With Tardive Dystonia

Charité University Medicine Berlin

Status and phase

Unknown

Phase 2

Conditions

Dystonia

Movement Disorder

Treatments

Procedure: deep brain stimulation

Study type

Interventional

Funder types

Other

Industry

Identifiers

NCT00331669

DBS and tardive dystonia

Details and patient eligibility

About

The purpose of this randomized, double blind, multi-center study is to assess the efficacy and safety of bilateral pallidal deep brain stimulation in patients with tardive dystonia.

Full description

Deep brain stimulation (DBS) has been established as a new reversible, neurosurgical therapeutic option for patients suffering from disabling neurological movement disorders such as essential tremor and Parkinson´s disease. Recently, deep brain stimulation has been successfully applied in patients with primary generalized and segmental dystonia. Additionally, a number of case reports suggest that pallidal deep brain stimulation may also improve tardive dystonia, which may for instance result from the intake of neuroleptics and which is notoriously difficult to treat medically. The present study will investigate the effects of pallidal DBS using a double blind, randomized design (sham- versus verum-stimulation within a 3-months interval post implantation of the electrodes).

Initially 60 patients had been calculated in a power analysis to assess significant results based on an average improvement of dystonic symptoms of 30%. However, in a recent study (Damier et al., Archives of General Psychiatry, 2007), 10 out of 10 showed a successful outcome of approximately 50% decrease on the extrapyramidal symptoms rating scale score. The exact one- sided lower 95% confidence limit would be 0.794 for this result. If such an approach is chosen for sample size estimation with 18 verum and 18 placebo patients one would obtain a power of 82% against a placebo effect of 30% success rate. For a placebo effect of 25% one needs 16+16 patients and for the placebo effect of 20% one needs 12+12 patients. We thus decided to reduce the sample size to 36- 32- 24 patients. It is expected that the continuous primary outcome measure will preserve even higher power than the binary one used in the study mentioned above. The local ethical committee has approved this.

Enrollment

24 estimated patients

Sex

All

Ages

18 to 75 years old

Volunteers

No Healthy Volunteers

Inclusion criteria

Operational criteria for tardive dystonia for > 18 months after cessation of neuroleptic exposure
18-75 years
Relevant functional impairment in daily living activities
BFMDRS > 8 or AIMS > 16
Informed written consent

Exclusion criteria