Deep Brain Stimulation (DBS) for the Suppression of Tremor

The purpose of the proposed study is to demonstrate the safety and efficacy of the ANS Totally Implantable Deep Brain Stimulation System in the VIM nucleus of the thalamus implanted for the treatment of tremor due to essential tremor.

This study will be included in the Pre-Market Approval Application to support the safety of this device in use.

This study is designed as a prospective, multi-centered study for 365 days in duration from device implantation. A maximum of 12 sites will enroll 160 patients.

Each patient will be screened and then undergo a baseline evaluation followed by unilateral or bilateral implantation of the DBS system. During the implantation procedure, each patient will undergo a trial of stimulation in the operating room. The device may be internalized after a successful intra-operative trial or at a later surgery (no later than 4 weeks after initial lead placement). If the device is not activated immediately postsurgery, the patient may return to the clinic to determine optimum stimulation programming. Device programming will be optimized in as many visits as necessary following implantation. The day that the device is fully implanted will be classified as "Day 0" for each patient.

After "Day 0" the patient will return to clinic for evaluations at, Day 90 (±14 days), and Day 180 (±14 days) and Day 365 (approximately 12 months ± 30 days after Day 0). These evaluations consist of the CRST, the QUEST, the SF36, Patient and caregiver Global Ratings and the Patient Satisfaction Rating.

At Baseline and Day 180, the CRST evaluation session will be video recorded for analysis by an independent evaluator unaware of the functioning of the device. Additionally, at the Day 180 visit, the physician will have the option to provide the patient with amplitude control. A comparison of measures within the same person from pre-treatment to post-treatment will be performed. Also, pre-treatment and post-treatment group means and standard deviations will be determined.

Patients completed follow-up visits as part of the original protocol (C-04-02) for one year (or in some cases longer if patient was bilaterally implanted) and continued to complete additional visits as part of the Long-Term Follow-up protocol (C-06-03) for up to 5 years post implant.

Eligibility Criteria:
Inclusion criteria:

1. Patient or authorized representative has signed an informed consent.
2. Patient is over 18 years of age.
3. Patient is diagnosed with essential tremor for at least 3 years.
4. Patient has a disabling medical-refractory upper extremity tremor with no evidence of supraspinal central nervous system disease or injury (tremor not adequately controlled by medications for at least three (3) months before implant).
5. Patient has a postural or kinetic tremor severity score of at least 3 out of 4 in the extremity intended for treatment on the Fahn-Tolosa-Marin Clinical Rating Scale for Tremor.
6. Patient will maintain a constant dose of anti-tremor medication indicated as best medical management for one (1) month prior to enrollment in study.
7. Patient is available for appropriate follow-up times for the length of the study.

Exclusion criteria:

1. Patient is not surgical candidate;
2. Patient has other clinically or medically significant disease;
3. Patient has any neurological injury or disease other than essential tremor;
4. Patient has any condition requiring repeated MRI scans;
5. Patient has any condition requiring diathermy;
6. Patients on anticoagulant medications;
7. Patient has untreated clinically significant depression;
8. Patient has had an electrical or electromagnetic implant (cochlear prosthesis, pacemaker etc);
9. Patient has had a prior thalamotomy or surgical ablation procedure in either side of the brain;
10. Patient has dementia interfering with their ability to co-operate or comply with study requirements or comprehend the informed consent (mini-mental exam score \<24);
11. Patient abuses drugs or alcohol;
12. Patient has had botulinum toxin injections in the six (6) months prior to enrollment;
13. Patient has a history of cranial surgery;
14. Patient has a history of seizures;
15. Patient has any metallic implants that may interfere with the functioning of the device (e.g. aneurysm clips);
16. Patient has a history of stimulation intolerance in any area of the body;
17. Patient is a female of child bearing potential with a positive urine pregnancy test or not using adequate contraception.