Expanding the Therapeutic Window of Deep Brain Stimulation in Parkinson's Disease by Means of Directional Leads

Expanding the Therapeutic Window of Deep Brain Stimulation in Parkinson's Disease by Means of Directional Leads: a Double-blind Cross-over Pilot Study

Exploring directional lead

This is a single-centre, double-blinded cross-over study comparing the standard electrode configuration (ring-mode) vs. directional electrode configuration for steered stimulation of deep brain stimulation (DBS) patients.

The study will follow 2 phases.

Phase 1:

Visit 1 Screening/Baseline (T0):

As per current standard care for patients undergoing subthalamic deep brain stimulation (STN-DBS), participants will be screened 3-6 months before the DBS STN implant surgery (T0) according to the inclusion/exclusion criteria.

Visits for standard practiced care for programing of DBS Between 1 to 3 months after the surgery, programing of the DBS system for the 20 patients will be done in an open label fashion in order to find the contact able to reduce the motor symptoms without the side effects. This will be done according to the standard of practice currently adopted at Toronto Western Hospital.

Phase 2:

Visit 1

Randomization: 4 months +/- 4weeks after the surgery, patients will be randomized to two type of stimulation:

1. Standard : The percentage of current allocated to the central split contacts will be evenly distributed in order to perfectly mimic a standard ring contact. All possible types of frequencies and pulse widths will be used. The same amount of current for each of the active contacts will be used.
2. Directional: contacts 1-8 will be used in any possible configuration and using different amount of current for each of the active one as well as different frequencies. In conclusion, all the capabilities of the DBS system will be used.

Possible adjustments to stimulation parameters (e.g. pulse width, amplitude threshold) will be performed to achieve an optimal therapeutic window for each patient.

Visit 2 Follow up visit at 6 months +/- 4 weeks of the surgery for neurological examination if required.

Visit 3 (T1):

Cross over : 7 months +/- 4 weeks after the surgery patients will be switched to the other type of stimulation . Raters and patients will be blinded to the group allocation.

Visit 4:

Follow up visit at 9 months +/- 4 weeks of the surgery for neurological examination if required.

Visit 5 (T2):

End of study visit at month 10 +/- 4 weeks after the surgery. There might be unscheduled visits in case of unexpected clinical conditions (i.e. occurrence of side effects or worsening of motor conditions). Participants will be in this study for a maximum of 16 months. Throughout the whole study, participants will visit the clinic without their regular medication as part of standard treatment practice. All the stimulation adjustment will be performed by the same unblinded physician or sub-investigator.

1. Patients with a diagnosis of Parkinson's disease (PD) according to the British Parkinson's Disease Society Brain Bank criteria, who fulfilled the inclusion and exclusion criteria proposed by the core assessment programme for surgical interventional therapies in PD panel
2. Male and female patients with idiopathic PD, who have symptoms responsive to L- dopa medications, but who have significant impairment related to PD that is no longer well controlled with pharmacotherapy (i.e., refractory to optimized medical therapy)
3. Patients considered as subthalamic nucleus deep brain stimulation (STN-DBS) candidates as per current standard of care. These patients will subsequently undergo STN-DBS surgery and maintain stimulation therapy.
4. Patients aged 18 to 80 years.
5. Quality of life and social functioning influenced by levodopa-responsive symptoms 6) No major comorbidities

Exclusion criteria will include patients with other significant neurologic or psychiatric illnesses or cognitive deficit.