• Primary Analysis: Change in Seizure Rate [ Time Frame: Through the end of the three-month blinded phase ] [ Designated as safety issue: No ]
  
• Alternative Primary Analysis: Change in Seizure Rate [ Time Frame: Through the end of the three-month Blinded Phase ] [ Designated as safety issue: No ]
  

• Adverse Events Experienced With the Medtronic DBS system [ Time Frame: Through Year 2 of the long-term follow-up phase ] [ Designated as safety issue: Yes ]
  
• Incidence of Sudden Unexplained Death in Epilepsy (SUDEP) [ Time Frame: Inclusive of all study follow-up after device implantation (mean follow-up 3.7 years) ] [ Designated as safety issue: Yes ]
  
• Seizure Responder Rate [ Time Frame: Through the end of the three-month blinded phase ] [ Designated as safety issue: No ]
  
• Change in Percentage of Days Seizure-free [ Time Frame: Through the end of the three-month blinded phase ] [ Designated as safety issue: No ]
  
• Percent Change in the Maximum Length of Seizure-free Intervals [ Time Frame: Through the end of the three-month Blinded Phase ] [ Designated as safety issue: No ]
  
• Proportion of Treatment Failures [ Time Frame: Through the end of the three-month Blinded Phase ] [ Designated as safety issue: No ]
  

Medtronic, Inc. is sponsoring an investigational study of the Medtronic DBS Therapy for epilepsy, the company's deep brain stimulation (DBS) therapy for patients with refractory epilepsy. Epilepsy is a condition that affects 2.3 million Americans, and about one-third of these patients are refractory, or continue to experience seizures despite a wide range of treatment options.

The prospective, randomized, double-blind trial uses existing technology to test whether bilateral stimulation of the anterior nucleus of the thalamus can safely and effectively reduce seizure frequency in patients with epilepsy. It includes enrollment of 157 patients at 17 sites in the U.S. 110 patients were implanted and monitored for 13 months following implant, with long-term follow-up until the device is approved or the study is stopped.

Patients in the active group, who received neurostimulation, were monitored for a reduction in seizure rates compared to the control group, who did not receive neurostimulation during the three-month double-blind phase. After the double-blind phase, all patients received neurostimulation.

Candidates for the trial were adults with partial-onset epilepsy for whom at least three antiepileptic drugs have proven ineffective. They were to have had an average of six or more seizures per month. Candidates continued to receive their epilepsy medications while participating in the trial.

Deep brain stimulation therapy has already received approval in the United States, Europe, Canada, and Australia for the treatment of Essential Tremor and Parkinson's disease. Deep brain stimulation is not approved for the treatment of epilepsy.