CLINICAL OUTCOMES: EPILEPSY Deep Brain Stimulation
SANTE (Stimulation of the Anterior Nucleus of the Thalamus in Epilepsy) was a multicenter, prospective, randomized, double-blind, parallel groups study intended to evaluate the safety and efficacy of bilateral stimulation of the anterior nucleus of the thalamus (ANT) as an adjunctive therapy for the treatment of medically refractory epilepsy, characterized by partial-onset (focal) seizures, with or without secondary generalization.
The study was conducted at 17 centers in the United States. The study enrolled 157 adult subjects, of which 110 were implanted.
The SANTE trial provides Level 1 Clinical Evidence for Medtronic Deep Brain Stimulation for Epilepsy. The outcomes of the study demonstrated the safety, effectiveness and long-term benefits of Deep Brain Stimulation therapy for medically refractory partial-onset (focal) seizures in adults.1,2
For patients receiving Medtronic Deep Brain Stimulation Therapy for Epilepsy in the SANTE study, the responder rate (percentage of subjects with ≥50% seizure reduction) was 43% (n=99) at one year and 74% (n=50) at year seven.
Significant seizure reductions were observed for certain subgroups, including those with temporal seizure origin, and those with or without prior Vagus Nerve Stimulation at seven years compared to baseline.
During the blinded phase, DBS was shown to significantly reduce patients’ most severe seizures, complex partial seizures, and incidence of epilepsy-related injury.
The SANTE study showed a significant increase in quality of life for patients with epilepsy. After seven years, 43% of patients experienced a clinically meaningful improvement in quality of life.
After 7 years, 84% of patients (54 out of 64) said they were satisfied or greatly satisfied with the results.
Safety was assessed in the SANTE trial with 110 implanted subjects having a combined 713 device-years of device experience. The following summary reflects data on all active subjects, followed for a minimum of seven years after device implantation.
Device-related serious adverse events (SAEs) were reported by 34.5% of subjects. Most occurred during the first few months after implant. The most frequent SAEs included:
No symptomatic hemorrhage events were associated with lead implant or replacements. Of eight intracranial hemorrhage events, one SAE in the long-term follow-up resulted in clinical symptoms and was attributed to a head injury after two seizure related falls. The event resolved without sequelae or surgical intervention.
The most frequent device-related adverse events were:
There were no unanticipated adverse device effects reported in the study.
Neuropsychological test scores for mood and cognition were stable acutely during the blinded phase and long-term through seven years. No subject discontinued the study due to depression or memory impairment. However, self-reports of depression and memory impairment were higher in the active group during the blinded phase.
Memory impairment was reported in 30.9% of subjects at any time after implant (30.0% at 7 years). Of the 34 subjects who reported memory impairment, 38.2% had a history of memory impairment.
Depression was reported in 39.1% of subjects at any time after implant (37.3% in 7 years). Three events in three subjects were device related. Of the 43 subjects who reported depression, 65.1% had a prior history of depression.
Twelve subjects (10.9%) reported 15 suicidality events after DBS implant. Nine of the 15 events were serious in seven subjects (6.4%). There was one completed suicide four years after implantation (not device related). Of seven subjects reporting suicidality SAEs, six had a medical history of depression or suicide attempt.
Status epilepticus was reported in seven subjects (6.4%) at the time of database cutoff:
There were seven deaths that occurred at the time of the database cutoff:
Including pilot studies, SUDEP rate (definite/probable) was 2.5 per 1,000 patient years including all follow-up.2 Published SUDEP rate for epilepsy surgery candidates is 9.3 per 1,000 patient years.3 The three other deaths were attributed to completed suicide, cardiorespiratory arrest, and liver cancer.2
Fisher R et al. Electrical stimulation of the anterior nucleus of the thalamus for treatment of refractory epilepsy. Epilepsia 2010; 51(5): 899-908.
Medtronic DBS Therapy for Epilepsy Clinical Summary, 2018.
Dasheiff RM. Sudden unexpected death in epilepsy: a series from an epilepsy surgery program and speculation on the relationship to sudden cardiac death. J Clin Neurophysiol 1991; 8(2): 216-222.