Table 1 Approved invasive stimulation methods for epilepsy. Replicated from [70]
From: Neural stimulation systems for the control of refractory epilepsy: a review
Data | Vagus nerve stimulation | Thalamic stimulation | Responsive focus stimulation |
|---|---|---|---|
Approval | 1997 (FDA)/(EU) (also heart rate triggered closed loop since 2015) | 2011 (EU) | 2013 (FDA) |
Stimulation site | Left vagus nerve (neck) | Anterior nuclei of the thalamus (bilaterally) | Epileptic focus (cortex) |
Stimulator placement | Subcutaneous, left pectoral/sub clavicular | Subcutaneous, abdominal | Within the skull |
Stimulation mode | Open-loop/closed-loop based on detection of tachycardia | Open-loop | Closed-loop based on detection of ictal EEG patterns |
Stimulus parameters | Intensity: 0.25–3 mA Frequency: 20–30 Hz Pulse width: 250–500 μs Duty cycle: 30 s on/ 5 min off (standard); 7 s on/30 s off (“rapid cycling”) | Intensity: 5 V Frequency: 145 Hz Pulse width: 95 μs Duty cycle: 1 min on/5 min off | Intensity: ∼1 mA Frequency: 200 Hz Pulse width: 160 μs Duty cycle: ∼5.9 min/day; (closed loop) |
Side effects of implantation | 1.6% infections 1% vocal cord paralysis | 12,7% infections 10.9% local pain 18.2% paraesthesia at implantation site 4.5% in cranial bleeding | 7.8% infections 4.7% intracranial bleeding |
Side effects of stimulation | Hoarseness (intensity-dependent up to 66%) Cough (up to 45%) | 14.8% depression 13.0% memory impairment | No statistics |