While the traditional methods of treating epilepsy – with antiseizure drugs and with brain surgery – continue to advance, a further method of controlling seizures – neuromodulation – is rapidly evolving. ‘Neuromodulation’ is the process by which certain brain areas are activated electrically so that they may influence other brain areas to reduce the tendency for seizures. The science behind neuromodulation remains incompletely understood, but the positive effect on seizures can be significant. The first neuromodulatory treatment to be FDA-approved was vagal nerve stimulation (VNS), but in recent years RNS (responsive neurostimulation) and DBS (deep brain stimulation) have been approved for use in selected patient populations.
Vagal Nerve Stimulation (VNS)
Vagal nerve stimulation (VNS) was FDA-approved in 1997 as an adjunctive therapy for refractory epilepsy. The University of Florida was part of the early trials for VNS, and we have a large population of patients with VNS currently under our care. While the detailed mechanisms of VNS’s efficacy remain under investigation, it is clear that the therapy can be a valuable addition to treatment options available for patients who continue to experience seizures despite optimum drug treatment. All patients who may benefit from VNS are first vetted at our multidisciplinary patient management conference for their suitability. Following a consensus decision to proceed with VNS, the patient is counseled and scheduled for the procedure. The insertion of the VNS itself is a short surgery under general anesthesia, where the battery pack is inserted into the upper chest, and the stimulation wire attached to the vagus nerve in the neck. Patients usually go home the day following their procedure, and subsequently attend the clinic for follow up where the settings of stimulation are gradually adjusted. Benefit from VNS can take several months to become evident.
Deep Brain Stimulation (DBS)
Deep brain stimulation (DBS) was FDA-approved in 2018 as adjunctive therapy for refractory epilepsy. DBS is different from RNS and similar to VNS in that treatment is designed to reduce the frequency of seizures over time, rather than target specific seizures at the time of their occurrence. DBS therapy can be a valuable addition to treatment options available for patients who continue to experience seizures despite optimum drug treatment, though full benefits may take months or years to accrue. As with all complex patients, patients who may benefit from DBS are first vetted at our multidisciplinary patient management conference for their suitability. Following a consensus decision to proceed with DBS, the patient is counseled and scheduled for the procedure. The insertion of the DBS itself involves surgery under general anesthesia, where the stimulation wires are inserted into the anterior nucleus of the thalamus of the brain, and the stimulator pack is situated under the skin on the upper chest. At the University of Florida, we have pioneered these surgeries for other types of neurological patients (those with movement disorders such as Parkinson’s disease) and our surgeons have extensive experience of the practical aspects of the surgical procedure. Patients usually go home a day or two after the procedure, and subsequently attend the clinic for follow up where the settings of stimulation are gradually adjusted. The benefits of DBS for epilepsy takes time to build up – at least several months, and sometimes a few years.
Responsive Neurostimulation (RNS)
Responsive neurostimulation (RNS) was FDA-approved in 2013 as adjunctive therapy for refractory epilepsy. RNS is different from VNS and DBS in that treatment is designed to abort seizures when they happen. This is done by sensing wires with electrode contacts placed within specific seizure-producing areas in the brain that detect seizures as they arise, and deliver small electric current stimulation to stop or slow them. RNS therapy can be a valuable addition to treatment options available for patients who continue to experience seizures despite optimum drug treatment, though full benefits may take months or years to accrue. As with all complex patients, patients who may benefit from RNS are first vetted at our multidisciplinary patient management conference for their suitability. Following a consensus decision to proceed with RNS, the patient is counseled and scheduled for the procedure. The insertion of the RNS itself involves surgery under general anesthesia, where the stimulation wires are inserted into predetermined locations within the brain and the stimulator pack situated within the skull. Patient usually go home a day or two after the procedure, and subsequently attend the clinic for follow up where the settings of stimulation are gradually adjusted.