Department of Clinical Neuroscience, Sahlgren University Hospital, Sweden, Department of Neurology, University of Pennsylvania, USA
Pro AED: The central issue in medical decision-making is risk-benefit assessment. Surgery of any type is still considered to be a major undertaking. To warrant these risks, the patient has a right to expect that they have a greater chance of a good outcome with an invasive therapy than with a non-invasive one. The main question is when, if ever, this becomes the case when comparing implantation of a VNS Therapy System versus adding an antiepileptic drug (AED)? After the first drug? The second? After all AEDs have failed? To date, no randomized trial comparing the addition of an AED against vagus nerve stimulation (VNS Therapy) has been undertaken, although several are currently being contemplated. Without this information, it is more difficult to make a case for early implementation of VNS Therapy. Unfortunately, few data are available regarding the potential for patients to become seizure-free after implantation of a VNS Therapy System. Another issue is side effects. It is important to remember that VNS Therapy also produces adverse events, albeit very different in character than those associated with AEDs, to which physicians have become accustomed. These include cough, dyspnea, pharyngitis, voice alteration and sleep apnea. A less frequently discussed, potentially negative consequence of VNS Therapy relates to the ability to obtain imaging of the patient. Patients who have undergone VNS Therapy System implantation are not candidates for imaging of the chest, breast, or abdomen. A second issue is that imaging of the brain can only be performed with MRI scanners that meet certain requirements, and as MRI technology develops, scanners meeting these requirements may become harder to find. However, to summarize, VNS Therapy is an excellent and useful treatment choice. Fortunately, the choice between AEDs and VNS Therapy is not an “either/or” decision. Each has a role in the treatment of patients with epilepsy, and the advantages and disadvantages of each should be kept in perspective. Pro VNS Therapy: VNS Therapy is no longer a new treatment for patients with refractory epilepsy. The first implant was performed in l988, and since then more than 30,000 patients have received this therapy. It is no longer considered an unusual or dangerous procedure, but it is still used almost exclusively for refractory epilepsy patients and it has not been generally accepted for use as a first line or even second line therapy. However, compared to the new AEDs, VNS Therapy has similar efficacy results in clinical trials and in many epilepsy syndromes and the long-term efficacy results are even more positive, with continued improvement in seizure reduction for up to two years. Two of the major reasons for not using VNS Therapy early are that it is a surgical procedure, and its safety during MRI procedures, especially with 3 Tesla, has not yet been elucidated. The safety profile of VNS Therapy is very favorable; the side effects being totally different from those seen with AEDs. The most important aspects are that there have been no pharmacological interactions, cognitive or sedative side effects reported, and it is safe for use in all age groups. Side effects are restricted to local irritation, hoarseness, coughing and, in a few cases, swallowing difficulties when the stimulator is on, but these tend to disappear with time. No idiosyncratic side effect has emerged during the 16 years of use. Compliance is guaranteed. The cost of the implantation of the VNS Therapy System, when spread out over 8 years (battery life), is actually less than the cost of using a new AED over an eight-year period, and real savings as regards hospital costs due to seizures can be expected.