Effectiveness of vagal nerve stimulation in medication-resistant epilepsy. Comparison between patients with and without medication changes
Vagal nerve stimulation (VNS) response is not immediate. A progressive decline in seizure frequency is usually found during a period of 12–18 months after implantation. During this time, the patient’s medication is usually modified, which can create doubts about whether their clinical improvement is due to medication changes or to VNS itself. Our goal is to compare two groups of patients treated with VNS, with and without changes in their medication.
We prospectively analyze 85 patients who were treated with VNS in our hospital between 2005 and 2014. In 43 patients, changes in the antiepileptic drugs (EAD) were not allowed during the postoperative follow-up and they were compared with 42 patients who were left at the option of neurologist make changes in medication. We analyzed the clinical situation at 18 months and compared the two groups.
Overall, 54.1% of patients had a reduction in seizures of 50% or higher (responders). In the group with no changes in medication, responders reached 63%, while in the group in which changes in medication were allowed, 45.2% were responders. Between responders and non-responders, there were no statistical differences in type of epilepsy, frequency, previous surgery, or intensity of stimulation.
We did not find a statistical difference in seizure frequency reduction between patients with or without changes in medication during their follow-up, so changes in medication did not improve the outcome. Furthermore, the absence of changes in AED can help to optimize the parameters of the stimulator in order to improve its effectiveness.
KeywordsAntiepileptic drugs Epilepsy surgery Seizures Vagus nerve
- 1.Alonso-Vanegas MA, Austria-Velasquez J, Lopez-Gomez M, Brust-Mascher E (2010) Chronic intermittent vagal nerve stimulation in the treatment of refractory epilepsy: experience in Mexico with 35 cases. Cir Cir 78(15–23):24Google Scholar
- 4.Ben-Menachem E, Manon-Espaillat R, Ristanovic R, Wilder BJ, Stefan H, Mirza W, Tarver WB, Wernicke JF (1994) Vagus nerve stimulation for treatment of partial seizures: 1. A controlled study of effect on seizures. First International Vagus Nerve Stimulation Study Group. Epilepsia 35:616–626Google Scholar
- 9.DeGiorgio CM, Schachter SC, Handforth A, Salinsky M, Thompson J, Uthman B, Reed R, Collins S, Tecoma E, Morris GL, Vaughn B, Naritoku DK, Henry T, Labar D, Gilmartin R, Labiner D, Osorio I, Ristanovic R, Jones J, Murphy J, Ney G, Wheless J, Lewis P, Heck C (2000) Prospective long-term study of vagus nerve stimulation for the treatment of refractory seizures. Epilepsia 41:1195–1200CrossRefPubMedGoogle Scholar
- 11.Elliott RE, Morsi A, Kalhorn SP, Marcus J, Sellin J, Kang M, Silverberg A, Rivera E, Geller E, Carlson C, Devinsky O, Doyle WK (2011) Vagus nerve stimulation in 436 consecutive patients with treatment-resistant epilepsy: long-term outcomes and predictors of response. Epilepsy Behav: E&B 20:57–63CrossRefGoogle Scholar
- 13.Englot DJ, Rolston JD, Wright CW, Hassnain KH, Chang EF (2015) Rates and predictors of seizure freedom with vagus nerve stimulation for intractable epilepsy. Neurosurgery 79(3):345–353Google Scholar
- 16.Handforth A, DeGiorgio CM, Schachter SC, Uthman BM, Naritoku DK, Tecoma ES, Henry TR, Collins SD, Vaughn BV, Gilmartin RC, Labar DR, Morris GL 3rd, Salinsky MC, Osorio I, Ristanovic RK, Labiner DM, Jones JC, Murphy JV, Ney GC, Wheless JW (1998) Vagus nerve stimulation therapy for partial-onset seizures: a randomized active-control trial. Neurology 51:48–55CrossRefPubMedGoogle Scholar
- 19.Morris GL 3rd, Gloss D, Buchhalter J, Mack KJ, Nickels K, Harden C (2013) Evidence-based guideline update: vagus nerve stimulation for the treatment of epilepsy: report of the guideline development subcommittee of the American Academy of Neurology. Epilepsy Curr Am Epilepsy Soc 13:297–303CrossRefGoogle Scholar
- 21.Panebianco M, Rigby A, Weston J, Marson AG (2015) Vagus nerve stimulation for partial seizures. Cochrane Database Syst Rev 4:CD002896Google Scholar
- 23.Ryvlin P, Gilliam FG, Nguyen DK, Colicchio G, Iudice A, Tinuper P, Zamponi N, Aguglia U, Wagner L, Minotti L, Stefan H, Boon P, Sadler M, Benna P, Raman P, Perucca E (2014) The long-term effect of vagus nerve stimulation on quality of life in patients with pharmacoresistant focal epilepsy: the PuLsE (open prospective randomized long-term effectiveness) trial. Epilepsia 55:893–900CrossRefPubMedPubMedCentralGoogle Scholar
- 24.Sola RG, Hernando-Requejo V, Pastor J, Garcia-Navarrete E, DeFelipe J, Alijarde MT, Sanchez A, Dominguez-Gadea L, Martin-Plasencia P, Maestu F, DeFelipe-Oroquieta J, Ramon-Cajal S, Pulido-Rivas P (2005) Pharmacoresistant temporal-lobe epilepsy. Exploration with foramen ovale electrodes and surgical outcomes. Rev Neurol 41:4–16PubMedGoogle Scholar