cqvip:Objectives: To identify predictive factors for the seizure-free outcome of va gus nerve stimulation (VNS). Methods: All 47 patients who had undergone VNS impl antation at one centre and had at least one year of followup were studied. They underwent complete presurgical evaluation including detailed clinical history,ma gnetic resonance imaging, and long term video-EEG with ictal and interictal rec ordings. After implantation, adjustment of stimulation parameters and concomitan t antiepileptic drugs were at the discretion of the treating physician. Results: Mean (SD) age of the patients was 22.7 (11.6) years (range 7 to53). Six patients (13%) became seizure-free after the VNS implantation.Only two variables showe d a significant association with the seizure-free outcome: absence of bilateral interictal epileptiform discharges (IED) and presence of malformation of cortic al development (MCD). Epilepsy duration showed a non-significant trend towards a negative association with outcome.By logistic regression analysis, only absenc e of bilateral IED correlated independently with successful VNS treatment(p < 0. 01, odds ratio = 29.2 (95%confidence interval, 2.4 to 353)). Bilateral IED (ind ependent or bilateral synchronous)was found in one of six seizure-free patients and in 33 of 41non-seizure-free patients. When bilateral IED were absent, the sensitivity for seizure-free outcome was 0.83 (0.44 to 0.97),and the specifici ty was 0.80 (0.66 to 0.90). Conclusions: Bilateral IED was independently associa ted with the outcome of VNS. These results are preliminary because they were based on a small patient population. They may facilitate prospective VNS studi es enrolling larger numbers of patients to confirm the results.
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