VNS is described as an effective palliative treatment option for DRE [4, 8, 19, 25]. A major indication for VNS is symptomatic epilepsy with multifocal independent foci. Several etiologies are implicated in multifocal ictal foci, such as neuronal migration disorders, cerebral palsy, traumatic brain injury, infections, phacomatosis, and metabolic syndromes [11, 12, 28]. Cryptogenic generalized epilepsy with diffuse epileptogenic abnormalities (e.g., Lennox-Gastaut syndrome) is another indication for VNS therapy. These patients are suitable candidates both for corpus callosotomy (CC) and VNS. In 2013, Lancman et al. published an interesting metaanalysis demonstrating that VNS offered rates comparable to CC in patients with tonic, generalized tonic-clonic, and complex partial and myoclonic seizures [22]. Other cases suitable for VNS can also be considered: refractory idiopathic generalized epilepsy (IGE) [24] and failed resective epilepsy surgery [3]. As widely described, resective surgery offers a satisfactory seizure outcome in patients with focal symptomatic epilepsy and is the recommended treatment option in such patients [10, 27]. Furthermore, advances in neuroimaging and the employment of intracranial recordings, as well as the recent developments in digital EEG analysis, allow a better identification of the epileptogenic zone, increasing the number of candidates for resective surgery. However, if the epileptogenic focus arises from/overlaps with the eloquent cortex, open cranial surgery should be excluded. In addition, some patients may refuse the risks associated with intracranial procedures.

In line with the current literature, VNS in our series was performed in 29 patients (91 %) due to multifocal epilepsy, and in 2 patients (6 %) in whom resective surgery could not be performed, since the epileptogenic zone involved the eloquent cortex. Only 1 patient (3 %), with left temporal lobe epilepsy that was suitable for resective surgery, underwent VNS device implantation because he refused “open” cranial surgery.

During a mean follow-up of 6 years (range 2–9) we observed 41 % of responders in our series (percentage with seizure reduction ≥50 %). DeGiorgio et al. reported a responder rate of 35 % [7]; in the E01-E05 study, 440 patients were followed-up for 3 years, with responder rates of 36.8 % at 1 year, 43.2 % at 2 years, and 42.7 % at 3 years [1, 18, 23]. The largest retrospective study, with 436 patients, demonstrated a mean seizure reduction rate of 55.8 % in nearly 5 years of mean follow-up duration, and also found that the mean seizure reduction at 10 years was 75.5 % in 65 consecutive patients [12, 13]. In their review of more than 1800 patients, Connor et al. [5] reported a mean seizure reduction of 42.8 %, with 50.9 % of patients being responders. Other studies have been performed to explore changes in health-related quality of life in patients treated by VNS [6, 15]. Patients were evaluated with the Quality of Life in Epilepsy-l0 (QOLIE-l0), and demonstrated significant improvements in outcomes such as energy level, memory difficulties, social aspects, mental effects, and fear of seizures [6]. VNS implantation and therapy was associated with a persistent and positive improvement in subjective quality of life [15].