Efficacy Of Vagus Nerve Stimulation Research Articles

Comparison of corpus callosotomy and vagus nerve stimulation in children with Lennox–Gastaut syndrome

Purpose: To compare the efficacy of corpus callosotomy and vagus nerve stimulation (VNS) for long-term adjunctive therapy in children with Lennox–Gastaut syndrome (LGS). Method: Fourteen patients underwent a total corpus callosotomy and 10 patients received VNS implantation. The patients were monitored for more than 12 months after treatment, and seizure rates and complications were retrospectively evaluated. Results: Seizure types among the 24 patients included atonic or tonic seizures with head-drops in 17 patients, generalized tonic seizures in two patients, atypical absence seizures in one patient, generalized tonic–clonic seizures in one patient, and myoclonic seizures in three patients. Of the 14 patients who underwent a corpus callosotomy, nine (64.3%) had a greater than 50% reduction in seizure frequency and five (35.7%) had a greater than 75% reduction. Of the 10 patients who underwent VNS implantation, seven (70.0%) had a greater than 50% reduction in seizure frequency and two (20.0%) had a greater than 75% reduction. There was no significant difference between the two procedures in terms of final efficacy. Complications of corpus callosotomy included aphasia in one patient, ataxia in another, and paresis in a third. Among patients receiving VNS, one patient experienced dyspnea while sleeping and one patient suffered from drooling. These complications were transient and tolerable, and were controlled by simple adjustments of VNS treatment parameters. Conclusion: The efficacy and safety of corpus callosotomy and VNS were comparable in children with LGS.

Vagus nerve stimulation for medically refractory epilepsy: A long-term follow-up study

Vagus nerve stimulation (VNS) is thought to have a cumulative effect in time on seizure frequency reduction. There also might be other variables than reduction of seizure frequency in order to determine VNS efficacy. In this study we describe the long-term outcome of the first group of vagus nerve stimulation patients with pharmacoresistant epilepsy at the Medisch Spectrum Twente, The Netherlands. This long-term descriptive prospective study included 19 patients, 11 males and 8 females, aged 17-46 years with pharmacoresistant epilepsy. They had received 3-16 (mean 9) different anti-epileptic drugs and were not eligible for surgical resection of an epileptic focus. A vagus nerve stimulator was implanted in the period April 1999-October 2001. Follow-up ranges from 2 to 6 years (mean 4 years). Efficacy was measured as the percentage change in seizure rate during 1 year and then after each year follow-up of VNS compared to 5 months baseline before implantation. Mean seizure reduction at 1-6 years was, respectively, 14% (n = 19), 25% (n =1 9), 29% (n = 16), 29% (n = 15), 43% (n = 9) and 50% (n = 7). Because of VNS two patients were able to start living without supervision. One patient died after 2 years of follow-up possibly as a result of SUDEP. Four patients had no apparent reduction in seizure frequency. Two of them had their stimulator removed. The other two patients however had significantly reduced post-ictal periods and seizure time and received a new pulse generator when the battery was depleted. One stimulator was switched off due to adverse effects, even though there was a positive effect on his seizure reduction. In six patients the medication regimen was changed during VNS by adding one anti-epileptic drug, however without significant change in seizure reduction. Adverse effects were hoarseness and coughing during stimulation. One patient had a temporary paralysis of his left vocal cord. We think that VNS is an effective treatment for pharmacoresistant epilepsy and its positive effect persists during the years of follow-up. Our results suggest that seizure reduction should not be considered as the only variable of importance to describe the outcome of VNS on epilepsy and it is worthwhile to look at other outcome measures.

Vagus nerve stimulation: Clinical experience in drug-resistant pediatric epileptic patients

Vagus nerve stimulation (VNS) is an effective alternative treatment for patients with partial refractory epilepsy. Nevertheless, information regarding VNS in children is still limited. The clinical efficacy, safety and neuropsychological effects of VNS in 34 children (mean age 11.5 years) with drug-resistant epilepsy were studied. Mean follow-up was 30.8 months. Nine patients have been diagnosed with Lennox-Gastaut Syndrome, nine patients were affected by severe partial epilepsy with bisynchronous EEG and drop attacks, and 16 patients suffered from partial epilepsy without bisynchronous EEG and fall seizures. Forms were designed for prospective data collection on each patient's history, seizures, implants, device settings, quality of life (QOL), neuropsychological assessment and adverse events. Surgical technique was performed both by standard two incisions and single neck incision. Mean reduction in total seizures was 39% at 3 months, 38% at 6 months, 49% at 12 months, 61% at 24 months and 71% at 36 months. Significant better results were obtained in partial epilepsy, with and without drop attacks, than in Lennox-Gastaut syndrome--three patients being seizure-free. No operative morbidity was reported. Side-effects were minor and transient--the most common were voice alteration and coughing during stimulation. In two patients, electrode breakage occurred 3 years after surgical procedure; in both cases, a new device was implanted after removing the vagal electrode coils and generator. VNS can be considered an appropriate strategy as an add-on treatment in children affected by drug-resistant partial epilepsy and ineligible for resective epilepsy surgery.

VNS Therapy in Treatment-Resistant Depression: Clinical Evidence and Putative Neurobiological Mechanisms

Currently available therapeutic interventions for treatment-resistant depression, including switch, combination, and augmentation strategies, are less than ideal. Observations of mood elevation during vagus nerve stimulation (VNS) therapy for pharmacoresistant epilepsy suggested a role for VNS therapy in refractory major depression and prompted clinical investigation of this neurostimulation modality. The VNS Therapy System has been available for treatment of pharmacoresistant epilepsy since 1997 and was approved by the US Food and Drug Administration for treatment-resistant depression in July, 2005. The physiology of the vagus nerve, mechanics of the VNS Therapy System, and efficacy and safety in pharmacoresistant epilepsy are reviewed. Promising results of VNS therapy for treatment-resistant depression have been forthcoming from both acute and long-term studies, evidenced in part by progressive improvements in depression rating scale scores during the 1st year of treatment with maintenance of response thereafter. VNS therapy is well tolerated in patients with either pharmacoresistant epilepsy or treatment-resistant depression. As in epilepsy, the mechanisms of VNS therapy of treatment-resistant depression are incompletely understood. However, evidence from neuroimaging and other studies suggests that VNS therapy acts via innervation of the nucleus tractus solitarius, with secondary projections to limbic and cortical structures that are involved in mood regulation, including brainstem regions that contain serotonergic (raphe nucleus) and noradrenergic (locus ceruleus) perikarya that project to the forebrain. Mechanisms that mediate the beneficial effects of VNS therapy for treatment-resistant depression remain obscure. Suggestions for future research directions are described.

Vagus nerve stimulation use and effect in epilepsy: What have we learned?

Vagus nerve stimulation (VNS) for epilepsy has been available in the United States for 8 years. Pivotal randomized, blinded clinical trials leading to FDA approval in patients age 12 and older with refractory partial seizures have not been performed for other age groups or epilepsy syndromes. This practical review takes stock of the current information about VNS use and efficacy in various types of epilepsy. We review the evidence for commonly used stimulation parameters, end of battery life, predictors of response including duration of epilepsy, seizure type/epilepsy syndrome, bihemispheric seizures, age at implant, and prior cranial surgery. We review adverse events and VNS effects on respiratory patterns, cardiac function, and mood and behavior. With the recent U.S. approval of VNS for treatment-resistant depression, we anticipate that lessons learned from treating patients with epilepsy will be useful to physicians using VNS to treat patients with depression and possibly other conditions.

The Acute and Chronic Effect of Vagus Nerve Stimulation in Genetic Absence Epilepsy Rats from Strasbourg (GAERS)

The aim of this study was to evaluate the efficacy of acute and chronic vagus nerve stimulation (VNS) in genetic absence epilepsy rats from Strasbourg (GAERS). This is a validated model for absence epilepsy, characterized by frequent spontaneous absences concomitant with spike and wave discharges (SWD) on the EEG. Although absences are a benign form of seizures, it is conceptually important to investigate the efficacy of VNS in a controlled study by using this chronic epilepsy model. Both control and stimulated GAERS were implanted with five epidural EEG electrodes and a stimulation electrode around the left vagus nerve. In the first experiment, VNS was given when SWD occurred in the EEG; this was repeated the next day. A randomized crossover design (n = 8) was used. In the chronic experiment, GAERS underwent EEG monitoring during a first baseline week. During the second week, the treated group (n = 18) received VNS; controls (n = 13), on the other hand, only underwent EEG recordings. On day 1 of the acute VNS experiment, the mean duration of the SWD when VNS was applied was higher than in baseline conditions (p < 0.05). However, on day 2, there was no difference in mean duration of the SWD. In the chronic VNS experiment, no statistically significant differences were found between control and stimulated GAERS. Acute VNS applied shortly after the onset of SWD prolonged the mean duration of SWD in GAERS at least during the first day of VNS. Chronic stimulation hardly affected SWD in GAERS.

Cerebral Blood Flow during Vagus Nerve Stimulation – a Transcranial Doppler Study

Background and Objectives: Vagus nerve stimulation (VNS) is an approved treatment of partial onset seizures and has recently shown antidepressant effects in patients with treatment-resistant depression. This study was conducted to investigate whether acute VNS has an influence on cerebral blood flow (CBF) in humans. Methods: This investigation was designed as an add-on study. In 10 patients with an implanted stimulator who participated in a multicenter clinical trial to evaluate the efficacy of VNS in depression, CBF was investigated by functional transcranial Doppler at baseline (before the stimulator was turned on for the first time) and during stimulation with three different stimulation intensities in a randomized order. Results: Immediately after every increase of the current, CBF velocity showed a nonsignificant increase. Otherwise, no change of CBF above standard deviation could be registered. Conclusion: Acute VNS does not have an influence on CBF velocity in depressive patients.

Vagus nerve stimulation as a potential option for treatment-resistant depression

Despite the availability of numerous treatment options, many patients continue to suffer with chronic or recurrent major depression due to treatment non-response or intolerance. Several novel interventions for the treatment of mood disorders are under study, including vagus nerve stimulation (VNS). VNS involves intermittent electrical stimulation of the vagus nerve via the NeuroCybernetic Prosthesis system. This intervention has demonstrated acute and long-term safety and efficacy in the treatment of refractory epilepsy, and several lines of evidence suggest a role for VNS in the treatment of depression. Studies investigating the safety and efficacy of VNS in patients with treatment-resistant chronic or recurrent depression are currently underway, and results thus far are promising. This article provides an overview of VNS, including its current clinical uses, the rationale for studying VNS as a treatment for depression, current data regarding VNS in treatment-resistant depression, and suggestions for future directions of VNS in mood disorders.

Acute vagus nerve stimulation does not suppress spike and wave discharges in “Genetic Absence Epilepsy Rats from Strasbourg”

We evaluated the efficacy of vagus nerve stimulation (VNS) in Genetic Absence Epilepsy Rats from Strasbourg (GAERS), a validated model for absence epilepsy. In the first experiment, we investigated whether VNS applied at seizure onset can interrupt spike and wave discharges (SWD). In the second experiment, we investigated whether SWD are suppressed or shortened in duration when VNS is applied several hours per day. Both control and VNS groups underwent EEG and VNS electrode implantation. For the first experiment, a randomized crossover design was used. Stimuli (amplitude: 3 V; frequency: 30 Hz; pulse duration: 500 μs) were given when an SWD occurred on the EEG. The experiment was repeated the next day. In the second experiment, treated animals were stimulated (amplitude: 1.5 mA; frequency: 30 Hz; pulse duration: 500 μs; on/off time cycle: 30 s/5 min) for 3 h per day, during five consecutive days. In the first experiment, the duration of the SWD was increased on day 1, ( P < 0.05). There was no difference in SWD duration on Day 2. In the second experiment, no significant differences could be found in number, duration and EEG frequency of SWD. VNS applied at the onset of an SWD can prolong the duration of SWD in GAERS. As a 5-day stimulation protocol had no effect, long-term VNS might be necessary to affect SWD.

Novel physical treatments for major depression: vagus nerve stimulation, transcranial magnetic stimulation and magnetic seizure therapy

Purpose of review Transcranial magnetic stimulation, vagus nerve stimulation and magnetic seizure therapy are currently studied as potential treatment options for affective disorders. We review the recent developments (mainly since July 2002) in their clinical applications and new contributions to the basic understanding of their mechanisms of action. Recent findings Transcranial magnetic stimulation has clear antidepressant properties, as supported by several recently published metaanalyses. It is not yet clear, however, whether these effects are clinically meaningful and, if so, in which population of depressed people. To assess these questions, large controlled and comparative (against pharmaco- and electroconvulsive therapy) multicenter studies are needed but are not available to date. In addition, optimal treatment parameters (place of stimulation, stimulation parameters, number of sessions etc.) have to be defined. Since July 2002, no new data concerning the efficacy of vagus nerve stimulation in depression have been published. Published and unpublished results indicate that the best antidepressant effects of this treatment can be expected at 12 months after the start of stimulation. A recently published case report on magnetic seizure therapy describes the first successful antidepressant treatment of a treatment refractory patient. The application of this methodology is still experimental. Summary If these novel physical treatments will have a place as treatment modalities of affective disorders and how they exert their antidepressant effects is not yet known. Many studies are being conducted addressing these basic questions and they may help to elucidate crucial issues of the neurobiology of depression itself.

Correlation between GABA A receptor density and vagus nerve stimulation in individuals with drug-resistant partial epilepsy

Vagus nerve stimulation (VNS) is an important option for the treatment of drug-resistant epilepsy. Through delivery of a battery-supplied intermittent current, VNS protects against seizure development in a manner that correlates experimentally with electrophysiological modifications. However, the mechanism by which VNS inhibits seizures in humans remains unclear. The impairment of γ-aminobutyric acid (GABA)-mediated neuronal inhibition associated with epilepsy has suggested that GABA A receptors might contribute to the therapeutic efficacy of VNS. We have now applied single photon emission computed tomography (SPECT) with the benzodiazepine receptor inverse agonist [ 123 I ]iomazenil to examine cortical GABA A receptor density (GRD) before and 1 year after implantation of a VNS device in 10 subjects with drug-resistant partial epilepsy. VNS therapeutic responses resulted significantly correlated with the normalization of GRD. Moreover, a comparable control group, scheduled for a possible VNS implant, failed to show significant GRD variations after 1 year of a stable anti-epileptic treatment. These results suggest that VNS may modulate the cortical excitability of brain areas associated with epileptogenesis and that GABA A receptor plasticity contributes to this effect.

Vagus Nerve Stimulation As Treatment for Epileptic Seizures.

Vagus nerve stimulation is a unique therapy for epileptic seizures. Two randomized controlled trials in patients with medically refractory partial seizures have demonstrated efficacy, leading to US Food and Drug Administration approval of vagus nerve stimulation therapy in 1997. Extensive safety testing has not revealed significant effects on cardiac, respiratory, or gastrointestinal function, though recent reports of intraoperative asystole and sleep-related airway obstruction have raised concerns. Vagus nerve stimulation is indicated for adjunctive therapy of partial-onset seizures in children and individuals older than 12 years (Class I evidence). Based on controlled, randomized trials, approximately 30% of these patients can be expected to have at least a 50% decrease in overall seizure frequency. Vagus nerve stimulation efficacy is similar to that of several newer antiepileptic drugs when used in similar populations in controlled, randomized trials. Long-term follow-up studies suggest continued efficacy over more than 1 year (Class III evidence). Case series suggest similar or greater efficacy in younger children, and in patients with refractory generalized seizures, including those associated with the Lennox-Gastaut syndrome (Class III evidence). Vagus nerve stimulation is appropriate therapy for patients with medically refractory epileptic seizures who are not optimal candidates for resective epilepsy surgery.

VNS in patients with previous unsuccessful resective epilepsy surgery: antiepileptic and psychotropic effects

To assess the efficacy of vagus nerve stimulation (VNS) in patients with medically and surgically intractable complex partial seizures (CPS). Sixteen patients with previous temporal [15] and frontal [one] resections were treated with VNS between 1994 and 1999 at King's College Hospital, London, UK. Post-operative video-electroencephalogram telemetry had shown that CPS started from the operated side in 12 patients, contralaterally in three and bilaterally independently in one. Three patients (18.75%) had 50% or more reduction in seizure frequency, but one showed severe worsening of epilepsy, which remitted upon VNS discontinuation. The antiepileptic effect of VNS was not different with respect to the type of operation (anterior temporal lobectomy vs amygdalohippocampectomy), the side of operation, or the side of seizure onset. We observed psychotropic effects in two patients with post-ictal psychosis, in two others with depression, and in a child with severe behavioral disorder. VNS may have a rather limited antiepileptic role to play in patients with persistent seizures following epilepsy surgery, but may independently possess useful antipsychotic and mood-stabilizing properties.

Do Cardiac Neurons Play a Role in the Intrinsic Control of Heart Rate in the Rat?

Three experiments were performed to see whether cardiac neurons contribute to the intrinsic control of heart rate in right atria of adult rats. The intrinsic heart rate response (IRR) was examined by raising right atrial pressure from 2 to 8 mmHg for 3 min. In isolated preparations of the right atrium, the IRR was not significantly altered by the addition of either 1 microM atropine (n =6; control +19+/- 3 min(-1) ; atropine+18+/-3 min(-1); (mean /+/-S.E.M.)) or 1 microM propranolol (n = 5; control +22+/- 4 min(-1); ; propranolol +21+/-3 min(-1); ). Tetrodotoxin (0.5 microm) had no effect on the IRR (n = 6; control +37+/-5 min(-1); tetrodotoxin 38+/-5 min(-1); ). In another experiment, 2-day-old rat pups were injected with capsaicin (50 mg kg(-1); treated) or with vehicle(control). There was no difference in the IRR of right atrial preparations taken from control and treated animals after they reached adulthood (control (n = 7) and treated (n = 8): +30+/- 4 and +32+/- 4 min(-1)). The influence of right atrial pressure on the efficacy of vagal stimulation was examined. The rate response to vagal stimulation was reduced similarly in control and treated preparations when pressure was elevated from 2 to 4 mmHg (control and treated: -34+/- 5% and -33+/- 3%). The effectiveness of the capsaicin treatment was confirmed by the depletion of substance P-immunoreactive nerve fibres in cardiac tissues. Together, these results strongly suggest that cardiac neurons are not involved in intrinsic heart rate control.

Use of vagal nerve stimulation as a treatment for refractory epilepsy in dogs

To evaluate safety and efficacy of vagal nerve stimulation in dogs with refractory epilepsy. Placebo-controlled, double-masked, crossover study. 10 dogs with poorly controlled seizures. A programmable pacemaker-like device designed to deliver intermittent stimulation to the left cervical trunk of the vagus was surgically implanted in each dog. Dogs were assigned randomly to two 13-week test periods, 1 with nerve stimulation and 1 without nerve stimulation. Owners recorded data on seizure frequency, duration, and intensity, as well as adverse effects. No significant difference in seizure frequency, duration, or severity was detected between overall 13-week treatment and control periods. During the final 4 weeks of the treatment period, a significant decrease in mean seizure frequency (34.4%) was detected, compared with the control period. Complications included transient bradycardia, asystole, and apnea during intraoperative device testing, and seroma formation, subcutaneous migration of the generator, and transient Horner's syndrome during the 14-day period between surgery and suture removal. No adverse effects of stimulation were detected, and most owners were satisfied with the treatment. Vagal nerve stimulation is a potentially safe approach to seizure control that appears to be efficacious in certain dogs and should be considered a possible treatment option when antiepileptic medications are ineffective.

Long-term effects of 24-month treatment with vagus nerve stimulation on behaviour in children with Lennox–Gastaut syndrome

The long-term effects of vagus nerve stimulation (VNS) on behaviour were studied in 19 children with Lennox–Gastaut syndrome. We used the following stimulation parameters: output current: 1 1 2 to 2 mA; signal frequency: 30 Hz frequency; signal pulse width: 500 μs; signal ‘on and off’ time: 30 s ‘on,’ 3 min ‘off.’ The test battery consisted of cognitive tests assessing mental age and quality of life measurements assessing independency, behavioural problems, and mood. The results show relatively small changes in the behavioural outcomes, concurrent with the modest effects of VNS on seizure frequency (an average of 20.6% seizure reduction). When baseline measurements are compared with the follow-up measures, neither the cognitive measure nor the quality of life measures show any deterioration and the cognitive measure (mental age) showed mild positive changes (gain of 4.2 months mental age during the follow-up period). None of the changes were statistically significant. Treatment effect was most prominent in the group with the highest mental age at baseline, which suggests that mental retardation is a negative prognostic factor for VNS treatment. Moreover, in this specific patient group, treatment effect did not increase with treatment duration. Some evidence during follow-up suggests a direct positive effect of VNS on behavioural function, independent of changes in seizure frequency. Long-term treatment with VNS is not associated with adverse behavioural effects. Mental retardation is a negative prognostic factor for the efficacy of VNS.

Vagus nerve stimulation for treatment of medically intractable seizures. Evaluation of long-term outcome

Vagus nerve stimulation (VNS) constitutes an adjunctive, modern management of medically intractable seizures, especially when surgery is inadvisable. Objective: To evaluate the long-term results as regards efficacy, safety and tolerability of VNS in epileptic subjects, with focal and/or generalised seizures, refractory to old and new AEDs, without indication for resective surgery. Patients: 51 epileptic subjects (30 males, 21 females), aged 7–49 years, have been implanted so far. Results: The results refer to the 47 subjects with a follow-up longer than 6 months. 22 (46.8%) of them had a greater than 50% reduction in seizure frequency, with a more than 75% reduction in 6. No significant difference was found in relation to type of seizures. The efficacy maintained steadily over time during the follow-up (mean 26.4 months). Twelve out of the 47 subjects had an improvement in alertness, attention and psychomotor activity. Complications were observed in 5 cases, leading to removal of the stimulator in 2. A moderate vocal hoarseness (40.4%), paresthesia (6.3%), pharingodinia and cough (4.3%) were the registered adverse events. Conclusions: Our results confirm that VNS is effective, safe and well tolerated and constitutes an alternative treatment for pharmacoresistant epileptic seizures.

Programmed and magnet-induced vagus nerve stimulation for refractory epilepsy.

Vagus nerve stimulation (VNS) is an effective alternative treatment for patients with refractory epilepsy. The generator produces intermittent stimulation trains and does not require patient intervention. Using currently available technology, continuous stimulation is incompatible with a reasonable battery life. Because earlier studies have demonstrated the persistence of a stimulation effect after discontinuation of the stimulation train, we intended to evaluate the clinical efficacy of VNS in both the programmed intermittent stimulation mode and the magnet stimulation mode. Patients, companions, and caregivers were instructed on how to administer additional stimulation trains when an aura or a seizure onset occurred. We assumed that patients or caregivers could recognize habitual seizures and were able to evaluate sudden interruption of these seizures. During a mean follow-up of 35 months, 46% of patients became responders, with a reduction in seizure frequency of more than 50%. Twenty-nine percent of patients stopped having convulsive seizures. In two thirds of patients who were able to self-administer or receive additional magnet stimulation, seizures could be interrupted consistently or occasionally. More than half of the patients who reported a positive effect of magnet stimulation became responders. Only three patients were able to use the magnet themselves. In most cases, support from caregivers was necessary. This study is the first to document the efficacy of magnet-induced VNS in a larger patient population during long-term follow-up. The magnet is a useful tool that provides patients who are treated with VNS and mainly caregivers of such patients with an additional means of controlling seizures. To further confirm the self-reported results from our patients, additional studies comparing programmed stimulation and magnet-induced stimulation during monitoring conditions are needed.

Vagus nerve stimulation and Lennox-Gastaut syndrome: a review of the literature and data from the VNS patient registry.

Lennox-Gastaut syndrome (LGS) is a severe form of childhood epilepsy that is usually refractory to medical management. When medication fails, alternative therapies are considered. Among these are two surgical options: corpus callosotomy and vagus nerve stimulation (VNS). Safety and efficacy are two important factor to consider when selecting an appropriate treatment. VNS is safer than callosotomy, but its efficacy is more difficult to assess. Available studies evaluate its effectiveness using a mixed population of patients (some with prior epilepsy surgery), a multitude of VNS settings, and variable endpoints. To estimate the efficacy of VNS in patients with LGS, a review of the medical literature and the VNS Patient Registry was performed. Within the limits of this type of study, the results showed that VNS appears to be equally as effective as callosotomy. Because VNS has a lower potential for adverse effects, these results suggest that VNS should be considered first in appropriately selected patients.

Vagus Nerve Stimulation in the Developmentally Disabled

Vagus nerve stimulation (VNS) with the neuro cybernetic prosthesis (NCP) is an approved treatment of partial seizures for patients 12 years and older. Developmentally disabled or mentally retarded patients with epilepsy may also benefit from VNS; however, their evaluation and management pose greater problems. A retrospective chart review was conducted on all patients diagnosed with mild to severe mental retardation who had an NCP implanted. Records of these 21 patients, ranging in age from 3 to 56 years, were reviewed regarding VNS efficacy, side effects, behavioral changes, and alterations in antiepileptic drugs (AEDs). Seizure types included partial onset and generalized. Sixteen patients had clearly evaluable seizures both pre- and postimplant, with a greater than 50% reduction in seizures noted in 68% (11/16) after 6 months of implant. There were no adverse events that prevented chronic stimulation. Institutional staff and family members were provided with both pre- and postoperative education on VNS and magnet use. VNS appeared to be an effective and well-tolerated therapy in this group of developmentally disabled patients with refractory epilepsy.