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. (C) 2001 Academic Press