Estimulador do nervo vago: taxa e predição de resposta em pacientes adultos e crianças com epilepsia farmacorresistente

Abstract

JUSTIFICATION: Approximately 50 million people globally have epilepsy and 80% of them live in low and middle income countries. It is well recognized that 30% of the epileptics patients will not achieve seizure freedom after two or more tolerate and effective anti epileptics drugs. This condition is known as refractory epilepsy and it has an elevate morbimortality rate. Despite of epilepsy surgery be the major treatment for this group, several patients are not candidate. For them it is necessary to propose others options as cetogenic diet or neuromodulation. Vagus nerve stimulation (VNS) is a neuromodulation therapy, approved in Europe (1994), USA (1997) and Brazil (2000) as adjunctive for treatment for refractory epilepsies, which an electrical stimulus is applied in the cervical vagus nerve. It has been demonstrated that VNS is effective in reducing seizure frequency over than 50% in approximately 50% of patients, but better responders patients characteristics is not clear. It is important to identify who will be the best responders to guide an early indication and reduce costs in the treatment. OBJECTIVE: The objective of the present study was to evaluate the response rate of adults and children implanted with VNS and identify variables for better response to VNS therapy. METHODOLOGY: Cross-sectional study with donated data of medically intractable epilepsy patients and in use of VNS therapy from 6 epilepsy centers in Brazil. Were excluded from this study patients with less than 6 months of VNS implant. RESULTS: Data from 191 patients (3 to 69 years), 54,4% male and 45,55% female, was collected from patients charts. We observed 127 (66,4%) with respond to VNS therapy which 10 patients (5,2%) were seizure free. Mental disability was seen in 115 (60,4%) patients, 22 (11,5%) had Lennox Gastaut syndrome. The majority of patients, 177 (92,7%) had electroencephalogram (EEG) abnormalities in which 114 (60,9%) had focal activity and 79 (41,6%) generalized activity. Regarding seizure characterization it was observed 100 patients (51%) with focal seizure, 51 (25.5%) with generalized seizures and 40 (23.4%) with multiple seizure patterns. The statistically significant variables for better response were: female gender (p=0,014), absence of mental disability (p=0,05), absence of Lennox Gastaut syndrome (p=0,012), focal activity in the EEG (p=0,005), focal seizure (p=0,003) and absence of prior neurosurgery (p=0,008). CONCLUSION: VNS is a well-tolerated and effective adjuvant therapy in patients with intractable epilepsy. Notably, female patients, presence of isolated focal epileptiform discharges and focal seizures maybe better features associated with good response to VNS in Brazilian population. The absence of Lennox Gastaut syndrome, absence of mental disability and absence of prior neurosurgery was correlated with good response