All data, either from the prospective or the retrospective cohort, will be entered in an electronic Case Report Form (eCRF) by individual investigators at each center. Demographic and clinical variables will be obtained from all available medical records and by in-person interview, if possible. Clinical variables and biomarkers as neuron-specific enolase (highest recorded value), electroencephalogram, somatosensory evoked potentials (N20 component with median nerve stimulation) and brain imaging, are encouraging to be collected in the prospective cohort, if available. VF recordings prior to the first DC shock will be scanned using commercial desktop scanners (600 dots per inch) and uploaded to the eCRF. Data consistency and quality will be weekly monitored by one of the investigators (M.M.B).