Transcranial electrical stimulation （TCES） is effective in treating many conditions, but it has not been possible to accurately forecast current density within the complex anatomy of a given subject＇s head. We soug...Transcranial electrical stimulation （TCES） is effective in treating many conditions, but it has not been possible to accurately forecast current density within the complex anatomy of a given subject＇s head. We sought to predict and verify TCES current densities and determine the variability of these current distributions in patient-specific models based on magnetic resonance imaging （MRI） data. Two experiments were performed. The first experiment estimated conductivity from MRIs and compared the current density results against actual measurements from the scalp surface of 3 subjects. In the second experiment, virtual electrodes were placed on the scalps of 18 subjects to model simulated current densities with 2 mA of virtually applied stimulation. This procedure was repeated for 4 electrode locations. Current densities were then calculated for 75 brain regions. Comparison of modeled and measured external current in experiment 1 yielded a correlation of r = .93. In experiment 2, modeled individual differences were greatest near the electrodes （ten-fold differences were common）, but simulated current was found in all regions of the brain. Sites that were distant from the electrodes （e.g. hypothalamus） typically showed two- fold individual differences. MRI-based modeling can effectively predict current densities in individual brains. Significant variation occurs between subjects with the same applied electrode configuration. Individualized MRI- based modeling should be considered in place of the 10-20 system when accurate TCES is needed.展开更多
Near zero stroke rates can be achieved in carotid endarterectomy （CEA） surgery with selective shunting and electrophysiological neuromonitoring.though false negative rates as high as 40% have been reported.We sought...Near zero stroke rates can be achieved in carotid endarterectomy （CEA） surgery with selective shunting and electrophysiological neuromonitoring.though false negative rates as high as 40% have been reported.We sought to determine if improved training for interpretation of the monitoring signals can advance the efficacy of selective shunting with electrophysiological monitoring across multiple centers,and determine if other factors could contribute to the differences in reports.Processed and raw beta band （12.5-30 Hz） electroencephalogram （EEG） and median and tibial nerve somatosensory evoked potentials （SSEP） were monitored in 668 CEA cases at six surgical centers.A decrease in amplitude of 50% or more in any EEG or SSEP channel was the criteria for shunting or initiating a neuroprotective protocol.A reduction of 50% or greater in the beta band of the EEG or amplitude of the SSEP was observed in 150 cases.No patient showed signs of a cerebral infarct after surgery.Selective shunting based on EEG and SSEP monitoring can reduce CEA intraoperative stroke rate to a near zero level if trained personnel adopted standardized protocols.We also found that the rapid administration of a protective stroke protocol by attending anesthesiologists was an important aspect of this success rate.展开更多
基金supported by the Sutter Institute for Medical Researchthe Aaken Research Institute
文摘Transcranial electrical stimulation （TCES） is effective in treating many conditions, but it has not been possible to accurately forecast current density within the complex anatomy of a given subject＇s head. We sought to predict and verify TCES current densities and determine the variability of these current distributions in patient-specific models based on magnetic resonance imaging （MRI） data. Two experiments were performed. The first experiment estimated conductivity from MRIs and compared the current density results against actual measurements from the scalp surface of 3 subjects. In the second experiment, virtual electrodes were placed on the scalps of 18 subjects to model simulated current densities with 2 mA of virtually applied stimulation. This procedure was repeated for 4 electrode locations. Current densities were then calculated for 75 brain regions. Comparison of modeled and measured external current in experiment 1 yielded a correlation of r = .93. In experiment 2, modeled individual differences were greatest near the electrodes （ten-fold differences were common）, but simulated current was found in all regions of the brain. Sites that were distant from the electrodes （e.g. hypothalamus） typically showed two- fold individual differences. MRI-based modeling can effectively predict current densities in individual brains. Significant variation occurs between subjects with the same applied electrode configuration. Individualized MRI- based modeling should be considered in place of the 10-20 system when accurate TCES is needed.
文摘Near zero stroke rates can be achieved in carotid endarterectomy （CEA） surgery with selective shunting and electrophysiological neuromonitoring.though false negative rates as high as 40% have been reported.We sought to determine if improved training for interpretation of the monitoring signals can advance the efficacy of selective shunting with electrophysiological monitoring across multiple centers,and determine if other factors could contribute to the differences in reports.Processed and raw beta band （12.5-30 Hz） electroencephalogram （EEG） and median and tibial nerve somatosensory evoked potentials （SSEP） were monitored in 668 CEA cases at six surgical centers.A decrease in amplitude of 50% or more in any EEG or SSEP channel was the criteria for shunting or initiating a neuroprotective protocol.A reduction of 50% or greater in the beta band of the EEG or amplitude of the SSEP was observed in 150 cases.No patient showed signs of a cerebral infarct after surgery.Selective shunting based on EEG and SSEP monitoring can reduce CEA intraoperative stroke rate to a near zero level if trained personnel adopted standardized protocols.We also found that the rapid administration of a protective stroke protocol by attending anesthesiologists was an important aspect of this success rate.
