Quantification of spindles in comatose patients.

Quantification of spindles in comatose patients is easily possible by measurement of ERD (event-related desynchronization). ERD can either be positive (e.g., alpha blocking or alpha attenuation) or negative (spindle activity within the alpha band) or can be missing. Follow-up measurements in a comatose patient demonstrate the different time courses of VEP (visual evoked potential) and ERD during clinical recovery. That means that VEP and ERD are generated by different neuronal systems as reactions to the same external stimulus.