DISCHARGE-1 is a prospective, clinical multicenter trial on treatment stratification to determine how distinct patterns of tsunami-like electrical brain waves, called spreading depolarization (SD), correlate with evolution of delayed tissue damage after aSAH as assessed by serial magnetic resonance imaging scans. For the development of treatment and assessment of interventions in stroke, global ischemia and brain trauma, recording of SD might prove to be as significant as were similar electrophysiological tools in the past for the fields of epilepsy or cardiology since the culprit becomes visible. E.g., SD could help us as an on-line brain injury biomarker to determine optimal ranges for cerebral perfusion pressure, systemic glucose or temperature in intensive care patients. Moreover, blockade of SDs or normalization of their neuro-vascular responses are novel targets for treatment.