- No loss of consciousness after the hemorrhage with WFNS grade 1 or 2 on admission in combination with a perimesencephalic hemorrhage Definition: on CT examination presence of hyperdensities exclusively in the basal cisterns maximal extending to the proximal part of the Sylvian fissure or posterior part of the interhemispheric fissure, without evidence for intracerebral or intraventricular haemorrhage (except slight sedimentation)