Spontaneous and ICP controlled SAH. Scheme depicts start (down arrow) and stop (red X) procedures of shunt-induced SAH. (A) ‘Spontaneous SAH’. The shunt is closed after ICP either reached a plateau (10 s; short horizontal arrow) or started to decrease (30 s; long horizontal arrow). (B) ‘Controlled SAH’. The shunt is closed at any level prior to development of ICP plateau.