The waffle-cone technique may enhance the possibilities of the endovascular treatment of these complex aneurysms. Due to the high rate of recanalization requiring endovascular retreatment, stringent angiographic and clinical follow-up is warranted.

Five patients, who developed progressive neurological deterioration within hours due to subarachnoid haemorrhage (SAH) are reported. The computertomographic (CT) appearance of a noncommunicating hydrocephalus (n.c.h.) was a unique feature in 4 cases. CT during the early phase of neurological deterioration after SAH permits the differentiation between an ischaemic, an oedematous, a haemorrhagic-compressive lesion and an increase in intracranial pressure (ICP) due to n.c.h.