Ruptured cerebral aneurysm not detected by magnetic resonance angiography in juvenile autosomal dominant polycystic kidney

Recently, it has been reported that magnetic resonance angiography (MRA) is useful for screening and following up cerebral aneurysms in patients with autosomal dominant polycystic kidney disease (ADPKD). However, a patient wa s encountered with a ruptured cerebral aneurysm that was not detected by ro utine MRA. The patient, a 29-year-old man with ADPKD, was followed up at ou r hospital for more than 5 years. Ten months after an MRA examination, he s uddenly developed severe headache. Brain computed tomography revealed subar achnoid hemorrhage. Digital subtraction angiography detected an aneurysm wi th a diameter of approximately 2 mm in the anterior communicating artery. C lipping of the aneurysm was immediately performed and he recovered without sequela after operation. Magnetic resonance angiography is useful to detect cerebral aneurysms, but it can not detect aneurysms measuring less than 4 mm.