Subarachnoid haemorrhage due to a lateral spinal artery aneurysm misdiagnosed as a posterior inferior cerebellar artery aneurysm: case report and literature review

A 61 year old man presenting with subarachnoid haemorrhage had a distal posterior inferior cerebellar artery (PICA) aneurysm diagnosed on the initial cerebral angiogram. However, a PICA aneurysm was not found during surgery. A follow-up, super-selective vertebral artery (VA) performed demonstrated a saccular aneurysm located on the lateral spinal artery (LSA). A right sub-occipital craniotomy was performed and the aneurysm arising was identified and obliterated with a small titanium clip. We describe the first example of an LSA aneurysm without occlusion or severe stenosis of the VA and PICA. This extremely rare lesion illustrates how knowledge of the angiographic features and super-selective cerebral angiography aids the precise diagnosis and the prevention of surgical complications.