[Large kissing aneurysms of the middle cerebral artery: a case report--classification of kissing aneurysms].

We report a rare case of kissing aneurysms located at the middle cerebral artery. A 69-year-old man had a severe subarachnoid hemorrhage associated with intracerebral hematoma (Hunt and Hess grade 5, WFNS grade V). Angiography revealed two large-sized aneurysms of the middle cerebral artery, and these aneurysms were seen as contacting each other. Both aneurysms were adherent, with fibrous tissue at each dome site. Neck clipping was performed. The difficulty of neck clipping with kissing aneurysms is dependent upon the relationship between the two aneurysmal necks. We classify kissing aneurysms into two groups based on the location of the aneurysmal neck (Type 1: each aneurysmal neck is located on the same parent artery. Type 2: each aneurysmal neck is located on different parent arteries.). In Type 1, preoperative diagnosis of kissing aneurysms is difficult and premature rupture during the application of a clip occurs frequently. Therefore, careful and meticulous dissection between the aneurysms is especially required. On the other hand, with Type 2 cases, large aneurysms (> 15 mm) are seen much more frequently than in cases of Type 1. Our classification of kissing aneurysms is useful to assess the difficulty of neck clipping for these aneurysms.