Subarachnoid hemorrhage due to middle cerebral artery dissection mimicking aneurysm - Case report.

We report a case of subarachnoid hemorrhage due to a dissecting middle cerebral artery that was misdiagnosed as saccular aneurysm. A 74-years old female patient presented with headache and neck pain for 4 days. Brain magnetic resonance imaging revealed subarachnoid hemorrhage in both Sylvian fissures. A ruptured left middle cerebral artery bifurcation saccular aneurysm and unruptured basilar tip aneurysm were diagnosed. The patient was treated surgically using the transsylvian approach. However, no saccular aneurysm was found during the surgery, and the diagnosis was corrected for middle cerebral artery dissection. We treated the dissected segment of the middle cerebral artery and performed clip reinforcement. We experienced a case of middle cerebral artery dissection with no neurological deficit, which was misdiagnosed as a saccular aneurysm. If the stump of the occlusion is conical, dissection should be suspected. High-resolution magnetic resonance imaging and angiography should be performed for a differential diagnosis if dissection is suspected.