[The usefulness of 3D-CTA for the diagnosis of a ruptured aneurysm at the origin of the duplicated middle cerebral artery: case report].

Duplication of the middle cerebral artery is known as a rare anomalous vessel arising from the internal carotid artery and an aneurysm at the origin of the duplicated middle cerebral artery is very rare. We presented a case of ruptured aneurysm at the origin of the duplicated middle cerebral artery and discussed the usefulness of 3D-CTA (three-dimensional computed tomographic angiography) for its diagnosis. A 34-year-old female suffered from severe headache and was admitted to our hospital. CT scan revealed diffuse subarachnoid hemorrhage and angiography revealed duplication of the right middle cerebral artery and dilatation at its origin. We could not identify it as an aneurysm by angiography, so we performed 3D-CTA. 3D-CTA was able to demonstrate clearly the aneurysm at the origin of the duplicated middle cerebral artery and we performed neck clipping of the ruptured aneurysm. To our knowledge, previously there have been only 14 cases which reported such an aneurysm at the origin of a duplicated middle cerebral artery. We reviewed the 15 cases including ours and found that, in 4 cases, the aneurysm could not be detected by the initial angiography. We suspected that most of these aneurysms were small, so the detection of the aneurysms by angiography was difficult. We conclude that 3D-CTA is useful for diagnosing aneurysms at the origin of the duplicated middle cerebral artery even when thy can't be detected by angiography.