Early diagnosis of vertebral dissecting aneurysm: a magnetic resonance angiography study.

We report a patient with dissecting aneurysm who presented with a sudden severe headache without any neurological symptoms. Although brain computed tomography (CT) scan and MRI were negative, magnetic resonance angiography (MRA) showed a pseudocavity in a segment of the left vertebral artery. In addition, the dissecting wall of the left vertebral artery was clearly visualized in the original images of MRA. Our findings indicate that brain CT, MRI or cerebral angiography alone are sometimes inadequate for the diagnosis of vertebral dissecting aneurysm, and that MRA and its original images are necessary to establish the correct diagnosis.