Ruptured middle cerebral artery bifurcation aneurysm manifesting as caudate head hemorrhage extending into the ventricle: case report and literature review

Ruptured intracranial aneurysm usually manifests as subarachnoid hemorrhage (SAH) or SAH with hematoma. Aneurysms that only present with intracerebral hemorrhage or intraventricular hemorrhage are mostly confined to the distal artery. It is very rare that ruptured middle cerebral artery bifurcation aneurysms manifest signs of caudate head hemorrhage extending into the cerebral ventricle. One such case was reported in this paper. A 48-year-old man experienced an abrupt episode of headache and dizziness. Computed tomography (CT) showed caudate head hemorrhage that extended into the cerebral ventricle. CT angiography (CTA) and digital subtraction angiography (DSA) revealed ruptured middle cerebral artery bifurcation aneurysms to be the cause of the intracranial hemorrhage. A favorable outcome was achieved after surgical clipping. During surgery, this aneurysm was located in a deep region adjacent to the insular lobe surface and close to the caudate head. This ruptured aneurysm caused caudate head hemorrhage extending into the cerebral ventricular system. Upon a retrospective review of the literature, we concluded that this unique bleeding pattern was due to the projection of the aneurysm; this aneurysm was uniquely anteriorly projected and attached to caudate head. When the aneurysm ruptured, blood extended into the cerebral ventricular system through the caudate head. Thus, SAH was not present. These findings suggest that ruptured aneurysms originating from main branches of the cerebral artery in certain rare conditions, such as the middle cerebral artery bifurcation aneurysm in this case, could only manifest as an intracerebral hemorrhage extending into the ventricle. Attention should be paid to these rare cases, and CTA should be performed on a regular basis to avoid a misdiagnosis.