Two Cases of Subarachnoid Hemorrhage with Microaneurysmal Changes and Spontaneous Disappearance in the Basilar Artery.

A 79-year-old woman presented at our hospital with sudden headache and vomiting. Computed tomography revealed diffuse subarachnoid hemorrhage. Although digital subtraction angiography (DSA) performed on admission and on the following day revealed no vascular abnormalities, DSA on Day 22 revealed microaneurysmal changes in the dorsal basilar artery. However, the aneurysmal changes gradually became smaller during follow-up, and DSA on Day 73 revealed complete disappearance. A 53-year-old man also presented to our hospital with sudden headache and vomiting. Computed tomography revealed perimesencephalic subarachnoid hemorrhage. DSA on Days 9 and 16 revealed microaneurysmal changes in the dorsal basilar artery. Conservative treatment was continued, and DSA on Day 42 revealed spontaneous disappearance of the lesion. It has been reported that basilar artery perforating aneurysms cause angiogram-negative subarachnoid hemorrhage, which disappears spontaneously. The fact that lesions previously reported as basilar artery perforating aneurysms may include cases of acute dissection of the main trunk or perforating branches of the basilar artery implies that surgical or endovascular treatment may worsen the condition. Therefore, conservative treatment may be an important option.