Surgical Treatment of an Aneurysm in the Subacute Stage of Hemorrhagic Moyamoya Disease: Aneurysm Resection Combined With STA-MCA Bypass: A Case Report.

INTRODUCTION

There is no consensus on the optimal management of intracranial aneurysms in patients with moyamoya disease. Here, we report a case of a patient in the subacute hemorrhagic stage of moyamoya disease with a presumed pseudoaneurysm detected on interval imaging, who was treated with aneurysm resection combined with superficial temporal artery (STA)-middle cerebral artery (MCA) bypass. This report illustrates a feasible individualized surgical approach for similar cases.

CASE REPORT: A 27-year-old male without a prior history of cerebrovascular disease was admitted for a right temporal intracerebral hemorrhage following external ventricular drainage. Initial computed tomography angiography (CTA) at admission showed no aneurysm. One week later, follow-up CTA revealed a newly developed 10 × 9 mm aneurysm in the right MCA region. Subsequent digital subtraction angiography (DSA) demonstrated occlusion of the right MCA M1 segment with the development of characteristic moyamoya collateral networks. The patient underwent microsurgical resection of the aneurysmal lesion, combined with a right STA-MCA bypass. Postoperative imaging demonstrated complete obliteration of the aneurysm, patency of the bypass, and a reduction in moyamoya collateral vessels. Histopathological examination revealed a red blood cell clot surrounded by fibrous connective tissue without definitive evidence of a preserved arterial wall, consistent with a presumed pseudoaneurysm. The patient recovered well, with improved neurological function on follow-up imaging.

CONCLUSIONS

In patients with moyamoya disease, a peripheral aneurysmal lesion may become detectable on interval imaging after an initially negative CTA and may represent an unstable hemorrhage-related vascular lesion. In carefully selected cases, lesion resection combined with STA-MCA bypass during the subacute phase may be a feasible individualized treatment strategy, particularly when direct lesion treatment and hemodynamic revascularization are both required. However, longer clinical and imaging follow-up is needed before any firm conclusions can be drawn regarding outcome improvement, or prevention of rebleeding.