Infected aneurysm of middle meningeal artery causing intracerebral hemorrhage: illustrative case.

backgroundMiddle meningeal artery (MMA) aneurysms are rare and typically associated with trauma. Nontraumatic MMA aneurysms are very rare, and their rupture can lead to intracranial hemorrhage. OBSERVATIONS: The authors present a case of a ruptured MMA aneurysm causing intracranial hemorrhage in the temporal lobe, for which immediate hematoma evacuation and aneurysm resection were performed. Pathological examination revealed severe inflammatory infiltration and destruction of the aneurysm wall, consistent with an infected aneurysm. Additionally, they conducted a systematic search and literature review of previously reported cases of nontraumatic MMA aneurysms to identify their characteristics. Data from 33 published cases were extracted and summarized. Nontraumatic MMA aneurysms are rare, with sporadic reports linking them to hemodynamic stress. There were only a few cases linked to infectious etiologies. In the illustrative case, inflammation from periodontal disease likely spread to the MMA, leading to aneurysm formation and rupture. This case underscores the potential for devastating outcomes in infected MMA aneurysms and highlights the need for prompt diagnosis and treatment. LESSONS: Although nontraumatic MMA aneurysms are extremely rare, their rupture necessitates immediate medical intervention due to the risk of fatal intracranial hemorrhage. https://thejns.org/doi/10.3171/CASE25214.