Evidence-based fitness-to-fly assessment for military aviators with untreated unruptured intracranial aneurysms: A 5-year retrospective at a single center.

The increasing detection of untreated unruptured intracranial aneurysms (UIAs) in military aviators poses a challenge for aeromedical clearance. This study aimed to introduce the fitness-to-fly criteria for military aviators with UIAs in our center and try to develop evidence-based aeromedical guidelines. We retrospectively reviewed active-duty military aviators diagnosed as UIAs by digital subtraction angiography (DSA) in a single center between 2019 and 2024. A multidisciplinary team performed comprehensive rupture risk stratification to determine patients for intervention. Afterwards, a dedicated aeromedical review board evaluated in-flight incapacitation risk and flight eligibility in the non-intervention group. Clinical features, aneurysm characteristics (size, location, morphology) and the final aeromedical disposition of these untreated cases were reported and analyzed. Twenty-three active-duty military aviators were diagnosed with UIAs by DSA at our institution over a 5-year period. Seven patients underwent intervention, whereas 16 were placed under conservative surveillance. All conservatively managed cases involved male aviators (mean age: 36 years) with small (< 5 mm), saccular UIAs, primarily in the paraclinoid internal carotid artery (ICA) segments (68.8%). None had hypertension or smoking history. The estimated annual rupture risk was < 0.5% for small paraclinoid aneurysms and nearly 0% for cavernous ICA aneurysms. Therefore, flight clearance was granted with operational restrictions for 11 pilots with small paraclinoid aneurysms (dual-seat or captaincy duties), while 5 with cavernous ICA aneurysms received unrestricted certification. Annual case-by-case inspections, along with MRA surveillance and psychological support, are required. This study represents one of the largest real-world practice of aeromedical certification for untreated UIAs. The annual rupture risk is extremely low (< 0.5%) for small saccular aneurysms located at the medial wall of the paraclinoid segment and nearly negligible for those in the cavernous segment of the ICA. Granting flight qualification to military personnel with such aneurysms is medically appropriate, provided enhanced surveillance protocols are implemented. Our protocol maximizes retention of experienced aircrew while ensuring operational safety.