Spectra of intracranial diseases in Chinese military pilots (cadets) unqualified for transfer to pilot modified high performance aircraft.

Background: With very high mortality and disability rates, cerebrovascular diseases and intracranial tumors severely threaten the health and fighting strength of flying personnel, requiring great concern and intensive screening in clinic, early warning in an early and accurate manner and early intervention of diseases possibly resulting in inflight incapacitation are key emphases of aeromedical support in clinic.

Aim: To probe into the spectra of intracranial diseases, flight factors and medical imaging characteristics of military pilots (cadets) in the physical examination for transfer to pilot modified high performance aircraft, thus rendering theoretical references for clinical aeromedical support of pilots.

Methods: A total of 554 military pilots (cadets) undergoing physical examination for transfer to pilot modified high performance aircraft from December 2020 to April 2024 in a military medical center were enrolled in this study. Then, a retrospective study was carried out on intracranial disease spectra and head magnetic resonance imaging (MRI) data of 36 pilots (cadets) who were unqualified for transfer to pilot modified high performance aircraft. Besides, a descriptive statistical analysis was conducted on the clinical data, age, fighter type and head MRI data of such pilots (cadets).

Results: Abnormal head images were found in 36 out of 554 pilots (cadets) participating in the physical examination for transfer to pilot modified high performance aircraft, including arachnoid cyst in 17 (3.1%) military pilots (cadets), suspected very small aneurysm in 11 (2.0%), cavernous hemangioma in 4 (0.7%), vascular malformation in 2 (0.4%), and pituitary tumor in 3 (0.5%, one of which developed cavernous hemangioma simultaneously). Among the 17 pilots (cadets) with arachnoid cyst, 4 were identified as unqualified for transfer to pilot modified high performance aircraft because the marginal brain tissues were compressed by the cyst > 6 cm in length and diameter. The 11 pilots (cadets) with suspected very small aneurysms identified by 3.0T MRI consisted of 6 diagnosed with conus arteriosus by digital subtraction angiography and qualified for transfer to pilot modified high performance aircraft, and 5 identified as very small intracranial aneurysms with diameter < 3 mm and unqualified for transfer to pilot modified high performance aircraft. No symptoms and signs were observed in the 4 military pilots (cadets) with cavernous hemangioma, and the results of MRI revealed bleeding. The 1 of the 4 had the lesion located in pons and developed Rathke cyst in pituitary gland at the same time, and unqualified for transfer to pilot modified high performance aircraft. The 2 of the 4 were unqualified for flying, and 2 transferred to air combat service division. The 2 pilots (cadets) with vascular malformation were identified as unqualified for transfer to pilot modified high performance aircraft. Among the 3 pilots (cadets) with pituitary tumor, one pilot cadet was identified as unqualified for flying since the tumor compressed the optic chiasma, one had cavernous hemangioma in pons in the meantime and transferred to air combat service division, and one was diagnosed with nonfunctional microadenoma and qualified for transfer to pilot modified high performance aircraft.

Conclusion: High-resolution head MRI examination is of great significance for screening and detecting cerebrovascular diseases and intracranial tumors in military flying personnel, and attention should be paid to its clinical application to physical examination for transfer to pilot modified high performance aircraft.