Chiari-I malformation in two fighter pilots.

This report describes two cases of Chiari Malformation Type I (Chiari-I) in fighter pilots of the Turkish Air Force. Chiari-I is a congenital malformation characterized by herniation of cerebellar tonsils through the foramen magnum. Patients have symptoms and signs related to dysfunction of the brainstem, spinal cord, and cerebellum. They generally are symptomatic in the earlier years of life. However, asymptomatic cases can eventually become symptomatic in later years. Symptoms can be provoked by increasing intracranial pressure (Valsalva or straining). We report on two pilots with Chiari-I malformation who had no symptoms or signs in their daily activities. Furthermore, these pilots had successfully completed physiological training, including centrifuge training, without any symptoms. However, they suffered from headache, neck spasms, and/or disequilibrium under +Gz during flight training sorties. The clinical presentation, diagnosis, treatment, possibility of acquired cases, and aeromedical disposition of Chiari malformations are discussed.