Arnold-Chiari malformation type I in military conscripts: symptoms and effects on service fitness.

Arnold-Chiari I malformation (Chiari I) is a congenital disorder characterized by caudal herniation of cerebellar tonsils through the foramen magnum. The symptoms and signs include headaches precipitated by coughing or exertion, dizziness, visual or oculomotor symptoms, dysphagia, trunk or extremity dysesthesias, ataxia, and drop attacks indicating cerebellar or cervical cord lesion. The symptoms may be provoked by increased intracranial pressure. The mean age of onset of symptoms is 25 years; consequently, previously unidentified Chiari I malformations occur in military personnel. Chiari I is associated with deaths following minor trauma, with acute respiratory failure, and with transient quadriparesis occurring in contact sports. Furthermore, Chiari I symptoms may be aggravated by chiropractic manipulation. This report describes symptoms and signs of Chiari I in four military conscripts in the Finnish Defense Forces. It is important to detect Chiari I in military personnel to establish appropriate service fitness and safety for these patients.