Algorithm for evaluation and disposition of a single episode of loss of consciousness

The presentation of a solitary episode of loss of consciousness in aviators presents a challenge to the aerospace physician, who has certain vital obligations to fulfill: to find the cause of loss of consciousness; to find the likely pathology; and to make a decision about fitness for flying duties. Evaluation of loss of consciousness focuses on three systems: the cardiovascular system; the central nervous system; and the mental functioning. If an abnormality is found in any of the three systems, specific evaluation and treatment is warranted. However, if no pathophysiology is found, aeromedical disposition of such a case is determined by three questions. Is it a case of syncope? If it is indeed syncope, is it vaso-vagal syncope (VVS) or something more sinister? If it is VVS, is it likely to recur in flight? VVS may be a one-time occurrence due to sudden cessation of blood supply to the brain and is the most common cause of loss of consciousness. Correct diagnosis of VVS, while a daunting task, can be made possible by proper attention to history, clinical examination, and relevant clinical investigations. Once diagnosed, a single episode of VVS is considered compatible with flying duties. Two cases of loss of consciousness in different settings have been presented to highlight the dilemmas faced by an aerospace physician. An algorithm for evaluation of cases with a solitary episode of loss of consciousness is also suggested.