Dominant frequency uncertainty analysis of EEG alpha activity in pilots with transient ischemic attacks.

Objective. To study the characteristics of EEG after transient ischemic attack and to offer reference for screening procedure of aircrew and astronaut selection. Method. The dominant frequency uncertainty of alpha band EEG in 12 pilots (males; age 30 +/- 5) with transient ischemic episodes in middle cerebral artery (MCA) territories and in 20 normal healthy pilots was analyzed with frequency-fluctuation analysis. Result. The dominant probability of the main frequency coinciding with sites affected by transient ischemic attack (TIA) in patient pilots was higher than that in healthy pilots (P<0.01), and the dominant probability ratio logarithmic index I >or= 0 in all patient pilots with normal EEG, but I<0 in all healthy pilots. It was also found that not only I >or= 0, but the second component shifted to lower frequency (8 Hz) in patients with slight focal EEG alterations, i.e. slowing of frequency. The relative entropy values (percentage) were decreased significantly in pilots with TIA as compared with healthy pilots (P<0.05). Conclusion. The dominant frequency uncertainty analysis of alpha band showed clear superiority of computerized evaluation over routine visual assessment for the diagnosis of minor cerebral ischemia. It offers not only a possibility of studying pathophysiological functional parameter, but also the reference for screening procedure in aircrew and astronaut selection.