Medical fitness examination of commercial pilots: new criteria for evaluation of vestibular tests.

In medical fitness examinations of commercial pilots, extensive vestibular investigations should be conducted. In particular, the pendular test, as a weak rotational stimulation method, can disclose central vestibular disorders. Thus, the central nystagmus tracing can be considered as a sign of irritation of vestibular centers, most frequently as a consequence of head trauma, a finding that may influence the decision in the enlistment of the pilot. In contrast, a small nystagmus amplitude tracing is observed in cases of insufficient blood supply, occurring mostly in elderly persons. Therefore, this finding helps to demonstrate and treat arteriosclerotic dizziness in elderly pilots. Cervical-nystagmus--elicited by neck-torsion while keeping the labyrinth fixed at rest--is an objective demonstration of a cervical-spine-syndrome. Aimed therapy, namely chiropractic manipulation, may help the pilot become fit to fly again. Further processing of the data from the vestibular investigations by means of a computer and plotting can provide the so-called cumulative eye position. This enables one to evaluate the compensation capacity which is a measure of the intensity of the vestibular response, important in the assessment of normal function of the vestibular system.