Head stabilization in peripheral vestibular syndromes.

In classical posturography the standing position has been evaluated by recording the postural sway on a force-plate and measuring some parameters such as surface and velocity (Platform or P-recording). The postural sway not only results in forces exerted on the support surface by the feet, but the head also participates in the movements of this postural sway. For recording of the head movements (H-recording), a lightbulb is placed on top of the head and the described light-path is recorded by a TV camera. Such an H-recording can be achieved simultaneously with the platform-recording. A comparative study indicates that, for some patients differences could be found between H- and P-recordings, for others not. The H-recording, in fact, gives information about the stabilization of the head, compared with the stability on the platform (P-recording). The importance of the information furnished by the double recording in Static Posturography type IV (SPGIV) can be deduced from the number of patients showing one or more differences between the types of recording. Nearly 70% showed a difference in at least one test. In fact, 55% showed it in two or more tests. In half of the tests, considered separately, a difference was noted. The differences observed provide complementary information in this combined recording. If the H-recording were to be used as a separate technique, it has to be born in mind that the results are certainly not always the same as when using P-recording, as in classical posturography.