[Posturography in unilateral peripheral vestibular deficiency].

A thorough study of vestibular function cannot be limited to the evaluation of VOR alone; it must also include the study of VSR which serves to control erect stance under both static and dynamic conditions. In unilateral peripheral vestibular lesions (UVL) computerized stabilometry makes it possible to perform a more accurate evaluation of the VSR complex through the quantification of "postural sway". Furthermore, the diagnostic potential of stabilometry can be further fine-tuned by introducing a sensitization test, in particular the head retroflexion (OCR) and head shaking (OC-HST) tests. In the present study 61 patients with UVL of various etiology (viral, toxic, vascular, idiopathic) were studied. Besides electrooculography, stabilometry was performed under base conditions (eyes open and closed) and with sensitizing tests (OCR, OC-HST). L and S were used as statokinesigram parameters while frequency and oscillation amplitude on the sagittal and transverse planes were used as stabilogram parameters. Of the 61 UVL patients, 47.5% showed VOR compensation while static postural alterations were found in 31.1%; this raised to 50.8% when the sensitization test was introduced. Apparently the compensation phenomena became manifest more quickly for VOR than for VSR. The introduction of the sensitization test, however, markedly reduced this variance. The two sensitization, maneuvers used provided quantitatively equivalent results although in the absence of reciprocal agreement. Agreement was not even recorded between stabilometric HST and the head shaking test. This confirms the presence of two different routes for VOR and VSR. Nonetheless, the introduction of the sensitization test made it possible to identify those "false negative" VSR cases which were really pathological, thus making it possible to properly identify the patients' condition and arrange for adequate treatment.