Videonistagmoscopia digital com lente de contato para identificação de movimentos oculares e apoio ao topodiagnóstico da vertigem posicional paroxística benigna

Abstract

Benign paroxysmal positional vertigo (BPPV) is characterized by vertigo crisis, triggered by sudden head position changes, associated with the appearance of paroxysmal positional nystagmus. The characterization of torsional nystagmus has fundamental importance while conducting a patient with BPPV, because it turns possible to identify the affected semicircular channel, as well as the physiopathological mechanism involved. However, the majority of existing videonystagmography devices are not capable of identifying these torsional movements with the required precision. This work aims to develop and test a method to model and identify torsional eye movements, when present. This new model uses a videonystagmograph prototype, comercial ophthalmic contact lens with geometric figures and a computer program, which was specially designed with this objective. Complementarily, a webapp program has also been created to support the topodiagnosis of the BPPV. Subjects with BPPV and without BPPV have been evaluated. The subjects have undergone the Dix-Hallpike maneuver, using the contact lens with geometrical figures on the left eye and the capture device. Among these evaluations, forty videos have been recorded (23 with counter-clockwise rotating movement phenomena, 10 clockwise and 7 videos with eye at rest). The extracted videos were analyzed with the developed software. The success rate in classifying the direction of the rotating movement (counter-clockwise or clockwise) and the resting position was evaluated. The accuracy of the software in correctly finding the geometric lines of the ophthalmic lens was also evaluated. Among the forty analyzed videos, the software had a success rate of 85% (70-94%) in identifying direction of movement or at rest; considering only the success rate in direction of movement, the total was 81% (64-93%). The accuracy in the measuring of the interest zone of the frames was 82,2% (81,5-82,8%) with p<0,05 significance level. Therefore, the new developed model should be able to have an important part on the topodiagnosis of the BPPV in the future, providing a more precise and effective therapeutic management to the patients with this disease.