Development of a Device for Stimulation of Optokinetic Nystagmus to Support Assessment and Rehabilitation of Postural Balance

Yohane Cristina Guimarães Jardim¹; Helton de Freitas Cota¹; Paulo Roberto Cetlin¹; Patrícia Cotta Mancini¹; Antônio Eustáquio de Melo Pertence¹

¹ UFMG

doi:10.20906/CPS/COB-2015-0262

Resumo

Vectoelectronystagmography consists in recording eye movements to assess the labyrinth and its relationship to the central nervous system. This test allows the identification of balance disorders and the side, type and extent of injury. The optokinetic test is a neuro-ophtalmologic tool that is used in vectoelectronystagmography battery to reveal evidence of central nervous system's dysfunction. Optokinetic nystagmus is a rhythmic eye movement, produced during the visualization of moving targets that fill at least 80% of the visual field. In normal individuals, the optokinetic nystagmus is symmetrical in both clockwise and counterclockwise directions of stimulation. There are several techniques for obtaining optokinetic nystagmus. In Brazil, partial visual field devices, including LED bars and small-motorized drums, are used to produce eye movements close to that of optokinetic nystagmus. However, due to the fact that only a small portion of the visual field is stimulated, such equipments produce nystagmus of small amplitude, but not the true optokinetic nystagmus. This study developed and tested a device for eliciting clockwise and counterclockwise optokinetic nystagmuses at varying speeds, from the projection of visual stimuli filling the visual field of the individual with white and black stripes. Nystagmuses were acquired using the LED bar and the developed device in the velocities of 20, 40 and 60 degrees per second, in both clockwise and counterclockwise directions. Paired t-test was used to compare nystagmuses acquired on both devices. Participants were 34 adults from both sexes, with no balance disorders, with mean age of 25.44 years. Results showed no difference between sexes. We observed higher mean amplitude nystagmus in all speeds and in both directions using the new equipment (p<0,05). It showed to be better appropriate to promote stimulation of full visual field, thus contributing to the identification of patients with central vestibular dysfunction in vectoelectronystagmography testing.

Palavras-chave: Optokinetic Nystagmus; Electronystagmography; Dizziness; Postural Balance; Photic Stimulation