Influence of endolymph inertial chain direction on vestibular evoked response by stimulus in rotational stimulus on computed rotatory chair

• Grant number: 13/22037-3
• Support Opportunities: Scholarships in Brazil - Scientific Initiation
• Start date: January 01, 2014
• End date: December 31, 2014
• Field of knowledge: Health Sciences - Medicine - Surgery
• Principal Investigator: Jeanne da Rosa Oiticica Ramalho
• Grantee: Luiz Felipe Moreira Bittar
• Host Institution: Hospital das Clínicas da Faculdade de Medicina da USP (HCFMUSP). Secretaria da Saúde (São Paulo - Estado). São Paulo , SP, Brazil

Abstract

The vestibule-ocular reflex (VOR) is the most widely used reflex of vestibular origin for the diagnosis and follow up of vestibular diseases that result in body imbalance. One of the main used evaluation method to measure and clinical follow up VOR is the sinusoidal stimulus in the computed rotary chair. The stimulus generated by the rotation of the chair triggers responses in the semicircular canals, whose physiological properties follow the model of the pendulum. The displacement of the cupulo-endolymphatic system during head rotations, for the same angle of stimulation, is proportional to the speed of the head and not the acceleration. In a previous study, we found that, for the same plane of rotation the weight variation of the system does not influence the vestibular response in the Sinusoidal Harmonic Test (SHT) in the computed rotating chair for the same individual - when stimulated by the same rotation frequency and highest speed. According to physical laws, the deflection of the pendulum must obey the laws governing fluid and harmonic oscillators, both the anatomical structure of the side channel, as the polarization of hair cells determine different responses in different directions due to the endolymph. The objective of this undergraduate research project is to build a method of evaluation and comparison of vestibular responses evoked by the type PSH for the same individual, varying the stimulus plan ampullary crest. The purpose is to verify the positioning of the head influences the gain of nystagmus response to the same frequency and the same final rotational speed. (AU)