Crista ampullaris evoked response by endolymph volumetric change

• Grant number: 14/21938-0
• Support Opportunities: Scholarships in Brazil - Scientific Initiation
• Start date: February 01, 2015
• End date: January 31, 2016
• 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 vestibulo-ocular reflex (VOR) is a vestibular source reflex most commonly used for diagnosis and follow up of vestibular disorders that result in body imbalance. Perhaps the most frequently used assessment method for measuring and clinical follow up of the VOR is the bithermal caloric test of the external ear. The heat transmission by temporal bone causes volumetric expansion of the endolymph, while the cooling generates its contraction. The temperature gradients triggers low frequency shifts of the ampullary cupula present in the semicircular canals, which physiological properties follows the model of the pendulum. We can imply that the direction of the displacement caused by temperature variation will be consistent with the resulting vector of expansion or shrinkage of the endolymph. Thus, the responses elicited in VOR are reversed during cooling or heating, since crista sensory cells have polarization response. The objective of this research project is to evaluate the vestibular responses evoked by seven degrees higher or lower shifts in the body temperature applied through external auditory canal in the same subject bithermal caloric test. The purpose is to verify if the temperature shifts really induces or not the displacement of the ampullary cupula. (AU)