Baclofen affects the semicircular canals but not the otoliths in humans

Abstract

Conclusion: This study showed that GABA_B agonist baclofen (10 mg) affects the semicircular canals (SCCs), both centrally and peripherally, but does not influence the otolithic function. Objectives: The aim of the study was to identify the effects of baclofen on the complete vestibular system, i.e. semicircular canals, saccules and utricles. Methods: The study had a double-blind, placebo-controlled, repeated measures design and was conducted on healthy male volunteers. With electronystagmography (ENG), the SCC function was evaluated, whereas utricular function was determined by means of unilateral centrifugation (UC). Cervical vestibular evoked myogenic potentials (cVEMPs) tested saccular integrity. Results: Baclofen caused a significant increase of the vestibulo-ocular reflex (VOR) phase and a significant decrease of the total caloric response (TCR), both measured during ENG. The drug also decreased the maximal contribution of the SCCs to ocular counter-rolling (OCR) evaluated during UC. No effects on saccules and utricules were observed.

Keywords::

• Space motion sickness
• SMS countermeasures
• GABAB agonist
• vestibular system
• velocity storage

Acknowledgments

This research was funded by ESA and PRODEX. We are very grateful to the volunteers who participated in the study.

Declaration of interest: The authors report no conflicts of interest. The authors alone are responsible for the content and writing of the paper.