Outcomes of Endolymphatic Shunt Surgery in Ménière's Disease Indicate Potential Contribution of Shear Stress Instead of Relieving the Endolymphatic Hydrops

Abstract

Believing that the attack of Meniere's Disease (MD) resulted from overpressure of the endolymphatic fluid, Georges Portmann introduced a surgery on the endolymphatic sac for the control of vertigo through releasing the endolymphatic hydrops in 1927. Since then, different types of ES surgery have been sued to treat MD all over the world for more than 80 years and the endolymphatic shunt surgery by inserting drainage tubing into the ES became a standard procedure in treating MD. However, this therapeutic theory was challenged by a specifically designed study performed in Denmark. A recent temporal bone study of MD patients who underwent surgery showed that endolymphatic sac surgery did not relieve hydrops in patients with MD but did relieve vertigo in some patients. In this review, we provided a novel hypothesis on the endolymphatic shunt surgery in MD, which is that potential shear stress induced by the endolymphatic shunt surgery in MD patients may modulate activities of the afferent system of the vestibular end organ, enhance plasticity of the vestibular system, and result in symmetric sensitivity in the vestibular system. TRPV may be involved in the molecular mechanism in endolymph cationic ion circulation affected by shear stress. Matrix maintenance in the vestibule may also be enhanced after shear stress. Shear stress-promoted differentiation of BMSC toward certain cell types may have beneficial effects on the vestibular system in MD.