Our recent publication: “Endolymph movement visualized with light sheet fluorescence microscopy in an acute hydrops model“, used our Light Sheet Fluorescence Microscope to suggest that at some stage during endolymphatic hydrops, some mechanism ‘triggers’ the rapid uptake of endolymph into the endolymphatic sac, and most likely the utricle and semicircular canals. This mechanism may explain the sudden vertigo attacks observed in Meniere’s.
Moreover, the result highlight that there is an apparent uptake of endolymph into the micro-vasculature surrounding the endolymphatic duct. This uptake appears (at first glance) to be a ‘paracellular’ uptake (i.e. the endolymph fluid flows directly into the microvasculature, rather than flowing through cells).
Figure from Brown et al., 2016 showing uptake of fluorescent fluid marker into the microcanals surrounding the endolymphatic duct.
This is a remarkable possibility, because it suggests that the endolymphatic compartment isn’t actually a ‘closed’ compartment as it is typically viewed, but rather this pathway normally allows endolymph to ‘leak’ out into either trabeculated bone or blood. Interestingly, there was a series of histological studies performed by Prof. Fred Linthicium between 2010-2014, where they noted the abnormal morphology of the microcanals surrounding the endolymphatic compartment in Meniere’s sufferers as compared to non-Meniere’s ears. Currently, the link between these microcanals and Meniere’s disease is unclear, although their apparent involvement in endolymph volume regulation makes them prime candidates for further study and pharmacological targeting.
Figure from Linthicium et al., 2014, showing a 3D reconstruction of the microcanals in human temporal bones. In previous studies by this research group, they have noted that the canals appear to be decellularized in Meniere’s sufferers.