The Permeability of the Blood Perilymph Barrier in Meniere's Disease: An Application of Dynamic Contrast-Enhanced MRI

Abstract

Ménière’s disease (MD) is a debilitating disease that is characterised by episodic vertigo attacks and accompanying fluctuating hearing symptoms. It is thought that autoimmune and inflammatory mechanisms may be involved in the development of this condition with evidence of elevated systemic inflammatory markers and association between the MD population and other autoimmune diseases. However, this theory is still debated and there is an overall lack of a centralised theorem to explain the mechanisms of MD. Therefore, it is important to investigate MD to elucidate its mechanisms and allow development of more effective treatments. Dynamic contrast-enhanced magnetic resonance imaging (DCE-MRI) is a perfusion MRI technique that has been used to quantitatively analyse various tumours, vascular networks, and inflammation. The use of pharmacokinetic models to quantitatively analyse the permeability of the bloodperilymph barriers (BPB) of the inner ear provides a surrogate measure of inflammation. As previous studies have revealed the utility of DCE-MRI in monitoring inflammation, this study aims to apply DCEMRI techniques to the human inner ear and investigate any potential differences in the permeability of the blood-perilymph barriers between non-MD and MD participants. Five non-MD (controls), eleven unilateral MD, and five bilateral MD participants were recruited for this study. The inner ears of each participant were split into control, unilateral unaffected, unilateral affected, and bilaterally affected ears. This was further segregated into recently diagnosed and longstanding MD participants. The cochlea, semi-circular canals, vestibule, endolymphatic duct and sac, and the internal auditory meatus are the regions of interest (ROI) segmented and analysed. The twocompartment model was used to estimate the parameter Ktrans which reflects the permeability of the BPB in these ROIs. This study revealed small but not significant differences in Ktrans, implying there is no difference in BPB permeability between groups. However, trends were observed in most ROI indicating higher permeability in bilateral MD and unilateral MD ears compared with controls. Additionally, the longstanding unilateral ears have greater permeability compared with their recently-diagnosed longstanding unilateral ears have greater permeability compared with their recently-diagnosed counterparts, and the opposite is shown in bilateral ears. Further validation of these findings is required.