Composition of the Endolymphatic Sac Luminal Fluid in a Patient with Mondini Dysplasia

Abstract

Objectives We determined the chemical composition of the human endolymphatic sac luminal fluid in a patient with Mondini dysplasia. Methods Four milliliters of endolymphatic sac luminal fluid was sampled in a 41-year-old patient who presented with bilateral Mondini dysplasia and underwent auditory brain stem implantation. Ion and protein concentrations, as well as the osmolarity of the fluid, were analyzed by means of biochemical automated procedures. Results The sodium, potassium, and protein concentrations and the osmolarity of the sample were 87 mmol/L, 24 mmol/L, 33.5 g/L, and 258 mOsm/L, respectively. Conclusions The composition of the endolymphatic sac luminal fluid found in our patient was similar to that determined in guinea pigs under physiological conditions, and very different from the usual composition of the cochleovestibular endolymph. Contamination of the cochleovestibular endolymphatic compartment by this sodium-rich, potassium-poor, and hypo-osmotic fluid might impair cochleovestibular function by altering the chemical composition of the cochleovestibular endolymph.