Secondary Endolymphatic Hydrops (SEH)
Endolymphatic hydrops is a disorder of the inner ear and can affect the endolymphatic fluid of the cochlea, the vestibular apparatus, or both. Although its underlying cause and natural history are unknown, it is believed to result from abnormalities in the quantity, composition, and/or pressure of the endolymph (the fluid within the endolymphatic sac, a compartment of the inner ear).
In a normal inner ear, the endolymph is maintained at a constant volume and with specific concentrations of sodium, potassium, chloride, and other electrolytes. This fluid bathes the sensory cells of the inner ear and allows them to function normally. In an inner ear affected by hydrops, these fluid-system controls are believed to be lost or damaged. This may cause the volume and concentration of the endolymph to fluctuate in response to changes in the body’s circulatory fluids and electrolytes.