Allan is 48 years old and works as a business executive. One day after returning from a lunch ...

Allan is experiencing the symptoms of Mnire disease. The disease is thought to result from the impaired filtration and excretion of the endolymphatic sac. The condition may be exacerbated by an abnormal increase in endolymph production. This excessive production may occur on its own, or as a compensatory mechanism for an abnormal decrease in perilymph.

The sensory cells of the utricle and saccule respond to static head position in relation to gravitational pull. They also provide sensory input for changes in linear motion and changes in head position.
The semicircular canals are positioned to detect rotational movements of the head. They sense head tilting with acceleration and detect turning movements in concert with locomotion.

Endolymph is a potassium-rich fluid contained in the scala media of the cochlea. It receives sound waves as they pass through the perilymph of the scala vestibuli and translate across the vestibular membrane. When the endolymph is set in motion, the basilar membrane vibrates and the receptor cells in spiral organ of Corti are stimulated so that the perception of sound occurs.
The endolymphatic potential exists because of an electrolyte gradient in the cochlear apparatus, maintained by Na+/K+ active transport pumps. The resting membrane potential between endolymph and perilymph acts to sensitize the hair cells of the spiral organ of Corti, allowing them to perceive the quietest of sounds.