In 1861, Prosper Menière described the classical triadic symptomatology of hearing loss,
vertigo and tinnitus, which he attributed for the first time to a labyrinthine disorder. The
underlying pathophysiology of this disabling inner ear disease was not known, but since
Hallpike and Cairns, and also Yamakawa in 1938 discovered hydrops of the endolymphatic
system in the temporal bones of patients with Menière’s disease, endolymphatic
hydrops has been generally accepted as the basic histopathological substrate of Menière’s
disease.
Endolymphatic hydrops may arise as a result of the destabilization of natural regulation
through overproduction of endolymph and/or reduced absorption of endolymph.
Total destruction of the endolymphatic sac, which is considered to be responsible for the
absorption of endolymph, and obliteration of the vestibular aqueduct, resulted in endolymphatic
hydrops in the guinea pig, and has been established as the classical guinea pig
model for Menière’s disease (Kimura, 1965). However, obliteration of the vestibular
aqueduct is regarded as a non-physiological model for Menière’s disease. In patients with
Menière’s disease, endolymphatic sac tissue still remains present, although the size of
the endolymphatic sac is reduced, suggesting a reduction in resorptive capacity.
The production of endolymph is thought to be regulated by Na/K-ATPase in the marginal
cells of the stria vascularis of the cochlea, as well as in the dark cells of the utricle
and the cristae ampullares of the semicircular canals. In recent experiments, a relationship
between circulating adrenal steroids and Na/K-ATPase activity in the inner ear was
observed. Emotional stress leads to the activation of neuroendocrine effector systems,
including the production of adrenal steroids such as aldosterone, and could thus increase
the production of endolymph.
A borderline capacity of the ES, in combination with a periodic increase of endolymph
production caused by stressful situations may be responsible for the development of
Menière’s disease. Indeed, manifestations of Menière’s disease frequently occur during
stressful experiences in patients with physiological systems under challenge due to a
neurasthenic psychological profile.
We developed the two-phase endolymphatic hydrops model in guinea pigs which was
based on two compromising fators; mild chronic endolymphatic sac dysfunction has been
established by dissection of the distal part of the endolymphatic sac from the sigmoid
sinus, in combination with periodic increase of endolymph production by stimulation of
the Na/K-ATPase pumps in the stria vascularis by administration of aldosterone. This
model, which seemed to represent a functional model combining multiple etiologies, and
may resemble the fluctuant characteristics of Menière’s disease.