Endolymphatic hydrops in perilymphatic fistula

Area of Science:

• Otoacoustic Emissions
• Inner Ear Physiology
• Pathology

Background:

• Cochlear hydrops is a condition characterized by excess fluid in the inner ear.
• The precise mechanisms leading to cochlear hydrops and its relationship with other inner ear structures remain incompletely understood.
• Investigating the effects of altered inner ear fluid dynamics is crucial for understanding various audiovestibular disorders.

Purpose of the Study:

• To experimentally induce cochlear hydrops in guinea pigs.
• To examine the resulting pathological changes in the cochlea, vestibule, and semicircular canals.
• To explore the potential correlation between induced cochlear hydrops and conditions like perilymphatic fistula.

Main Methods:

• Cochlear hydrops was induced by injecting artificial perilymph into the subarachnoid space or aspirating perilymph via the round window.
• Animals were either immediately fixed or observed for 1-3 months post-induction.
• Serial sectioning using conventional celloidin embedding was performed on 13 selected guinea pigs.

Main Results:

• Induced cochlear hydrops ranged from slight to moderate, with normal or collapsed endolymphatic spaces in the vestibule and semicircular canals.
• The pars superior did not exhibit hydrops, and saccular wall changes were minimal.
• One case showed marked cochlear hydrops, leading to atrophy of Corti's organ and stria vascularis, with vestibular collapse and ductus reuniens/saccule obstruction.

Conclusions:

• Blocking the longitudinal endolymph flow effectively produces marked cochlear hydrops.
• The findings suggest a potential association between cochlear hydrops and clinical cases of perilymphatic fistula.
• Further research is warranted to elucidate the complex pathologies of the endolymphatic space in related conditions.