Mechanism of the Ménière attack

Area of Science:

• Otolaryngology
• Neuroscience
• Physiology

Background:

• Ménière's disease is characterized by episodic vertigo, tinnitus, and hearing loss.
• The precise pathophysiology of Ménière's disease remains incompletely understood.
• Alterations in inner ear fluid composition are suspected to play a role.

Purpose of the Study:

• To investigate the direct effects of varying potassium concentrations in the inner ear fluids on neural activity.
• To determine if altered potassium levels can experimentally induce symptoms consistent with Ménière's disease.

Main Methods:

• Review of experimental evidence on potassium concentration effects on cochlear and vestibular nerves.
• Analysis of animal studies involving induced nystagmus via potassium manipulation.
• Correlation of experimental findings with known pathology of Ménière's disease.

Main Results:

• Low perilymph potassium (20-30 mM) increased nerve action potential frequency.
• Low potassium in animal models induced ipsilateral nystagmus.
• Elevated endolymph potassium, within normal limits, blocked vestibular nerve conduction, causing contralateral nystagmus.

Conclusions:

• Potassium concentration in perilymph is a critical factor in reproducing Ménière's attack symptoms.
• Ruptures in hydrops leading to endolymph potassium diffusion into perilymph are hypothesized as the basis for Ménière's attacks.