Vestibular evoked myogenic potentials and glycerol testing

Area of Science:

• Otolaryngology
• Neurotology
• Audiology

Background:

• Endolymphatic hydrops is a condition characterized by fluid imbalance in the inner ear.
• Dizziness can be an early symptom, but its precise role in initial endolymphatic hydrops development requires further investigation.
• Identifying early-stage endolymphatic hydrops is crucial for timely intervention and management of potential Meniere's disease.

Purpose of the Study:

• To evaluate dizziness as a potential first symptom of endolymphatic hydrops.
• To determine if a combination of glycerol and vestibular evoked myogenic potential (VEMP) glycerol tests can diagnose early endolymphatic hydrops and identify Meniere's disease.
• To assess the utility of VEMP glycerol testing in detecting saccular dysfunction.

Main Methods:

• Thirty-eight untreated patients with dizziness as their sole vestibular symptom were enrolled.
• Patients underwent traditional glycerol testing and VEMP glycerol testing.
• Improvement in VEMP glycerol test was defined as a >20% increase in latency and amplitude post-glycerol intake.

Main Results:

• One patient experienced VEMP reappearance.
• Six patients showed increased VEMP amplitudes (unilateral in four, bilateral in two).
• One patient demonstrated bilateral amplitude and unilateral latency improvement.

Conclusions:

• The study suggests saccular dysfunction, not early saccular hydrops, was documented in patients with dizziness.
• VEMP glycerol testing identified saccular dysfunctions not detectable by routine methods.
• VEMP glycerol testing is a promising additional diagnostic tool for patients experiencing vertigo or dizziness.