Positional End-Point Nystagmus during Positional Testing: Prevalence, Characteristics and Differences with Benign...

Area of Science:

• Neurology
• Ophthalmology
• Vestibular System

Background:

• Positional end-point nystagmus can manifest during Dix-Hallpike testing when subjects look towards the tested ear.
• Understanding this phenomenon is crucial for accurate vestibular assessment.

Purpose of the Study:

• To determine the prevalence of end-point nystagmus in healthy subjects.
• To characterize the features of end-point nystagmus during positional testing.

Main Methods:

• Sixty healthy participants underwent eight positional tests (Dix-Hallpike and Pagnini-McClure).
• Eyes were positioned in various directions during testing.
• Two observers documented nystagmus presence, latency, duration, direction, and sense.

Main Results:

• 65% of healthy subjects exhibited positional end-point nystagmus.
• Nystagmus presented with short latency and persisted as long as the head was held in position.
• Common directions included clockwise torsion for left-sided tests and anticlockwise for right-sided tests.

Conclusions:

• Positional end-point nystagmus is a frequent finding in healthy individuals.
• Unlike BPPV, it is asymptomatic, not present in the primary gaze position, and does not habituate.
• Characterization aids in differentiating it from pathological nystagmus.