Active versus passive head-shaking nystagmus

Area of Science:

• Neurology
• Otolaryngology
• Vestibular System Function

Background:

• Head-shaking nystagmus (HSN) is a key indicator of vestibular dysfunction.
• HSN can be elicited through active (patient-performed) or passive (examiner-performed) head shaking.

Purpose of the Study:

• To compare the frequency of HSN detected by active (aHSN) versus passive (pHSN) testing.
• To investigate if age or disease state influences HSN test results.
• To determine if HSN test methods correlate with other vestibular function tests.

Main Methods:

• Prospective study involving 100 patients at a tertiary care center.
• HSN tested actively and passively on the same day as caloric, rotatory chair tests, and disability assessments.
• HSN defined by duration (>5s) or slow-phase velocity (>3°/s).

Main Results:

• Similar frequencies for aHSN (47%) and pHSN (46%) when presence of nystagmus was the criterion.
• When nystagmus velocity was considered, results agreed in 74% of patients and differed in 26%.
• Age-dependent nystagmus patterns observed in vestibular neuritis patients, which disappeared when velocity was the criterion.

Conclusions:

• Active and passive HSN tests yield comparable results for nystagmus detection.
• Recommend initiating HSN testing actively, then proceeding to passive testing if negative.
• Discrepancies between active and passive testing may relate to specific vestibular conditions and age.