Characteristics and Mechanisms of Aperiodic Alternating Nystagmus

AND PURPOSE: Aperiodic alternating nystagmus (AAN) is defined as spontaneous alternating nystagmus in which the direction of nystagmus reverses repeatedly but the reversals do not occur at a consistent cycle interval and the cycle durations and/or peak slow-phase velocities are irregular. The etiologic distribution of vestibular disorders associated with AAN and the underlying mechanisms remain unclear....

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This is a characterisation study of a rare eye-movement finding; no immediate change to routine audiology or vestibular practice is warranted, but familiarity with AAN may aid differential diagnosis in complex vestibular cases.

Understanding AAN's mechanisms may help vestibular specialists differentiate central from peripheral causes of directional-changing nystagmus, refining workup pathways for patients with unexplained dizziness.

1. 01Aperiodic alternating nystagmus (AAN) is a spontaneous nystagmus with irregular — not periodic — directional reversals.
2. 02The study investigated both the clinical features and proposed underlying neurological mechanisms of AAN.
3. 03AAN is distinct from the better-known periodic alternating nystagmus (PAN), which reverses at regular intervals.
4. 04Identifying AAN correctly is important because it may indicate specific central nervous system pathology.
5. 05Study published in the Journal of Clinical Neurology (DOI: 10.3988/jcn.2026.0111).

PMID

42683799

DOI

10.3988/jcn.2026.0111.

Journal

Journal of Clinical Neurology

Publication type

research_article

Evidence level

4

Population

Patients presenting with aperiodic alternating nystagmus

Intervention

Clinical characterisation and mechanistic investigation of aperiodic alternating nystagmus