The Epidemiology and Clinical Presentation of the Acute Imbalance Syndrome (AIS)-A Systematic Review and Meta-Analysis

OBJECTIVES: The acute imbalance syndrome (AIS) refers to acute-onset and persistent vertigo, dizziness and/or imbalance without nystagmus, reflecting a subset of the acute vestibular syndrome (AVS) with or without nystagmus. While AVS with nystagmus is well characterized and the approach to these patients is validated, much less is known about patients presenting with AIS....

✦ Clinical Takeaway ✦

Clinicians assessing acute vestibular syndrome should be aware that AIS — presenting without nystagmus — is an undercharacterised subtype with distinct epidemiology; this review provides a reference framework but does not yet support specific protocol changes.

✦ Why It Matters ✦

Systematic characterisation of AIS fills a significant gap in vestibular disorder classification, potentially improving diagnostic accuracy and reducing misdiagnosis of stroke or other central causes in patients lacking nystagmus.

✦ Key Points ✦

01Systematic review and meta-analysis is the highest tier of observational evidence for defining AIS epidemiology.
02AIS is defined by persistent vertigo, dizziness, or imbalance without the presence of nystagmus — distinguishing it from classic acute vestibular syndrome.
03Published in the European Journal of Neurology, a high-impact peer-reviewed journal.
04Findings have direct relevance to vestibular audiologists and neuro-otologists managing acute dizziness presentations.
05Better epidemiological definition of AIS could improve triage and referral pathways in audiology and emergency settings.

✦ Claims & Evidence ✦

ClaimEvidenceSupport

Acute Imbalance Syndrome is a distinct subset of acute vestibular syndrome characterised by persistent vertigo, dizziness, and/or imbalance without nystagmus.

studysupported

The epidemiology and clinical presentation of AIS can be systematically characterised through meta-analysis of existing literature.

studysupported

✦ Research metadata ✦

PMID: 42226567
DOI: 10.1111/ene.70651.
Journal: European Journal of Neurology
Publication type: meta_analysis
Evidence level: 2a
Population: Patients presenting with acute vestibular syndrome subtype (AIS) characterised by persistent vertigo/dizziness/imbalance without nystagmus
Intervention: Systematic review and meta-analysis of epidemiology and clinical presentation of AIS
Comparator: Broader acute vestibular syndrome population (contextual comparison)

Primary outcomes

Epidemiological characteristics of AIS; Clinical presentation features of AIS; Prevalence and incidence estimates across studies

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