The first hour of acute vertigo decides the case.

Dizziness is one of the commonest reasons people come to an ED. Most have a peripheral cause that needs a Frenzel-and-bedside diagnosis, an antiemetic, and a referral. But posterior-circulation stroke (PCS) shows up as acute vertigo too — and early CT and even early MRI miss many of these.

The first task in the dizzy patient is not the scan. It is the structured bedside exam. The TiTrATE framework triages by timing and triggers; the HINTSbattery separates peripheral from central in the acute, sustained presentation.

Dizziness accounts for ≈ 3.9 million U.S. ED visits a year (~4% of total presentations).1 Around 3–5% of these patients are having a posterior-circulation stroke, and stroke is missed in close to one in three of those who are discharged with isolated dizziness as the working diagnosis.2,3

The structured first hour is built on three layers. Triage: the TiTrATE framework partitions the presentation into triggered episodic, spontaneous episodic, or acute vestibular syndrome (AVS).4 Bedside: HINTS in the AVS patient, Dix-Hallpike / supine roll in the triggered patient.6 Action:activate the stroke pathway for central signs; treat at the bedside for BPPV; manage and refer for peripheral neuritis.

The diagnostic frame for acute vertigo has shifted decisively in the last two decades, from "symptom quality" (vertigo vs disequilibrium vs presyncope) totiming and triggers as the discriminating dimensions.5,4 The quality-based framing was unreliable; the temporal one is reproducible and maps cleanly to actionable testing pathways.

The chapter is organised in three pulses: recognise the syndrome (AVS & TiTrATE), localise with HINTS, then act — specific conditions, imaging decisions, acute pharmacology, and disposition. The interactive AVS Decision Tool walks the same logic with case-by-case state.