<keypoints>
- **Stroke/central cause** is the most critical diagnosis to exclude: look for the "5 Ds" of posterior circulation stroke: Dizziness, Diplopia, Dysarthria, Dysphagia, Dystaxia
- The **HINTS exam** (Head Impulse, Nystagmus, Test of Skew) is the key bedside tool for differentiating peripheral from central causes in acute vestibular syndrome, with reported 100% sensitivity and 96% specificity
- **"Dizziness plus" any focal neurological symptom** should raise concern for a central (vascular) aetiology
- Posterior circulation strokes are **missed twice as often** as anterior strokes due to non-specific symptoms like dizziness, nausea, and vomiting
- MRI can be **false-negative** in posterior circulation strokes within the first 48 hours
</keypoints>
Red Flags Requiring Emergency Assessment
The following features alongside dizziness/vertigo suggest a potentially life-threatening cause (stroke, cardiac event, or serious neurological condition):
Neurological red flags (posterior circulation stroke/TIA):
- Focal neurological deficits: limb weakness or numbness, facial droop
- Dysarthria, diplopia, dysphagia, dysphonia
- Gait ataxia or severe truncal ataxia (inability to sit unsupported or walk)
- Downbeat nystagmus, pure torsional nystagmus, or bidirectional gaze-evoked nystagmus (central nystagmus patterns)
- New severe headache ("thunderclap" or unlike previous headaches)
- Depressed consciousness or confusion
Cardiac red flags:
- Chest pain, shortness of breath, or palpitations
- Syncope or pre-syncope
Other red flags:
- Acute unilateral hearing loss with vertigo (anterior inferior cerebellar artery territory)
- Dizziness following head trauma
- New-onset vertigo with fever and severe headache (consider CNS infection)