What are the key clinical features to differentiate between peripheral and central causes of dizziness in adults?

To differentiate between peripheral and central causes of dizziness in adults, key clinical features include the nature of the nystagmus, the results of the head impulse test, the presence of other neurological symptoms or signs, and the characteristics of the dizziness itself ¹,².

• Nystagmus: Purely vertical or torsional nystagmus, or direction-changing nystagmus, are red flags indicative of a central cause, such as a brainstem stroke ¹,².
• Head Impulse Test (HINTS): In adults with sudden-onset acute vestibular syndrome (vertigo, nausea/vomiting, gait unsteadiness), a normal head impulse test suggests a central cause (e.g., stroke) and warrants immediate neuroimaging ¹,². A negative HINTS test makes a diagnosis of stroke very unlikely ².
• Associated Neurological Symptoms/Signs: The presence of central neurological symptoms or signs strongly suggests a central cause ¹. These include new type of headache (especially occipital), gait disturbance, truncal ataxia, new-onset unsteadiness, new-onset unilateral deafness, cranial nerve weakness or sensory loss, or limb weakness or sensory loss ¹,². Dizziness without imbalance or other focal neurological deficit is unlikely to indicate a serious neurological condition ².
• Onset and Persistence: Very sudden onset of vertigo (within seconds) that is not provoked by positional change and is persistent, or isolated persistent vertigo lasting over 24 hours with hyperacute onset, are red flags for a central cause ¹. Transient rotational vertigo on head movement, however, is characteristic of a peripheral cause like benign paroxysmal positional vertigo (BPPV) ².
• Ataxia: Severe ataxia is a red flag for a central cause ¹.
• Altered Consciousness: Recurrent fixed-pattern dizziness associated with alteration of consciousness may indicate epilepsy ².

Common peripheral causes of dizziness include benign paroxysmal positional vertigo (BPPV), Meniere's disease, and vestibular neuronitis ¹. Vestibular migraine is another possibility, characterized by episodes of dizziness lasting between 5 minutes and 72 hours with a history of recurrent headache ². If a central cause is suspected, urgent admission to hospital or referral to a balance specialist (e.g., neurologist or audiovestibular physician) is recommended, with urgency depending on symptom severity and suspected diagnosis ¹.