Central Causes

1. 0:00Central causes are the diseases this atlas spends every prior chapter trying to exclude. They are also the diseases that DVA alone cannot diagnose — and the ones where missing the diagnosis has the highest stakes. The most clinically important question in vestibular medicine is not 'what kind of peripheral vestibular disease does this patient have' but 'is this patient peripheral at all'. This chapter is about that question.
2. 0:35The clinical setting that matters most is the acute vestibular syndrome — sudden onset of vertigo, nausea, head-motion intolerance, and unsteadiness, lasting at least 24 hours. Most patients with this presentation have vestibular neuritis. A minority have posterior circulation stroke. The difference matters enormously — neuritis is benign and self-limiting; stroke kills people, particularly when the cerebellar oedema progresses over the first 48 hours.
3. 1:10The HINTS exam — Head-Impulse, Nystagmus, Test-of-Skew — is the bedside discriminator. Kattah and Newman-Toker showed in 2009 that in high-risk acute vestibular syndrome patients, a dangerous HINTS result was 100% sensitive and 96% specific for central lesions, outperforming early MRI diffusion-weighted imaging. The dangerous pattern is the INFARCT mnemonic: Impulse Normal, Fast-phase Alternating, Refixation on cover test.
4. 1:50The most counterintuitive piece for trainees is the head-impulse test. A normal HIT in a patient with acute vertigo is <em>dangerous</em>, because it suggests the vestibular nerve is intact and the lesion must be central. An abnormal HIT with catch-up saccades is <em>reassuring</em>, because it localises the lesion to the periphery. This reversal trips up clinicians who learned HIT first in the context of unilateral peripheral disease.
5. 2:25The vestibular test battery in established central disease is heterogeneous and not localising in itself. DVA may be abnormal but the pattern does not localise the lesion. vHIT is often normal because the peripheral vestibular system is intact. Calorics are usually normal. The diagnosis is made on bedside oculomotor findings, additional central neurological signs, and MRI — not on the vestibular test battery.
6. 3:00Three practical points. First, in any patient with acute vestibular syndrome and vascular risk factors, the HINTS exam is mandatory before any peripheral diagnosis is made. Second, MRI within 48 hours of onset misses up to 20% of posterior circulation strokes — the false-negative rate is much higher than for anterior circulation strokes. Third, DVA's role in central disease is to characterise the functional consequence and to guide rehabilitation; it does not contribute to the central-versus-peripheral question, for which HINTS plus additional central signs is the standard.

Why central causes matter

Every previous disease page in this atlas covered a peripheral vestibular disorder — an end-organ disease or eighth-nerve disease in which the vestibular system itself is damaged. Central causes are different in mechanism and different in stakes. The vestibular periphery is intact; the lesion is in the brainstem vestibular nuclei, the cerebellum, the medial longitudinal fasciculus, the thalamic relays, or the cortical vestibular network. The most common and most consequential cause is posterior circulation stroke.⁴⁸

The clinical setting that matters most is the acute vestibular syndrome (AVS) — sudden onset of vertigo, nausea, head-motion intolerance, and unsteadiness lasting ≥ 24 hours. Most AVS is vestibular neuritis. A clinically important minority — around 10–25% in high-risk populations — is posterior circulation stroke. Neuritis is benign and self-limiting; stroke can kill the patient through cerebellar oedema, herniation, and brainstem compression over the first 48 hours.^46,48

The HINTS exam

The Head-Impulse, Nystagmus, Test-of-Skew (HINTS) exam was formalised by Kattah and Newman-Toker in 2009 from prior bedside oculomotor work. In a prospective study of 101 high-risk AVS patients, the dangerous-HINTS battery was 100% sensitive and 96% specific for central lesions — and notably outperformed early MRI diffusion-weighted imaging, which has a significant false-negative rate in posterior circulation stroke within the first 48 hours.⁴⁶

The "dangerous" pattern is captured by the INFARCT mnemonic: Impulse Normal, FAst-phase Alternating, Refixation on Cover Test. Any one dangerous feature in an AVS patient is sufficient to raise concern for stroke and warrant urgent neuroimaging.⁴⁶

Additional bedside central signs

HINTS is highly sensitive but not the only set of useful findings. The Newman-Toker neuro-vestibular examination identifies several additional central oculomotor signs worth checking in any AVS patient — particularly those with vascular risk factors:

• Impaired smooth pursuit — saccadic intrusions during slow eye-tracking; floccular or parafloccular dysfunction.
• Impaired VOR cancellation — patient cannot suppress VOR when head and target move together; the bedside sign least attributable to peripheral disease.
• Gaze-evoked nystagmus — beats in the direction of eccentric gaze; failure of the neural integrator. (Distinct from direction-changing nystagmus on the HINTS exam, which is a related but specific finding.)
• Vertical nystagmus (downbeat or upbeat in primary position) — almost always central.
• Severe truncal instability — inability to sit unaided is suggestive of cerebellar disease.
• Limb dysmetria, dysdiadochokinesis, dysarthria — classical cerebellar signs, but frequently absent in inferior cerebellar infarcts.
• Other focal neurological signs — internuclear ophthalmoplegia, gaze palsy, hemiparesis, sensory loss, facial weakness, dysphagia. Present in approximately 42% of central AVS cases in prospective studies.⁴⁶

Vascular causes — Bárány 2022

The 2022 Bárány Society consensus on vascular vertigo and dizziness classifies vascular causes by symptom duration and mechanism:⁴⁸

• Acute prolonged vascular vertigo/dizziness — ≥ 24 h. Posterior circulation stroke (PICA, AICA, vertebrobasilar territory) or, rarely, isolated labyrinthine infarction.
• Transient vascular vertigo/dizziness— minutes to < 24 h. Posterior circulation TIA. Recurrent transient vestibular symptoms preceding stroke are an important warning sign that should not be dismissed as benign.
• Isolated labyrinthine infarction — vascular disease that does involve the inner ear via the labyrinthine artery (terminal AICA branch). The picture is identical to vestibular neuritis with cochlear involvement. May precede ponto-cerebellar infarction.
• Vertebral artery compression syndrome — vertigo on sustained eccentric neck position with imaging evidence of posterior-circulation flow reduction.

Non-vascular central causes

• Demyelinating disease (MS) — episodic vertigo from brainstem demyelination. May produce INO, gaze-evoked nystagmus, dysmetric saccades. Vertigo can be the presenting symptom in 5–15% of MS cases.
• Cerebellar degeneration — including spinocerebellar ataxias and the CANVAS syndrome (cerebellar ataxia + sensory neuronopathy + vestibular areflexia). Slowly progressive rather than acute.²⁶
• Brainstem tumours — gliomas, metastases, cavernomas. Subacute and progressive.
• Wernicke encephalopathy — thiamine deficiency producing the classic triad of confusion, ataxia, and oculomotor findings (often bilateral abducens palsy with nystagmus). Reversible if treated promptly.
• Migrainous brainstem aura — see also the Vestibular Migraine page. Distinct from vestibular migraine; the ICHD criteria require additional posterior-circulation aura features.
• Superficial siderosis — chronic CSF haemosiderin deposition; slowly progressive cerebellar and vestibular symptoms.

MRI caveats in acute AVS

A common clinician error is to over-rely on MRI in acute AVS. Two quantitative limits matter:

• False-negative rate within 48 hours: Posterior circulation stroke has a much higher MRI false-negative rate than anterior circulation stroke — up to 20% of small cerebellar or brainstem infarcts are missed on initial diffusion-weighted imaging in the first 24–48 hours. The lesion may appear only on repeat imaging at 48–72 hours.^46,48
• HINTS outperforms early MRI: In the Kattah 2009 study, the dangerous-HINTS battery was 100% sensitive for central lesions, while early DWI had a false-negative rate that allowed several strokes to be missed. The bedside exam should not be short-circuited by a "negative MRI" — repeat imaging and clinical observation are warranted when HINTS is dangerous.⁴⁶

Cerebellar stroke syndromes worth knowing

• PICA (posterior inferior cerebellar artery) stroke — most common cerebellar-stroke cause of isolated vertigo. Affects inferior cerebellum and lateral medulla (Wallenberg syndrome). Bedside HIT typically normal; direction-changing nystagmus often present. May appear "isolated" on examination — this is the most dangerous mimic of vestibular neuritis.⁴⁷
• AICA (anterior inferior cerebellar artery) stroke — distinctive because it can involve the labyrinthine artery and produce ipsilateral peripheral signs (abnormal HIT, hearing loss, peripheral nystagmus pattern) alongside central signs. The HINTS exam may be misleadingly "negative" — additional features such as ipsilateral facial weakness, sensory change, or ataxia are crucial.⁴⁸
• SCA (superior cerebellar artery) stroke — usually produces obvious cerebellar signs (limb ataxia, dysarthria) rather than isolated vertigo. Less likely to be confused with vestibular neuritis.
• Vertebrobasilar TIA — recurrent transient vestibular symptoms in a patient with vascular risk factors should be investigated as TIA until proven otherwise. The Kim 2021 study (cited in the Bárány vascular criteria) showed that transient vestibular symptoms commonly precede posterior circulation stroke.⁴⁸

What DVA contributes in central disease

DVA does not contribute to the central-versus-peripheral discrimination at the acute presentation. Its role in established central disease is similar to its role in established Ménière's or schwannoma — quantifying the functional consequence and guiding rehabilitation.

• Post-stroke rehabilitation: Cerebellar stroke survivors with persistent oscillopsia and gait instability benefit from vestibular rehabilitation; DVA tracks recovery similarly to peripheral disease, though the underlying mechanism (development of compensatory eye-movement strategies despite intact peripheral VOR) is different. Functional gains are smaller than in pure peripheral disease.
• MS monitoring: DVA can document the impact of relapse and the response to rehabilitation. Useful as a functional outcome measure alongside the Expanded Disability Status Scale and the timed 25-foot walk.
• Cerebellar degeneration: DVA worsens with disease progression. Serial DVA may detect functional decline before clinical examination reveals it.

Reading the report

The central-versus-peripheral question in acute vestibular syndrome is answered by the HINTS exam plus additional central neurological signs — not by the vestibular test battery or by DVA.^46,47 The Bárány 2022 vascular vertigo criteria require acute central signs, dangerous HINTS findings, or vascular risk factors with additional features to support the diagnosis.⁴⁸ DVA's contribution is to the management phase: quantifying functional consequence, guiding rehabilitation, and monitoring recovery or progression. In acute AVS, the message of this chapter is the inverse of every previous chapter: do not let a normal DVA reassure you that the patient does not have a stroke.