Reference

Glossary

The working vocabulary of central vertigo. Inline dotted terms throughout the chapter link here.

Acute vestibular syndrome (AVS) · AVS: Rapid-onset, continuous vertigo lasting more than 24 hours with nausea/vomiting, nystagmus, head-motion intolerance and gait unsteadiness. The clinical battleground where vestibular neuritis must be separated from posterior-circulation stroke.
AICA (anterior inferior cerebellar artery) · anterior inferior cerebellar artery: Branch of the basilar artery supplying the lateral pons, flocculus and — via the internal auditory artery — the labyrinth and cochlea. AICA infarction can mimic vestibular neuritis but adds hearing loss and facial signs.
Central vertigo: Vertigo arising from disease of the central vestibular structures — vestibular nuclei, brainstem, cerebellum, thalamus or cortex — rather than the labyrinth or vestibular nerve. Typically non-fatiguing, often with other neurological signs, and frequently not suppressed by visual fixation.
Clinically isolated syndrome (CIS): A first, monophasic episode of CNS demyelination — which may present as isolated vertigo or a brainstem syndrome — not yet meeting full MS criteria. Requires follow-up and repeat imaging to establish or exclude MS.
Demyelination: Loss of the myelin sheath around central axons, slowing or blocking conduction. The pathological hallmark of multiple sclerosis; plaques in vestibular pathways produce central vertigo.
Diffusion-weighted imaging (DWI) · DWI: An MRI sequence highly sensitive to acute ischaemia. Far superior to CT for posterior-fossa infarcts, but can be falsely negative in up to ~20% of small early strokes — so a normal early scan does not exclude stroke.
Direction-changing gaze-evoked nystagmus: Nystagmus whose fast phase reverses with the direction of gaze. A central sign; peripheral nystagmus is unidirectional and obeys Alexander's law.
Dissemination in space and time: The two pillars of MS diagnosis: lesions in ≥2 characteristic CNS sites (space) and lesions arising at different times (time), shown clinically, on serial MRI, or — for time — by simultaneous enhancing and non-enhancing lesions or CSF oligoclonal bands.
Downbeat nystagmus: Vertical nystagmus with downward fast phases, present in primary gaze. A classic central sign, often localising to the cerebellar flocculus/paraflocculus or the cervicomedullary junction.
Head impulse test (HIT) · h-HIT · vestibulo-ocular reflex test: A rapid, small-amplitude passive head turn while the patient fixates a target. A corrective catch-up saccade (abnormal VOR) localises to the peripheral vestibular system; a normal HIT in a patient with AVS is a red flag for stroke.
HINTS · Head Impulse–Nystagmus–Test of Skew: A three-step bedside oculomotor battery for acute vestibular syndrome: Head Impulse, Nystagmus (direction), Test of Skew. A central (dangerous) pattern is more sensitive than early MRI for posterior-circulation stroke.
Internuclear ophthalmoplegia (INO) · internuclear ophthalmoplegia: Impaired adduction of one eye with abducting-eye nystagmus, caused by a lesion of the medial longitudinal fasciculus. Bilateral INO in a young adult is highly suggestive of multiple sclerosis.
Lhermitte's sign: A transient electric-shock sensation radiating down the spine on neck flexion, classically from cervical-cord demyelination. A supportive clue to multiple sclerosis when it accompanies central vertigo.
McDonald criteria (2017): The diagnostic framework for multiple sclerosis, requiring dissemination in space and time. CSF-specific oligoclonal bands can now substitute for dissemination in time, allowing earlier diagnosis.
Medial longitudinal fasciculus (MLF): A brainstem tract linking the abducens nucleus to the contralateral oculomotor nucleus to coordinate horizontal conjugate gaze. Demyelination or infarction of the MLF produces internuclear ophthalmoplegia.
Oligoclonal bands (OCBs) · OCBs: Bands of immunoglobulin present in CSF but not in matched serum, indicating intrathecal IgG synthesis. Found in ~85–95% of clinically definite MS and used as a supportive criterion.
PICA (posterior inferior cerebellar artery) · posterior inferior cerebellar artery: Branch of the vertebral artery supplying the dorsolateral medulla and inferior cerebellum. Occlusion causes lateral medullary (Wallenberg) syndrome or isolated cerebellar infarction; hearing is usually spared.
Posterior circulation: The vertebrobasilar arterial system — vertebral arteries, basilar artery and their branches (PICA, AICA, SCA) — supplying the brainstem, cerebellum, thalamus and occipital lobes. Around 20% of ischaemic strokes occur here.
Posterior fossa: The compartment of the skull base housing the brainstem and cerebellum. Tumours, infarcts and haemorrhage here can cause vertigo and threaten the fourth ventricle, risking obstructive hydrocephalus and brainstem compression.
Test of skew (skew deviation): Vertical ocular misalignment revealed by the alternate cover test. In acute vestibular syndrome a skew points to a brainstem (central) lesion and is part of the dangerous HINTS pattern.
Vestibular schwannoma · acoustic neuroma: A benign Schwann-cell tumour of the vestibulocochlear nerve, usually in the cerebellopontine angle. It more often causes asymmetric hearing loss and imbalance than true vertigo, but is a key posterior-fossa mass to exclude.
Wallenberg syndrome · lateral medullary syndrome: Lateral medullary infarction, usually from vertebral or PICA disease: vertigo, ipsilateral facial numbness, Horner's syndrome, dysphagia/dysarthria, limb ataxia and contralateral body hypoalgesia, with hearing typically preserved.