When to image
Indications & red flags
Routine imaging is not indicated for routine vertigo. The right question is not “should I scan?” — it is “which clinical features change my pre-test probability of a dangerous central or retrocochlear cause enough that imaging will change management?”
Triggers for imaging
Image the patient when the vertigo behaves out of character for benign peripheral disease — when neurology accompanies it, when hearing changes suddenly, when the patient is older with vascular risk and acute symptoms, when the picture does not settle with the usual approach.
Use the TiTrATE framework as the bedside gate: classify the presentation as AVS, EVS (triggered or spontaneous), or a chronic vestibular syndrome, then add red-flag neurology.1 The imaging question follows from the syndrome:
- AVS with a central HINTS pattern → MRI brain with DWI and CTA of the posterior circulation.
- s-EVS with vascular risk → MRA/CTA looking for VBI substrate.
- t-EVS with classic Dix-Hallpike → no imaging.7
- Sudden / asymmetric SNHL with vertigo → gadolinium MRI of the IAC.
Population studies put the prevalence of stroke among ED dizzy patients at roughly 3–4%, with much higher rates once central features are present.2 Vascular substrate — stenosis, dissection, hypoplasia — drives a similar but separate imaging decision.3
Two facts complicate the simple “central features = image” rule. First, early-window DWI has a documented ~12% false-negative rate for small posterior-fossa strokes in the first 24–48 h — when a patient is most likely to present.5 A negative DWI in that window does not exclude infarction.
Second, isolated vertigo from a small cerebellar (typically PICA medial-branch or nodulus) infarct can present as pure peripheral vertigo, without other neurology.6HINTS catches most of them; if it is central or equivocal, image despite a “peripheral” feel. The operating rule: HINTS is more sensitive than early DWI for the first day or two of an AVS.4
Red flags — features that should prompt imaging
- Focal neurological signs — diplopia, dysarthria, hemiparesis, limb ataxia, hemisensory loss.
- New severe occipital headache or neck pain (suspect vertebral dissection).
- Vertical, direction-changing or persistent spontaneous nystagmus.
- Acute or fluctuating asymmetric sensorineural hearing loss with vertigo.
- Age > 60 with vascular risk factors and acute persistent vertigo.
- Failure to improve with conservative or vestibular rehabilitation therapy.
- Pre-operative planning (intractable Ménière’s, schwannoma resection, SSCD repair).
Features that argue against imaging
- Classic Dix-Hallpike–positive posterior-canal BPPV that resolves with Epley.
- Recurrent stereotyped vestibular migraine with a normal interval examination.
- Orthostatic dizziness with a documented orthostatic blood-pressure drop.
- Brief presyncope explained by a clear vasovagal trigger.
Recap — the modality decision
Match the clinical scenario to the modality. The decision tree below is also surfaced on the chapter landing page; coming back to it whenever the bedside is unclear is a reasonable habit.
MRI brain + DWI/ADC + CTA posterior circulation
- Protocol
- Stroke protocol MRI; CTA aortic arch to circle of Willis
- Why
- DWI detects cytotoxic oedema in cerebellum / brainstem; CTA reveals basilar / vertebral occlusion or dissection. Note false-negative DWI in 12–20% of small posterior-fossa strokes in the first 24–48 h.