Neurologic Imaging

What Imaging Is Best for Acute Vertigo with a Reassuring Peripheral Exam?

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What Imaging Is Best for Acute Vertigo with a Reassuring Peripheral Exam?

An emergency department physician is evaluating a 48-year-old patient with 12 hours of constant, severe vertigo, nausea, and vomiting. The patient has a history of hypertension but is otherwise healthy. The neurologic examination is entirely normal, with intact cranial nerves, full strength, normal sensation, and coordinated movements. A carefully performed HINTS (Head-Impulse, Nystagmus, Test-of-Skew) examination is reassuring, consistent with a peripheral cause. The core clinical question is whether this patient, despite the reassuring exam, requires neuroimaging to exclude a central pathology mimicking a peripheral vestibulopathy.

For this specific presentation, the American College of Radiology (ACR) Appropriateness Criteria rate MRI head without IV contrast as May be appropriate. This rating reflects the clinical nuance that while most such patients have a benign condition, imaging can be a crucial tool to rule out a small but significant risk of posterior circulation stroke.

Who Fits This Clinical Scenario for Acute Vertigo?

This guidance applies to a specific subset of adult patients presenting with acute, persistent vertigo. The key inclusion criteria are:

  • Acute and Persistent Symptoms: The vertigo began recently (typically within the last 72 hours) and has been continuous, not episodic.
  • Normal Neurologic Examination: A thorough examination reveals no focal deficits such as weakness, sensory loss, dysarthria, or ataxia.
  • Reassuring HINTS Examination: The HINTS exam findings are consistent with a peripheral etiology. This typically includes a corrective saccade on the head-impulse test, unidirectional horizontal nystagmus, and a normal (negative) test of skew.

It is critical to distinguish this scenario from similar presentations that require a different diagnostic approach. This workflow does not apply if:

  • The neurologic or HINTS exam is abnormal: Any finding suggestive of a central cause (e.g., direction-changing nystagmus, abnormal test of skew, new focal neurologic deficit) places the patient in a different, higher-risk category where imaging is more strongly indicated. This corresponds to the ACR scenario for acute persistent vertigo with an abnormal neurologic examination.
  • Vertigo is brief and positional: If symptoms are episodic, lasting seconds to minutes, and reliably triggered by head movements (as confirmed by a Dix-Hallpike maneuver), the likely diagnosis is benign paroxysmal positional vertigo (BPPV), which is a clinical diagnosis that does not typically require initial imaging.
  • Symptoms are chronic or recurrent: Patients with a long-standing history of vertigo, especially when associated with unilateral hearing loss or tinnitus, require a workup focused on conditions like Meniere’s disease or vestibular schwannoma, which follows a different imaging pathway.

What Diagnoses Are You Working Up in This Scenario?

Even with a reassuring exam, the decision to obtain imaging is driven by the need to exclude a few “can’t-miss” central diagnoses that can masquerade as peripheral vertigo. The differential diagnosis guides the choice of imaging modality.

The most probable diagnosis in this scenario is vestibular neuritis or labyrinthitis. This inflammatory condition of the vestibular nerve or labyrinth is the classic cause of acute, persistent vertigo with a peripheral HINTS exam. It is a self-limited, benign condition that does not have specific imaging findings and is diagnosed clinically. The fact that this is the most common cause is why imaging is rated May be appropriate rather than Usually appropriate—many patients can be managed without it.

The primary reason to consider imaging is to rule out a posterior circulation stroke, specifically an ischemic event in the cerebellum or brainstem supplied by the posterior inferior cerebellar artery (PICA) or anterior inferior cerebellar artery (AICA). A small but significant fraction of these strokes can present with isolated vertigo and a falsely reassuring, “pseudo-peripheral” HINTS exam. This is the most consequential diagnosis to exclude, particularly in patients with vascular risk factors like hypertension, diabetes, hyperlipidemia, or a history of smoking.

Less commonly, an initial presentation of multiple sclerosis (MS) can manifest as acute vertigo due to a demyelinating plaque in the brainstem’s vestibular pathways. While not the typical first presentation of MS, it remains a key diagnostic consideration in the differential for a younger adult with this syndrome.

Finally, vestibular migraine is a common cause of vertigo, but it is a clinical diagnosis of exclusion. Imaging in this context serves to rule out the structural and vascular pathologies listed above before confidently making a diagnosis of vestibular migraine.

Why Is MRI Head Without Contrast Rated ‘May Be Appropriate’ for This Presentation?

The ACR rates MRI head without IV contrast as May be appropriate because it directly addresses the primary diagnostic uncertainty: ruling out an acute posterior circulation stroke while balancing the high pre-test probability of a benign peripheral cause.

The rationale for this specific recommendation is multifaceted:

  • High Sensitivity for Acute Ischemia: The key advantage of MRI is its Diffusion-Weighted Imaging (DWI) sequence, which is highly sensitive and specific for detecting cytotoxic edema from an acute ischemic stroke within minutes of onset. This is the single most important feature needed to exclude the “can’t-miss” diagnosis of a posterior fossa infarct.
  • Avoiding Unnecessary Contrast and Radiation: An MRI of the head performed without intravenous contrast is sufficient to visualize an acute infarct on DWI sequences. This avoids the potential risks associated with gadolinium-based contrast agents. Furthermore, MRI involves no ionizing radiation (Relative Radiation Level: O 0 mSv), a significant advantage over CT.
  • Clinical Context of the Rating: The “May be appropriate” rating acknowledges that the HINTS exam, when performed by a trained clinician, is highly accurate in differentiating central from peripheral causes. In a low-risk patient with a classic presentation and a clearly peripheral HINTS exam, a clinician may reasonably choose to defer imaging and manage the patient clinically. However, in patients with vascular risk factors, an equivocal exam, or failure to improve as expected, MRI becomes a critical tool.

Alternative imaging studies are considered Usually not appropriate for this initial workup for clear reasons:

  • CT head without IV contrast: This study is readily available but has notoriously poor sensitivity for acute non-hemorrhagic infarcts in the posterior fossa. The dense petrous bones create significant beam-hardening artifacts that obscure the brainstem and cerebellum, which is precisely the area of concern. While CT can rule out hemorrhage, ischemic stroke is the primary worry in this scenario.
  • CTA head and neck with IV contrast: While a computed tomography angiogram is excellent for evaluating the vasculature for dissection or stenosis, it is not the primary tool for identifying the parenchymal brain injury of an acute infarct. It is a downstream study that may be considered if an infarct is found on MRI, but it is not the appropriate initial test for this specific clinical question.

What’s Next After MRI? Interpreting the Results and Planning Downstream Care

The results of the non-contrast head MRI create a clear branch point in the patient’s management plan.

  • If the MRI is negative: A negative MRI, particularly with clean DWI sequences, provides strong evidence against a central cause like a stroke or a demyelinating plaque. This result solidifies the clinical diagnosis of a peripheral vestibulopathy, such as vestibular neuritis. The downstream workflow is non-radiological and focuses on symptom management with short-term vestibular suppressants (e.g., meclizine, benzodiazepines) and, crucially, referral for vestibular rehabilitation therapy to promote central compensation and recovery.
  • If the MRI is positive for acute infarction: This finding dramatically changes the diagnosis and management. The patient has had a posterior circulation stroke. The immediate next steps involve admission to a stroke service, initiation of secondary stroke prevention (antiplatelet therapy, statin), and a comprehensive stroke workup to determine the etiology. This often includes vascular imaging (CTA or MRA of the head and neck), cardiac monitoring for atrial fibrillation, and an echocardiogram.
  • If the MRI shows an unexpected finding (e.g., demyelinating plaques): If the MRI reveals findings suggestive of multiple sclerosis, the patient should be referred to a neurologist for further evaluation. This typically includes a more extensive MRI protocol (cervical and thoracic spine with contrast) and potentially a lumbar puncture for cerebrospinal fluid analysis.

Pitfalls to Avoid (and When to Get Help)

Navigating this clinical scenario requires avoiding several common diagnostic and management traps.

First, do not substitute a non-contrast head CT for an MRI when the clinical concern is a posterior fossa stroke. The low sensitivity of CT in this region can provide false reassurance and lead to a missed diagnosis. Second, be wary of over-reliance on the HINTS exam if you are not experienced in performing all three components accurately; an incorrectly performed test is misleading. Third, remember that a small percentage of posterior circulation strokes can have a normal initial DWI sequence on MRI, especially if performed very early after symptom onset. If clinical suspicion for stroke remains high despite a negative initial MRI, a repeat MRI in 24-48 hours may be warranted.

If a patient’s symptoms worsen, if new neurologic deficits develop, or if the diagnosis remains unclear after initial evaluation and imaging, prompt consultation with a neurologist is the most appropriate next step.

Related ACR Topics and Tools

This article covers one specific variant within the broader topic of Dizziness and Ataxia. For a comprehensive overview of imaging recommendations across all related clinical scenarios, from BPPV to chronic disequilibrium, please see our parent guide.

For additional decision support and technical details, the following GigHz resources are available:

Frequently Asked Questions

If the HINTS exam is so reliable, why is imaging ever needed in this scenario?

While the HINTS exam is highly sensitive for stroke when performed by a trained expert, a small percentage of posterior circulation strokes can present with a ‘pseudo-peripheral’ HINTS exam that falsely suggests a benign cause. The ACR rating of ‘May be appropriate’ for MRI reflects this small but critical diagnostic uncertainty. Imaging serves as a safety net, especially for patients with vascular risk factors (e.g., hypertension, diabetes) where the pre-test probability of stroke is higher.

Why is a non-contrast MRI sufficient? Shouldn’t I order it with contrast?

For the primary question in this scenario—ruling out an acute ischemic stroke—the Diffusion-Weighted Imaging (DWI) sequence is the most important part of the MRI, and it does not require intravenous contrast. Adding contrast does not typically increase the sensitivity for acute stroke and introduces the unnecessary, albeit small, risks associated with gadolinium. Contrast would be considered if the differential included a tumor or an inflammatory/infectious process, but those are not the primary concerns in this specific acute presentation.

Can I order a non-contrast head CT in the emergency department just to be safe?

According to the ACR, a non-contrast head CT is ‘Usually not appropriate’ for this indication. Its primary utility is to rule out hemorrhage, which is a rare cause of this syndrome. It has very poor sensitivity for acute ischemic stroke in the posterior fossa due to bone artifact. Ordering a CT can provide false reassurance if it is negative and may delay the definitive study, which is an MRI.

What if my patient has a pacemaker and cannot get an MRI?

This is a significant clinical challenge. If MRI is absolutely contraindicated, a CT/CTA of the head and neck may be the next best option, despite its limitations. A CTA can identify vertebral or basilar artery occlusion or dissection, and a CT perfusion study might show a perfusion deficit. However, the sensitivity for small lacunar infarcts in the brainstem remains low. This situation requires careful clinical judgment and often a neurology consultation to weigh the risks and benefits of alternative testing versus clinical observation.

If the MRI is negative, is a stroke completely ruled out?

A negative MRI with high-quality DWI sequences makes an acute stroke highly unlikely. However, in very rare cases, a small brainstem infarct may not be visible on an initial MRI, especially if performed within the first few hours of symptom onset. If the patient’s symptoms persist or worsen and the clinical suspicion for stroke remains very high despite the negative scan, a repeat MRI in 24 to 48 hours should be considered.

Reviewed by Pouyan Golshani, MD, Interventional Radiologist — May 30, 2026