What type of stroke is most likely in an older adult with vascular risk factors who presents with acute vertigo?

Posterior Circulation Stroke: The Primary Stroke Type Associated with Vertigo

When an older adult with vascular risk factors presents with acute vertigo, posterior circulation stroke—specifically involving the cerebellum, brainstem (medulla and pons), or their connecting structures—is the stroke type most likely responsible. 1

Epidemiology and Clinical Significance

Posterior circulation strokes account for approximately 25% of all acute vestibular syndrome (AVS) presentations, rising to 75% in high vascular risk cohorts (patients over 50 with hypertension, diabetes, atrial fibrillation, or prior stroke). 1, 2 Critically, 75-80% of these patients lack focal neurologic deficits on standard examination, making bedside vestibular testing essential. 2, 3

Specific Anatomic Locations

The most commonly involved structures in stroke-related vertigo include:

• Cerebellum (particularly posterior inferior cerebellar artery [PICA] territory): Approximately 11% of isolated cerebellar infarctions present with isolated vertigo mimicking peripheral vestibular disorders 4, 5
• Brainstem structures: Lateral medulla (Wallenberg syndrome), pons, and medulla 1, 6
• Cerebellar peduncles (inferior and superior) 5
• Basilar artery territory 6

Multiple logistic regression analysis demonstrates that cerebellar location carries the strongest association with vertigo (OR 5.59), followed by medulla (OR 2.87) and pons (OR 2.39). 6

Critical Diagnostic Approach

High-Risk Features Mandating Imaging

MRI brain without contrast (with diffusion-weighted imaging) is the first-line imaging modality for suspected posterior circulation stroke, as it has 4% diagnostic yield versus <1% for CT head. 1, 7, 2 CT misses most posterior circulation infarcts and should not substitute for MRI when stroke is suspected. 1

Obtain urgent MRI when any of these features are present:

• Vascular risk factors (age >50, hypertension, diabetes, atrial fibrillation, prior stroke) even with normal neurologic examination 1, 2
• Abnormal HINTS examination (normal head impulse test, direction-changing nystagmus, or skew deviation) 1, 3
• Focal neurologic deficits (diplopia, dysarthria, dysphagia, limb weakness) 3
• New severe headache or neck pain 2, 3
• Sudden unilateral hearing loss (suggests anterior inferior cerebellar artery [AICA] stroke) 2, 3
• Inability to stand or walk 2

HINTS Examination Caveats

The HINTS (Head Impulse, Nystagmus, Test of Skew) examination achieves 100% sensitivity for stroke when performed by trained specialists, superior to early MRI (46% sensitivity). 1, 2, 3 However, emergency physicians without specialized training cannot perform HINTS with sufficient accuracy to exclude stroke, and meta-analysis confirms inadequate sensitivity when used in isolation by non-neurologists. 1, 3 Therefore, do not rely on HINTS alone in the emergency department—proceed with MRI for high-risk patients regardless of HINTS results. 1, 3

Common Pitfalls to Avoid

• Assuming normal neurologic examination excludes stroke: 75-80% of posterior circulation stroke patients have no focal deficits 2, 3
• Relying on CT head: Sensitivity is only 10-20% for posterior fossa ischemic strokes 1
• Trusting non-expert HINTS interpretation: Subspecialists achieve 97.6% specificity versus 89.1% for non-subspecialists 3
• Missing the 15% false-negative rate of early MRI: Small posterior fossa strokes may not appear on imaging within 48 hours 3

Isolated Vestibular Syndrome

Isolated vestibular syndrome (vertigo without other neurologic symptoms) occurs in approximately 25% of posterior circulation strokes, predominantly involving the cerebellum, cerebellar peduncles, and caudal lateral or rostral dorsolateral medulla. 5 The head impulse test differentiates cerebellar stroke from peripheral vestibular disorders, as cerebellar strokes show a normal (central) head impulse test while peripheral disorders show an abnormal response. 4

Vertebrobasilar Insufficiency

Transient ischemic attacks in the vertebrobasilar distribution can produce isolated vertigo attacks lasting minutes to <24 hours without hearing loss, representing a warning sign of impending posterior circulation stroke. 2, 8

1, 7, 2, 3, 4, 8, 6, 5