In a middle‑aged adult who experienced a brief (30‑60 s) episode of severe vertigo while seated, followed by transient episodes of mental blankness, persistent skull‑base dizziness, intermittent right‑ear pressure and constant white‑noise tinnitus, worsened by rapid head movements, with normal ER labs and non‑contrast CT, what is the most likely diagnosis and appropriate urgent work‑up?

Posterior Circulation Stroke or Vertebrobasilar Insufficiency Until Proven Otherwise

This patient requires urgent MRI brain with diffusion-weighted imaging (DWI) to rule out posterior circulation stroke, given the combination of transient episodes of mental blankness (possible transient ischemic attacks), persistent skull-base dizziness, unilateral auditory symptoms, and symptom provocation with head movements—all red flags that elevate stroke risk despite normal CT. 1

Most Likely Diagnosis

This presentation does not fit benign paroxysmal positional vertigo (BPPV) despite the brief initial vertigo episode. The key distinguishing features pointing toward a central/vascular etiology include:

• Episodes of mental blankness while conscious — these are concerning for transient ischemic attacks affecting the posterior circulation
• Persistent dizziness localized to skull base — suggests brainstem involvement rather than peripheral vestibular pathology
• Unilateral tinnitus and ear pressure — while these can occur with Menière's disease, the combination with mental blankness episodes and persistent symptoms raises concern for vertebrobasilar territory involvement
• Symptom provocation with rapid head movements — could indicate vertebrobasilar insufficiency or even vertebral artery dissection

The differential diagnosis includes:

1. Posterior circulation stroke/TIA (most urgent to exclude)
2. Vertebrobasilar insufficiency 1
3. Vertebral artery dissection 1
4. Less likely: Vestibular paroxysmia (though episodes are typically much briefer, <1 minute) 2
5. Less likely: Menière's disease (episodes typically last 20 minutes to hours, not seconds) 3

Critical Pitfall: Non-Contrast CT is Inadequate

The normal CT scan provides false reassurance. Non-contrast CT has extremely poor sensitivity for acute posterior circulation stroke, with only 2% positivity rate in ED patients with dizziness 1. Even when neurologic findings are present, CT misses many acute brain lesions that MRI detects 1.

Urgent Work-Up Algorithm

Immediate (Within Hours):

1. MRI brain with DWI sequences — This is the gold standard and increases diagnostic yield to 12% when neurologic symptoms are present 1. DWI is specifically sensitive for acute ischemia that CT misses.

2. MRA of head and neck or CTA — To evaluate for:

   • Vertebral artery dissection (CTA has nearly 100% sensitivity) 1
   • Vertebrobasilar stenosis or insufficiency 1
   • Neurovascular compression (if vestibular paroxysmia is considered) 2

3. Bedside HINTS examination (if trained examiner available) — Though designed for acute vestibular syndrome with persistent symptoms, components may help risk-stratify. However, do not rely on HINTS alone given the episodes of mental blankness, which are neurologic symptoms that mandate imaging 1.

If MRI is Unavailable or Contraindicated:

• CTA head and neck becomes the next best option, though inferior to MRI for detecting small posterior circulation infarcts 1

Additional Considerations:

• Audiometry — Document the hearing status given unilateral auditory symptoms
• Consider transcranial Doppler if available and vascular insufficiency suspected 1
• Conventional angiography — Reserved for specific scenarios if dynamic positional insufficiency of posterior circulation is suspected and non-invasive imaging is inconclusive 1

Why This Patient Cannot Wait

The episodes of mental blankness represent potential TIAs, placing this patient at high risk for completed stroke. The combination of:

• Transient neurologic events
• Persistent posterior fossa symptoms
• Unilateral cranial nerve VIII territory symptoms
• Normal CT (which is insensitive)

...creates a clinical picture where stroke risk outweighs the low probability of benign conditions like BPPV or Menière's disease, which have different temporal patterns and lack the mental status changes 3, 4.

Treatment Considerations Pending Imaging

• Avoid vestibular suppressants until diagnosis is clear
• Aspirin may be considered if TIA is suspected and no contraindications exist
• Admit for observation given recurrent neurologic symptoms and stroke risk
• Do not attempt Epley maneuver or other BPPV treatments until central pathology is excluded

The normal labs and CT do not exclude life-threatening pathology in this presentation. MRI with DWI and vascular imaging are non-negotiable next steps to prevent missing a treatable cause of posterior circulation ischemia.