What is the recommended evaluation and management for a patient presenting with dizziness, bilateral lower limb weakness, and blurred vision?

Urgent Neurological Evaluation for Posterior Circulation Stroke

This patient requires immediate MRI brain with diffusion-weighted imaging (DWI) to rule out posterior circulation stroke, as the triad of dizziness, bilateral lower limb weakness, and blurred vision strongly suggests vertebrobasilar insufficiency or brainstem/cerebellar ischemia.

Initial Assessment Priority

The combination of symptoms presented—dizziness, bilateral lower limb weakness, and blurred vision—represents a high-risk constellation for posterior circulation stroke that demands urgent evaluation 1, 2. These symptoms align with vertebrobasilar territory involvement affecting the brainstem and cerebellum 1.

Key Clinical Features to Assess Immediately

• Timing and onset: Determine if symptoms are acute (hours to 2 days), as this presentation suggests acute vestibular syndrome requiring differentiation between peripheral vestibular disorders and central stroke 3, 4
• Additional brainstem signs: Assess for diplopia, perioral numbness, ataxia, bilateral sensory deficits, or dysarthria—all indicating vertebrobasilar insufficiency 1, 2
• Cranial nerve examination: Look for abnormal eye movements, facial weakness, or swallowing difficulties 3
• HINTS examination (Head Impulse, Nystagmus, Test of Skew): This bedside test helps distinguish peripheral from central causes, with central findings (normal head impulse, direction-changing nystagmus, or skew deviation) indicating stroke 3, 5, 4

Diagnostic Algorithm

Step 1: Immediate Neuroimaging

MRI brain with DWI is the diagnostic test of choice for this presentation 6, 1. While CT head has very low sensitivity (20-40%) for posterior fossa lesions and diagnostic yield <1% for isolated dizziness 6, this patient has bilateral lower limb weakness and blurred vision—not isolated dizziness—which dramatically increases pretest probability for stroke 6.

• MRI DWI has 4% yield in isolated dizziness but substantially higher yield when neurological deficits are present 6
• CT is inadequate for posterior fossa evaluation due to poor soft tissue contrast 6

Step 2: Vascular Imaging

MRA or CTA of head and neck should be obtained to evaluate vertebrobasilar circulation 1, 2:

• MRA/CTA has 94% sensitivity and 95% specificity for vertebral artery occlusion 2
• Vertebral artery atherosclerosis causes approximately 20% of posterior circulation strokes 1
• The proximal (V1) vertebral artery segment is the most common site of atherosclerotic stenosis 2

Step 3: Rule Out Alternative Diagnoses

While posterior circulation stroke is the primary concern, rapidly exclude:

• Postural hypotension: Check orthostatic vital signs, though this typically causes dizziness with position change from supine to upright, not bilateral weakness 6, 4
• Posterior reversible encephalopathy syndrome (PRES): Consider if patient has hypertension, renal disease, or recent immunosuppression; presents with impaired consciousness, seizures, and bilateral occipito-parietal lesions on MRI 7
• Benign paroxysmal positional vertigo (BPPV): Unlikely given bilateral weakness, but BPPV is triggered by head position changes relative to gravity and diagnosed with Dix-Hallpike maneuver 6, 3, 4

Critical Management Decisions

If Stroke is Confirmed

Antiplatelet therapy must be initiated immediately if vertebrobasilar stroke is diagnosed 1:

• Aspirin plus dipyridamole reduces recurrent vertebrobasilar strokes (5.7% vs 10.8% with placebo) 1
• Annual stroke rates for symptomatic vertebral/basilar stenosis are 8-11% 1
• Revascularization may be considered for severe stenosis in a multidisciplinary vascular team discussion 1

If Imaging is Negative

Consider functional neurological disorder only after comprehensive neurological evaluation excludes organic pathology 6. However, bilateral lower limb weakness with blurred vision makes functional etiology less likely.

Common Pitfalls to Avoid

• Do not rely on symptom quality alone (vertigo vs. lightheadedness) to guide diagnosis—timing and triggers are more reliable 3, 4
• Do not obtain CT head alone in patients with suspected posterior circulation pathology—it misses most posterior fossa lesions 6
• Do not delay imaging for extensive bedside testing if stroke is suspected—time is brain 1
• Do not dismiss bilateral symptoms as benign—peripheral vestibular disorders cause unilateral symptoms, while bilateral findings suggest central pathology 3, 5

Follow-Up Considerations

If vertebrobasilar disease is identified, serial noninvasive imaging (MRA/CTA) is recommended to assess disease progression and exclude new lesions 1, 2. Annual stroke risk after vertebral artery intervention remains approximately 3% 1.