What are the typical signs, diagnostic steps, and acute and secondary treatment recommendations for Wallenberg (lateral medullary) syndrome in an adult with vascular risk factors?

Wallenberg Syndrome (Lateral Medullary Syndrome)

Clinical Presentation

Wallenberg syndrome presents with a characteristic constellation of symptoms including vertigo, ataxia, ipsilateral facial sensory loss, dysphagia, dysarthria, Horner's syndrome, and contralateral body sensory deficits due to lateral medullary infarction, most commonly from posterior inferior cerebellar artery (PICA) occlusion. 1, 2, 3

Cardinal Signs to Identify

• Vestibular symptoms: Acute vertigo, nystagmus, and severe imbalance are prominent early features due to vestibular nucleus involvement 4, 1, 2
• Cranial nerve deficits:
  • Ipsilateral facial pain and sensory loss (CN V involvement) 4, 3
  • Ipsilateral Horner's syndrome (ptosis, miosis, anhidrosis) from descending sympathetic tract damage 2, 3
  • Dysphagia and dysarthria from CN IX and X nuclei involvement 4, 2, 3
  • Loss of ipsilateral gag reflex 3
• Motor findings: Ipsilateral limb ataxia without significant weakness, though contralateral hemiparesis may occur 4, 2, 3
• Sensory dissociation: Ipsilateral facial hypoalgesia/thermoanaesthesia with contralateral body hypoalgesia/thermoanaesthesia (classic crossed pattern) 2, 3
• Additional symptoms: Hiccups, nausea, vomiting, and headache are common 1, 2, 5

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Diagnostic Approach

Imaging Strategy

Do NOT order CT scanning as initial imaging—posterior fossa ischemic strokes have sensitivity as low as 10% on CT. 4

MRI with diffusion-weighted imaging (DWI) is the gold standard for diagnosis, though initial MRI may be falsely negative in the first 24-48 hours. 2, 6

• Thin-section coronal DWI detects nearly 25% more acute brainstem infarcts than standard axial DWI 4
• If clinical suspicion remains high despite negative initial MRI, repeat imaging in 2-3 days 6, 5
• MRI typically shows hyperintensity on T2-weighted FLAIR and DWI in the lateral medulla 2, 6

Vascular Workup

• Assess for vasculopathic risk factors: hypertension, diabetes mellitus, hyperlipidemia, smoking history 2, 5
• Obtain ECG and echocardiography to evaluate for cardioembolic sources, particularly atrial fibrillation 1, 2
• Consider vertebral artery imaging (MRA or CTA) to identify PICA or vertebral artery occlusion 2

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Acute Management

Immediate Interventions

Initiate antiplatelet therapy with aspirin in all eligible patients immediately, as early antithrombotic administration is a recognized quality-of-care indicator. 4

Keep patients NPO and perform immediate swallowing assessment—dysphagia occurs when CN IX and X nuclei are affected and poses aspiration risk. 4, 1

• If oral intake is unsafe, provide nutrition via nasogastric, nasoduodenal, or PEG tubes 4
• Do not postpone PEG placement if dysphagia persists beyond 7-10 days 4

Blood Pressure Management

• Manage blood pressure cautiously during the acute phase, avoiding aggressive reduction unless severely elevated, to preserve cerebral perfusion 4
• Target permissive hypertension in the first 24-72 hours unless contraindicated 4

Supportive Care

• Provide deep-vein thrombosis prophylaxis using intermittent pneumatic compression devices or anticoagulant medication 4
• Manage vestibular symptoms with antiemetics and vestibular suppressants as needed 1, 2
• Early physical and occupational therapy for ataxia and balance deficits 2, 6

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Secondary Prevention

Implement aggressive modification of vascular risk factors to reduce recurrence risk, including control of hypertension, diabetes, and hyperlipidemia. 4

• Continue long-term antiplatelet therapy (aspirin or clopidogrel) after the acute episode 4
• Advise and support smoking cessation 4
• If atrial fibrillation is identified, initiate anticoagulation therapy 1
• Consider statin therapy regardless of baseline cholesterol levels for stroke prevention 4

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Prognosis and Rehabilitation

Wallenberg syndrome carries a favorable prognosis if early hospitalization and treatment are applied, with many patients showing significant improvement within days to weeks. 2, 6

• The small size of these infarcts and lack of hemorrhagic transformation suggest favorable outcomes 4
• Dysarthria and dysphagia often improve substantially within the first week of treatment 2
• Early detection, management, and rehabilitation are critical for improving post-stroke recovery 6
• Physical rehabilitation should begin as soon as the patient is medically stable 2

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Critical Pitfalls to Avoid

• Do not dismiss the diagnosis based on negative initial CT or MRI—repeat imaging if clinical suspicion remains high 4, 6, 5
• Do not allow oral intake without formal swallowing assessment—aspiration pneumonia is a major complication 4, 1
• Do not misattribute vertigo and vomiting to benign peripheral vestibular disorders—consider brainstem stroke in patients with vascular risk factors 1, 5
• Do not delay antiplatelet therapy while awaiting complete vascular workup 4