What are the typical presentation, diagnostic work‑up, and acute treatment recommendations for lateral medullary (Wallenberg) syndrome in an adult with vascular risk factors?

Lateral Medullary (Wallenberg) Syndrome: Clinical Approach

Typical Clinical Presentation

Lateral medullary syndrome presents with a characteristic constellation of vertigo, ataxia, ipsilateral facial sensory loss, dysphagia, and contralateral body sensory deficits—recognizing this pattern is critical because posterior fossa strokes are notoriously difficult to detect on initial CT imaging. 1, 2

The classic symptoms include:

• Vertigo and nystagmus due to vestibular nucleus involvement 1, 3, 2
• Ipsilateral ataxia from inferior cerebellar peduncle or cerebellar involvement 2, 4, 5
• Ipsilateral facial sensory loss (pain and temperature) when the spinal trigeminal nucleus is affected 1, 5
• Contralateral body sensory loss (pain and temperature) from spinothalamic tract involvement 5
• Dysphagia and dysarthria resulting from cranial nerves IX and X nuclei damage 1, 3, 2
• Ipsilateral Horner's syndrome (ptosis, miosis, anhidrosis) from descending sympathetic pathway disruption 2, 4, 5
• Hiccups are common and result from medullary irritation 2

The syndrome most commonly results from posterior inferior cerebellar artery (PICA) occlusion, though vertebral artery occlusion can produce identical findings. 3, 2, 6 Vascular risk factors including hypertension, diabetes, and smoking are typical. 3, 2, 6

Diagnostic Work-Up

CT scanning should NOT be routinely ordered as initial imaging, as posterior fossa ischemic strokes are difficult to detect on CT with sensitivity as low as 10%. 1 This is a critical pitfall that leads to missed diagnoses and delayed treatment. 6

Imaging Algorithm:

• MRI with diffusion-weighted imaging (DWI) is mandatory and represents the gold standard for diagnosis 1, 2, 6
• Thin-section coronal DWI detects nearly 25% more acute brainstem infarcts than standard axial DWI 1
• False-negative DWI can occur with very small ischemic brainstem infarcts, so clinical suspicion must remain high even with initial negative imaging 1
• MRI provides superior visualization of the lateral medulla and can confirm the characteristic wedge-shaped infarct 2, 6

Additional Diagnostic Evaluation:

• Immediate swallowing assessment is mandatory, as dysphagia occurs when cranial nerves IX and X nuclei are affected 1
• Vascular imaging (CT angiography or MR angiography) to identify vertebral or PICA occlusion 2
• Cardiac evaluation including ECG and echocardiography to identify cardioembolic sources 2
• Vertebral artery Doppler ultrasound 2

Acute Treatment Recommendations

Acute stroke management follows standard ischemic stroke protocols, with particular attention to aspiration risk and blood pressure management. 7, 2

Immediate Management:

• Antiplatelet therapy with aspirin should be initiated unless contraindicated, as administration of antithrombotic agents before discharge is a quality-of-care indicator for stroke treatment 7, 2
• Low molecular weight heparin may be used in the acute phase, particularly if cardioembolic source is suspected 2
• Blood pressure management requires careful titration—avoid aggressive lowering in acute phase unless severely elevated 7

Critical Supportive Care:

• NPO status with immediate swallowing evaluation before any oral intake, as dysphagia is common and aspiration risk is high 1, 3
• Nasogastric, nasoduodenal, or PEG feeding should be initiated for patients who cannot safely take food and fluids orally 7, 3
• The timing of PEG placement depends on expected recovery trajectory, but should not be delayed if dysphagia persists beyond 7-10 days 7
• Vestibular symptom management with antiemetics for nausea/vomiting 3, 2
• Deep vein thrombosis prophylaxis with intermittent external compression devices or anticoagulants 7

Secondary Prevention:

• Aggressive vascular risk factor modification including treatment of hypertension, diabetes, and hyperlipidemia 7
• Smoking cessation 7
• Long-term antiplatelet therapy 7

Prognosis Considerations:

The small size of these infarcts and lack of hemorrhagic transformation typically suggest favorable prognosis, though recovery may take weeks to months. 1, 2 Early hospitalization, accurate diagnosis, and appropriate supportive care significantly improve outcomes. 2

Common pitfall: Misdiagnosing as peripheral vertigo or vestibular neuritis due to prominent vestibular symptoms—always consider central causes in patients with vascular risk factors, and never rely on CT alone to exclude posterior circulation stroke. 1, 6