What are the signs and symptoms of a bilateral medullary infarction?

Bilateral Medullary Infarct: Signs and Symptoms

Bilateral medial medullary infarction presents with a characteristic triad of quadriplegia, bulbar palsy, and respiratory failure, often progressing rapidly within days of onset and carrying high mortality and morbidity rates.

Core Clinical Presentation

The clinical syndrome of bilateral medullary infarction is distinctive and severe 1:

Motor Deficits

• Quadriplegia or quadriparesis (78.4% of cases) - the most common presenting feature
• Initially may present as flaccid weakness that can mimic Guillain-Barré syndrome 2
• Progressive weakness developing over hours to days
• Asymmetric weakness patterns are common

Bulbar Symptoms

• Dysarthria (48.6% of cases) - slurred or difficult speech
• Hypoglossal nerve palsy (40.5% of cases) - tongue weakness/deviation
• Dysphagia - swallowing difficulties with high aspiration risk
• Bilateral vocal cord paralysis causing stridor (rare but reported) 3

Respiratory Complications

• Central respiratory failure - the most life-threatening complication
• Prolonged apnea episodes
• Irregular breathing patterns
• Occurs in approximately 75% of bilateral cases, particularly with long lesions extending ventral to dorsal 4
• May develop suddenly, requiring emergency intubation

Additional Neurological Features

• Sensory disturbances - hemibody or bilateral sensory loss
• Nystagmus
• Dizziness and vertigo - often initial presenting symptoms
• Urinary retention
• Preserved consciousness initially (distinguishes from hemispheric strokes)

Temporal Pattern and Progression

Critical pitfall: Initial brain imaging may be normal 2. The condition characteristically shows:

• Acute onset with dizziness or unsteadiness
• Stepwise deterioration over 1-3 days
• Progressive development of quadriplegia by day 2-3
• Respiratory failure typically within the first week
• Follow-up MRI on days 3-6 reveals the characteristic "heart sign" or "V-shape" pattern on diffusion-weighted imaging 5, 6

High-Risk Clinical Indicators

Monitor intensively for deterioration 7:

• Depression in level of consciousness
• Glasgow Coma Scale score <12 on admission or decline ≥2 points
• Pupillary abnormalities: anisocoria, pinpoint pupils
• Loss of oculocephalic responses
• Bradycardia (indicates brainstem compression)
• Sudden apnea

Complications Requiring Immediate Recognition

Respiratory Management

• Aspiration pneumonia - develops in majority of cases due to bulbar dysfunction 8
• Ineffective cough and secretion clearance
• Acute respiratory failure requiring mechanical ventilation
• May require tracheostomy for prolonged airway management

Pulmonary Infection

Significantly more common in patients with respiratory failure - requires aggressive respiratory physiotherapy including mechanical insufflation-exsufflation 8, 9

Distinguishing Features from Other Conditions

Unlike Guillain-Barré syndrome (which it may initially mimic):

• Presence of bulbar symptoms from onset
• Central respiratory pattern (not peripheral)
• Nystagmus and other brainstem signs
• Bilateral medullary lesions on follow-up MRI 2

Unlike hemispheric strokes:

• Bilateral motor involvement
• Preserved consciousness initially
• Prominent bulbar and respiratory symptoms
• Characteristic "heart-shaped" or "fidget spinner" MRI pattern 5, 6

Prognosis

The clinical outcome is typically poor 1:

• Inpatient mortality: 23.8%
• Dependency rate: 61.9%
• 12-month case fatality remains high
• Survivors often require prolonged rehabilitation with persistent severe disability

Monitoring Recommendations

Clinicians should frequently monitor for level of arousal and new brainstem signs in patients with medullary stroke at high risk for deterioration (Class I recommendation) 7. Specific attention to:

• Respiratory rate and pattern every 1-2 hours
• Oxygen saturation continuously
• Bulbar function and aspiration risk
• Pupillary responses
• Motor strength progression
• Development of pulmonary complications

The key to diagnosis is maintaining high clinical suspicion when patients present with progressive quadriplegia and bulbar symptoms, even with initially normal imaging, and obtaining repeat MRI within 3-6 days to capture the characteristic bilateral medial medullary lesions.