What are the key features and management strategies for a pontine stroke?

Pontine Stroke Features

Pontine strokes present with distinctive clinical syndromes based on the specific vascular territory involved, with ventral pontine infarcts causing motor deficits and tegmental infarcts producing eye movement disorders, cranial nerve palsies, and sensory disturbances. 1

Clinical Presentation by Anatomical Location

Ventral Pontine Infarcts (Most Common)

• Motor deficits range from mild hemiparesis in ventrolateral pontine syndrome to severe hemiparesis with bilateral ataxia and dysarthria in ventromedial pontine syndrome 1
• Approximately three-fourths of patients with ventral infarcts also demonstrate mild tegmental dysfunction despite the primarily ventral location 1
• Large ventral infarcts are associated with severe clinical symptomatology, progressive or fluctuating course, and risk of local recurrence 1

Tegmental Pontine Infarcts

• Present with eye movement disorders (including horizontal gaze palsies), cranial nerve palsies, and sensory disturbances 2, 1
• Usually accompanied by mild motor deficits rather than severe weakness 1
• Only one-fourth of patients present with classic alternating deficits, and these rarely correspond to textbook pontine syndromes 1

Bilateral Ventrotegmental Pontine Infarcts

• Present with acute pseudobulbar palsy, bilateral motor deficits, and tegmental signs 1
• This pattern represents the most severe presentation 1

Pontine Warning Syndrome: A Critical Recognition

Pontine warning syndrome consists of crescendo transient ischemic attacks with stereotyped, frequent, short-lasting episodes of focal neurological deficits that fluctuate with blood pressure changes and signal imminent basilar artery branch infarction. 3, 2

Key Features

• Fluctuating neurologic status that can vary dramatically (e.g., National Institutes of Health Stroke Scale ranging from 3 to 15 within hours) 2
• Episodes of complete bilateral horizontal conjugate gaze palsy lasting minutes, with preserved consciousness, vertical gaze, and convergence 2
• Blood pressure-dependent symptoms: neurological worsening correlates with hypotension, improvement with permissive hypertension 3
• Recurrent stereotyped episodes of motor or sensory dysfunction, dysarthria, or ophthalmoplegia 2

Mechanism and Management

• Caused by basilar artery branch disease with intermittent hypoperfusion of terminal arteries lacking sufficient collateral flow 3, 2
• Avoid hypotension/hypoperfusion during treatment; maintain asymptomatic normotension to permissive hypertension 3
• Standard thrombolytic therapy may not prevent continued fluctuations for 12+ hours after administration 2

Pontine Hemorrhage Presentations

Centro-Paramedian Pontine Hemorrhage (Most Severe)

• Presents with coma, hypertensive crisis, respiratory failure, cardiac arrhythmia, miosis, and tetraparesis 4
• Mortality approaches 97% (30 of 31 patients died in one series) 4
• Frequently involves mesencephalon extension and fourth ventricle rupture 4

Dorsotegmental or Hemipontine Hemorrhage (Better Prognosis)

• Presents with complex neuro-ophthalmologic signs, cranial nerve lesions, and ataxia or hemiparesis 4
• All patients survived in reported series, some without neurological deficit 4
• Arterial hypertension remains the most common risk factor 4

Stroke Mechanisms and Recurrence Patterns

Basilar Artery Branch Disease (Most Common)

• Accounts for 44% of isolated pontine infarcts 1
• Particularly associated with large ventral infarcts, progressive/fluctuating course, and local recurrence 1
• 61.2% of recurrent pontine infarctions occur at the same site as the index stroke 5
• Branch atheromatous disease-induced index infarction is 6 times more likely to recur with the same mechanism (OR 6.056) 5

Small-Artery Disease

• Accounts for 25% of isolated pontine infarcts 1
• Associated with small ventral or tegmental infarcts and rapidly improving lacunar syndromes 1

Large-Artery Stenosis and Cardioembolism

• Less common than in other posterior circulation strokes, accounting for 22% and 3% respectively 1

Acute Management Priorities

Initial Stabilization

• Immediate brain imaging (CT or MRI) within 24 hours to distinguish ischemic from hemorrhagic stroke 6, 7
• Assess for respiratory compromise requiring intubation, particularly with centro-paramedian hemorrhages 8, 4
• Monitor for cardiac arrhythmias during the first 24 hours 8, 6

Blood Pressure Management

• For ischemic pontine stroke without thrombolysis: avoid antihypertensive treatment unless systolic BP >220 mmHg or diastolic >120 mmHg 6, 9
• For pontine warning syndrome: maintain permissive hypertension to ensure adequate perfusion 3
• For pontine hemorrhage with hypertension: lower systolic BP to target of 140 mmHg (strictly avoiding <110 mmHg) within 6 hours 8

Thrombolytic Therapy Considerations

• Intravenous alteplase within 4.5 hours for eligible ischemic stroke patients 6, 7
• Be aware that fluctuations may persist for 12+ hours after thrombolysis in pontine warning syndrome 2
• Maintain BP <180/105 mmHg for patients receiving thrombolysis 8, 6

Stroke Unit Care and Monitoring

• Admit all pontine stroke patients to a geographically defined stroke unit with specialized interdisciplinary staff 8, 6, 7
• Monitor neurological status frequently during the first 24-48 hours, as approximately 25% of stroke patients deteriorate during this period 8
• Perform swallowing screening within 24 hours using a validated tool before allowing oral intake 6, 7

Prognosis and Recovery

• Recovery is good in two-thirds of patients with isolated pontine infarcts 1
• Worse outcomes are associated with large ventral infarcts, bilateral involvement, and centro-paramedian hemorrhages 4, 1
• Dorsotegmental and hemipontine hemorrhages have significantly better prognosis than centro-paramedian hemorrhages 4

Common Pitfalls to Avoid

• Do not dismiss fluctuating symptoms as functional or non-organic; they may represent pontine warning syndrome requiring urgent intervention 3, 2
• Avoid aggressive blood pressure lowering in acute ischemic pontine stroke, particularly with pontine warning syndrome, as this worsens perfusion 3
• Do not expect classic textbook pontine syndromes; only 25% present with alternating deficits 1
• Recognize that tegmental signs often accompany ventral infarcts, making pure syndromes uncommon 1