Infectious Vasculopathies and Stroke

Infections remain an underdiagnosed but treatable cause of stroke, particularly in younger patients and the immunocompromised. Infectious vasculopathies encompass a diverse group of conditions—from direct viral invasion of vessel walls (VZV, HIV) to basilar meningitis with secondary arteritis (TB, syphilis, fungi) to septic embolism (endocarditis). Recognition is critical because these strokes require pathogen-specific therapy in addition to standard stroke care, and delayed diagnosis leads to recurrence and worse outcomes.

When to Suspect an Infectious Vasculopathy

Infectious causes should be considered in stroke patients with:

• Young age (<50 years) without traditional vascular risk factors
• Immunocompromised state (HIV, transplant, chemotherapy, biologics)
• Recent or concurrent infection (rash, fever, meningismus)
• Herpes zoster, especially ophthalmic distribution (4.5× increased stroke risk)
• Cranial nerve palsies (especially CN II, VI, VII, VIII)
• Altered mental status or encephalopathy
• Multifocal infarcts in multiple vascular territories
• Imaging showing vessel wall enhancement or basilar meningeal enhancement
• CSF pleocytosis or elevated protein

Varicella Zoster Virus (VZV) Vasculopathy

VZV vasculopathy is likely the most common infectious cause of stroke, though frequently underdiagnosed. The virus spreads transaxonally from cranial nerve ganglia to cerebral arteries, producing a granulomatous arteritis with segmental stenosis and thrombosis. Both large and small vessels can be affected.

Clinical Features

• Temporal relationship: Average 4.1 months from rash to neurological symptoms (range: weeks to months)
• Herpes zoster ophthalmicus: Highest risk (affects V1 distribution → proximity to intracranial vessels)
• No rash in 37%: Absence of rash does not exclude VZV vasculopathy
• Vessel involvement: Both large (50%) and small (37%) arteries; 13% large only
• Prodromal symptoms: Cranial nerve palsies (CN III, IV, VI, VII) may precede stroke
• Immunocompromised: Higher risk and more severe disease

Diagnosis

• CSF anti-VZV IgG: Most sensitive test (~93% sensitivity); indicates intrathecal antibody synthesis
• CSF VZV PCR: Specific but less sensitive (~30% after 7 days); best in early disease
• CSF profile: Mononuclear pleocytosis (<100 cells) in 67%; elevated protein; oligoclonal bands may be present
• MRI: Multifocal infarcts at grey-white matter junctions; lesions may enhance
• Vascular imaging: Segmental stenosis, "beading," occlusion; both anterior and posterior circulation
• HR-VWI: Vessel wall enhancement and thickening

Treatment

• Acyclovir: IV 10–15 mg/kg every 8 hours for 14–21 days
• Oral transition: Valacyclovir 1g TID may follow IV course for prolonged treatment
• Corticosteroids: Role uncertain; often added for severe vasculitis, but no RCT data
• Antiplatelets: Aspirin generally recommended for secondary prevention
• Prognosis: ~67% stabilize or improve with treatment

HIV-Associated Vasculopathy

HIV infection increases stroke risk through multiple mechanisms. "HIV vasculopathy" encompasses several distinct phenotypes, and opportunistic co-infections add further complexity.

Mechanisms and Phenotypes

• Non-atherosclerotic intracranial stenosis: Direct HIV-mediated endothelial injury
• Dolichoectasia and fusiform aneurysms: Vessel wall remodeling, particularly in children
• Accelerated atherosclerosis: Chronic inflammation + metabolic effects of some antiretrovirals
• IRIS-related vasculitis: Inflammatory syndrome in first 6 months after cART initiation
• Opportunistic infections: VZV, TB, cryptococcus, syphilis, CMV—all more common in HIV
• Cardioembolism: HIV cardiomyopathy, marantic endocarditis
• Coagulopathy: Protein S deficiency, antiphospholipid antibodies

Clinical Features

• Stroke patients with HIV are younger and have fewer traditional risk factors
• Both ischemic and hemorrhagic stroke occur
• Low CD4 count associated with higher stroke risk
• IRIS-related stroke: Consider in patients with new/worsening symptoms within 6 months of starting cART, especially with low CD4 and suppressed viral load

Management

• Combined antiretroviral therapy (cART): Cornerstone of management; consider high CNS penetration regimens
• Aspirin: Recommended for secondary prevention
• Risk factor control: Aggressive management of hypertension, diabetes, dyslipidemia
• Screen for co-infections: Syphilis, VZV, TB, cryptococcus
• IRIS management: Corticosteroids may be considered in severe cases (limited evidence)

Neurosyphilis (Meningovascular Syphilis)

Syphilis is resurgent globally, and neurosyphilis remains the "great imitator." Meningovascular syphilis causes an endarteritis obliterans with concentric vessel wall thickening, most commonly affecting the MCA and basilar artery.

Clinical Features

• Prodrome: Headache, personality changes, dizziness, insomnia may precede stroke by days to weeks
• Sudden onset: "Syphilitic apoplexy" in >75% of cases
• Vessel predilection: MCA, basilar artery, and their branches most commonly affected
• Young patients: Consider in any stroke patient <50 without traditional risk factors
• HIV co-infection: Present in 5–16% of syphilis cases; accelerates progression

Diagnosis

• Serum screening: Treponemal tests (FTA-ABS, TP-PA) are sensitive; RPR/VDRL for disease activity
• CSF-VDRL: Highly specific but sensitivity only 30–70%; positive result is diagnostic
• CSF findings: Lymphocytic pleocytosis, elevated protein, positive VDRL
• HR-VWI: Concentric vessel wall enhancement (distinguishes from atherosclerosis)
• Angiography: Segmental stenosis, typically MCA or basilar

Treatment

• Penicillin G: IV 18–24 million units/day (3–4 million units q4h) for 10–14 days
• Penicillin allergy: Ceftriaxone 2g IV daily × 10–14 days (desensitization preferred if possible)
• Antiplatelets: Aspirin recommended for secondary stroke prevention
• Corticosteroids: May be considered for severe inflammation (limited evidence)
• Follow-up: Repeat CSF at 6 months; retreatment if CSF WBC fails to normalize

Tuberculous Meningitis (TBM)

TBM causes a basilar meningitis with thick inflammatory exudates that encase and inflame the vessels at the base of the brain. Stroke occurs in 15–57% of cases, primarily affecting perforator vessels supplying the basal ganglia, thalamus, and internal capsule.

Pathophysiology

• Basilar exudates: Inflammatory material surrounds vessels of the Circle of Willis
• Arteritis: Present in up to 77% of autopsy cases
• Vasospasm: MCA, terminal ICA, basilar artery most commonly affected
• Perforator involvement: Medial and lateral lenticulostriate arteries → basal ganglia infarcts

Clinical Features

• Subacute presentation: Days to weeks of headache, fever, meningismus
• Cranial nerve palsies: CN II, VI, VII, VIII commonly affected
• Stroke timing: 83% occur within 3 months of meningitis onset; may be presenting feature
• Infarct location: Basal ganglia (57%), thalamus, internal capsule most common
• Hydrocephalus: Complicates ~1/3 of cases

Diagnosis

• CSF: Lymphocytic pleocytosis (typically 100–500 cells), elevated protein, low glucose
• CSF ADA: Adenosine deaminase often elevated (>10 U/L suggestive)
• GeneXpert MTB/RIF: Rapid PCR; sensitivity ~60–70% in CSF (Xpert Ultra ~77%)
• AFB smear: Low sensitivity (~10–30%); examine large CSF volume
• MRI: Basal meningeal enhancement, hydrocephalus, basal ganglia infarcts, tuberculomas
• Chest imaging: ~50% have concurrent pulmonary TB

Treatment

• Anti-TB therapy: Intensive phase (2 months): Isoniazid + Rifampin + Pyrazinamide + Ethambutol; Continuation phase (10 months): Isoniazid + Rifampin
• Adjunctive dexamethasone: Reduces mortality in HIV-negative patients (tapered over 6–8 weeks)
• Aspirin: RCTs suggest reduced infarcts and mortality; optimal dose uncertain (81–150 mg studied); not yet universal standard but increasingly used
• Hydrocephalus: May require ventriculoperitoneal shunt or external ventricular drain

Fungal Vasculopathies

Fungal CNS infections primarily affect immunocompromised patients and carry high mortality. Angioinvasion with hemorrhagic infarcts is characteristic.

Aspergillus

• Most important fungal cause of stroke
• Risk factors: Neutropenia, stem cell/solid organ transplant, prolonged corticosteroids
• Mechanism: Angioinvasive → hemorrhagic infarcts, mycotic aneurysms, abscess
• Imaging: Hemorrhagic infarcts, ring-enhancing lesions, dural enhancement
• Diagnosis: Serum/CSF galactomannan; brain biopsy often needed
• Treatment: Voriconazole (first-line); surgical debridement if accessible; high mortality (50–90%)

Mucormycosis

• Risk factors: Diabetic ketoacidosis, iron overload, deferoxamine therapy
• Rhino-orbital-cerebral spread: Paranasal sinus → orbit → cavernous sinus → ICA
• Imaging: Sinus opacification, orbital apex involvement, ICA thrombosis/invasion
• Treatment: Liposomal amphotericin B + aggressive surgical debridement; correct underlying conditions

Cryptococcus

• Common in HIV with CD4 <100
• Mechanism: Basilar meningitis (similar to TB) with secondary vasculopathy
• Diagnosis: CSF cryptococcal antigen (highly sensitive), India ink
• Treatment: Amphotericin B + flucytosine induction → fluconazole maintenance

Lyme Neuroborreliosis

Lyme disease can cause a lymphocytic meningitis with secondary vasculitis, though stroke is a rare complication. It should be considered in endemic regions (Northeast US, Upper Midwest, Northern Europe).

Clinical Features

• Meningovascular arteritis: Often affects posterior circulation
• Associated findings: Facial palsy (can be bilateral), radiculopathy, lymphocytic meningitis
• History: Erythema migrans rash, tick exposure in endemic area

Diagnosis

• Two-tier serology: ELISA screening → Western blot confirmation
• CSF Lyme antibody index: Demonstrates intrathecal antibody synthesis
• CSF: Lymphocytic pleocytosis, elevated protein

Treatment

• Ceftriaxone: 2g IV daily for 14–28 days
• Alternatives: Penicillin G, cefotaxime

COVID-19 and Stroke

SARS-CoV-2 infection has been associated with increased stroke risk, though the mechanisms remain incompletely understood and true "vasculitis" appears rare.

Proposed Mechanisms

• Hypercoagulability: Elevated D-dimer, fibrinogen; COVID-associated coagulopathy
• Endothelial dysfunction: ACE2 receptor expression on endothelium; direct viral injury
• Cardioembolism: COVID-related myocarditis, arrhythmias
• Cytokine storm: Systemic inflammation in severe disease
• Critical illness: Hypoxia, hypotension, immobilization

Clinical Considerations

• Most COVID-associated strokes are likely cardioembolic or related to critical illness/hypercoagulability
• True CNS vasculitis appears rare; avoid overcalling "vasculitis" without supporting evidence
• Evidence is largely observational; causation difficult to establish
• Standard stroke workup and treatment apply; consider prophylactic anticoagulation in hospitalized COVID patients

Infective Endocarditis

Neurological complications occur in 25–70% of left-sided infective endocarditis, making it the most common extracardiac complication. While technically embolic rather than vasculopathic, endocarditis-related stroke requires specific management considerations.

Neurological Manifestations

• Ischemic stroke: 40–50% of neurological complications; septic emboli from vegetations
• Hemorrhagic stroke: Hemorrhagic transformation, septic arteritis, mycotic aneurysm rupture
• Mycotic aneurysms: ~2% of IE cases; distal vessel location typical; >50% rupture
• Silent lesions: MRI shows cerebral abnormalities in up to 80% (many asymptomatic)
• Meningitis: 5% of neurological complications
• Brain abscess: ~2% of cases

Diagnosis

• Echocardiography: TTE first; TEE if negative with high suspicion or for surgical planning
• Blood cultures: At least 3 sets before antibiotics
• Brain MRI: Superior to CT; reveals multiple lesions in most patients
• Vascular imaging: CTA or MRA to screen for mycotic aneurysms, especially before surgery
• Modified Duke criteria: For diagnosis of endocarditis

Management Considerations

• Antibiotics: Pathogen-directed IV therapy for 4–6 weeks
• Anticoagulation:
  • Discontinue for 10–14 days after moderate-large ischemic stroke
  • For smaller/asymptomatic infarcts: May continue with heparin and close monitoring
  • Contraindicated if mycotic aneurysm present
• Timing of cardiac surgery:
  • Ischemic stroke: Do not delay surgery if otherwise indicated (heart failure, uncontrolled infection, high embolic risk)
  • Intracranial hemorrhage: Delay surgery 2–3 weeks if possible
  • Comatose or severe deficit: Surgery may be contraindicated
• Mycotic aneurysms: Endovascular treatment preferred if no severe mass effect; serial imaging if managed conservatively

Other Infectious Causes

Bacterial Meningitis

• Stroke occurs in 15–25% of bacterial meningitis cases
• Mechanism: Contiguous arteritis from subarachnoid inflammation
• Pneumococcal meningitis has highest stroke risk
• Treatment: Appropriate antibiotics + dexamethasone (before or with first antibiotic dose)

Chagas Disease

• Endemic in Latin America (Trypanosoma cruzi)
• Mechanism: Chagasic cardiomyopathy → cardioembolic stroke
• Consider in immigrants from endemic regions with cardiomyopathy and stroke

Diagnostic Approach

The following algorithm guides workup when infectious vasculopathy is suspected:

Comparison of Infectious Vasculopathies

Guideline Recommendations

Key Takeaways for Clinical Practice

• Maintain high suspicion in young patients, immunocompromised hosts, and those with atypical presentations
• Lumbar puncture is essential when infectious vasculopathy is suspected—CSF pattern guides diagnosis
• VZV is underdiagnosed: Request CSF anti-VZV IgG (not just PCR); can occur without rash
• Screen for HIV in all patients with neurosyphilis or unexplained young stroke
• Treat early: Delayed treatment leads to recurrence and worse outcomes
• Avoid thrombolysis in endocarditis: High hemorrhage risk from septic emboli and mycotic aneurysms
• Multidisciplinary care: Involve infectious disease, neurology, and cardiology/cardiac surgery as needed

References

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