Non-Atherosclerotic Arteriopathies in Stroke

Non-atherosclerotic arteriopathies represent a diverse group of structural vascular disorders that cause ischemic stroke through mechanisms distinct from traditional atherosclerosis. These conditions are particularly important in younger patients (age <50), where they account for 15–25% of ischemic strokes. Recognizing these entities is critical because they often require different diagnostic approaches, treatment strategies, and long-term management compared to atherosclerotic disease.

This article focuses on structural and mechanical arteriopathies — conditions affecting the arterial wall architecture or causing mechanical compromise of cerebral blood flow. Inflammatory vasculitides, hypercoagulable states (e.g., antiphospholipid syndrome), and genetic small vessel diseases (e.g., CADASIL) are covered in separate dedicated articles.

1. Dissection-Related Arteriopathies

1.1 Cervical Artery Dissection

Cervical artery dissection (CeAD) — involving the internal carotid artery (ICA) or vertebral artery (VA) — is the leading cause of ischemic stroke in young adults, accounting for 10–25% of strokes in patients under 50. The annual incidence is approximately 2.5–3 per 100,000 for carotid dissection and 1–1.5 per 100,000 for vertebral dissection.

Pathophysiology: Dissection occurs when an intimal tear allows blood to enter the arterial wall, creating an intramural hematoma. This can cause stroke through two mechanisms: (1) luminal stenosis or occlusion leading to hemodynamic compromise, or (2) thromboembolism from the disrupted intimal surface or pseudoaneurysm.

Clinical Presentation:

• ICA dissection: Unilateral headache, neck pain, partial Horner syndrome (ptosis and miosis without anhidrosis), pulsatile tinnitus, cranial nerve palsies (XII most common), and ischemic stroke in carotid territory
• VA dissection: Occipital or posterior neck pain, posterior circulation stroke, lateral medullary syndrome
• Pain often precedes stroke by hours to days — a critical window for diagnosis

Imaging:

• CTA: "String sign" (tapered stenosis), "flame sign" (tapered occlusion), intimal flap, pseudoaneurysm
• MRI/MRA: Fat-saturated T1 axial images show crescent-shaped intramural hematoma; 3D TOF MRA demonstrates stenosis or occlusion
• DSA: Gold standard but rarely needed; reserved for equivocal cases or endovascular intervention

Antithrombotic Therapy

The choice between antiplatelet and anticoagulation therapy has been debated for decades. Four major studies inform current practice:

CADISS (2015, extended follow-up 2019): This randomized trial of 250 patients with symptomatic CeAD found no significant difference between antiplatelet therapy and anticoagulation. Stroke occurred in 2.5% of both groups at 3 months. Recanalization rates were similar (~60% complete). The trial was underpowered for stroke outcomes but established equipoise between strategies.

TREAT-CAD (2021): This trial randomized 194 patients to aspirin 300 mg daily vs. VKA (INR 2–3). The primary composite outcome (stroke, major hemorrhage, or death) occurred in 23% of the aspirin group vs. 15% of the VKA group. Importantly, all strokes occurred in the aspirin group (8% vs. 0%). Non-inferiority of aspirin was NOT demonstrated. Extended follow-up (TREAT-CAD 6-months) showed no ischemic strokes in either group from months 3–6, supporting transition to antiplatelet after the high-risk early period.

STOP-CAD (2024): This large observational study (n=3,636) compared antiplatelet (n=2,453) vs. anticoagulation (n=402). Overall, there was a trend toward lower stroke rates with anticoagulation (1.5% vs. 3.3%, p=0.059). Critically, subgroup analysis showed significant benefit of anticoagulation in patients with occlusive dissection (HR 0.40, 95% CI 0.18–0.88). Major hemorrhage rates were similar (~0.5–0.7%).

STOP-CAD tPA (2024): Analysis of 1,653 patients with CeAD presenting with acute ischemic stroke found that IVT was associated with better 90-day functional outcomes (mRS 0–2: aOR 1.67, 95% CI 1.23–2.28, p=0.001) without significantly increased symptomatic ICH. This supports that dissection is not a contraindication to IVT in eligible patients.

1.2 Fibromuscular Dysplasia

Fibromuscular dysplasia (FMD) is a non-inflammatory, non-atherosclerotic arteriopathy characterized by abnormal cell growth in arterial walls. It predominantly affects medium-sized arteries, with renal (60–75%) and cervicocephalic (25–30%) arteries most commonly involved.

Epidemiology: Based on data from the US Registry for Fibromuscular Dysplasia, FMD has a marked female predominance (~90%) with mean age at diagnosis of 52 years. Cervicocephalic FMD is present in approximately 15–20% of patients with spontaneous cervical artery dissection.

Classification:

• Multifocal FMD: "String of beads" appearance on angiography; most common type (~80%)
• Focal FMD: Concentric or tubular stenosis; more common in children

Stroke Mechanisms:

• Arterial dissection (FMD is present in 15–20% of spontaneous CeAD cases)
• Thromboembolism from irregular arterial surface
• Hemodynamic compromise from high-grade stenosis (rare)

Evaluation: When FMD is identified in one vascular bed, screening for multivessel involvement is recommended (head-to-pelvis CTA or MRA). Up to 50% of patients have involvement of multiple territories. Annual surveillance imaging is recommended.

Management:

• Antiplatelet therapy for stroke prevention
• Blood pressure control (target <130/80 mmHg)
• Surveillance imaging every 3–5 years or with new symptoms
• Endovascular intervention reserved for symptomatic high-grade stenosis or recurrent events

1.3 Connective Tissue Disorders

Hereditary connective tissue disorders predispose to arterial dissection and should be considered in patients with recurrent dissections, dissections at young age, or systemic features.

Vascular Ehlers-Danlos Syndrome (EDS Type IV):

• Caused by COL3A1 mutations affecting type III collagen
• Highest risk of arterial complications among EDS subtypes
• Spontaneous arterial dissection, aneurysm, and rupture
• Important: Avoid catheter-based angiography when possible due to high complication rates; use non-invasive imaging (CTA, MRA)

Marfan Syndrome: FBN1 mutations affecting fibrillin-1; aortic root dilation and dissection most common; cervicocephalic dissection less frequent.

Loeys-Dietz Syndrome: TGFBR1/TGFBR2 mutations; aggressive arterial disease with dissection and aneurysms at younger ages than Marfan.

2. Focal Intimal Abnormalities

2.1 Carotid Web

A carotid web is a shelf-like intimal projection at the posterior wall of the carotid bulb, considered a focal variant of intimal fibromuscular dysplasia. It creates a pocket of flow stasis that promotes local thrombus formation and subsequent embolism.

Epidemiology: Based on the CAROWEB registry and French cohort studies (Joux et al.), carotid web is increasingly recognized as a cause of cryptogenic stroke, particularly in women (62.9% in CAROWEB) and patients of African descent. Mean age at presentation is approximately 50 years. In the MR CLEAN registry analysis (Compagne et al.), carotid web was identified in 1.7% of patients with acute intracranial LVO stroke.

Recurrence Risk: The French Caribbean cohort (Joux et al., 2021) followed 92 patients with first-ever symptomatic carotid web for a mean of 50 months. Key findings:

• 20.7% experienced recurrent ipsilateral cerebral ischemic events (16 strokes, 3 TIAs)
• Annual recurrence rate: 5.1 events per 100 person-years
• Recurrence was associated with thrombus formation at the web on initial imaging

Imaging:

• CTA: Best visualized on sagittal reformats; thin linear filling defect arising from posterior bulb wall. Sagittal reconstructions are essential — carotid webs are frequently missed on axial imaging alone.
• DSA: "Septum" or shelf-like projection with contrast stasis
• Carotid duplex ultrasonography has poor sensitivity (<5% detection rate)

Management (based on CAROWEB registry data):

• Treatment is heterogeneous across centers; no randomized trials exist
• Medical therapy: Antiplatelet or anticoagulation; high failure rate with recurrence reported in multiple cohorts
• Revascularization: CEA (complete resection) or carotid stenting (dual-layer stents show promise)
• In CAROWEB, 53% underwent invasive treatment; those without vascular risk factors and milder strokes were more likely to receive intervention
• The high rate of invasive treatment reflects clinical concern that medical therapy alone is insufficient

3. Non-Inflammatory Vasoconstrictive Disorders

3.1 Reversible Cerebral Vasoconstriction Syndrome (RCVS)

RCVS is characterized by recurrent thunderclap headaches with reversible multifocal segmental vasoconstriction of cerebral arteries. It can cause ischemic stroke, convexity subarachnoid hemorrhage, and intracerebral hemorrhage.

Epidemiology: Based on the French cohort studies by Ducros et al. (2007, 67 prospective patients), RCVS affects predominantly women (64%) with mean age 42 years. RCVS accounts for approximately 0.26% of emergency department headache presentations.

Etiology (from Ducros et al.):

• Spontaneous: 37%
• Secondary (63%): Cannabis (most common), SSRIs, nasal decongestants, triptans, sympathomimetics, postpartum state, blood products

Clinical Features (French cohort outcomes):

• Recurrent thunderclap headaches in nearly all patients; headaches may recur over 1–4 weeks
• TIAs: 16%
• Ischemic stroke: 4%
• Convexity SAH: 22%
• Important temporal pattern: hemorrhagic events occur early; ischemic events occur later (typically second week)

Diagnosis — RCVS2 Score:

The RCVS2 score (Rocha et al., 2019) distinguishes RCVS from other arteriopathies, particularly primary angiitis of the CNS (PACNS):

• Score ≥5: 90% sensitivity, 99% specificity for RCVS
• Score ≤2: 85% sensitivity, 100% specificity for EXCLUDING RCVS
• Scores 3–4 are indeterminate; clinical judgment and follow-up imaging required

Management:

• Remove triggers (vasoactive substances)
• Calcium channel blockers (nimodipine, verapamil) — limited evidence but commonly used
• Avoid aggressive blood pressure lowering (may worsen ischemia)
• Corticosteroids are not recommended (may worsen outcomes)
• Condition is typically self-limited with resolution within 12 weeks

3.2 Postpartum Angiopathy

Postpartum angiopathy is considered a subset of RCVS occurring within 1–4 weeks of delivery. In the Ducros et al. cohort, postpartum cases represented 7.5% of RCVS. Management is similar to RCVS; prognosis is generally favorable.

4. Moyamoya and Moyamoya-Like Arteriopathies

4.1 Moyamoya Disease (Idiopathic)

Moyamoya disease is a progressive steno-occlusive arteriopathy affecting the terminal internal carotid arteries and their proximal branches. The name derives from the Japanese word for "puff of smoke," describing the hazy network of collateral vessels on angiography.

Epidemiology: Highest incidence in East Asian populations. Bimodal age distribution: first peak in childhood (5–10 years), second in adults (30–50 years). Female predominance.

Clinical Presentation:

• Children: Predominantly ischemic — TIAs, strokes, often triggered by hyperventilation, crying, or exertion
• Adults: Both ischemic and hemorrhagic — intracerebral hemorrhage from fragile collaterals occurs in up to 40%

Diagnostic Criteria: Stenosis or occlusion of terminal ICA and/or proximal ACA/MCA; abnormal vascular networks (moyamoya vessels) near occlusive lesions; bilateral involvement for definite diagnosis.

Surgical Revascularization — Evidence

JAM Trial (Japan Adult Moyamoya Trial, 2014): This multicenter RCT randomized 80 adult patients with hemorrhagic moyamoya to bilateral direct EC-IC bypass (STA-MCA) vs. conservative care over 5 years:

• Primary endpoint (adverse events): 14.3% surgical vs. 34.2% conservative (HR 0.39, p=0.057)
• Rebleeding: 11.9% surgical vs. 31.6% conservative (HR 0.36, p=0.052)
• Kaplan-Meier analysis: 3.2%/year vs. 8.2%/year; p=0.048
• Perioperative complications: 9.5%, mostly transient
• Conclusion: Direct EC-IC bypass reduces rebleeding in hemorrhagic moyamoya, though benefit was statistically marginal

For context — COSS Trial (2011): EC-IC bypass did NOT reduce stroke in patients with atherosclerotic carotid occlusion (21.0% vs. 22.7%, p=0.78). However, this population is distinct from moyamoya, and COSS results should not be extrapolated to moyamoya disease where revascularization remains the standard of care.

Management:

• Medical therapy alone is insufficient for symptomatic disease
• Antiplatelet therapy (aspirin) for ischemic symptoms
• Surgical revascularization is mainstay:
  • Direct bypass: STA-MCA anastomosis — immediate flow augmentation
  • Indirect bypass: EDAS, EMS, multiple burr holes — rely on neoangiogenesis over months
  • Indirect procedures often preferred in children (smaller vessels)
• Avoid hypotension, dehydration, hyperventilation

4.2 Moyamoya Syndrome (Secondary)

Moyamoya syndrome refers to moyamoya-pattern vasculopathy occurring in association with other conditions:

• Sickle cell disease — most common cause in Western populations
• Neurofibromatosis type 1 — ~6% develop moyamoya
• Down syndrome
• Radiation-induced vasculopathy

Sickle Cell Disease — Stroke Prevention Trials

Sickle cell disease (SCD) carries a 200–400 fold increased stroke risk compared to the general pediatric population. The evidence base for stroke prevention is robust:

STOP Trial (1998): The landmark trial establishing TCD screening and chronic transfusion for primary prevention. Children with SCD (HbSS or HbSβ0 thalassemia) and abnormal TCD (≥200 cm/s) were randomized to transfusion (target HbS <30%) vs. standard care:

• Stroke incidence: 0.9 vs. 10.7 per 100 patient-years
• 92% relative risk reduction (p<0.001)
• Trial stopped early for overwhelming benefit

STOP II Trial (2005): Tested whether transfusions could be discontinued after TCD normalized (≥30 months of therapy):

• 34% reverted to abnormal TCD within 1 year
• 2 strokes in discontinuation group vs. 0 in continued transfusion
• Trial stopped early for safety concerns
• Conclusion: Once initiated, transfusion should be continued indefinitely

TWiTCH Trial (2016): Tested whether hydroxyurea could replace transfusions for primary stroke prevention in children with abnormal TCD who had received ≥12 months of transfusions without severe vasculopathy:

• 121 patients randomized to continued transfusion vs. hydroxyurea (MTD ~27 mg/kg/day)
• Primary endpoint (24-month TCD velocity): 143 cm/s (transfusion) vs. 138 cm/s (hydroxyurea)
• Non-inferiority demonstrated (p<0.001); post-hoc superiority (p=0.023)
• No strokes in either arm; 3 TIAs per arm
• Hydroxyurea arm had better iron profiles (ferritin decreased by 1047 ng/mL more)
• Conclusion: For children with ≥1 year of transfusions and no severe MRA vasculopathy, hydroxyurea can substitute for transfusions

SWiTCH Trial (2012): Tested hydroxyurea + phlebotomy vs. transfusion + chelation for secondary stroke prevention in children with prior stroke:

• 133 patients randomized; mean 7 years on chronic transfusion at entry
• Trial stopped early: 7 strokes in hydroxyurea arm vs. 0 in transfusion arm (10.4% vs. 0%)
• Liver iron concentration was not significantly different between arms at interim analysis
• Conclusion: Hydroxyurea is INFERIOR to transfusion for secondary stroke prevention; transfusion remains standard of care after stroke

SIT Trial (Silent Cerebral Infarct Transfusion Trial, 2014): Tested whether transfusion prevents progression of silent cerebral infarcts (SCI) detected on MRI in children with normal TCD:

• 196 children with SCI and normal TCD randomized to transfusion vs. observation
• Primary endpoint (new overt stroke or new/enlarged SCI): 6% transfusion vs. 14% observation
• 58% relative risk reduction (p=0.04)
• Conclusion: Transfusion reduces SCI recurrence; consider for children with silent infarcts

BABY HUG Trial (2011): Tested hydroxyurea (20 mg/kg/day) vs. placebo in infants (9–18 months) for organ protection:

• 193 infants randomized regardless of disease severity
• Primary endpoints (spleen and kidney function): Not significantly different
• Secondary clinical outcomes: Reduced pain, dactylitis, acute chest syndrome, hospitalizations, and transfusions
• No significant increase in infections despite mild myelosuppression
• Conclusion: Hydroxyurea is safe in infants and reduces acute complications, supporting early treatment initiation

5. Mechanical/Compression Arteriopathies

5.1 Bow Hunter Syndrome

Bow Hunter syndrome (rotational vertebral artery occlusion) occurs when the vertebral artery is compressed during head rotation, typically at the C1-C2 level.

Clinical Features: Posterior circulation symptoms (vertigo, diplopia, dysarthria, ataxia) with head turning; symptoms resolve with head in neutral position.

Diagnosis: Dynamic CTA or MRA with head in neutral and rotated positions; DSA with provocative maneuvers is gold standard.

Management: Conservative measures (avoid provocative positions, cervical collar); surgical C1-C2 fusion or decompression for refractory cases.

5.2 Eagle Syndrome

Eagle syndrome results from an elongated styloid process (>30 mm) or calcified stylohyoid ligament compressing the internal carotid artery.

Clinical Features: TIAs or strokes with head turning or neck extension; throat/neck pain, dysphagia, pulsatile tinnitus.

Diagnosis: CT with 3D reconstruction visualizes elongated styloid and relationship to ICA; CTA demonstrates ICA compression.

Management: Surgical styloidectomy is definitive; antiplatelet or anticoagulation as bridge therapy.

Trial Comparison Table

References

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