Cervical Artery Dissection

Arterial wall mechanics and dissection formation

• Intimal tear creation: Mechanical stress (trauma) or underlying arterial pathology (fibromuscular dysplasia, connective tissue disorders) causes a breach in the intimal layer, exposing the subintimal space to arterial pressure and blood flow
• Hematoma expansion: Blood enters the arterial wall through the intimal tear and accumulates in the media or between media and adventitia, creating an expanding mass that progressively narrows the true lumen (dynamic stenosis)
• Luminal compromise: The dissecting hematoma acts as an expanding mass lesion, compressing the residual vessel lumen; additionally, intimal flaps may protrude into the lumen or thrombosis may develop within the false channel

Thromboembolism and stroke mechanisms

• Thrombogenic surface: The exposed subintimal tissue and disrupted endothelium activate tissue factor and platelets, promoting local thrombus formation within the dissection cavity or at the intimal tear site
• Artery-to-artery embolism: Thrombus from the dissection channel can embolize distally into the cerebral circulation, causing acute ischemic stroke despite variable degrees of luminal stenosis
• Hemodynamic insufficiency: Severe stenosis or occlusion reduces cerebral perfusion pressure distal to the dissection; depending on collateral adequacy, this may cause borderzone infarction or global hypoperfusion

Inflammatory response

• Arterial wall injury triggers inflammatory infiltration and cytokine release, which may perpetuate endothelial damage and promote continued thrombosis over days to weeks
• Mechanical stress on the weakened arterial wall may lead to pseudoaneurysm formation (communication between the true lumen and the false channel), which carries risk of rupture

Major/Significant Causes

• Connective tissue disorders: Ehlers-Danlos syndrome (EDS) (especially type IV), Marfan syndrome, osteogenesis imperfecta, and Loeys-Dietz syndrome significantly increase dissection risk due to arterial wall fragility; these account for ~10-15% of dissection cases
• Fibromuscular dysplasia (FMD): Present in 15-20% of CAD/VAD cases; characterized by abnormal muscular development of medium-sized arteries, predisposing to dissection even with minor trauma
• Minor head/neck trauma: Motor vehicle accidents, whiplash, falls, sports injuries, chiropractic neck manipulation, and even minor trauma (e.g., aggressive coughing, vomiting, straining) can precipitate dissection
• Spontaneous dissection: Occurs without recalled trauma in 40-60% of cases, suggesting underlying arterial pathology or predisposing conditions

Risk Factors and Associated Conditions

• Hypertension: Chronic and acute elevations in blood pressure increase arterial wall stress
• Migraine: Particularly migraine with aura; proposed mechanisms include vasomotor instability and increased vascular fragility
• Recent infection: Upper respiratory infections, COVID-19, and other systemic infections have been associated with increased dissection risk (proposed autoimmune mechanism)
• Pregnancy and postpartum state: Increased dissection risk in third trimester and immediate postpartum period, possibly due to hemodynamic changes and hormonal effects on vessel wall
• Oral contraceptive use: Modest increased risk; cumulative risk higher in those with additional prothrombotic factors
• Smoking and cocaine use: Increase arterial wall stress and vasoconstriction
• Thrombophilia: Inherited (Factor V Leiden, prothrombin mutation) and acquired thrombophilic states increase stroke risk in dissection
• Age: Bimodal distribution with peaks at age 40-50 (spontaneous) and younger ages with significant trauma

Cardinal Symptoms

• Neck pain: Present in 50-90% of CAD and 25-50% of VAD; typically ipsilateral, sharp or throbbing, and may precede neurological symptoms by hours to days; characteristically localized to the lateral neck or angle of the jaw
• Headache: Common in VAD (60-70%); usually occipital or posterior cervical, may mimic migraine
• Focal neurological deficits: Typically develops within 24-48 hours of symptom onset; ischemic stroke in middle cerebral artery (MCA) or anterior cerebral artery (ACA) territory with CAD; posterior circulation territory with VAD
• Transient ischemic attack (TIA): Recurrent amaurosis fugax or transient motor/sensory deficits may precede frank stroke

Carotid Artery Dissection (CAD) Presentation

• Horner syndrome: Classic triad of miosis (pinpoint pupil), ptosis (drooping eyelid), and anhidrosis (decreased sweating on ipsilateral face/forehead); occurs in 25-50% of CAD due to involvement of sympathetic fibers running along the internal carotid artery; may be present without stroke
• Hemispheric stroke symptoms: Contralateral motor weakness, sensory loss, language disturbance (if dominant hemisphere), or visual field defect
• Monocular vision loss: Amaurosis fugax or transient monocular blindness from ophthalmic artery hypoperfusion
• Pulsatile tinnitus: Hearing heartbeat in ears (rare but characteristic)

Vertebral Artery Dissection (VAD) Presentation

• Posterior circulation stroke: Ataxia, vertigo, nystagmus, visual field defects, Wallenberg syndrome (lateral medullary syndrome) with crossed sensory loss
• Basilar artery syndrome: If dissection propagates intracranially; presents with severe brainstem signs, including ophthalmoplegia, altered consciousness
• Neck pain and headache: Often prominent, may be the only symptom initially

Physical Examination Findings

• Horner syndrome: See above; pathognomonic for CAD when present
• Focal neurological deficits: Hemiparesis, hemisensory loss, aphasia (dominant hemisphere CAD), or posterior circulation signs
• Neck bruit or pulsatile mass: May be present if pseudoaneurysm formation
• Neck tenderness: Focal tenderness over the dissection site (non-specific)
• Visual acuity loss: With amaurosis fugax or retinal infarction
• Cervical radiculopathy: Rare; nerve root compression by dissection hematoma causing arm pain and weakness

Clinical Suspicion (Diagnostic Criteria)

1. 1.Acute ischemic stroke or TIA in arterial distribution with recent minor trauma or spontaneous onset in young/middle-aged patient
2. 2.Ipsilateral neck pain and headache preceding neurological deficit
3. 3.Horner syndrome (for CAD) with or without stroke
4. 4.Unexplained posterior circulation stroke with neck pain (VAD)
5. 5.Recurrent amaurosis fugax or TIA in single vascular distribution

Imaging Studies (Gold Standard)

• Catheter angiography: Remains the gold standard; shows characteristic findings: "string sign" (severe long-segment stenosis appearing as a thin thread of contrast), "flame-shaped" appearance, intimal flap, pseudoaneurysm, or tapered occlusion; allows definitive diagnosis but invasive with procedural risk
• Magnetic resonance imaging (MRI) with MR angiography (MRA): Preferred non-invasive modality; T1-weighted sequences with fat saturation show hyperintense crescent-shaped hematoma in arterial wall (subacute, 1-2 weeks sensitivity ~90%); MRA shows luminal narrowing or occlusion; excellent sensitivity (85-95%) and specificity (95%+); may identify dissection even when acute stroke is absent
• Computed tomography angiography (CTA): Increasingly used as first-line imaging in acute stroke evaluation; shows eccentric intimal flap, double-lumen appearance, arterial narrowing, or occlusion; sensitivity 85-90%, specificity >95%; faster than MRI in acute setting
• Doppler ultrasound: Can demonstrate elevated resistance index, turbulent flow, or intimal flap; useful for follow-up to assess recanalization; limited sensitivity (~60%) so not suitable for ruling out dissection
• Conventional angiography: Reserved for cases where non-invasive imaging is inconclusive or when endovascular intervention is anticipated

Laboratory Studies

• Coagulation profile (PT/INR, aPTT): Obtain baseline before initiating anticoagulation
• Platelet count and fibrinogen: Essential if considering anticoagulation
• Thrombophilia workup: Consider in younger patients (<40), recurrent dissections, or family history; obtain Factor V Leiden, prothrombin G20210A, antithrombin, protein C/S, and antiphospholipid antibodies (though testing should not delay acute treatment)
• Connective tissue disorder screening: Clinical evaluation for EDS or other connective tissue disorders; genetic testing if suspicion is high

Diagnostic Confirmation Criteria (CADISS Trial)

Acute Phase Management

First-line anticoagulation therapy

• Unfractionated heparin (UFH) or low-molecular-weight heparin (LMWH): Initiated immediately upon diagnosis (no need to wait for further imaging); mechanism is prevention of thrombus propagation and reduction of artery-to-artery embolism
• UFH: Initial bolus 80 units/kg IV, then infusion 18 units/kg/hour, target aPTT 1.5-2.5× baseline (approximately 60-85 seconds)
• LMWH (enoxaparin): 1 mg/kg SC twice daily or 1.5 mg/kg once daily
• Duration: Anticoagulation typically continued for 3-6 months, with reassessment on follow-up imaging (CTA or MRA) for evidence of recanalization; some experts use shorter durations (6-12 weeks) if rapid recanalization documented

Alternative or adjunctive therapy

• Aspirin monotherapy: 325-650 mg daily as alternative to anticoagulation; less robust evidence than anticoagulation but reasonable option if anticoagulation contraindicated
• Combination antiplatelet therapy: Aspirin plus clopidogrel may be considered in select cases with recurrent TIA on anticoagulation, though evidence is limited

Acute stroke management (if stroke present)

• Thrombolysis (IV tPA): Previously considered relatively contraindicated in dissection due to concern for pseudoaneurysm rupture; however, recent guidelines suggest IV thrombolysis is reasonable if patient meets standard inclusion criteria and there is no evidence of pseudoaneurysm or severe dissection (Level 2B evidence)
• Mechanical thrombectomy: Consider in patients with large-vessel occlusion and imaging evidence of salvageable penumbra; increasingly used as primary therapy for acute ischemic stroke with cardioembolism or arterial occlusion
• Blood pressure management: Goal is permissive hypertension (SBP <180 mmHg) to maintain cerebral perfusion while minimizing hemorrhagic transformation risk

Monitoring and Follow-up

• Serial neurological examinations: At least every 4-6 hours in first 24-48 hours to detect stroke progression
• Repeat vascular imaging: CTA or MRA at 3-6 months to assess for recanalization (occurs in 70-90% of cases) and guide duration of anticoagulation
• Blood pressure monitoring: Target <140/90 mmHg chronically to minimize wall stress
• Migraine management: Optimize migraine prophylaxis if present
• Lifestyle modifications: Smoking cessation, avoid high-impact sports/activities during healing phase (3-6 months)

Endovascular Intervention

• Pseudoaneurysm with high risk of rupture: Imaging features suggesting impending rupture or enlarging pseudoaneurysm
• Recurrent embolism despite anticoagulation: Persistent TIA or stroke recurrence on therapeutic anticoagulation
• Failed conservative management: Patient deterioration with infarct expansion despite anticoagulation
• Intracranial extension: VAD propagating into intracranial vertebral artery with pseudoaneurysm
• Techniques: Stent placement (bare metal or covered stent to seal pseudoaneurysm), intra-arterial thrombus aspiration, or coil embolization (for high-risk pseudoaneurysm)

Non-Pharmacological Management

• Neck immobilization: Limited evidence; may provide symptomatic relief of neck pain but does not alter natural history
• Physical therapy: After acute phase, graduated cervical range-of-motion exercises as tolerated
• Genetic counseling: If connective tissue disorder suspected, referral for evaluation and family counseling

Ischemic stroke

• Most common complication, occurring in 50-85% of CAD and 25-50% of VAD
• Results from thromboembolism, hemodynamic insufficiency, or both
• Management: Acute thrombolysis/thrombectomy per acute stroke protocol; continuation of anticoagulation to prevent recurrence

Pseudoaneurysm formation and rupture

• Develops in 5-10% of dissections when intimal tear allows communication between true lumen and false channel
• Risk of subarachnoid hemorrhage (SAH) if pseudoaneurysm ruptures intracranially; extracranial rupture rare but catastrophic
• Warning signs: Sudden severe headache, expansion of pulsatile mass, acute neurological deterioration
• Management: Urgent endovascular repair (stent or coil embolization); surgical ligation rarely used in current practice
• Monitoring: Serial imaging (CTA or MRA) to assess size and stability of pseudoaneurysm; intervention typically considered for enlarging lesions

Recurrent dissection

• Risk of ipsilateral recurrence: 2-3% at 1 year, up to 10% at 10 years (higher in connective tissue disorders)
• Bilateral CAD or CAD with VAD: Occurs in 5-15% of cases, particularly in those with underlying arterial fragility disorders
• Management: Investigation for underlying predisposition; consider longer anticoagulation or antiplatelet therapy; lifestyle counseling

Arterial occlusion and chronic stenosis

• Complete occlusion develops in 10-20% of dissections; most undergo spontaneous recanalization over 3-6 months
• Persistent stenosis: 5-10% develop chronic stenosis; risk of recurrent stroke in territory depends on collateral circulation
• Management: Vessel imaging at 3-6 months to assess recanalization; consider extended anticoagulation if persistent severe stenosis

Cranial nerve palsies

• Uncommon but can occur with dissection involving the carotid canal or styloid process
• Facial nerve (CN VII) or hypoglossal nerve (CN XII) involvement possible
• Usually transient and resolve with dissection resorption; surgical intervention rarely needed

The stem that screams dissection

• Young or middle-aged patient with unilateral neck/face pain plus a focal deficit: stroke under age 50 with no atherosclerotic risk factors is dissection until proven otherwise; look for a preceding trivial event (whiplash, chiropractic manipulation, heavy lifting, violent coughing, roller coaster).
• "Painful partial Horner syndrome": ptosis and miosis without facial anhidrosis is the classic internal carotid dissection tell — postganglionic oculosympathetic fibers ascend on the ICA, while the sudomotor fibers to the face travel with the external carotid and are spared. A complete Horner with anhidrosis points elsewhere (e.g., Pancoast tumor, central lesion).
• Occipital/posterior neck pain then vertigo, ataxia, crossed sensory loss: vertebral dissection producing Wallenberg (lateral medullary) syndrome.

Single best next step

• CTA or MRA of the head and neck (MRI with fat-saturated T1 showing a crescentic intramural hematoma is the most specific non-invasive finding). Do not answer carotid duplex — poor sensitivity, misses the distal ICA and vertebral origin. Do not answer catheter angiography first-line.
• Non-contrast head CT first only if the question is about thrombolysis eligibility; per the AHA/ASA acute ischemic stroke guideline, IV thrombolysis is reasonable in known or suspected extracranial dissection, whereas intracranial dissection raises subarachnoid hemorrhage concern.

The association examiners test

• Fibromuscular dysplasia (string of beads on angiography) and vascular Ehlers–Danlos (COL3A1) — screen for a heritable arteriopathy in spontaneous, recurrent, or multivessel dissection.
• Intracranial extension of a vertebral dissection can cause subarachnoid hemorrhage — a thunderclap headache after neck trauma is not automatically an aneurysm.

Common distractors

• Antithrombotic choice is not the trick: after CADISS, the AHA/ASA secondary prevention guideline regards either antiplatelet therapy or anticoagulation for 3–6 months as reasonable; picking "heparin" over "aspirin" is rarely the tested point.
• Do not label it migraine or cervical strain simply because the head CT is normal — early dissection often has a normal parenchymal scan.