Epidemiology & Risk Factors

Major cause of ischemic stroke in young/middle-aged patients (<45 yo).
Mechanical/Trauma:
- Carotid artery dissection, cervical spine manipulation (chiropractic), motor vehicle collisions (whiplash). c
- Strenuous physical activity, yoga, coughing/vomiting paroxysms, rollercoasters.
Connective Tissue Disorders:
- Fibromuscular Dysplasia (FMD) (high association).
- Ehlers-Danlos syndrome (vascular type IV), Marfan syndrome, Osteogenesis Imperfecta.
Other: HTN, smoking, migraine history.

Clinical Features

Internal Carotid Artery Dissection (ICAD):
- Unilateral frontotemporal/periorbital headache and ipsilateral neck pain.
- Partial Horner syndrome: Ptosis + miosis without anhidrosis (facial sweat fibers travel along external carotid artery). c
- Amaurosis fugax (transient monocular blindness) or retinal artery occlusion.
- Pulsatile tinnitus, lower cranial nerve palsies (CN IX-XII, esp. CN XII / tongue deviation).
- Ischemic signs: Contralateral motor/sensory deficits, aphasia (MCA/ACA territory).
Vertebral Artery Dissection (VAD):
- Unilateral occipital headache and posterior neck pain.
- Posterior circulation ischemia (Lateral Medullary / Wallenberg syndrome):
  - Ipsilateral ataxia, loss of facial pain/temperature sensation, Horner syndrome, dysphagia, hoarseness.
  - Contralateral body loss of pain/temperature sensation.
  - Vertigo, nystagmus, diplopia.

Initial / Screening (Suspected acute stroke/dissection):
- Non-contrast Head CT: Initial step in acute focal deficit to rule out hemorrhage before thrombolysis.
- CTA of head and neck or MRA of head and neck: Initial diagnostic vascular imaging of choice (rapid, non-invasive, high sensitivity/specificity).
Confirmatory / Gold Standard:
- Digital Subtraction Angiography (DSA) / Conventional catheter angiography (gold standard, but largely replaced by CTA/MRA).
Key Imaging Findings:
- “String sign” (tapering long-segment stenosis).
- “Flame sign” (tapered occlusion).
- Crescentic intramural hematoma (seen best on axial T1 fat-saturated MRI).
- Intimal flap, false lumen, or pseudoaneurysm.
Key Labs: CBC, PT/INR, PTT, BMP (renal function for CTA contrast), cardiac biomarkers.

Subarachnoid Hemorrhage (SAH):
- Diff by: Sudden-onset “thunderclap” headache, meningismus, subarachnoid hyperdensity on non-contrast CT / RBCs on LP (xanthochromia).
Cluster Headache:
- Diff by: Severe retro-orbital pain + autonomic signs (rhinorrhea, lacrimation), but transient/episodic (<3 hours) without focal neurological deficits or mural hematoma on imaging.
Giant Cell (Temporal) Arteritis:
- Diff by: Age >50 yo, jaw claudication, scalp tenderness, markedly ↑ ESR/CRP, temporal artery biopsy.
Musculoskeletal Neck Strain:
- Diff by: Absence of headache/Horner syndrome, normal vascular imaging, pain reproduced exclusively by mechanical palpation/movement.
Migraine with Aura:
- Diff by: Gradual aura progression (<60 min) followed by pulsating headache with photophobia/nausea; lacks Horner syndrome or vascular imaging abnormalities.

Acute Phase (<4.5 hours from ischemic stroke onset):
- IV Alteplase (rtPA) or Tenecteplase: First-line for acute ischemic stroke within 4.5 hours if no contraindications (extracranial dissection is NOT a contraindication).
- Endovascular Thrombectomy (EVT): Indicated for acute large vessel occlusion (LVO) of anterior circulation within eligible time windows (up to 24 hours).
Subacute / Maintenance Medical Therapy (First-line):
- Antithrombotic Therapy for 3–6 months:
  - Antiplatelet therapy (e.g., Aspirin monotherapy or DAPT [Aspirin + Clopidogrel]) OR Anticoagulation (e.g., Heparin bridging to Warfarin/DOAC).
  - Note: Guidelines demonstrate equivalent stroke prevention efficacy between antiplatelet and anticoagulation. Antiplatelet is often preferred due to lower bleeding risk.
- Strict BP control (avoid extreme hypertension to prevent hematoma extension; avoid excessive hypotension to maintain cerebral perfusion).
Refractory / Interventional (Second-line / Rescue):
- Endovascular Angioplasty / Stenting: Indicated for:
  - Recurrent TIA/ischemic stroke despite optimal antithrombotic therapy.
  - Expanding dissecting pseudoaneurysm.
  - Hemodynamic compromise from severe luminal hypoperfusion.

Thromboembolic Ischemic Stroke / TIA (most common cause of long-term morbidity).
Dissecting Pseudoaneurysm (risk of distal embolization or local compressive neuropathy).
Subarachnoid Hemorrhage (SAH) (occurs if dissection extends intradurally beyond the dural ring).
Complete arterial occlusion leading to massive hemispheric or brainstem infarction.

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