Inclusion Criteria1. Extracranial carotid or vertebral artery dissection with symptom onset within the last 7 days. This includes:
1. Ipsilateral transient ischemic attack or stroke
2. Ipsilateral Horner's syndrome or neck pain with known date of onset.
2. Imaging evidence of definite or probable dissection on MRI/MRA, CTA or ultrasound.
Exclusion Criteria1. Intracranial cerebral artery dissection
2. Symptom onset after 7 days
3. Contraindication to either antiplatelet agents or anticoagulation therapy
4. Patient's refusal to consent
5. Patients who are undergoing angiography and stenting or surgery for treatment of their dissection.