ISCHEMIC STROKE / CLASSIFICATION AND ETIOPATHOGENESIS

Created 16/12/2021, last revision 07/11/2023

• a progressive disease characterized by elongation, dilation and tortuosity of the arteries, sometimes called dilated arteriopathy
  • the vertebrobasilar arteries are most commonly affected (also known as vertebrobasilar dolichoectasia or megadolichobasilar artery)
  • (pseudo)aneurysm, on the other hand, is characterized by a focal dilation, creating a weakened area prone to rupture
• incidence 0.06-6% [Brutto, 2021]
• associated with increased risk of stroke recurrence (up to 19%/2 years) [Chen, 2019]
  • likely cause of a fraction of strokes initially classified as cryptogenic [Brutto, 2021]
• the following characteristics also apply to large fusiform aneurysms

dolichoectasia may lead to:

• ischemic stroke through
  • thrombus formation (due to slowed flow)
    • occlusion of perforators
    • distal embolization
  • atherosclerotic plaques with stenosis or occlusion of penetrating (perforating) arteries
    
    • possible combination with thrombosis
  • distortion of the origin of the penetrating artery due to tortuosity
• intracranial hemorrhage (ICH) or subarachnoid hemorrhage (SAH)
  • due to rupture of the fragile wall l (risk 20 times higher than in the general population)
  • risk factors: hypertension, antiplatelets/anticoagulants, the extent of lateral artery displacement
• compression syndrome may affect the brainstem and/or cranial nerves

• atherosclerosis (atherosclerotic dolichoectasia)
  • affects both intra- and extracranial arteries
  • usually occurs in individuals aged > 40 years
    
  • the combined effect of increased age, chronic hypertension with arterial wall remodeling, and chronic inflammation that may weaken the arterial wall; typical vascular risk factors are present
• congenital disorders  (non-atherosclerotic dolichoectasia)
  • individuals aged < 40 years; more common in women
  • distal branches of the posterior circulation are typically affected
  • Marfan syndrome, Ehlers-Danlos, Fabry disease
• can develop as a complication of arterial dissection

• ischemic stroke/TIA (30% risk over 5 years)
• intracranial bleeding, subarachnoid hemorrhage
• compressive phenomena
  • brainstem compression (associated with basilar dolichoectasia)
  • hydrocephalus
  • neurovascular compression syndrome (NVCS)
    • compression of the optic nerve near the optic chiasma (ICA)
    • impairment of one or more cranial nerves is associated with a tortuous and elongated BA (CN VII, VIII, VI)

• factors influencing clinical outcome:
  • severity of arterial dilation and the extent of lateral shift
  • signs and symptoms at the time of diagnosis
  • presence of intraluminal mural thrombus
  • progression of ectasia on follow-up imaging

• due to the potential for significant morbidity, a multidisciplinary approach involving neurologists, vascular surgeons, and radiologists is often recommended for comprehensive management and prognostic assessment
• there is no universally accepted treatment with proven benefit
• serial imaging to monitor disease progression is suggested
• patients with previous stroke/TIA may receive antiplatelet therapy or anticoagulation  (AHA/ASA 2021 2a/L-CD)
• in primary prevention, the benefit of antiplatelet/anticoagulant therapy is uncertain
• intervention/surgery is reserved for symptomatic cases; the benefit is uncertain (better results in the anterior circulation)
  • bypass
  • resection with anastomosis
    
  • transposition
  • endovascular flow diverter/stent placement with or without additional coiling
• lifestyle modifications + management of vascular risk factors, especially hypertension
• intravenous thrombolysis or mechanical thrombectomy are not contraindicated in acute stroke

• variable nature of the disease with asymptomatic to malignant course
• progression more common in younger patients with anterior circulation ectasia
• relatively high risk of stroke recurrence (up to 60% over 11 years)