Etiologic Subtypes of Watershed Infarcts

Area of Science:

• Neurology
• Vascular Neurology
• Stroke Medicine

Background:

• Watershed infarcts (WI) are classified as internal or external.
• Internal WI are typically linked to severe large artery stenosis or hypotension.
• External WI are generally presumed to result from embolism.

Purpose of the Study:

• To investigate the etiologic background of internal and external watershed infarcts.
• To determine the prognosis associated with different types of watershed infarcts.
• To identify stroke subtypes contributing to internal and external WI.

Main Methods:

• Retrospective review of medical records and diffusion-weighted images.
• Inclusion criteria: patients admitted with acute ischemic stroke between January 2012 and November 2014.
• Etiologic stroke subtypes determined using the automated Causative Classification System.

Main Results:

• Fifty-three patients with WI were identified; 21 (39.6%) had external WI and 32 (60.4%) had internal WI.
• External WI etiologies included large-artery atherosclerosis (LAA) (33.3%) and cardioembolism (38.1%).
• Internal WI were significantly associated with LAA (P = .024) and hypertension (P = .035).

Conclusions:

• Cardioembolism was the primary cause of external WI in this cohort.
• Large-artery atherosclerosis (LAA) was significantly associated with internal WI.
• The study highlights the importance of investigating uncommon etiologies in cryptogenic stroke cases.