Objective:

To assess the etiology of LVO-AIS in young adults presenting to our racially diverse comprehensive stroke center using both TOAST and ASCOD classification to identify underlying stroke mechanisms, especially in regards to those labeled as cryptogenic.

Background:

Large vessel occlusion acute ischemic stroke (LVO-AIS) is considerably uncommon in young adults as they often have elusive stroke mechanisms compared to older populations.

Design/Methods:

This retrospective study cohort was composed of patients 18-50 years of age presenting with ischemic stroke from Jan 2017 to December 2021. We included patients who had a large vessel occlusion (LVO) on CTA or MRA at presentation. We excluded those without LVO or those who did not have intracranial vessel imaging available. We assessed demographics and stroke etiology using both the TOAST and ASCOD classification systems. We then compared those labeled as cryptogenic by TOAST with their respective ASCOD classification. 

Results:

213 patients were found to have LVO-AIS. Median age was 42 (18, 49). Median NIHSS was 8 (0, 29). By TOAST, "stroke of undetermined etiology" (35.2%) was the most commonly identified etiology followed by "stroke of other determined etiology" (28.6%). Of those, 70 (32.8%) were found to be cryptogenic. However, their ASCOD classification (number, percentage) for each category, including causal, potentially causal and present but unclear significance grading, was as follows: atherosclerosis (11, 15.7%), small vessel disease (7, 10%), cardiac (21, 30.1%), other (3, 4.3%), dissection (0, 0%).

Conclusions:

In our young patient cohort, a high proportion were labeled cryptogenic. Of those patients, the ASCOD classification revealed potential contributing factors that may have been overlooked. Given this, ASCOD may be more informative in establishing etiology for LVO-AIS in young patients.