Intracranial dolichoectasia in patients with symptomatic intracranial atherosclerotic disease: Results from the MYRIAD study

Background and Purpose: It is unknown whether intracranial atherosclerotic disease (ICAD), in addition to causing stenosis, also associates with abnormal arterial enlargement, a condition known as intracranial dolichoectasia (IDE). Across symptomatic ICAD patients, we aim to determine IDE prevalence and IDE impact on cerebral hemodynamics and recurrent cerebral ischemia. Methods: We analyzed 98 participants (mean age 63.8 (Formula presented.) 11.9 years, 56.1% men) of the prospective observational study MYRIAD. Participants were enrolled within 21 days of an ischemic stroke or transient ischemic attack caused by moderate-to-severe ICAD. Semi-automatic vessel segmentation was used to determine diameters, length, and tortuosity-index of proximal intracranial arteries. Either ectasia (increased diameter) or dolichosis (increased length or TI) defined IDE. We assessed IDE association with new infarcts during 12-month follow-up, and IDE correlation with cerebral hemodynamics determined by quantitative MR-angiography (QMRA), MR-perfusion weighted-imaging, and transcranial Doppler breath-holding index. Results: IDE was present in 35.7% of patients and 10.2% of symptomatic arteries. Basilar stenosis was associated with higher IDE prevalence (27.8% vs. 8.8%, p = 0.04), whereas other symptomatic arteries showed no association with IDE. Symptomatic arteries with IDE had lower hypoperfusion prevalence on MR-PWI (11.1% vs. 28.4%, p = 0.03). Increased diameter (r = 0.33, p<0.01) and tortuosity-index (r = 0.29, p = 0.01) showed positive correlation with QMRA flow rate. IDE was not associated with new infarcts during follow-up. Conclusions: IDE was common among symptomatic ICAD patients. IDE was not associated with stroke recurrence. Instead, increased diameter and tortuosity correlated with improved blood flow across the stenotic artery, suggesting that IDE may originate as an adaptive mechanism in ICAD.