Rete anomaly of the middle cerebral artery: case series of 13 patients from the Northeastern United States.

Background: Rete middle cerebral artery (MCA) is a rare anomaly of the intracranial circulation that mimics congenital Moyamoya disease (MMD). Similar to MMD, it is reported almost exclusively in East-Asian ethnicities. Here, we report 13 patients with rete MCA anomaly from a predominantly non-Asian background in the USA.
Methods: Consecutive patients (≥18 years of age) with rete MCA seen in the neurovascular clinic at Columbia University Medical Center (2014-2024) were included. We retrieved demographics, clinical presentation, imaging findings, neurosurgical interventions, and clinical outcomes.
Results: 13 patients were identified (mean age 42±21 years, 83.3% female): 7 were White (53.8%), 3 were multiracial Hispanic (23.1%), 2 were South-Asian (15.4%), and 1 was Black (7.7%). Rete MCA was unilateral in all (n=13) and collaterals typical of MMD were absent. MRI vessel wall imaging (n=6) did not show enhancement characteristic of MMD. With serial imaging (n=12), there was no progression or contralateral MCA involvement. Strokes occurred in 5 (38.5%): subarachnoid hemorrhage (n=2), intracerebral hemorrhage (n=2), and ischemic stroke (n=1) from cardioembolism (n=1). 5 (38.5%) underwent neurosurgical bypass (encephaloduroarteriosynangiosis) due to presumed initial diagnosis of MMD (n=4), or for hypoperfusion on imaging related to rete MCA (n=1). Over a 4±3-year mean follow-up, there were no acute neurovascular events.
Conclusions: Rete MCA anomaly occurs in non-Asian populations, and is likely benign relative to MMD. The diagnosis should be considered with unilateral, non-progressive findings, and absent MMD-type collaterals. Neurosurgical bypass appears safe, but studies are required to assess the natural history and stroke risk in this condition.
Competing Interests: Competing interests: None declared.
(© Author(s) (or their employer(s)) 2024. No commercial re-use. See rights and permissions. Published by BMJ Group.)