Angioarchitecture of Twig-like Middle Cerebral Artery: the Looping Lenticulostriate Artery Anastomoses as an Angiographic Landmark for Hemorrhagic Presentation.

Purpose: The twig-like middle cerebral artery (TL-MCA) is a vascular anomaly reconstituting the MCA-M1 segment through a plexiform arterial network. Most patients with TL-MCA have a high risk of hemorrhage, but the associated vascular anatomical risk factors are poorly understood. To investigate the angioarchitecture of TL-MCA in detail to distinguish the radiological differences between hemorrhagic and non-hemorrhagic onset.

Methods: 3214 cerebral digital subtraction angiography procedures were performed, and patients with TL-MCA were included and their clinical and anatomical characteristics were retrospectively reviewed.

Results: 12 patients (median age 47 years, and 9 women) with TL-MCA were included (incidence rate, 0.37%). Among them, four had hemorrhagic stroke, five had ischemic stroke, and three had no symptoms. Perforator anastomoses were identified in five patients (41.6%). Among the four patients with intraparenchymal hemorrhage (IPH), three had looping lenticulostriate artery (LSA) anastomoses and one had non-looping LSA anastomosis. One looping LSA anastomosis was discovered fortuitously in a patient explored for headaches. The recurrent artery of Heubner, which is responsible for the plexiform arterial network, was identified in 10 patients (83.3%). Angiographic evolutions (de novo TL-MCA) were observed in three patients, and one patient experienced a clinical evolution of a TL-MCA with non-looping LSA anastomosis, progressing from no symptoms to IPH.

Conclusions: In this small series, looping LSA anastomoses were mainly observed in TL-MCA with IPH. This anatomical disposition could represent a potential risk factor. The TL-MCA always affects the subpallial segment of the MCA-M1, and may be a subpallium-related pathology.