Rete Middle Cerebral Artery

A 53 year-old woman presented with a 4 year history of recurrent dizziness episodes. Each episode lasted approximately 1 week and was not accompanied by nausea, or vomiting. Comprehensive vestibular assessments, including vestibular function tests, Dix–Hallpike maneuver, and the roll test, were all negative. The patient reported no atherosclerotic risk factors, such as hypertension, hyperlipidemia or diabetes mellitus, and her family history was unremarkable. General physical and neurological examinations were unremarkable. Central causes of dizziness were considered. A computed tomography angiography of the head revealed a plexiform configuration in the M1 segment of the right middle cerebral artery (MCA), with no other significant abnormalities (Figure 1a). Moyamoya disease was considered a possible diagnosis. Subsequent digital subtraction angiography demonstrated the absence of a normal right M1 segment, with a twig-like vascular network connecting to the distal MCA (Figure 1b,c). Additionally, the right carotid canal was found to be smaller than the left, suggesting potential congenital variants consistent with rete MCA (Figure 1d). The patient was treated with betahistine 6 mg three times daily, resulting in alleviation of her dizziness.

Rete MCA, also known as twig-like MCA, is a rare vascular anomaly characterized by the presence of a twig-like arterial network in the M1 segment of the MCA. This variant may present with either hemorrhagic or ischemic strokes, or, as in this case, with no clinical symptoms. The primary differential diagnoses for rete MCA include moyamoya disease/syndrome and atherosclerotic occlusion. In contrast to these conditions, rete MCA is typically unilateral, occurs exclusively in the M1 segment with a distinctive twig-like appearance, and does not involve atherosclerotic risk factors. Notably, it preserves the caliber and flow of the distal MCA. In surgical settings, rete MCA often presents as a white cord-like structure. Accurate diagnosis is essential, particularly for asymptomatic patients, to avoid unnecessary concerns about occlusion. For symptomatic individuals, surgical intervention may be considered.

Yongming Wang: writing–original draft (lead). Xi Chen: writing–original draft (equal). Junsheng Liu: writing–review and editing (equal).

This study was approved by the Ethics Committee of The People's Hospital of Pingchang in 2024 (Approval Number: 20240731-121).

The patient provided informed consent for the publication of the case.

The authors declare no conflicts of interest.