Anatomical variations of the middle cerebral artery:: Duplication and accessory artery implications in the treatment of acute stroke

Introduction. Less than half of all subjects display a normal configuration of the circle of Willis, according to anatomical studies. Variations of the middle cerebral artery (MCA) such as duplication or accessory MCA are infrequent but nevertheless have important clinical implications. We report the case of two patients with these variations of the MCA and their repercussions in the management of acute stroke are discussed. Case reports. Case 1: a 53-year-old male with a 2-hour history of sensory-motor syndrome; a transcranial Doppler (TCD) scan revealed asymmetrical speeds in the MCA. Spontaneous perforation of the MCA was suspected and we therefore decided to perform a magnetic resonance angiography scan before administering fibrinolytics. The magnetic resonance angiography scan showed an accessory MCA lying ipsilateral to the lesion. We interpreted the anomalies in blood flow detected in the TCD recording as being secondary to this anatomical variation and not due to reperfusion. Following the magnetic resonance angiography study, the possibility of fibrinolysis was ruled out. The patient recovered the neurological deficit in a matter of hours. Case 2: a 21-year-old female with headaches and transient hemiparesis, who was diagnosed as suffering from migraine with aura. Later following another stroke, it was shown that the previous clinical symptoms had been secondary to intracranial dissection with embolism in the lenticulostriate arteries and ischemic infarction in that territory. A magnetic resonance angiography scan showed duplication of the ipsilateral MCA. Conclusions. The double vascularisation of the hemisphere in cases of anatomical duplication can give rise to strokes with a better progression and prognosis, despite the occlusion of one of the MCA. The presence of anatomical variations of the MCA can lead to mistaken interpretations of the TCD scan and may affect decision-making as regards the therapy to be employed inpatients with acute stroke.