Implications of a Variation of Middle Cerebral Artery in the Interpretation of Transcranial Doppler

The accessory middle cerebral artery (MCA) is a variation of the MCA branching, which originates from the anterior cerebral artery (ACA). It is deemed as an incidental anatomical finding and the incidence is reported to be 0.3% to 4.0%. Although the accessory MCA is infrequent it nevertheless may have important implications in the interpretation of transcranial Doppler (TCD) findings. We report two patients having an accessory MCA and its clinical significance.