Presentation
Right sided numbness.
Patient Data
Normal MRA of the brain. The following anatomical variants are noted:
absent A1 segment of right anterior cerebral artery. A2 segment is perfused through the anterior communicating artery from the large left A1 segment.
fetal origin of the right posterior cerebral artery with hypoplastic right P1 segement
dominant left vertebral artery, small right vertebral artery
Case Discussion
Cerebral MR angiography shows absent right A1 segment, a common variant of circle of Willis present in 10% of individuals. The contralateral A1 segment supplies ipsilateral A2 segment by a prominent anterior communicating artery.
Fetal origin of right posterior cerebral artery is also incidentally noted. This is a common variant of the posterior cerebral circulation in which a prominent ipsilateral PCOM supplies the posterior cerebral artery rather than basilar artery.
This study was done in conjunction with a brain MRI which was normal.
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