A1 segment hypoplasia
Right sided numbness
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Normal MRA of the brain. The following anatomical variants are noted:
- absent A1 segment of right anterior cerebral artery. A2 segment is perfused through Acom artery
- fetal origin of right posterior cerebral artery, from right Pcom artery
- dominant left vertebral artery
Cerebral MR angiography shows absent right A1 segment, a common variant of circus of willis accounting for 10% of individuals. The contralateral A1 segment supplies ipsilateral A2 segment by a prominent anterior communicating artery.
Fetal origin of right posterior cerebral aretry also incidentally noted, 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 study which was normal.