Objective and importance: Accessory anterior cerebral artery (ACA), which is a type of median artery of anomalous triplicate ACA, is not rare, but aneurysmal formation is extremely rare. We report a rare case with ruptured aneurysm arising from a distal accessory ACA. We discuss the characteristics and causes of this type of aneurysm and classification of this anomaly.
Clinical presentation: A 63-year-old man suddenly developed severe headache and then loss of consciousness and paraplegia. Computed tomography disclosed thick and diffuse subarachnoid hemorrhage and interhemispheric hematoma. Subsequent bleeding occurred 2 hours after the first hemorrhage. Cerebral angiography disclosed a saccular aneurysm arising from the distal accessory ACA.
Intervention: Neck clipping of the aneurysm was performed 22 hours after the second episode, using an interhemispheric approach.
Conclusion: Although transient paraplegia occurred 8 days after onset, the patient recovered well after surgery without neurological deficit. The characteristics of the aneurysm arising from distal accessory ACA are considered similar to those of distal ACA aneurysm. There is, however, some confusion regarding the terminology of the anterior communicating artery complex anomalies, which we discuss.