Introduction: Aneurysms of the internal carotid artery (ICA)-anterior choroid artery (ACHA) are about 2-5% of all intracerebral aneurysms. The neck of the aneurysm typically engages both arteries. Aneurysms located on the ACHA itself without engaging the ICA present a rare pathology. They are usually called distal ACHA aneurysms or "true" ACHA aneurysms. Their frequency is about 0.2-0.4%.
Clinical presentation: a 42-year-old male with spontaneous subarachnoidal hemorrhage, Hunt & Hess grade II was admitted to the Pirogov Hospital. The cerebral angiography demonstrated an aneurysm of the left ACHA segment of the ICA. Intraoperatively we found an aneurysm of the ACHA itself--the neck was located 3 mm distally from the ICA-ACHA bifurcation. In spite of the meticulous dissection an intraoperative rupture of the anerysmal neck occurred and forced us to perform a trapping of the ACHA. The postoperative period was uneventful and the patient was discharged on the 7-th postoperative day without any neurological deficit.
Conclusion: the "true" aneurysm of the ACHA presents a rare pathology. We would like to confirm their aptitude for intraoperative rupture. The surgical challenge is caused by the importance of the ACHA for the cerebral circulation. In our case, probably due to the multiple anastomosis, the trapping of the ACHA was without neurological sequels.