Complete spontaneous thrombosis of giant upper basilar artery aneurysm: a case report

Abstract

The prognosis of the untreated giant upper basilar artery aneurysm is extremely poor. We present a case of complete spontaneous thrombosis of giant upper basilar artery aneurysm without any symptoms. A 22-year-old woman with no medical history suffered from brain stem infarction. Radiological examinations revealed a large (21 mm) partially thrombosis distal basilar artery aneurysm and left mid-brain infarction. On vertebral angiogram, the right posterior cerebral artery (PCA) and superior cerebellar artery (SCA) were not identified and the left PCA and SCA were originated from the aneurysm. She was treated conservatively. The follow-up MRI and cerebral angiogram performed 4 months after the onset showed the rapid progression of thrombosis of an aneurysm and the near occlusion of the left SCA origin without marked enlargement of an aneurysm. However, the 8-month follow-up MRI revealed that the aneurysm became giant (31 mm). The 3DCTA, at the same time, showed the enlargement of the circulating portion of an aneurysm and a protruded change of an aneurysmal wall at the origin of the left PCA. She was admitted for further management and cerebral angiography were performed 9 months after the onset, which demonstrated complete occlusion of an aneurysm and the distal basilar artery without any ischemic lesions. The patient was discharged in good condition and remains neurologically intact. The 2-year follow-up MRI demonstrated dramatic shrinkage without recanalization of an aneurysm. In this case, we speculate that the stepwise near occlusion of SCA and PCA origins plays an important role in complete thrombosis of an aneurysm.