An infundibulum of thalamoperforator arteries: Importance of angiographic images for appropriate diagnosis
A 39-year-old male was referred for management of a possible right P1 aneurysm. The patient was in good general health and his family history was negative for any cerebrovascular pathology. He recently experienced recurrence of his typical coital headaches, which had been diagnosed in his twenties. For completeness, the referring physician requested brain imaging.\nThe initial head computed tomography (CT) scan performed within 48 h of his last headache failed to show acute subarachnoid hemorrhage. The CTA revealed a rounded bulge arising from the right distal P1 segment of the right posterior cerebral artery (PCA) [Figure and ], suspicious for a saccular aneurysm. No other abnormality was identified. The brain magnetic resonance imaging (MRI) showed no hyperintense signal on T1WI or Flair sequences to suggest subarachnoid blood, no enhancement on the T1WI postgadolinium sequence, and no mass in the interpeduncular or crural cisterns, making a dissecting aneurysm much less probable []. The GRE sequence showed no hypointense hemosiderin deposit. The brain MRA showed the same right P1 bulge, with no additional information gained. The patient agreed to undergo a catheter angiogram in order to clarify the angioanatomy at the site of the right P1 bulge. A catheter angiogram with 2D projections and 3D rotational reconstructions revealed a small 3 mm outpouching just proximal to the junction of the right posterior communicating arteries (PcomA) and PCA [Figure and ]. In addition, two small thalamoperforators were now clearly seen arising from the dilatation creating a double-peaked shape to the infundibulum, rather than the conical shape more typically associated with infundibula. The catheter angiogram also enabled visualization of two additional small infundibula, each measuring approximately 2 mm in maximal diameter at the origins of the left anterior choroidal artery (AchoA) and left PcomA [Figure and ]. No true aneurysm was seen.