A 74-year-old man presented with subarachnoid hemorrhage (SAH) and underwent neck clipping of a left middle cerebral artery (MCA) aneurysm 10 years ago. This patient presented with SAH again due to rupture of a de novo aneurysm of the anterior communicating artery (A-com. aneurysm). The A-com. aneurysm was clipped successfully. The “old” left MCA aneurysm was then inspected. A collapsed “old” aneurysmal dome and a previously applied clip were identified. The “old” aneurysmal dome was resected for histopathological examination. The wall of this aneurysmal dome varied in thickness and consisted of a thin layer of fibrous connective tissue. Fibroblasts were scattered in the aneurysmal wall and either the muscular layer or internal elastic lamina was absent. The aneurysmal dome collapsed to a certain degree, but the lumen of the dome was completely intact. In addition, neovascularization of microcapillaries was observed both inside and outside the aneurysmal dome. Some of these microcapillaries were filled with fresh erythrocytes. Thus the aneurysmal wall was apparently “vigorous.” The previous orifice of the aneurysm did not fuse together at all and could be opened widely with ease during preparation for histopathologic examination. We speculated that the clipped aneurysmal dome survived for 10 years for the following reasons: 1) Although the mechanism of neovascularization of the microcapillaries is unclear, the clipped aneurysmal dome may have obtained nourishment from the microcapillaries. 2) The cerebrospinal fluid may have incubated the dome and provided optimal circumstances for its survival. Considering the radical cure for ruptured cerebral aneurysms by neck clipping or coil embolization, the findings described in this report will be valuable for neurosurgeons and neurointerventionists.
Regardless of the time since treatment, ruptured aneurysms treated by either neck clipping and/or coil embolization are at risk of recurrent subarachnoid hemorrhage when the blood re-enters the aneurysms in cases such as clip slip-off or coil compaction.
