Direct surgery for paraclinoid aneurysm arising from the anterolateral wall of the internal carotid artery

The internal carotid aneurysm (ICA) arising from the paraclinoid region is associated with the origins of the superior hypophyseal artery and the ophthalmic artery. Recently, other aneurysms which can arise in this region without involvement of the arterial branches has been reported. Among those aneurysms, there are very rare type of aneurysms located on the anterolateral aspect of the internal carotid artery. In this report, we described our experience with direct surgery for five cases of the unruptuted paraclinoid aneurysm arising from the anterolateral aspect of the ICA. Firstly, the common carotid artery was exposed to carry out proximal flow control. We used the pterional approach. The anterior clinoid process was deleted after having confirmed aneurysm and the dural ring was incised. Extreme care had to be taken during this step. All patients underwent successful neck clipping. In recent two cases we employed the neuroendoscope (EndoArmTM) to observe the unrecognized area of surgical microscope and untrasonic bone curette (SONOPETTM) to perform the safe removal of the anterior clinoid process. This procedure is very useful for carring out the neck clipping for aneurysms which are located on the anterolateral aspect of the internal carotid artery.