Neck clipping of paraclinoid small aneurysms.

Paraclinoid small aneurysms with a diameter less than 5 mm may be difficult to handle intraoperatively. We have encountered 9 such aneurysms among 375 cases. The most frequent location was the ophthalmic segment (n = 6) followed by the anterior wall (n = 3) of the internal carotid artery (ICA). The endovascular procedure was not suitable for this particular lesion because of the difficulty in deploying the coil across such small aneurysms. One patient with an ophthalmic segment aneurysm underwent endovascular treatment first; however, the procedure was aborted because of mechanical vasospasm. Finally the patient underwent craniotomy, and the aneurysm was successfully clipped. Two patients with anterior wall aneurysms presented with subarachnoid hemorrhage, and the blood blister-like aneurysms were clipped without sacrifice of the ICA. Five patients with unruptured aneurysms of the ophthalmic segment and one such case of the anterior wall of ICA were all clipped uneventfully. The operative procedure for these small aneurysms is deemed straightforward: (1) high attention should be paid to avoid premature rupture; (2) both the internal carotid artery and optic nerve are mobilized and the anterior clinoid process and falciform ligament are removed, then the aneurysmal neck is created; (3) the neck of the aneurysm is created by pushing the wall of the ICA slightly away during clip application; this is called the "nip on method." Although neck clipping of small aneurysms can be difficult, no efforts should be spared to accomplish direct neck clipping.