Incision of the anterior petroclinoidal fold during clipping for securing the proximal space of an internal carotid artery-posterior communicating artery aneurysm: a technical note.

Surgical clipping of an internal carotid artery (ICA)-posterior communicating artery (ICPC) aneurysm is often difficult in cases involving limited space to insert a clip at the proximal aneurysm neck hidden by the tent. In such cases, we perform incision of the anterior petroclinoidal fold to secure the proximal space for clip insertion. Between April 2013 and March 2018, we treated 89 ICPC aneurysm cases by clipping. Incision of the anterior petroclinoidal fold was performed in 15 of the 89 cases (16.8%). Fast imaging employing steady-state acquisition (FIESTA) magnetic resonance imaging (MRI) can indicate the locations of the aneurysm and tent and can help assess the need for tent incision. We widely dissected the distal sylvian fissure and sufficiently exposed around the aneurysmal space. We coagulated and cut the anterior petroclinoidal fold supra between the ICA and proximal neck of the aneurysm using a low-power bipolar system and needles or micro-scissors with care to avoid injury around structures such as the ICA, aneurysm, and oculomotor nerve. When using this strategy, we often select the Yasargil FT717 clip that has a curve along the skull base because of easy insertion. All cases showed complete aneurysm exclusion on three-dimensional computed tomography angiography, and there was no cerebral infarction, neurological deficit (such as hemiparesis), or oculomotor nerve palsy. Therefore, our strategy of incision of the anterior petroclinoidal fold during clipping for securing the proximal space of an ICA aneurysm is effective and safe.