PMC4533414_01
Lateral preoperative magnetic resonance angiography (A) and digital subtraction angiography of the left internal carotid artery (B) showing a funnel-shaped dilatation. C: Preoperative fast imaging employing steady-state acquisition showing a contact point between the oculomotor nerve (arrow) and the infundibular dilatation (ID) (arrowhead). D: Postoperative three-dimensional computed tomography scan showing the aneurysm clip (asterisk) and disappearance of the ID.
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Magnetic resonance (MR) angiography and digital subtraction angiography demonstrated left ID of the PcomA (Fig. 1A, B), and Allcock test demonstrated collateral blood supply from posterior circulation. Fast imaging employing steady-state acquisition (FIESTA) showed a point of contact between the oculomotor nerve and the ID of the PcomA (Fig. 1C). Postoperative CT angiography did not detect the ID (Fig. 1D).
Preoperative three-dimensional computer graphics image showing that the posterior communicating artery is dilated at its branch point and courses lateral to the oculomotor nerve. The infundibular dilatation has displaced the oculomotor nerve. AChA: anterior choroidal artery, ID: infundibular dilatation, Lt. ICA: left internal carotid artery, MCA: middle cerebral artery, ON: oculomotor nerve, PCA: posterior cerebral artery, PcomA: posterior communicating artery.
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These 3DCG images showed that the ID was located rostrolateral to the oculomotor nerve and had displaced the nerve (Fig. 2).
Intraoperative photographs, preclipping view (left) showing that the infundibular dilatation (asterisk) had displaced the medially located oculomotor nerve (arrow), and post-clipping view (right). ICA: internal carotid artery, MCA: middle cerebral artery.
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ID at the origin of the PcomA via left frontotemporal craniotomy with motor evoked potential (MEP) monitoring. Intraoperative findings revealed the oculomotor nerve was compressed by the ID from the lateral direction, as suggested by the preoperative 3DCG images, and had an indentation (Fig. 3).