Microsurgical anatomy around the origin of the ophthalmic artery with reference to contralateral pterional surgical approach to the carotid-ophthalmic aneurysm.

The supraclinoid segments of the internal carotid artery (ICA) and their surrounding structures were examined under magnification in 25 adult cadavers. Attention was paid to anatomical variations and relationships concerning ipsilateral and contralateral pterional microsurgical approaches to these regions, especially to the origin of the ophthalmic artery. Eighty-four percent of the ophthalmic arteries arose from the supraclinoid segment of the ICA. In the ipsilateral pterional approach, mobilization of the ipsilateral optic nerve was required to see the origin of the ipsilateral ophthalmic artery and the medial aspect of the proximal portion of the supraclinoid segment of the ICA. In the contralateral pterional approach, on the other hand, these areas on the contralateral side could be identified under the optic nerve with minimal or without retraction of the contralateral optic nerve. This was because 71% of the ophthalmic arteries arose from the supero-medial aspect of the ICA, and because there was nothing to intercept the view of the medial aspect of the ICA under the optic nerve. This study supports the usefulness of the contralateral pterional approach to the origin of the ophthalmic artery and the medial aspect of the supraclinoid segment of the ICA. This approach could be useful in certain cases of carotid-ophthalmic aneurysm. The authors' experience with the contralateral pterional approach to carotid-ophthalmic aneurysms is also described.