OLFACTORY DYSFUNCTION AFTER IPSILATERAL AND CONTRALATERAL PTERIONAL APPROACHES FOR CEREBRAL ANEURYSMS

OBJECTIVE This study investigated olfactory dysfunction after using a contralateral or ipsilateral pterional approach for anterior circulation aneurysms and related risk factors. METHODS This study included 189 patients who experienced an aneurysmal subarachnoid hemorrhage and in whom a pterional approach was used, including a contralateral pterional approach (12 patients), a pterional approach for an anterior communicating artery (AComA) aneurysm (70 patients), and an ipsilateral pterional approach for aneurysms of the anterior circulation, excluding the AComA (107 patients). In addition to questionnaires on olfactory function, Sniffin' Sticks tests were performed 12 to 38 months after the operation. RESULTS The incidence of olfactory dysfunction was high: 58% (7 of 12) with a contralateral pterional approach, 14% (10 of 70) with a pterional approach for an AComA aneurysm, and 4% (4 of 107) with an ipsilateral pterional approach for aneurysms of the anterior circulation, except for the AComA. In addition, patients 55 years and older had a higher incidence of olfactory dysfunction. Among the 12 patients in whom the contralateral pterional approach was used, 5 (42%) were anosmic and 2 (17%) were hyposmic. The incidence of olfactory dysfunction was also significantly higher at ages 55 years and older. The size and location of the contralateral aneurysm, if small (<1 cm) and located within a 3-cm lateral distance from the midline, were not found to influence the incidence. CONCLUSION A higher incidence of olfactory dysfunction was found in those patients in whom a contralateral pterional approach and a pterional approach for an AComA aneurysm were used. Another major risk factor was an age of 55 years and older.

Contralateral Pterional Approach to a Giant Internal Carotid-Ophthalmic Artery Aneurysm: Technical Case Report

OBJECTIVE AND IMPORTANCE The contralateral approach to internal carotid-ophthalmic artery aneurysms has been used in selected cases but has rarely been described for a giant internal carotid artery aneurysm. We report a case of giant aneurysm that was successfully clipped via the contralateral pterional approach. CLINICAL PRESENTATION A 69-year-old woman was found to have two aneurysms: a small aneurysm at the left internal carotid-posterior communicating artery and a giant aneurysm at the right internal carotid-ophthalmic artery. INTERVENTION A direct clipping operation was performed via the left pterional approach. After the small left internal carotid artery aneurysm was clipped, the contralateral giant aneurysm was further exposed and successfully clipped by use of the same approach via the prechiasmatic space. CONCLUSION The contralateral pterional approach can be applied even for a giant aneurysm of the carotid-ophthalmic artery aneurysm when the neck of the aneurysm is small and when there is a space between the anterior wall of the aneurysm and the tuberculum sellae. Furthermore, such a giant aneurysm can be clipped more easily and safely via the contralateral approach without compromising visual functions. To our knowledge, this is the first reported case of a giant internal carotid-ophthalmic artery aneurysm approached contralaterally. The feasibility of this approach can be assessed preoperatively by three-dimensional computed tomographic angiography as well as by conventional cerebral angiography.

Parameters for Contralateral Approach to Ophthalmic Segment Aneurysms of the Internal Carotid Artery

OBJECTIVE This study was undertaken to define more accurately the feasibility and indications of the contralateral pterional approach to ophthalmic segment aneurysms of the internal carotid artery (ICA). METHODS Between 1995 and 1999, 46 patients with ophthalmic segment aneurysms of the ICA were surgically treated in our institution. Eleven of the 46 aneurysms were operated using the contralateral pterional approach. All aneurysms were successfully clipped without complications; three patients required bone resection around the aneurysm neck. We studied the 11 patients who were treated with the contralateral approach by defining six parameters to assess the feasibility of the approach and to predict the necessity for bone resection: 1) Parameter A, the distance between the anterior aspect of the optic chiasm and the limbus sphenoidale; 2) Parameter B, the distance between the bilateral optic nerves at the entrance to the optic canal; 3) Parameter C, the interrelation of the optic nerve and the ICA, expressed as a/b in which a is the length from the midline to the optic nerve and b is the length from the midline to the ICA; 4) Parameter D, the size of the aneurysm neck; 5) Parameter E, the direction of the aneurysm from the ICA wall on the anteroposterior angiogram; and 6) Parameter F, the distance from the medial side of the estimated distal dural ring to the proximal aneurysm neck on the lateral angiogram. RESULTS Parameters A to F were 8.8 mm (range, 5.4–11.1 mm), 14.5 mm (range, 10.4–22.2 mm), 0.9 mm (range, 0.6–1.3 mm), and 3.0 mm (range, 2.3–4.7 mm), 5 to 160 degrees, and 1.3 mm (range, 0.3–2.4 mm), respectively. All patients had excellent operative outcomes without visual dysfunction. Three patients required drilling of the bone around the optic canal on the craniotomy side; bone drilling was not required when Parameter E was between 30 and 160 degrees and Parameter F was more than 1 mm. CONCLUSION Parameters A to D are important for assessing the feasibility of the contralateral approach to ICA-ophthalmic segment aneurysms, and Parameters E and F are most useful for calculating the difficulty of this approach.