[Basal interhemispheric approach for distal anterior cerebral aneurysms].
To investigate retrospectively the usefulness of basal interhemispheric approach for neck clipping of aneurysms located on genu or infracallosal portion of anterior cerebral artery. Seventeen aneurysms in 17 patietns treated by clipping with basal inter-hemispheric approach in our department for past 8 years were reviewed. Of them, 12 were ruptured aneurysm and 5 were unruptured one. The distance between frontal base and most frontally located bridging vein and the shortest distance from cranium to aneurysm were measured from angiograms of lateral view, and the point on cranium of the shortest distance was identified in each cases. Bridging vein damage suffered during surgical approach and the duration of brain retractor use were examined from operative videotapes. The clinical outcome was rated at discharge by Modified Rankin Scale. The distance between frontal base and most frontally located bridging vein was ranged as 15-69 mm (mean, 32 mm). The shortest distance between cranium and aneurysm in each case was ranged as 25-48 mm (mean, 33 mm), and the point on cranium of the shortest distance was these within 20 mm from frontal base in 11 cases. Any damage or cut of bridging vein were not seen in all cases. The duration of brain retractor for unilateral frontal lobe and for bifrontal lobe in recent 14 cases was ranged 0-46 minutes 41 seconds (mean, 8 minutes 55 seconds) and 0-16minutes (mean, 2minutes 24 seconds), respectively. No brain damage caused by operative procedure was detected on postoperative CT scan. All five patients of unruptured one and 8 patients of ruptured one were rated as 0 by Modified Rankin scale, 2 patients of ruptured one as 3 and 5, and 2 patients of ruptured one died. The basal interhemispheric approach for neck clipping of aneurysm located on genu or infracallosal portion of anterior cerebral artery would provide wide view of aneurysm and its surrounding structures with minimum retraction of frontal lobe, short distance to the aneurysm, and low risk of bridging vein damage.