gms | German Medical Science

Objective: To study the feasibility of temporary internal carotid artery (ICA) clipping for supraclinoid ICA aneurysm surgery.

Method: We dissected and analyzed in the anatomical lab three options of proximal ICA control: 1) Temporary clipping of the ICA in the neck- C1 segment (3 specimens, 6 sides) 2) Temporary clipping in the C4 segment (21 skull bases, 43 sides; 25 specimens, 50 sides) through a pterional approach with epidural peeling of the lateral cavernous sinus 3) Temporary clipping in the C5 segment (25 specimens; 50 sides) after an epidural clinoidectomy and dissection of the distal fibrous ring Particular attention was given to diameter and topographic position of the foramen spinosum, ovale and rotundum, the horizontal carotid canal, the greater superficial petrosal nerve as well as the anterior clinoid process.

Results: Dissection of the C1 segment gives direct access to the ICA in an early stage of surgery. Disadvantages are the additional cut in the neck, the sterile drapes and the distance to the operative situs (additional surgeon required). For temporary clipping of the C4 segment via an epidural, pterional approach essential landmarks are the foramen ovale, the lateral border of V3 as well as the greater superficial petrosal nerve. The mean distance from the posterior border of the foramen ovale to the anterior border of the horizontal carotid canal was 3,6 ± 1,5 mm (range 1,4 - 5,9 mm) on the left and 3,7 ± 1,7 mm (range 1,9 - 7 mm) on the right side. The AP diameter of the foramen ovale ranged between 2,8 - 5,7 (mean 4 ± 0,8) mm on the left and 2,5 - 4,9 (mean 3,8 ± 0,6) mm on the right side; its LL diameter ranged between 5,2 - 8,9 (mean 7,5 ± 0,9) mm on the left and 5,0 - 8,8 (mean 7,2 ± 0,9) mm on the right side. The bony groove of the greater superficial petrosal nerve signed for a mean distance of 10,2 ± 2,6 (6,6 - 17,7) mm on the left and 9,9 ± 2,6 (5,5 - 18,1) mm on the right the roof of the carotid canal. Extradural clinoidectomy via a pterional craniotomy gives sufficient space to dissect the outer fibrous ring and gain access with a temporary clip to the C5 segment. An advantage is the anatomic space gained for manipulation of the aneurysm, a disadvantage might be the drilling next to the ICA and the aneurysm in a stage of the procedure where the ICA is not yet under control.

Conclusions: All three techniques described allow a proximal control in case of supraclinoid ICA aneurysm. However, temporary clipping in the C4 segment seems to be the most safe and straight forward option.