[Extra-intracranial bypass and internal carotid artery ligation in one-stage operation for intracavernous and giant carotid aneurysm].

The combined one-stage operations, STA-MCA anastomosis and internal carotid artery (ICA) ligation (or trapping) were carried out in 11 cases (Age): 18-79 yrs, Av.: 45.8 yrs) of ICA aneurysms which were inaccessible for a direct operation because of their locations and sizes. First the STA-MCA anastomosis was performed under general anesthesia. Then the patient was awaken and thereafter under local anesthesia the ICA was temporarily clamped for 30 min. under induced hypotension to check whether any ischemic signs appeared. This was followed by proximal ICA ligation when no ischemic signs were observed. In all 11 cases, the anastomosis was patent. The aneurysms disappeared. Neither cerebral ischemia nor rebleeding from the aneurysms was seen during the long follow-up. The mean value of the bypass flow was 119 m/min which was twice as much as that in the cases of other occlusive cerebrovascular diseases and which was about one third of the blood flow of the ICA. Cerebral blood flow measurements through 133Xe inhalation method revealed that there was no difference in rCBF values between the operated and non-operated sides and that their values were within normal limits. The postoperative blood pressure was unchanged in 42% of our 11 cases, temporarily elevated and thereafter normalized in 33% and persistently elevated in 25%. Ophthalmodynamometry showed that the pressure of the central retinal artery decreased postoperatively in a degree of 5-10% in comparison to the non-operated side. No visual impairment was observed postoperatively (except case 3, see the text). These combined operations, STA-MCA anastomosis and ICA ligation were beneficial in preventing the potential postoperative cerebral ischemia. Intra-arterial pressure measurements of the STA and MCA suggested that the one-stage operations of these two procedures are better than the two-stage operations for the patency of the anastomosis because the pressure gradient between the donor and recipient vessels is increased (from 10.3 mmHg to 49.3 mmHg) by this technique. Temporary ICA clamp for 30 min. under induced hypotension in local anesthesia is useful to check whether the one-stage operations can be tolerated or not. EC/IC bypass with an interposed saphenous vein graft is a more beneficial surgical technique than a routine STA-MCA anastomosis, because an immediate and larger amount of bypass flow can be obtained.