Protocol to the induction of loco-regional mild hypothermia for temporay clipping in the surgery of the middle cerebral artery aneurysm

Introduction: Less than 30% of Middle Cerebral Artery (MCA) aneurysms are amenable for endovascular coiling. Microvascular surgery still carries a large number of complications, since many perforators arteries arise near to the neck of the aneurysm and, in many cases, one or more branches of bifurcation or trifurcation of the MCA originate in the aneurysm wall. Temporary clipping of the proximal MCA avoids the aneurysmal rupture, facilitates the aneurysm dissection and clip placement but long term temporary clipping carries a great risk of ischemic complications. Objective: We developed a protocol of brain protection based on the neuroprotective properties of mild hypothermia which would intend to permit a more extended time of temporary clipping. Methods: Sixty-eight cases of MCA incidental aneurysms or after the 12nd day of hemorrhage were operated on. Brain temperature was dropped at levels that varied from 29.5ºC at 15mm parenchymal depth to 32.5ºC at ventricular level. There was no change in the patient’s body temperature. Temporary MCA clipping varied from 8 to 28 minutes. Results: There was no intraoperative aneurysm rupture. All 68 patients were alive and neurologically unchanged at the 90th and 180th follow-up days. Conclusion: Loco-regional mild hypothermia may be effective in protecting cerebral parenchyma in cases of temporary clipping over 8 minutes up to 28 minutes in MCA aneurysms surgery.