To determine the efficacy of mild hypothermia in patients treated with temporary arterial occlusion during aneurysm surgery, we investigated postoperative neurological deficits relevant to the cerebral ischemia due to temporary occlusion and ischemic change on CT. There were 97 consecutive patients who underwent neck clipping with temporary occlusion under mild hypothermia (34ºC) anesthesia in the past 10 years at our hospital.
Ten patients (10%) had transient neurological deficits including mainly hemiparesis and 2 patients (2%) had permanent hemiplegia. Preoperative neurological state, such as an unruptured aneurysm, mild or severe subarachnoid hemorrhage, and patient's age did not correlate with the frequency of postoperative neurological deficits. More than 20 minutes of temporary occlusion increased the frequency of ischemic neurological signs after surgery. Permanent hemiplegia occurred with occlusion times between 19 and 28 minutes. Temporary occlusion of the middle cerebral artery tended to raise the frequency of postoperative neurological deficits. Small infarction of the perforating artery territory was revealed on CT scan in 17 percent of 12 patients who presented neurological dysfunction. Temporary arterial occlusion was mainly applied to reduce dome pressure of the aneurysm and make a proper clip placement in cases of large domes and multi-dimensional neck geometry in 35 patients with unruptured aneurysm at a mean occlusion time of 6.5 minutes. In 62 patients with ruptured aneurysm, temporary arterial occlusion was used to prevent intraoperative rupture as well at a mean time of 12.9 minutes.
Therefore, the option of mild hypothermia may be indicated for a complicated ruptured aneurysm surgery, which requires about 20 minutes of temporary arterial occlusion.