Alexander E. Merkler, MD
Mild hypothermia is an established neuroprotectant and has shown to improve neurological outcomes in both cardiac arrest and neonatal hypoxic-ischemic injury. Its role in stroke has yet to be established, and ongoing multicenter trials are underway.
Massive cerebral hemispheric infarction (MCHI) occurs in a subset of patients with stroke and confers a very high degree of mortality and morbidity. Without decompressive hemicraniectomy, mortality is over 70%, and in patients who receive a decompressive hemicraniectomy, approximately 40% of survivors are left disabled with a modified Rankin scale (mRS) of 4 (unable to walk without assistance and unable to attend to own bodily needs without assistance). Further strategies are therefore necessary to reduce morbidity and neurological impairment in patients with MCHI.
In the current manuscript, Dr. Su et al assess the role of mild hypothermia on neurologic outcomes in patients with MCHI. Patients were eligible if they were 18-80 years of age, had a unilateral MCHI (based on the same definition used in previous large trials investigating decompressive hemicraniectomy) within 48 hours, and were deemed ineligible to receive decompressive hemicraniectomy due to use of antithrombotic medications or refusal to undergo surgical treatment. Patients were randomized to receive mild hypothermia versus normothermia. Hypothermia was initiated as soon as possible after admission and continued for at least 24 hours. The temperature of patients in the control group was sustained between 36.5˚C – 37.5˚C to maintain normothermia. The primary outcomes were mortality and mRS at 6 months. An mRS of 0 to 3 was considered a good neurological outcome.
Overall, 33 patients were enrolled. There was no difference in mortality; however, although non-significant, there was a trend towards improved neurological outcomes in the patients who received therapeutic hypothermia. Seven of every eight surviving patients who received hypothermia versus four out of ten surviving patients who did not undergo hypothermia achieved a good neurological outcome. In fact, 3 patients in the hypothermia group and 0 patients in the control group achieved an mRS of 1 or 2. Complications were significantly more common in the hypothermia group and included arrhythmia, electrolyte disturbance, gastrointestinal bleeding, and hyperglycemia.
Limitations are 1) only patients who did not undergo decompressive hemicraniectomy were included, and 2) patients who received hypothermia were on average 10 years younger than the control group.
Hypothermia may prove to be a useful tool to improve functional outcome in patients who suffer from MCHI, especially in those in whom decompressive hemicraniectomy is not performed. Future studies are necessary to confirm these results.