Selective Brain Hypothermia Augmenting Neuroprotective Effects of Decompressive Craniectomy for Permanent Middle Cerebral Artery Infarction in a Rat Model

Objective: To evaluate the combined effects of a decompressive craniectomy and prolonged selective brain hypothermia on large hemispheric infarction in a rat model. Methods: Permanent middle cerebral artery infarction using an endovascular occlusion technique was created in rats assigned to 4 groups. Normothermia was maintained without a craniectomy in group A (n = 20) as the control, prolonged (>44 hours), selective brain hypothermic treatment was performed on group B (n = 20), a craniectomy was performed on group C (n = 18), and prolonged, selective brain hypothermic treatment using a cooling coil implanted in the craniectomy site was combined with a craniectomy for group D (n = 18). Results: Group B and C exhibited a significantly reduced infarct volume when compared with the control. Furthermore, group D showed a significantly reduced infarct volume when compared with group C, plus a significantly improved neurologic score. These results for group D were associated with an increased neuronal cell count and reduced hyperactive microglia and hypertrophic astrocytes in the cortical penumbra (P < 0.01). Moreover, a greater preservation of normal-appearing axonal bundles and the blood–brain barrier was observed in the core infarct region at the caudoputamen. Conclusions: A decompressive craniectomy reduced the infarct volume and improved the neurologic outcomes in a rat model of middle cerebral artery infarction. Furthermore, when combined with prolonged selective brain hypothermia, significant additional benefits were observed for the neurologic outcomes, infarct volume, and degree of neuroinflammation.