Effect of decompression craniotomy on increase of contusion volume and functional outcome after controlled cortical impact in mice

If, how, and when decompressive craniotomy should be used for the treatment of increased intracranial pressure after traumatic brain injury are widely discussed clinical subjects. Despite the large number of clinical studies addressing this issue, experimental evidence of a beneficial or detrimental role of decompressive craniotomy after brain trauma is sparse. Therefore, we investigated the influence of craniotomy on intracranial pressure, contusion volume, and functional outcome in a model of traumatic brain injury in mice. Male C57/Bl6 mice were craniotomized above the right parietal cortex and were subjected to controlled cortical impact injury. In control mice, the craniotomy was closed immediately after trauma, whereas in treated animals the craniotomy was left open. In control mice intracranial pressure (ICP) increased to a maximum of 23.7 +/- 3.1 mm Hg 6 h after trauma (p < 0.001), while in craniotomized animals, no ICP increase was observed. Twenty-four hours after trauma, the point in time of maximal lesion expansion, contusion volume in craniotomized mice was 40% smaller as compared to controls (18.3 +/- 2.0 vs. 30.2 +/- 3.5 mm(3), p < 0.04). Furthermore, craniotomized mice showed significantly improved motor function in a beam walking task (p < 0.04) and faster recovery of body weight after trauma (p < 0.02). Our results demonstrate that craniotomy blunts post-traumatic ICP increase, significantly reduces secondary brain damage and improves functional outcome after experimental TBI. Careful clinical evaluation of craniotomy as a therapeutic option after TBI in man may therefore be indicated.