Effect of decompressive craniectomy on outcome following subarachnoid hemorrhage in mice.

BACKGROUND AND PURPOSE Elevated intracranial pressure (ICP) is a key feature of subarachnoid hemorrhage (SAH). Here, we examined the role of elevated ICP in the pathophysiology of SAH, and we investigated whether decreasing ICP by performing decompressive craniectomy (DC) can improve outcome. METHODS SAH was induced in male C57BL/6 mice via endovascular Circle of Willis perforation in the following 4 groups: sham surgery, SAH, DC after SAH, and DC before SAH. DC was performed either 15 minutes before or after SAH induction. ICP, cerebral blood flow, heart rate, oxygen saturation, and end-tidal PCO2 were monitored for 45 minutes. After surgery, neurological function was evaluated daily for 7 days. After killing, hippocampal neurons, corpus callosum thickness, and ventricular volume were evaluated on paraformaldehyde-fixed coronal brain sections. RESULTS Although DC reduced SAH-induced ICP, it yielded no beneficial effect with respect to posthemorrhagic hypoperfusion; moreover, DC increased the incidence of rebleeding, induced more severe neurological impairments, and caused higher mortality. Post SAH, mice that survived 7 days had no histopathologic differences, regardless of whether DC was performed. CONCLUSIONS Performing DC to reduce ICP either during or acutely after SAH resulted in more severe bleeding, a higher incidence of rebleeding, and poorer outcome. Thus, elevated post-hemorrhagic ICP plays an important role in controlling bleeding after SAH and should therefore not be reduced acutely. If DC is considered for treating a patient with SAH, the timing of decompression should take these effects into consideration.