Visualization of cortical cerebral blood flow dynamics during craniotomy in acute subdural hematoma using laser speckle imaging in a rat model

Mass evacuation with decompressive craniotomy is considered a standard intervention for acute subdural hematoma (ASDH). However, hemispheric swelling complicates the intraoperative and postoperative management of ASDH patients, and previous studies have revealed that this approach can damage ischemic/reperfusion (I/R) injury. Few studies have focused on the cerebrovascular response following traumatic brain injury (TBI). To characterize the relative cerebral blood flow (rCBF) before and after removal of the hematoma, rats were injured by a subdural infusion of 400 μL of venous blood or paraffin oil. MRI scans were performed. Then, we monitored cortical rCBF during hematoma removal in real time using laser speckle imaging (LSCI) in ASDH rats. The CBF of arteriovenous and capillary regions were quantified and normalized to their own baseline values via a custom algorithm. In the sham group, the cortical CBF was higher post-craniotomy than pre-craniotomy. However, in the hematoma injection group, the CBF of arteries and capillaries was higher while the venous CBF was lower post-craniotomy than pre-craniotomy. The difference in the changes in vein CBF that occurred between the two groups was statistically significant. The three components of the vascular system showed heterogeneous responses to craniotomy, which may be the basis for secondary brain injury.