Controlled Cortical Impact Model for Traumatic Brain Injury

The overall goal of this procedure is to produce traumatic brain injuries using the controlled cortical impact model. This is accomplished by first anesthetizing and preparing a mouse for surgery. The second step of the procedure is to perform a C craniectomy.

The third step is to set up the impact system with the desired parameters. The final step is to impact the exposed brain. Ultimately, the results can show the cortical injury cavity through imaging of the dissected brain and immunohistochemistry.

Generally, individuals new to this method will struggle because they find it difficult to generate consistent brain injuries. Demonstrating the procedure will be Dr.Shang Gao, a research associate in our lab. After anesthetizing, a mouse shave its head between the ears, clean the exposed skin with alternating scrubs of 10%iodine and 70%ethanol.

Next, be sure to lubricate the eyes so they do not dry out. Then fix the mouse in the stereotactic frame, making use of the ear bars and bite plate. The head should be very stable.

Start the craniectomy with a longitudinal incision in the middle of the head using scissors. Then use a hemostat to hold the skin to the side with a cotton tipped applicator Wipe, clean and expose the skull bone. Allow it a minute to dry before proceeding.

Once dry, use forceps to apply pressure to the skull. Make sure that the preparation stays immobile. Identify the lambda and breg ma landmarks.

Then at their center, draw a circle with a four millimeter diameter that is half a millimeter from the midline. Next drill along the marked circle to make the bone easy to break, but do not penetrate to the dura mater. Remove the dust as needed.

Then use forceps to break off the circle of bone, exposing the dura mater. The C craniectomy is the most critical step. Producing consistent bone window parameters will allow for consistent injury severity.

Ensure that the proper drill size, speed, and force are used well. Drilling The The impact system uses an actuator to perform the impact into the cranium and has some parameters that must be set. Set the velocity of the actuator to three meters per second.

Next, secure the actuator to the stereotactic frame. Using the micro manipulators position the three millimeter wide actuator to the open skull area. Then adjust the actuator's tip so it is parallel to the surface of impact.

To set the zero point, extend the actuator and lower it until the tip just touches the location of impact. Set the corresponding Z channel on the frame to zero. Now retract the tip in this case one millimeter.

Then set the deformation depth for the appropriate traumatic brain injury, which will move the actuator. Then hit the impact button to make the injury after the impact. Clean up any blood with a cotton tipped applicator, but do not touch the injury.

Move the mouse to a warm pad and monitor the injury When the bleeding has stopped, suture up the wound, then return the mouse back to a clean cage on a warm pad and allow it to recover there overnight. After the impact, the amount of swelling, bleeding, and cranial distortion reveals the true severity of the injury. A limited to full breach of the dura will make a big difference in the amount of bleeding and makes a mild to moderate TBI.

Fixing the tissue and viewing it with microscopy easily distinguishes a moderate and severe TBI. Here nis. L staining is used to compare a control to a mouse that received a moderate TBIA cavity is visible that extends deep into the cortex.

This model can be used to investigate such defamations as well as neuronal death and other histopathological changes caused by brain injuries Once mastered, this technique can be completed in 15 minutes if it is performed properly.