Planning for DBS cases is completed on the ROSA software
PD is either STN or GPi.
Dystonia is GPi. Essential Tremor is VIM, or VOP (VOP not standard of care).
Imaging: you can sometimes see these structure on our FGATIR sequence, which is a white matter null sequence. Here the white matter structures appear dark.
STN- Look for the red nucleus on the axial view for STN, your target should be at the anterior border of the red nucleus. The STN typically appears dark and almond shaped on the FGATIR. STN is tilted when looking in the coronal view, so you want your entry points to be wide.
coordinates: STN- reference point mid ACPC. 12mm lateral, 3 mm posterior to mid ACPC, and 4 mm ventral.
GPi- you should look for the optic tract. This will appear dark at the most ventral and medial border of GPi. GPi is large and vertical, so you want your electrode to be placed vertically with entry points closer to midline.
coordinates: GPi- reference point mid ACPC. 20-24 mm lateral, 0 to 4 mm anterior to mid ACPC, and 3 to 5 mm ventral.
VIM- sometimes can see its shape but we rely more heavily on stereotactic coordinates and microelectrode recordings. VIM entry point is in between STN and GPi, more vertical.
coordinates: VIM- reference point is PC. 12 mm lateral, ¼ of ACPC length anterior to PC, and depth is at the ACPC line (0).
For VOP, you would do the above coordinates, and add 2 mm anterior.
Frame, Positioning
Placing the frame
As patients are sedated, make sure to use local lidocaine at your posterior pin sites prior to placing the frame
Make sure the frame’s front bar is upside down, should look like a mustache or frown face.
Usually easiest to start with 45 mm pins for the back two posts. Make sure you fully thread the 45 mm pins for security and safety.
Once you are happy with the placement of the back pins and place on the patient’s head (make sure on bone, and above the occiput), inject local through the pin openings on the front two posts, then select pins based on how much room the patient has. The front two pins usually go above the eyebrows, into the forehead.
Make sure to have the ends of the pins sticking out! Necessary for ROSA registration.
O-ARM Spin:
Get the spin before connecting to ROSA, with patient frame and head resting on the bed
Make sure the field of view is 40cm
Once scan is complete, check each pin site on imaging to ensure you are on bone and that none of the ends of the pins were cut off
Make sure the O-ARM is fully extended so that it will have the full range to lower fully or raise as needed with the patient positioning.
Leave the O-ARM open for the case, but in place.
ROSA:
Connect to ROSA. Make sure the ROSA arm is at 3.5 length for DBS cases. You will need to raise or lower the bed to the height of the ROSA arm, and have patient in a relaxed beach chair position.
Once connected (and anesthesia is happy with airway), you will need to register. DBS registration is completed by marking the pin sites on the imaging, then taking the ROSA arm to each pin site in a clockwise fashion starting from the front right pin. Registration must be 0.5 or lower.
Perfecting your registration: the sphere of the ball of the RSOA arm should be halfway into the pin site hole, as shown in examples here.
Once registered, take the ROSA arm to each of your incision points to draw your incisions.
Sterile set up
Microdrive- should always be set to 10.0
Microdrive holder- cannulas should be set up with the “plus sign” orientation, not in an “X” orientation.
Be very careful when setting up the Microdrive as the cables are very finnicky and can bend and break
**need photos
Surgery
Two incisions and open with Weitlaner (JGM does NOT like to bovie the skin or periosteum at this point)
ROSA will take you to the right side. Insert cannula into the center opening and bovie on the cannula, towards the bottom to mark your drilling target
Send ROSA home, and drill burr hole with perforator on the target.
Check the target again by bringing in ROSA again. Make sure that the Microdrive holder is aligned to the patient’s anatomy, and check the center, posterior, and medial trajectories to ensure they are in the burr hole.
Place the ring for the cap with two number 5 KLS screws.
If Boston Scientific, check the gate.
If Medtronic, do not check the gate
Repeat steps 2-5 for left side
Now we wake the patient up. Make sure BP is less than 160 and wait until well controlled prior to moving on.
We open dura at the center, posterior, and medial trajectories one at a time by inserting the cannula and using bovie towards the bottom. Do not bovie the cortex.
Once all three spots of dura have been opened, slowly insert one cannula at a time into the brain using slow quarter twists. If you have resistance, stop. The cannulas have a lip at the top so they will stop you where you should be.
Tighten the screws so the cannulas will not move. Once done, remove the inner stylet from each cannula
Connect the Microdrive to the Microdrive holder. Make sure it is flush with the platform, and tighten the screw so it will not move.
The Microdrive should have the round attachment on, and you should one by one insert the microelectrode through the attachment and through the cannulas. Once all three have been inserted, make sure to tighten them by tightening the screws on the round attachment.
Once inserted, push down the red part so it is flush with the yellow. Attach the cables to the microelectrodes (yellow to yellow, red to red). We always have 1-center, 2-posterior, 3-medial (if we ever use anterior, that is 4, and lateral would be 5)
Made with Bullet