Biopsy with BrainLab VarioGuide
Background
- BrainLab pamphlet ns_fl_en_varioguidebiopsyworkflow_mar23_rev1-1.pdf (brainlab.com) . Note this pamphlet is for a slightly newer version but the same principles apply.
- VarioGuide Alignment System—Precise Instrument Alignment (youtube.com)
- VARIOGUIDE: A NEW FRAMELESS IMAGE‐GUIDED STEREOTACTIC SYSTEM—ACCURACY STUDY AND CLINICAL ASSESSMENT | Semantic Scholar
General Notes & Tips
- Cutting window: unless you are actively cutting into tumor, always remember to have the cutting window on the needle biopsy in the closed ("on Christmas") position (see sidebar) - this means green and red are on top of each other. When red and red are on top of each other, that means the cutting window is open.
- Coaxial, coaxial, coaxial, coaaxial, coaaxial is the mantra for everything you do from drilling to passing the biopsy needle. Remember you're working on the orders of millimeters here so even the slightest gross bend in your instruments will put you way off target.
Pre-Sterile
1. Put images up on the screen (coronal and axial w/ contrast + axial FLAIR)
2. Post-op orders: CTH, pain meds, CAP 140, PT/OT
3. Set a target on the BrainLab monitor
Pinning
4. Position in standard fashion based on target location
5. Standard fashion pinning based on target location → attach to Mayfield. You'll want to attach Mayfield on the inside (see next step).
6. Connect T-guide to the outside of the Mayfield. Connect the Grid to one of the T-guide attachments. The VG arm will be connected completely by a tech once you're sterile
Figure 1: T-guide and attachments
7. Now register in standard fashion (make sure no eye tape on, focus on bony landmarks like canthi, nasion, mastoids, do not depress skin, stay perpendicular)
8. Place tegaderms over eyes once pinning accepted and verified.
Draping
There are two things you need to pass through to the unsterile world beneath the blue sheets, the (1) sterile half of Patient Reference Arm (Grid) and (2) VG arm.
9. The grid is attached in standard fashion with a scissors that gets trashed after.
10. The VG arm is passed through a large whole below the bag. To do this optimally, ask the tech under the sheets to point on the drape where they want you to cut the hole, you then grab this point and after asking them to move their hands you cut a line around 4 inches through then "deliver the baby" to them.
Figure 2: Draped Attachments to T-guide
Post-Sterile Setup
Below are all the joints viewed in a setup that's complete.
Figure 3A: All Joints
Figure 3B: Coarse Adjuster (joint 0)
This is the black knob that controls the position of the black ring over the skull.
11. Change the ring so that it is perfectly orthogonal to the entry point on the skull, and you use the bulls-eye guide on the screen to tell you that you're perpendicular. 
Figure 3C: Joints 1 and 2
12. Joint 1 is a rotational joint and joint 2 is a rotational / translational joint. Adjust both until it's green no your screened (-.2 to 0.2) 
14. There is a subtlety to adjusting this joint in that you need to bring your fingers from behind the balls (over the black ring) because if you come in front of the balls, you will interfere with the camera.
Figure 3E: Joint 3
15. On the Mayo table, use the ruler to mark on the VG trochar the distance to target from the middle of the cutting window (not the bottom of the entire apparatus). Then move the depth stop to this marked spot.
Figure 4: Setting Depth Stop on your biopsy needle
16. Insert drill guide (smaller one) into black ring and drill through skin until you feel breaking through skull. NOTE that drillbit is a conventional one and it's on you to not plunge!
Figure 5: Drill Guide 
Performing Biopsy
17. Insert needle with the cutting window closed down to the depth stop.
Figure 6: A Biopsy Needle with the cutting window closed.
Note the white depth stop with a side tightener that is preventing the needle from plunging beyond the target depth. 
The Art of Cutting
18. Turn the top half of the biopsy needle so that red is on red (see sidebar).
19A. Gentle suction about 1-2 cc so that you create negative pressure
19B. With the suction from above still held, rotate 180˚ so that cutting window goes from open to close. If you do this right, you are slicing and sucking at the same time and you will maximize your yield.
20. You should be "closed on Christmas" again. Now that youre cutting window is closed ,pull top half of biopsy needle apart and gently flush to give scrub all your specimen.
360˚ Sampling
Repeat steps 18-20 above three more times, each time rotating apparatus 90˚ so that you get a total biopsy.
20. While waiting for path, take out the needle and insert some saline that way if a bleed develops you see it while waiting.
21. Figure of 8 absorbable suture.
Sidebar Figure 1: "Closed on Christmas" - this means the cutting window is closed.
Sidebar Figure 2: An Open Cutting Window - red on red. Notice at the bottom of the needle is an open cutting window.
