This is unfortunately a very common problem. There is a few things you can do. Rather than using a drill to make a hole to insert a cannula or other instrument, I simply start the hole with the drill and then finish it with a 27g needle. I find that making the hole manually is more delicate and it gives you greater control over adjusting before you end up with a massive bleed. Depending on what you are doing, another tactic that people also use is targeting at an angle to avoid the problem completely. I have seen this done in papers, but have not tried it personally. I think this would be difficult with an infusion needle unless it was very stiff, and you'd have to practice adjusting your equipment to be able to insert at an angle. 

Hi Sam how are you? I never implanted in the mPFC but sometimes I have a similar problem while implanting in the MEC. I think that the reason is that on the midline you find the venous sinus. I see two possible solutions. The first one is to make a bigger hole to have a good view of the brain surface and of the vessels. Using a small needle (possibly a flat one) you can carefully (really carefully!!!) move the dura and the sinus while descending the cannula. The second solution (the one that I'd prefer) is to use a lateral angle to reach the mPFC. Hope it will help you. Good luck and say hello to everybody in the lab.

Hi Julia Hill, 

Thank you for the ideas. I am already doing the first idea that you gave to drill a bit and then to use a needle to open the dura. But the real problem is during the insertion of the cannula. And yes, I found papers too where they do angled surgeries for mPFC. I should maybe try doing this.

Hi Fab,

I am doing good. Hope you are fine there as well. I really liked your first idea, I will try doing this first. I don't know if I can be that careful but let me see. Else as Julia and even Arianna suggested, I should do a trial for the angled surgery. But even in that case I doubt there will be bleeding again. Thanks a lot Fab :) 

If the bleeding is caused by the sinus, as I suppose, by using the appropriate angle you should avoid it. If you will do a bigger hole, just remember to put a little bit vaseline in the space around the cannula to prevent the cement dropping inside! See you

Hi Samyutha , I am having the same problem As you probably know, there is a sinus that runs along the metopic suture and it's very easy to hit. I would highly recommend the suggestions mentioned earlier (i.e. Julia). I would add that you should use smaller holes as you will be less likely to hit the sinus. In addition, when there is bleeding, you can control it quickly with ice-cold sterile saline and/or hemostatic pellets (https://www.pattersondental.com/Supplies/ItemDetail/075568985). I actually put a pellet in the saline for even better control.