Hi there, I have had the procedure. In Australia it is done in 2 stages. The first, you are awake under mild sedation. This is so they can be sure they have the correct location for the probes. They ask you a number of questions repeatedly during the procedure to ensure you are still aware of what is going on and they need you to be able to respond with right and left hand actions to see if the stimulation is working. Once they have that all sorted, they place you under general anaesthetic to put the implanted device under your chest wall and run the wires from your brain down to the chest under your skin. I have had a rechargeable battery implant, which requires a recharge every 7-10 days, but lasts up to 9 years. The previous version was non rechargeable and had to be replaced after 5 years. The procedure has been a godsend for me, allowing me to continue working (I am 50, been dxed for 9 years). If it wasn't for the surgery I would have been retired. Now I can see me working for at least 6-10 years more!
Good luck with your procedure, and may it be all that you hope for.