is the numbness dangerous?

I am almost certain to be diagnosted CTS (I did the EMG-test). But as I take letrozole because of breast cancer my oncologist wants me to not do anything for the moment. I do not mind to wait even though it is very unpleasant especially at night (even with braces) but I do worry that the damage might become permanent and that one day my hands will not wake up any more .... Is this possible? In the month of May I will have a breast operation under full narcose and I am so very afraid to wake up with numb hands/arms that will never again recover .....