Dear strike3: Any time surgery is performed anywhere on the body, there are tiny little nerves that are damaged. It is not uncommon for there to be numbness in an area following a surgery. It may improve in time. The axilla is not unique when it comes to nerves but each persons anatomy and results may be a bit different. There are some important nerves that travel through the axilla and care is taken to avoid damage to these nerves but there are sometimes superficial nerves that are damaged without the surgeon even being aware that they are there.
Sentinel lymph node biopsy is actually a low risk procedure with regard to nerve damage. Nerve damage is not “common” at all. Nerve damage was much more common when complete axillary lymph node dissections were done. The risk goes up with the number of nodes that are removed.
Thought I would give you a little hope to your situation. I too had a long section along the backside of my arm that for quite a long while was numb and my entire armpit was numb. I had a mastectomy, full lymph node removal (after the sentinal node biopsy) in '05 and then TRAM reconstruction in '07. I have since gotten used to the new feeling with my arm.
To my surprise this morning at my exam... I got a tickle from the exam in my armpit. Haven't had any sensation there, if at all, since '05. The back of my arm that was entirely numb does now have sensation to a minor extent.
My doc (radiologist) said that nerve endings grow about a quarter of an inch a year and that in some cases, the loss of sensation will return. It may not return to what it was, but some sensation will return.
Hope this helps a bit, I feel for ya....