Hey Gail. I can add to what they all said to you... perineural invasion... it means the tumor is deep enough that it hit the nerve. Why is this important... because apparently to the research I did, cancer cells have a tendency to move along the path of least resistence. In this case it is easier for it to move along the nerve paths.
I too had perineural invasion. What this meant was post op, it put me in a gray area with regards to radiation and chemo therapy. It was one of the things they looked for. The second thing was spread to the lymph nodes. I did have one node involved... it`s all gone now along with 39 others. But they are still giving me chemo and radiation. Partially because the second marker they look for is ECE of the lymph node (extra capular extension) a little of the cancer outside the capsule of the node. I was told I was still in a gray area, however I expressed to them I wanted this treated aggressively - so they agreed and recommended it.

Best of luck in your surgery... PS I didn`t have my jaw split. My dr. made me sign off on it, he said he would only split my jaw if he couldn`t get all of the tissue with good margins without doing it. He told me later he lost 10 lbs in the OR because of that, but his smallest margin was 6mm... so I am duly grateful. One less thing to recover from.

Take care and hopefully things go well.