Dear Janine, It is difficult not to jump to conclusions regarding any new symptom when you have had a diagnosis of cancer. However, the lower the stage of cancer the less likelihood that there could be metastases, the possibility of metastasis decreases further with adjuvant therapy, but the possibility, even though very low, is still there. A tumor could cause numbness, however there are other problems/conditions that could also be the cause of your symptoms. You are doing the right thing by having this new symptom evaluated, to see just what is the cause of your problem.
the problem you describe is with the ulnar nerve. Problems with a specific nerve don't usually come from the brain, but from the nerve trunk itself. There are many things that can cause ulnar neuropathy, including various compression syndromes from scar tissue, etc. It would be a pretty rare but not absolutely impossible scenario to be due to metastatic cancer. Other explanations are more likely.
I will be speaking with my Oncologist by telephone tomorrow, 11/14. It appears that he wants to order a test prior to my live visit with him, my guess is an MRI, CT Scan or Bone Scan. Meanwhile, you mentioned scar tissue in your comments.
My questions to you are: What & where is the ulnar nerve? Where is the nerve trunk? What might have happened to suddenly cause this damage? Assuming my testing comes back negative, what type of doctor should I see? I'm sure my Oncologist will refer me to another doctor.
P.S. I, also, would like to thank you for being in the forum. I've read many of the questions and it's very nice of you to take the time to help us.
the ulnar nerve starts in the axilla (underarm), runs down the arm along the inside of the elbow (it's the nerve that gives the name "funny bone:" hitting the elbow in the right spot zaps the ulnar nerve), and into the palm to the ring and little fingers. Scar tissue entrapment can occur at the elbow, or in various places in the arm, due to injury or other processes that can tighten the tissues thru which it passes. Often one would start with a neurologist, and get a nerve conduction study which can pinpoint the area of pressure on the nerve, if there is one. If such a thing is diagnosed, then depending on the cause, a neurosurgeon (sometimes an orthopedic surgeon) would be the one to see in regards to releasing the entrapment.