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A contrast CT is very sensitive to rule out a brain tumor
. If it is normal it is unlikely you have brain tumor. Since you are working for a radiation oncologist
you anxiety level for a malignancy is very high which may also be partly responsible for aggravation of your symptoms. The problem could be related to cervical spondylitis
as you have numbness in the arms and hand and even tingling on face can be explained with this. It could also be related to vision. It is more important to get cervical spine
X ray, ESR, CBC, and to see opthalmologist. A carotid doppler, if indicated by your neurologist
, may rule out any insufficient vascularity of brain.