What Causes Cold And Warm Temperature On Fingers While On Tegretol?

Hello my husband is 57 and takes tegretol and pain meds due to cranial surgery in the past. He had two swollen blood vessels in his head and sponges were put in to absorb shock against the nerves. That was 10 yrs ago. He has 3 fingers on his right hand that stay cold and the others are warm to the touch. This has been for four days straight now and he is concerned. My question: Does this have something to do with his blood pressure or blood circulation or past medical history? Should I be concerned? Do you think it could spread?