Is it possible to have something in brain that can cause nerve twitching sensations in legs or in arms?? or is it only possible through something in spine?

Usually muscle twitching is due to metabolic/hormonal/ Local disorders . Depending on how much area, frequency and how often, the cause can be in basal ganglia in the brain as well. Please see your doctor. Hope it helps.

Time to see a neurologist and get a full neurological exam. The doctor is trained in locating the source of your symptoms and can design an appropriate program.