The invention provides a system and method for treating a subject having unwanted or overactive nerve activity. The method involves applying one or more of direct current, charge imbalanced time varying current and pulsatile current to a target nerve; and controlling the amplitude and the duration of the current such that there is a net charge delivered to the target nerve at a sufficient charge density to cause controlled ablation to the target nerve until unwanted or overactive nerve activity is reduced in one or both of the target nerve and a target body tissue innervated by the target nerve.