The presidential primary system has a rich and interesting history in American politics. From the nominations by caucus, in the days of the Founding Fathers, to the most recent contests, we have seen the electoral process go through a dramatic change.
Usually a nerve root block is only carried out when other methods of treatment have tried and failed and any nerve root that is blocked, will have been the most likely originator of pain. The procedure is not undertaken on each particular nerve.
1 Therapeutic nerve blocks are used to treat painful conditions. Such nerve blocks contain local anesthetic that can be used to control acute pain.  Diagnostic nerve blocks are used to determine sources of pain.