The purpose of peripheral nerve blocks is to inhibit impulse transmission distally in a nerve terminal, thus terminating the pain signal perceived by the cortex. Nerve blocks can be used to treat acute pain (e.g., procedural anesthesia and perioperative analgesia), as well as for diagnosis and treatment of chronic pain. Impulse blockade can be brief (hours) or prolonged (months), depending on the medication used in the block and the technique (e.g., single shot block versus catheter).

Reference : Benjamin D. Wiederhold1; Emily H. Garmon2; Maria C. O’Rourke3. https://www.ncbi.nlm.nih.gov/books/NBK431109 , June 30th, 2019