The most common cause of of neck and back pain is osteoarthritis. Nerves on the small joints in the spine, zygapophysial or facet joints, become aggravated and transmit pain information to the brain. Medial branch blocks are used to determine if the facet joints are the cause of a person’s pain. Local anesthetic is used to freeze the associated nerves and if pain is relieved it confirms that the joint is the source of pain. Multiple injections can be performed to pinpoint the exact joints which are causing pain. This is a diagnostic block. Local anesthetic wears off after a few hours and will not provide long term relief. These diagnostic blocks can be done in conjunction with therapeutic blocks where cortisone is injected into the joints to provide longer term relief.