Pain Management: Nerve Blocks
Marc Darrow (Physical Medicine and Rehabilitation, Joint Rehabilitation Sports Medical Center, Inc. ) gives expert video advice on: How long does the pain relief last after a nerve block is given? and more...
What is a "nerve block"?
A nerve block is the use of an analgesic to reduce the amount of peripheral nerve pain. Sometimes, when we use something that's very caustic like a phenol injection (which is an alcohol), that will actually lyse or destroy that nerve. We may also use something like radio frequency which is a heat wave that is injected into the area and heated up to actually kill some of these nerves. Or, we many use what we call cryotherapy or cold therapy to inject something and then freeze the area to disable the nerve fibres that go to these areas.
Are nerve blocks effective at managing chronic pain?
Nerve blocks have been proven very effective at managing chronic pain. Sometimes they last forever, but sometimes they last for a minute. We never know the answer to that until we do them.
What risks are associated with nerve blocks?
Risks to nerve blocks around the spinal chord have to do with what happens to the spinal chord if some fluid is introduced into the dural sac which surrounds the spinal chord, or a needle is actually introduced into the spinal chord. A person can get a terrible headache from this, or they can get what are called parethesias where they lose sensation in some parts of the body or where they may feel sensation or numbness around certain parts of the body. They may actually get an infection from breaking through tissue. They can have a spinal chord injury where they lose the ability to move part of their body or move certain muscles.
What is "cryoanalgesia"?
Cryoanalgesia is a very simple concept. Analgesia is the reduction or elimination of pain and cryo is cold. So we use ice on areas that are injured around the body with tendonitis or inflammation, and we can actually use it to reduce pain inside the body or around nerves. Or we can use extreme cold that's focused on an area, to burn tissue in a sense, or kill the tissue, and reduce the nerve fibers to the tissue.
What is "radiofrequency denervation"?
Radiofrequency denervation is typically the introduction of a needle through the skin to heat an area that is causing pain. This can typically be facet joints in the back where we will denervate the area, and we'll get rid of the nerves that are there; actually killing them with the heat.
How long does the pain relief last after a nerve block is given?
The length of pain relief after nerve block varies upon the solution that is being used or the technique that's being used. If it's a local anaesthetic, it may just last for a few hours. Then again, it may last forever, you never know. If it's a steroid injection like cortisone into the area, we typically find relief in that area for up to several months. If it's a phenol injection, it can actually kill the nerves; it may be permanent.