Some types of pain therapy are invasive, involving injections or implants
of devices. To simplify classification, all of these approaches may be termed
"anesthesiologic" because anesthesiologists with specialized training in pain
management usually perform the more sophisticated techniques. In practice,
however, injections are done by many different types of physicians, and even
the more sophisticated approaches are now being performed by physicians with
differing backgrounds, all of who have received special training
in pain management.
Injections
Injections are commonly administered for both acute and chronic pain.
Injection of a steroid or a local anesthetic, or both, into painful joints
or varied "trigger points" are commonly used to treat joint pain and pain
that originates in muscle or connective tissue. Sometimes, these types of
injections allow patients an opportunity to participate in physical therapy,
or reduce the pain long enough for a drug treatment to work.
Sometimes they provide longer lasting pain relief by themselves.
A controversial injection therapy still considered to be
unconventional is called prolotherapy. Prolotherapy is also
known as nonsurgical ligament reconstruction, and is used for
many different types of musculoskeletal pain. The treatment is
intended to cause the growth of new connective tissue in areas
where ligaments or tendons have become weak. The technique
involves injecting a substance, like dextrose (sugar water),
into a ligament or a tendon where it attaches to the bone. The
purpose is to cause local inflammation in the hope that this will
increase the blood supply and stimulate the tissue to repair itself.
This technique is unproven and controversial. Because it involves
injection of a substance into the body, it is not without risks, and
the long-term effects are unknown.
Nerve Blocks
Nerve blocks can be diagnostic, prognostic or therapeutic.
They can target different types of nerves in diverse areas of the body.
Although they can be done with caustic agents that damage nerve,
they are usually done with local anesthetic. Even though the local
anesthetic actually blocks the nerve for a brief period, pain relief
sometimes can outlast the injection for a prolonged time. This is most
dramatic in the case of sympathetic nerve block, which are used to treat a
specific type of neuropathic pain known as sympathetically-maintained pain.
Patients who have syndromes known as Complex Regional Pain Syndrome (CRPS)
type I and II (also known as reflex sympathetic dystrophy and causalgia,
respectively) are more likely to have sympathetically- maintained pain.
If a doctor diagnoses CRPS, a trial of nerve blocks will be suggested
early.
Spinal Cord Stimulation
Stimulation cord stimulation delivers a low voltage electrical
current to the spinal cord. It requires implantation of a
stimulator under the skin, which is connected to a wire that is
placed inside the spine. It is used to treat a wide variety of
more intractable chronic pain syndromes.
Neuraxial Infusion
Neuraxial infusion involves the implantation of a
device that is used to deliver drugs into the space
surrounding the nerves in the spine. By delivering medication
so close to the nervous system, effects can be achieved with very
tiny doses. Neuraxial infusion is now well accepted by pain
specialists and is usually tried when other, more conservative
therapies have not worked. There are numerous approaches to deliver
the medication into the spine. Implantation into the body of a
self-contained pump is preferred if the patient has chronic pain and
is expected to live for at least a period of months. A number of
medications can be delivered in this way. The ones used most
commonly include morphine and other opioids, local anesthetics
such as bupivacaine, clonidine (an adjuvant analgesic that is on the
market to treat hypertension) and baclofen (usually used in this way
to treat severe spasticity).
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