For patients with chronic pain who get no relief from conservative therapies,
an interventional therapy might be helpful. The simpler of these approaches
include trigger point injections (injecting local anesthetic and/or steroid
into myofascial trigger points), epidural steroid injections and joint
injections. The more complex include nerve blocks, spinal cord stimulation,
and intraspinal drug administration. These more sophisticated procedures
are typically provided by anesthesiologists with advanced training in
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
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.
Spinal cord stimulation (also called dorsal column stimulation) provides
low-voltage electrical current inside the spinal cord and may block or
decrease the pain signals going to the brain. It requires implantation
of a stimulator under the skin, which is connected to a wire that is placed
inside the spine. Electrical impulses block the pain signal traveling
to the brain, providing lasting pain relief. Patients have the ability
to control the stimulation by turning the device on or off, and to modulate
pain relief as needed based on their pain or activity. This technique
has been used to treat chronic low back pain, chronic sciatica, and complex
regional pain syndrome (reflex sympathetic dystrophy), among other conditions.
The ideal candidate for spinal cord stimulation is someone who suffers
from chronic pain that has not responded to medications, therapies, or
surgery. Once evaluated by a qualified pain specialist, an appropriate
patient can undergo an outpatient trial to experience spinal
cord stimulation and determine if the relief is significant enough to
proceed to a longer-lasting treatment.
Neuraxial infusion involves the implantation of a device that is used
to deliver low doses of analgesic drugs through a catheter inserted directly
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 many ways to deliver 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). Neuraxial Infusion is used often to manage cancer pain and
refractory nonmalignant pain.
Anesthesiology, April 2010, Vol 112, Issue 4, pp 810-33 - free full-text
and .pdf available
(American Society of Anesthesiologists and American Society of Regional
Anesthesia and Pain Medicine)