SPINAL PUMPS AND STIMULATORS
After multiple surgeries, Michelle G. had so much
back pain that she was taking 300 milligrams of morphine per day to
obtain relief. While the pain was finally bearable, Michelle suffered
from loss of appetite, nausea, constipation, and severe lethargy.
Ten years ago, Michelle had very little choice but to suffer with
the side effects. Not so today. Michelle is a new person thanks to
the amazing technology now available to us. Michelle is taking only
1 milligram of morphine per day with the improved pain relief, no
side effects, and she leads a normal, happy life. Here's how:
INTRATHECAL SPINAL PUMPS
Medicines taken orally get diffused throughout the entire body which
means that a great deal of medication must be ingested in order to
get the appropriate quantities to the place it is needed most to ease
pain: the spinal cord. Now we have the ability to get that medicine
to exactly where it's needed. By surgically implanting a pump under
the skin of a person's abdomen, and running a catheter to the precise
location in the spine where the pain is, we can pump medication directly
into the spinal fluid, allowing for a much more potent effect on the
spinal cord. This drastically cuts down the dose of medication that
is needed, and the medication often provides even better pain relief
with much fewer side effects.
Maintenance of the pump is fairly routine. The
pump is refilled every 1-3 months by inserting a needle through the
skin and through a diaphragm on the surface of the pump. Several different
medications can be administered this way, and even combinations of
drugs might be used. Because the whole system is under the skin, the
risk of infection is minimized and the patient can be fully mobile
and active.
Obviously, this technique should only be considered
when more standard (and less expensive) treatments have not been effective
or have caused intolerable side effects, but this is clearly a technological
advance that can directly improve the quality of life.
SPINAL, DORSAL COLUMN STIMULATORS
Another new advance for pain relief is electric
stimulators. For reasons that are not well understood, electric pulses
on the surface of the spinal cord often dramatically reduce pain.
The stimulators are similar to pumps in that they are surgically implanted
under the skin, of the chest, upper buttock, or the abdomen, but they
differ in that electric signals, rather than medication, is used to
ease pain.
Electric signals are passed through the tip of
the catheter, at the precise location near the involved segment of
the spinal cord, producing a tingling over the painful area which
eases the pain. Current theory is that the electrical input alters
the spinal processing of the pain so that the patient's pain is reduced.
The patient is able to control the stimulator
by holding a magnetic pulsing device over the skin on top of the implanted
generator disk. The stimulator appears to be effective for patients
with back and leg pain who did not get better with spinal surgery.
There is data that shows that these patients will do better with the
placement of a stimulator than they will with repeat surgery. Patients
with RSD (reflex sympathetic dystrophy) can also respond well to this
treatment. The response rates of patients with peripheral neuropathies
or with phantom limb pain are lower, but a temporary screening trial
with a stimulator is still worthwhile if the pain has not responded
to other treatments.
SUMMARY
Although far from panaceas, pumps and stimulators
have proven to be very effective with carefully selected patients
whose severe pain persists despite prior treatment efforts. Pumps
and stimulators are expensive, and should only be used when extensive
efforts at less invasive treatments have failed.
If this point is reached, and if an implant is
being considered, a psychological assessment can help to determine
the patient's emotional readiness for such technology. Only then should
a trial treatment phase be implemented during which a pump or stimulator
is tried on a short-term basis. If the desired benefit is achieved
without significant side-effects, then the team can proceed with a
permanent implant.
And by the way, research on new medications for
the pump is currently underway, so perhaps these tools will soon become
even more effective. They must be carefully administered, but clearly
they are valuable weapons in the fight against severe, persistent
pain.
Until next time…Steven Richeimer, M.D.