| Glossary of Spinal Neurostimulation: Devices For the Relief of Intractable Pain |
|
|
| Charles V. Burton, M.D., for the Burton Report |
 The
"intradural"(or endodural) placement of stimulating electrodes.
A microsurgically developed "pocket" has been created within
the dura mater. A bipolar electrode is shown in this pocket. Until
this advance electrodes had been inserted within the subarachnoid
space with serious attendant complications. The intradural technique
represented the key step in demonstrating that spinal electrodes could
be safely placed and fixed in position. |
 With
the intradural demonstration it then became evident that if electrode
design were to be improved a epidural placement was the practical
next step. Bipolar electrodes were too small to be stable in the epidural
space. Development of a multi-contact plate electrode then followed.
Shown to the right are catheter-type electrodes which have the advantage
of being inserted through a needle. |
 Shown
here is the placement of a multi-contact plate electrode into the
epidural space. This requires a small surgical incision and often
some bone removal. The procedure is typically carried out under local
anesthesia with parenteral drug supplementation. Immediately following
insertion multi-parameter testing can be carried out. |
 In
this x-ray the electrode assembly has been placed in the midline.
Positioning can be varied to achieve differing patterns of parasthesia
(perceived stimulation) in the body. |
 The
greatest attraction of the catheter type electrodes is the fact that
they can be inserted through a needle placed in the epidural space.
For this reason percutaneous epidural neurostimulating electrodes
(PENS) have attracted many physicians to this approach. Not all of
these physicians have been skilled in needle placement or in the use
of image intensification. Results have often been reminiscent of medicine's
past experience with chymopapain. |
 If
initial and subsequent ambulatory multi-parameter testing is found
to be successful the system is then totally implanted with either
a radio-frequency (RF) coupled system or a totally implanted pulse
generator system. In the RF model the batteries are in an external
unit which the patient controls directly. The "care and feeding"
of RF coupled systems is simple which makes them attractive to the
user. RF coupled systems have the best long-term success record. |
This illustration shows a epidural electrode connected to a totally implanted system. The batteries are contained in the implanted pulse generator. Battery change requires additional surgery. Frequency of surgery for battery replacement may be as frequent as less than 2 years. Change in parameters is performed by an external programmer. The system is turned on and off by the placement of a magnet over the pulse generator. Totally implanted systems require the highest amount of "care and feeding" for both the patient and the physician. |
 The
Burton Experience, based on over 1,000 spinal cord neurostimulators
implanted for the relief of intractable pain, has indicated that the
plate electrodes are the most stable and reliable and that the RF
coupled systems are the most user-friendly and most reliable over
a period of years. PENS systems, while simpler to use, are much less
reliable. |
 Depth
brain neurostimulation (DBS), although not presently in use, is presented
because it remains an important asset for the very small group of
patients with intractable pain for which there is no other humane
therapy available. The "death knell" of DBS was sounded
when government insurance programs decided to discontinue coverage
for it. It is clearly a valuable procedure and needs to continue to
be offered to desperate patients by a small group of experienced and
skilled neurosurgeons functioning in a tight peer review environment.
|
|
|
||
|
Home (Reload site / Break Frames) | About This Website | E-mail the Webmaster Copyright © 2000
Arachnoiditis Sufferers Action and |
||