Electrical Stimulation
Of the Paraplegic Bladder

ESPITE SIGNIFICANT improvements within the last
D 20 years, in both patient care and antibiotic ther-

apy, the major cause of death among victims of
paraplegia is still urologic disease.

In addition to this everpresent threat, many paraplegics
live with chronic high urine residuals and concomitant
urinary infections and suffer, as well, the embarrassment
caused by lack of voluntary control of micturition.

The estimated 150,000 paraplegics in the United States,
therefore, challenge the physician to consider more in-
genious methods than those of enhanced drug regimens
and improved patient management as the sole means of
prolonging life. Spurred on by the miniaturization of
electronic circuitry, investigators have begun a series of
investigations into the feasibility of using electric stimu-
lation for the treatment of neurogenic bladders.

Our own research, begun in 1962, at the Surgical Re-
search Laboratory of Maimonides Hospital of Brooklyn,
State University Downstate Medical Center, consists of a
series of studies, experimental and clinical, using an im-
plantable radio-linked bladder stimulator.

Developed in collaboration with the Avco-Everett Re-
search Laboratories of Everett, Massachusetts, the stimu-
lator consists of an electronic unit in two separate parts.
The transmitter portion, shaped like a boy-scout flashlight,
is powered by four 9 volt batteries that transmit voltage

 

Dr. Kantrowitz is director of the Department of Surgery at
Maimonides Hospital of Brooklyn and professor of surgery at
the State University of New York Downstate Medical Center.
A pioneer in the now burgeoning field of bioelectronic assistance
devices for the disabled, he has developed, among others, the
cardiac pacemaker, a prosthetic left ventricle or ‘‘booster heart,’
and the bladder stimulator described above. Envisioned, experi-

; mented with, but not
yet fully developed, is
an electronic device to
assist coordinated limb
movement in para-
plegics.

De. Hald is a surgi-
cal research associate in
the department of sur-

1. ES a gery at Maimonides
KANTROWITZ HALD Hospital. He is a grad-
uate of the University of Copenhagen, where he began his work
on the electrical stimulation of neurogenic bladders.

     

JANUARY-FEBRUARY, 1966, VOL. XXXII, NO. 1

ADRIAN KANTROWITZ, M.D., and TAGE HALD, M.D.

at 100 kilocycles per second with a 20 cycle modulation.
This compact unit with its simple push button can be
operated easily by any dextrous patient. The receiving
unit is implanted in a subcutaneous pocket created in the
patient's abdomen during a relatively simple operative
procedure under general anesthesia.

The disc-shaped receiver is approximately %” thick and
144” in diameter. Coated with silicone rubber, it is well
tolerated by the body and the implantation procedure
eliminates the need for transcutaneous wire connectors
which, in addition to enhancing its flexibility, reduces the
risk of infection. Two or four silastic-insulated leads ex-
tend from the receiver to the bladder wall where they are
implanted in loop-like fashion with the atraumatic suture
needles which are attached to the end of the electrodes.

The target of the stimulation can be either the motor
nerves of the bladder or the detrusor muscle surrounding
it which, when contracted spontaneously or artificially,
exerts the pressure which precipitates micturition.

Animal Experiments

We began our animal experiments with a large series
of mongrel dogs in order to evaluate the effectiveness of
these two methods. While the urinary tract function of
dogs and men is not entirely comparable because the
former lacks man’s urogenital diaphragm—the function
of the external sphincter in the human being equivalent
in the dog to the striated musculature located below the
apex of the prostate and extending to the bulb of the
urethra—results were encouraging enough to warrant more
extensive testing and, eventually, clinical trials.

From a theoretical point of view, nerve stimulation has
certain advantages over detrusor stimulation. However,
experimenting we found that this method could not be
employed in dogs for more than 60 days without subse-
quent nerve deterioration.

Detrusor muscle stimulation has been maintained in
animals for more than one year with isometric bladder
pressures of up to 50-90 centimeters of water obtained.
While this method of stimulation requires higher voltages
in order to activate those parts of the bladder most distant
from the electrode sites, it presently carries less risk than
direct nerve stimulation and in our clinical cases was used
exclusively.

we Concluded on next page

17
Clinica! Studies

These studies, undertaken with the cooperation of Joseph
Benton, M.D., Ali Khalili, M.D., were begun in 1963. To
date, the Kantrowitz-Avco bladder stimulator has been
implanted in four patients.

Our first, a seven-year-old boy with lumbar myelomen-
ingocele, had undergone surgery in the first month of life,
resulting in urine and fecal incontinence. He had a hyper-
tonic bladder with 125 cc capacity and 50-75 cc residual
urine. In April 1963, two wire electrodes were implanted
in his bladder. Isometric bladder pressures of 170 cm of
water were obtained during stimulation with 10 volts and
his bladder was completely emptied.

This successful preliminary trial was followed by im-
plantation of the receiver four months later. Unfortunately,
infection developed around the device, which finally had
to be removed after an attack of pyelonephritis. Several
bladder calculi due to a perforating electrode were re-
moved during the operation.

Because of his age and general condition, his parents
felt that reimplantation should be delayed. The patient is

 

Kantrowitz-Avco bladder stimulator. The transmitter section
is shown on top; below is the implantable receiver with two
electrodes.

an excellent candidate, however, and for the entire eight-
month period of treatment responded well to bladder stim-
ulation. Even with the limited clinical experience reported
to date, it appears that children with this lesion may even-
tually be primary candidates for bladder stimulation.

Our second patient was a 15-year-old boy with flaccid
paralysis which followed transverse myelitis eight months
prior to admission. Pressure and capacity measurements
showed a hypertonic detrusor muscle, 300 cc capacity and
residual urine up to 200 cc, but no reflex activity of the
bladder. A severe inflammation of the glans was present.

A stimulator was implanted in September 1963. During
contraction, bladder pressure resulting in 135 cm of water
was obtained. Perforation of the urethra secondary to the
catheter treatment occurred and the sphincter activity de-
creased and residual urine was reduced to 40 cc. Reflex
bladder activity has developed but the patient still requires
the support of the stimulator for satisfactory bladder
evacuation.

Renal function remains normal and there is no backflow
from the bladder to the ureters. (It is vesico-ureteral
reflux, or backup of urine into the ureters and kidneys,

18

that is responsible for the severe and non-eliminable in-
fections which frequently lead to renal failure in para-
plegics.) The patient is still using his device after two
and a half years.

Beneficial results were also obtained in a third patient,
a 50-year-old man who had become paraplegic 18 months
prior to admission. Concerning our fourth patient, a 40-
year-old man who sustained a fracture of the lower thoracic
vertebrae with cord compression, the stimulator failed after
four months of treatment, because of technical difficulties;
however, he was very satisfied with the device, and we are
considering reimplantation.

Discussion

Though our patient series is small, we feel that results
are satisfactory enough to warrant discussion at this time.
Comparison with the published cases from other labora-
tories, where disc shaped electrodes sutured to the outside
wall of the bladder were used, would seem to indicate
that the bladder stimulator used by us greatly enhances the
remaining expulsive force in the neurogenic bladder.

The principal problem we encounter is outflow obstruc-
tion. This appears to be due to activation of the striated
muscles of the pelvic floor. In selecting appropriate can-
didates for our procedure, it is of especial significance that
patients are chosen with special reference to good detrusor
contractility as well as the condition of the pelvic muscu-
lature.

Patients with lower motor neuron lesions or those with
convertible upper motor neuron lesions are the best can-
didates for this treatment. If the latter group have no
external sphincter function or an exaggerated sphincter
function which could be diminished significantly through
surgery, we would consider them as well. Among our
patient group, one had an autonomic bladder and _re-
sponded favorably to the procedure without further uro-
logical procedures. Three others (with upper motor neuron
lesions) had great sphincter trouble. Neurectomy im-
proved the results in one.

However, because activation of the striated sphincter
musculature is the greatest obstacle to good results, pa-
tients with autonomic bladders remain our first choice.

Conclusion

Our experimental and clinical experiences with elec-
tronically-induced micturition indicate to us that the long-
term successful use of a radio-linked stimulator in patients
with neurogenic bladder is entirely feasible. The method
used by us involves little operative risk and, even where
results do not warrant continued use, leave the patient as
he was prior to implantation. While using this device, we
saw no ureteral backflow so hazardous to paraplegics, nor
any severe decrease in bladder capacity. While urinary
infection was not reduced, these patients were frequently
catheterized during testing, which we feel accounts for this.

Therefore, it seems to us that, with continued explora-
tion into methods aimed at reducing sphincter resistance
without inducing paralytic incontinence, and ongoing daily
improvements in equipment, the future of the bladder
stimulator as a valuable clinical tool is assured.

We are in the beginning stages of our work with elec-
tronic assistance devices and part replacement. In the very
near future we will witness an impressive increase both
in the development and use of a wide variety of these
devices as well as their clinical application for the handi-
capped, and will then be capable of dealing with a wide
range of rehabilitation problems hitherto considered
insoluble. Ei

JOURNAL OF REHABILITATION