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Programmable Shunt Radiography 108
VOLUME 73/NUMBER 2
H
ydrocephalus, as described
by Wolpert,
1
is a neuro-
logical condition in which
the ventricular volume of
cerebrospinal uid (CSF) is
abnormally large in relation to brain vol-
ume. It can be broadly classi ed as either
obstructive, nonobstructive or functional
and there are various etiologies, includ-
ing hemorrhage, infection, tumor and
congenital anomalies. Hydrocephalus also
may be idiopathic.
Though not all patients respond well,
many experience measurable clinical
improvement from shunting CSF to
another location in the body where
it can be absorbed,
2
most commonly
the peritoneum. The ventriculoperi-
toneal (V-P) shunt has, for the most
part, replaced the ventriculoatrial
(VA) shunt due to the lessened
likelihood of infection or clotting.
Nevertheless, V-P shunts are subject
to complications such as breakage,
obstruction and migration or malpo-
sitioning of the catheters. An addi-
tional concern is proper maintenance
of the valve pressure in the shunting
device so that over- or underdrainage
does not occur. A variety of devices
ow-controlled valves, antisi-
phon devices and programmable
shunts have been introduced
because of this concern, but none are
completely free of overdrainage com-
plications.
3
As early as 1973, Hakim
4
proposed
an adjustable ventricular shunt using
a manual screw device or magnet. By the
mid 1980s, programmable valves were
manufactured by Sophy SA and available
in Europe and Japan. In 1989, Drs. Car-
los and Salomon Hakim introduced their
programmable ventricular shunt valve,
formerly referred to as the Codman Medos
or Medos Hakim programmable valve
(Medos SA, Le Locle, Switzerland) for
use in Japan, Europe, and South America.
Like the Sophy programmable valve, this
ventricular shunt valve was developed in
response to the shortcomings of traditional
This article discusses a
programmable ventricular
shunt valve system used to
treat hydrocephalus. With
this system, valve pressure
can be ascertained easily
with plain- lm radio-
graphs, thus avoiding
complications associated
with inappropriate pres-
sures. The authors describe
the shunts design and tech-
niques for imaging it, pres-
ent illustrative cases and
outline a strategy for coordi-
nating the care of patients
with these shunts.
Programmable Shunt
Radiography
RADIOGRAPHY
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A. ROBERT SCHLEIPMAN, M.A., R.T.(R)(N), CNMT
NANCY OLSEN BAILEY, R.N., B.S.N., M.B.A.
Fig. 1.
Lateral diagram demonstrating ventricular
draining tubes. (Diagram courtesy of Codman, a John-
son & Johnson Co, Raynham, Mass.) 109
RADIOLOGIC TECHNOLOGY
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valves, all of which operated at xed
pressures. It is estimated that more
than 20 000 of these valves have been
implanted worldwide. The Codman
Hakim valve was approved for use by
the U.S. Food and Drug Administration
in the summer of 1998. To date, it is
the only such device approved for use in
the United States (U.S. Food and Drug
Administration, Center for Devices and
Radiological Health, personal communi-
cation, September 2000.)
The system includes a ventricular
catheter, connectors, a molded silicone
elastomer valve unit, a titanium and
steel valve chassis containing a pro-
grammable stepper motor and drain-
age catheter. (See Figs. 1 and 2.) The
operating pressure can be changed
through the use of the magnetic ser-
vomotor and an externally applied
coded magnetic signal. The servomo-
tor consists of alternating north/south
magnets. (See Fig. 3.) The external
programmer activates the servomotor
which in turn rotates the cam, result-
ing in a change in the operating pres-
SCHLEIPMAN, OLSEN BAILEY
Fig. 2.
Valve mecha-
nism components.
(Diagram courtesy of
Codman, a Johnson
& Johnson Co, Rayn-
ham, Mass.)
Fig. 3.
Stepper motor with magnet placement. (Diagram courtesy of Codman, a
Johnson & Johnson Co, Raynham, Mass.) SHUNT IMAGING
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110
VOLUME 73/NUMBER 2
sure of the shunt valve. (See Fig. 4.) The motor can
be programmed to allow 18 discrete pressure settings
between 30 and 200 mm H
2
O, at increments of 10 mm.
This permits simple pressure adjustments that can be
quanti ed with skull radiographs without the need for
invasive surgical revision.
The Codman Medos Programmable valve system
(since 1998, the Codman Hakim) was rst introduced
via clinical investigation at our facility in 1991.
5
Our
experience with the programmable valve has been pri-
marily in an adult population diagnosed with normal
pressure hydrocephalus (NPH). With this valve, we have
observed fewer subdural collections and fewer cardiopul-
monary complications in the perioperative setting.
Standard postoperative care for nonprogrammable
shunt valves requires patients to remain in bed with the
head horizontal for 48 to 72 hours. With the program-
mable valve, patients are permitted to sit up immedi-
ately after surgery. If patients with the programmable
valve develop subdural uid collections, they usually
can be managed easily and nonsurgically by adjusting
the valve pressure with resultant subdural resolution.
Imaging Techniques
Medical imaging of the cerebral ventricular system
has a long history, both for documentation and quan-
titation of abnormalities. More invasive procedures
such as pneumoencephalography and cerebral angiog-
raphy have long been replaced by radionuclide cister-
nography, computed tomography (CT), sonography
(in children and neonates) and magnetic resonance
(MR) imaging.
Multiple imaging techniques are used to evaluate V-P
shunts.
6
For the head, cross-sectional techniques are
preferred.
7
In addition to providing structural informa-
tion, MR also can be used to characterize CSF ow.
8

Beyond the ventricular system, plain radiographs often
are used to con rm shunt catheter integrity. Additional
imaging methods may be employed in the diagnostic
work-up for complications resulting from shunt place-
ment procedures.
9
To detect catheter breakage, a series of radiographic
exams is performed: lateral skull, PA or Caldwell pro-
jection, AP and lateral chest and abdomen. Together,
these images demonstrate the course of the catheter
from the head to the peritoneal cavity. (See Figs. 5A-
D). As a diagnostic imaging adjunct, water-soluble
contrast may be administered to assist in the diagnosis
of catheter leak or obstruction. Alternatively, shunt
system abnormalities may be detected with noninvasive
scintigraphic techniques by injecting radiotracer into
the shunt reservoir.
10
Fig. 4.
Digital palpa-
tion and localization
of valve with external
programmer overlay.
(Illustration courtesy of
Codman, a Johnson &
Johnson Co, Raynham,
Mass.) 111
RADIOLOGIC TECHNOLOGY
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SCHLEIPMAN, OLSEN BAILEY
Fig. 5A.
PA skull radiograph demonstrating conven-
tional ventriculoperitoneal drain tubing.
Fig. 5B.
Lateral skull radiograph demonstrating conventional
ventriculoperitoneal drain tubing.
Fig. 5C.
AP chest/abdomen radiograph demonstrating conventional
ventriculoperitoneal drain tubing (arrow).
Fig. 5D.
AP abdominal radiograph demonstrating conven-
tional ventriculoperitoneal drain tubing (arrow). . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .