AJR 2004; 183:1507-1510
© American Roentgen Ray Society
Sonographically Guided Aspiration of Cerebrospinal Fluid Pseudocysts in Children and Adolescents
Brian D. Coley1,
William E. Shiels, II1,
Scott Elton2,
James W. Murakami1 and
Mark J. Hogan1
1 Department of Radiology, Children's Radiological Institute, Columbus
Children's Hospital, 700 Children's Dr., Columbus, OH 43205.
2 Department of Neurosurgery, Columbus Children's Hospital, Columbus, OH
43205.
Received September 9, 2003;
accepted after revision February 17, 2004.
Address correspondence to B. D. Coley
(bcoley{at}chi.osu.edu).
Abstract
OBJECTIVE. Cerebrospinal fluid (CSF) pseudocyst formation is an
uncommon cause of ventriculoperitoneal shunt malfunction in children.
Traditional staged treatment consists of shunt externalization, antibiotics,
and later shunt revision and internalization. We sought to evaluate whether
sonographically guided pseudocyst aspiration to alleviate acute symptoms and
to exclude CSF infection could obviate shunt externalization and expedite the
care of these patients.
CONCLUSION. Sonographically guided CSF pseudocyst aspiration is an
effective technique, allowing exclusion or confirmation of infection and
providing relief of abdominal symptoms. In patients with sterile collections,
staged surgical revision with shunt externalization can be avoided, speeding
and simplifying treatment.
Introduction
Ventriculoperitoneal shunting for hydrocephalus has become a routine
neurosurgical procedure over the last 40 years. Invaluable for patients,
ventriculoperitoneal shunts are nonetheless prone to an assortment of
complications and dysfunctions. The loculation of cerebrospinal fluid (CSF)
within the peritoneal space preventing normal resorption is most often
referred to as a CSF pseudocyst. These pseudocysts have traditionally been
treated with surgical shunt exteriorization, antibiotics for presumed or
documented shunt infection, and a second surgical procedure for shunt
reinternalization. A prior study reported the use of blind aspiration of CSF
pseudocysts as a potentially useful method of treatment
[1]. We report a different
approach using sonographically guided aspiration of the CSF pseudocyst as the
initial intervention to alleviate the patient's symptoms. Although aspiration
is not a curative procedure, we suggest that if aspirated CSF shows no sign of
infection, then a single operative shunt revision may be a reasonable and less
invasive method of treatment, sparing the patient a surgical procedure and
shunt externalization.
Materials and Methods
We retrospectively reviewed our experience from 1998 to 2002 in caring for
seven patients using sonographically guided aspiration of CSF pseudocysts as
the initial method of treatment. Medical records and radiology reports were
reviewed for pertinent history and presenting data, as well as for laboratory
results of CSF cultures, surgical interventions, and the length of time from
presentation to definitive surgical treatment. The study was approved by our
institutional review board.
CSF pseudocysts were diagnosed on CT or sonography. Freehand
sonographically guided aspiration was performed under sterile conditions with
the patient receiving local anesthetic and conscious sedation if required.
Drainages were performed with 4- or 5-French Yueh centesis catheters (Cook) or
5- or 8-French pigtail catheters. All CSF collections were aspirated
completely, and the catheters were removed immediately after the
procedure.
Results
Seven patients presented with 11 CSF pseudocysts during the study period.
Mean patient age was 13.6 years (range, 2–19 years). Five patients had
one aspiration each, and two patients each had three aspirations. In seven
encounters, the patient presented with abdominal complaints (mass, fullness,
and pain); in one encounter, with symptoms of shunt dysfunction (headache,
nausea, and vomiting); in two encounters, with both abdominal and shunt
dysfunction symptoms; and in one encounter, with neck pain. None had any
symptoms referable to localized or systemic infection. Prior shunt revisions
were common in our patients: four patients had had three or fewer (although
two patients had undergone other abdominal surgeries), and three patients had
had five or more previous shunt revisions.
Imaging findings of CSF pseudocysts showed fluid-filled masses surrounding
a ventriculoperitoneal shunt catheter. The diagnosis was made on CT for nine
pseudocysts and on sonography for the remaining two
(Fig. 1A). These were simple
collections, with only two exhibiting thin internal septations, and only one
had a slightly thick and enhancing wall after IV contrast administration
(Fig. 2). At diagnosis or time
of drainage, sonography showed no internal septations or debris to indicate
current infection. The collections tended to be large, with a mean largest
dimension of 16.6 cm (range, 8.7–30 cm).
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Fig. 1A. —19-year-old male adolescent with myelomeningocele and
abdominal pain. CT scan of abdomen shows large fluid-density mass surrounding
ventriculoperitoneal shunt (arrowhead), indicating cerebrospinal
fluid pseudocyst. Collection shows no internal septations, wall thickening, or
enhancement.
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Fig. 2. —17-year-old girl with posthemorrhagic hydrocephalus and
abdominal pain. CT scan of abdomen shows cerebrospinal fluid pseudocyst. Arrow
indicates shunt catheter. Note thickened and enhancing wall
(arrowheads) in patient with history of fungal infection.
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Aspiration was successful and without complication in all cases, resulting
in complete drainage of the collections (Figs.
1B,
1C,
1D). Three aspirations were
performed on an outpatient basis. The mean volume of aspirated fluid was 1,263
mL (range, 100–2,650 mL). In cases in which patient response was
documented in the medical record, patients reported symptomatic relief of
their abdominal symptoms after aspiration. Nine aspirates were clear and
colorless, one was straw-colored, and one was cloudy. The results of all CSF
cultures obtained from aspirations were negative, and no patients were
receiving antibiotics at the time of the procedure. However, subsequent
culture of the shunt tip in the one aspirate of cloudy fluid showed signs of
infection according to clinical notes, although no organism was identified.
The one aspirate with straw-colored fluid was from the collection with
enhancing walls on CT, and this patient had a prior CSF culture with positive
results for fungal infection. Portions of removed hardware from one patient
with a recurrent CSF pseudocyst (the recurrent cyst was not aspirated) grew
minimal coagulase-negative Staphylococcus bacteria. However, the
bacteria were believed to be only a contaminant, and the patient was not
treated for infection. It is possible that the initial negative result for the
cultured aspirate was a false-negative finding.
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Fig. 1C. —19-year-old male adolescent with myelomeningocele and
abdominal pain. Sonogram obtained during pseudocyst aspiration shows
sonographically guided placement of Yueh centesis catheter (Cook). Note
echogenic side holes (arrowheads) in catheter.
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Fig. 1D. —19-year-old male adolescent with myelomeningocele and
abdominal pain. Sonogram obtained after aspiration shows no appreciable
residual pseudocyst fluid. Arrow indicates shunt, and arrowheads indicate
drainage catheter.
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In seven encounters, shunt revision occurred at a mean ± SD of 4.7
± 2.2 days (range, 2–8 days) after sonographically guided
aspiration. Two patients had delayed revisions, one after 26 days, and one
after a period of shunt externalization. One patient had no revision after
sonographically guided aspiration and has not had any recurrence of CSF
pseudocyst or any further shunt malfunction. Of the eight shunt revisions
performed, two repositioned in the peritoneal cavity have remained functional
for more than 1 year, and two others have remained functional for more than 6
months. Two peritoneal revisions functioned less than 2 months and required
conversion to ventricular gallbladder shunts (one of these in the patient with
the finding of coagulase-negative Staphylococcus bacteria). One
revision was directly to a ventricular gallbladder shunt in the patient with
straw-colored fluid and prior fungal infection. In the patient with the
presumed occult hardware infection, a shunt was initially externalized and
then replaced into the peritoneum where it quickly failed; it was then
converted into a ventricular gallbladder shunt.
Discussion
Although ventriculoperitoneal shunts were first performed nearly 100 years
ago, it was not until the development of silicone rubber tubing and slit-valve
tips in the 1960s that the shunt placement became a reliable and feasible
procedure [2,
3]. Complications after shunt
placement are common and include shunt occlusion, infection, catheter
dislodgment, and tubing fracture. Complications related to the peritoneal
portion of the shunt may occur in as many as 25% of patients and include
occlusion, peritonitis, and intestinal perforation
[2,
3]. CSF pseudocysts occur in
0.7–10% of patients
[1–6].
The cause of CSF pseudocysts is unclear, with implicated factors including
a sterile inflammatory peritoneal response to CSF proteins or to shunt
materials, prior abdominal surgeries producing loculations and adhesions
within the peritoneal cavity, and sequelae of infection
[4,
6–9].
Infection is generally regarded as the primary causative factor, with a
reported incidence of 0–100%
[4–7,
9,
10]. Pooled data from seven
studies indicate an overall infection rate of 53% (37/70 cases)
[4–10].
Unlike adults with CSF pseudocysts, children commonly present with abdominal
symptoms [1,
4,
7], which we observed in our
patients as well. As in our patients, few children present with signs or
symptoms of infection.
The diagnosis of CSF pseudocysts is often made at physical examination,
with conventional radiography that is performed to evaluate the shunt and
confirm the presence of a soft-tissue density mass displacing normal
structures. Sonography has long been recognized as an excellent technique for
the diagnosis of CSF pseudocysts
[5–8,
11] and depicts features such
as internal septations and debris that often indicate infected collections
[7,
10]. That most of our patients
were diagnosed on CT reflects the current trend in this country for using CT
to evaluate abdominal complaints.
Traditional treatment is predicated on the assumption that there is
concurrent infection that requires shunt externalization (with or without
aspiration of the pseudocyst fluid from the peritoneal end of the shunt), a
course of antibiotics (typically 10 days, depending on culture results), and
then shunt revision and internalization
[1,
5,
8]. There have been a few prior
reports of aspiration of CSF pseudocysts. Agha et al.
[3] reported a fine-needle
aspiration of a subphrenic CSF loculation. Although culture results were
sterile, the investigators did not state how it affected treatment. Burchianti
and Cantini [4] reported one
aspiration performed during diagnostic sonography but did not think that this
procedure aided in case management. White et al.
[9] reported the successful
CT-guided aspiration of a recurrent pseudocyst after revision surgery, which
proved to be curative. An additional CT-guided aspiration was also
successfully performed in a patient who subsequently underwent shunt revision
6 weeks later. However, the earliest report by Gutierrez and Raimondi
[1] described aspiration of CSF
pseudocysts to help guide treatment in four patients. In their study, two
patients with evidence of infection underwent traditional treatment with shunt
externalization, whereas two other patients without evidence of infection
underwent direct shunt revision. These authors concluded that in the absence
of confirmed infection, simple shunt revision is an appropriate treatment and
that a period of shunt externalization is not required.
Our initial goal in performing sonographically guided aspiration was to
assess whether this two-stage procedure could be avoided. Because we excluded
the presence of CSF pseudocyst infection and provided relief of symptoms,
patients could undergo a single elective surgical shunt revision, with a
reduced period of hospitalization. This approach presumes that a negative
result on the CSF culture reliably excludes shunt infection. There are
pitfalls in our approach because cases of hardware infection without positive
results on CSF cultures have been reported
[8,
12], and it is likely that at
least one of our patients did have such an infection. Both the patient with
cloudy fluid and the patient with straw-colored fluid and peripheral CT
enhancement of the pseudocyst wall probably had infections despite having
negative culture results. Similarly, the patient with clear CSF whose hardware
subsequently grew minimal coagulase-negative Staphylococcus bacteria
may have had an infection at the time of aspiration. Thus, our true infection
rate is probably actually two or three (22% or 33%, respectively) of our 11
cases of pseudocysts. Although none of our patients developed a central
nervous system infection as a result of shunt infection, recognition of
infection is also important because these shunts typically fail rapidly after
revision [1]. Conversely, in
the absence of infection, shunt revisions may have a reasonable chance of
long-term success.
Our study involves a relatively small number of pseudocysts, and our
results would be strengthened from our further experience and the experience
of other groups with the procedure. Sonographically guided CSF pseudocyst
aspiration is not curative, but we believe that in the appropriate patient,
performance of the procedure to alleviate the acute symptoms followed by
elective shunt revision is a feasible alternative to the traditional treatment
approach. If the aspirated CSF is colored or cloudy or if imaging findings are
suspicious, patients should be treated with shunt externalization. However,
our patients with clear and colorless CSF aspirates and with no imaging
findings suggestive of infection (rim enhancement, septations, or debris) all
did well and had successful shunt revisions that functioned for reasonable
lengths of time. For patients with a lifelong requirement for shunt
maintenance, the opportunity for a less invasive effective treatment approach
may be beneficial.
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Abstract
Introduction
