Long-term Risk of Shunt Failure After Brain Tumor Surgery

Abstract

Long-term risks and survival times of ventriculoperitoneal (VP) shunts implanted due to hydrocephalus (HC) after craniotomy for brain tumors are largely unknown. The aim of this study was to establish the overall VP shunt survival rates during a decade post-shunt insertion and to determine risks of failure after brain tumor surgery in the long-term period. In this population-based cohort from a well-defined geographical region, all adult patients (> 18 years) from 2004-2013 who underwent craniotomies for intracranial tumors leading to VP shunt dependency were included. Our brain tumor database was cross-linked to procedure codes for shunt surgery (codes AAF) to extract brain tumor patients who became VP shunt dependent after craniotomy. The VP shunt survival times, i.e. the shunt longevity, was calculated from the day of shunt insertion after brain tumor surgery until the day of its failure. A total of 4174 patients underwent craniotomies, of whom 85 became VP shunt-dependent (2%) afterwards. Twenty-eight patients (33%) had one or more shunt failures during their long-term follow-up, yielding 1-, 5- and 10-year shunt success rates of 77%, 71%, and 67%, respectively. Patient age, sex, tumor location, primary/repeat craniotomy, ventricular entry, post-craniotomy hemorrhage, post-shunting meningitis/infection and multiple shunt revisions were not statistically significant risk factors for shunt failure. Median shunt longevity was 457.5 days and 21.5 days for those with and without pre-craniotomy HC, respectively (p < 0.01). This study can serve as benchmark for future studies.

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Long-term Risk of Shunt Failure After Brain Tumor
Surgery
Sayied Abdol Mohieb Hosainey (  mostyle1360@yahoo.com )
Oslo Universitetssykehus https://orcid.org/0000-0002-4287-4545
Benjamin Lassen Lykkedrang
Department of Radiology, Hospital of Southern Norway, Kristiansand, Norway
Torstein R Meling
Faculty of Medicine, Institute of Clinical Medicine, University of Oslo, Oslo, Norway
Research Article
Keywords: Brain tumor, Complications, Hydrocephalus, Shunt failure, VP shunt, Survival
DOI: https://doi.org/10.21203/rs.3.rs-522788/v1
License:   This work is licensed under a Creative Commons Attribution 4.0 International License. 
Read Full License

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Abstract
Long-term risks and survival times of ventriculoperitoneal (VP) shunts implanted due to hydrocephalus
(HC) after craniotomy for brain tumors are largely unknown. The aim of this study was to establish the
overall VP shunt survival rates during a decade post-shunt insertion and to determine risks of failure after
brain tumor surgery in the long-term period. In this population-based cohort from a well-dened
geographical region, all adult patients (> 18 years) from 2004-2013 who underwentcraniotomies for
intracranial tumors leading to VP shunt dependency were included. Our brain tumor database was cross-
linked to procedure codes for shunt surgery (codes AAF) to extract brain tumor patients who became VP
shunt dependent after craniotomy. The VP shunt survival times, i.e. the shunt longevity, was calculated
from the day of shunt insertion after brain tumor surgery until the day of its failure. A total of 4174
patients underwent craniotomies, of whom 85 became VP shunt-dependent (2%) afterwards. Twenty-
eight patients (33%) had one or more shunt failures during their long-term follow-up, yielding 1-, 5- and 10-
year shunt success rates of 77%, 71%, and 67%, respectively. Patient age, sex, tumor location,
primary/repeat craniotomy, ventricular entry, post-craniotomy hemorrhage, post-shunting
meningitis/infection and multiple shunt revisions were not statistically signicant risk factors for shunt
failure. Median shunt longevity was 457.5 days and 21.5 days for those with and without pre-craniotomy
HC, respectively (p < 0.01). This study can serve as benchmark for future studies.
Introduction
Surgical resection of brain tumors is considered to be the primary choice of treatment for patients with
debilitating neurological symptoms. The ecacy of craniotomy for brain tumors has been well
established with regards to quality of life [4,2,33,28] and prolongation of life [16,27,28,39,42,43,20].
Although the primary aim may be to cure disease or restore neurological function [7], risks of surgery
such as infection [30], bleeding [22,30,15], surgical morbidity and mortality [41,2,3,30], neurological
decits [25,5,31,6] and changes to cerebrospinal uid (CSF) dynamics leading to hydrocephalus (HC) and
subsequent ventriculoperitoneal (VP) shunt dependency [19,18] remain signicant concerns to the
neurosurgeon.
VP shunt insertion is the most commonly performed procedure for treatment of HC as it provides an
immediate and effective diversion of accumulated CSF in the brain due to changes in CSF dynamics.
Even though the main goal of shunting is to provide relief of intracranial pressure and improve
symptoms, shunt-failures remain a considerable challenge. Although studies of shunt-failures with
respect to the congenital conditions in the pediatric population [23,38,26], hemorrhage-related HC [12],
idiopathic conditions [34,1] and infections [26,29] have been published, reports on risks of long-term
shunt longevity after brain tumor surgery remains scarce in the literature [37,36,12].
In this large population-based study of all adult patients who underwent brain tumor surgery from a well-
dened geographical region spanning a period of ten years, we primarily wished to determine the 1-year,
5-year and 10-year shunt-failure rates in order to determine shunt longevities in the long-term period after

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craniotomy for brain tumors. The secondary endpoint was to identify possible risk factors of reduced
long-term shunt longevity.
Materials And Methods
Collection of Data
In this population-based cohort, our prospectively collected database was reviewed to identify all adult
patients operated at a single regional health care center between 2004 and 2013. The following patient
demographics were recorded: age at time of shunt insertion, sex, status of hydrocephalus prior to
craniotomy (yes/no), tumor location (supratentorial/infratentorial), intra-axial or extra-axial tumor
location (established on imaging diagnostics reported by neuroradiologists), primary/repeat (secondary)
tumor resection, histology, ventricular opening during craniotomy (yes/no), post-craniotomy hemorrhage
(yes/no), post-craniotomy meningitis/infection (yes/no) and number of shunt revision procedures with
conrmed shunt failures. The rst craniotomy in a specic location was dened as primary craniotomy
and all subsequent craniotomies in the same location were dened as secondary. Therefore, a patient
could have had more than one primary craniotomy, if operated on multiple/different locations. No
patients were lost to follow-up.
In order to identify patients who underwent VP shunting after brain tumor surgery, our tumor database
was cross-linked with our surgical procedure codes database using the Nordic Medico-Statistical
Committee Classication of Surgical Procedures (NCSP) codes for CSF-related procedures (operation
codes AAF). Subsequently, ICD-10 codes (G91) were reviewed to verify each case. Those who had
biopsies and those with pre-existing VP shunts prior to their craniotomies were excluded from this study.
Time from insertion of VP shunt to shunt-failure was recorded. Suspicion of VP shunt-failure was initially
based on clinical signs and symptoms of altered intracranial pressure and radiological signs of
ventricular enlargement as depicted on CT and/or MR imaging including T2/FLAIR weighted sequences.
A conrmed shunt-failure was if/when patients underwent a shunt revision procedure resulting in a
replacement of the whole shunt or in part by its individual components such as catheter replacement, as
a result of blockage and/or change or replacement of shunt valve. Otherwise, if the shunt was only tested
for functionality without any replacements, shunt malfunction was ruled out. All patients underwent
either MRI or CT head imaging at time of suspected shunt-failure.
For patients with conrmed shunt-failure, we reviewed operation notes to determine whether the ventricles
were opened during craniotomy for brain tumor in order to analyze this as a potential risk factor. We also
recorded post-craniotomy hemorrhage (intraparenchymal and/or intraventricular) and infection (positive
CSF and device cultures including CSF pleiocytosis with clinical picture of infection requiring shunt
removal) to analyze as risk factors for reduced shunt longevity.
The survival time of VP shunts, dened as VP shunt-longevity, was calculated from the day of shunt
insertion post-craniotomy for brain tumor until the day of conrmed shunt failure. VP shunt-failure rates

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were determined at 1 year, 5 years and 10 years after shunt insertion and risk factors were analyzed with
regards to overall long-term shunt-failure. Multiple VP shunt revisions was dened as shunt revision
procedures ≥ 2 shunt revisions due to shunt-failure. We excluded duplication of patient identication
numbers (IDs) in order to avoid multiple counts of the same patient in our analyses and to account for
multiple surgical interventions on the same patient. Hence, patient-to-craniotomy ratio was ensured to be
1:1 in the nal analysis for long-term shunt longevity and risks of failure. As such, one patient could have
multiple craniotomies and multiple shunt revision procedures for analyzing risks of reduced shunt
longevity.
Statistical Analysis
For analysis of long-term VP shunt-longevity, the Kaplan-Meier method was used to construct survival
curves and was calculated from rst day of VP shunt-insertion to date of rst revision or shunt removal.
The Kaplan–Meier survival curves were also dichotomized with respect to patients with and without pre-
craniotomy hydrocephalus in the 1-year and 5-year period. Log rank test was applied to determine
statistical signicance of different risk factors for shunt-failure. Cox proportional hazard regression
models were used to identify multiple potential predictor variables with respect to time to shunt-failure.
Chi-square (X2) and Fisher’s exact test were used for comparison between categorical variables. Analysis
of variance (ANOVA) and Student’s t test were used for continuous variables. Statistical signicance was
set at p <0.05 and for all analyses the statistical software JMP (version 9.03) was used.
Results
Overall demographics
In total, 4774 craniotomies were performed on 4174 adult patients. There were 85 patients (2% of
patients) who became VP shunt dependent after brain tumor surgery. Of these, 28 patients (33%) had
shunt revision with conrmed shunt-failure in the study period and constitute the study population (Figure
1, Table 1). There were 13 males (46.4%) and 15 (53.6%) females with a median age at time of shunt-
failure of 61 years (range 26.1 – 79.8). Twelve patients (42.8%) had HC prior to craniotomy for brain
tumor, while 16 patients (57.2%) did not. Tumors were located supratentorially in 25 patients (89.3%) and
infratentorially in 3 patients (10.7%). Twenty-one patients (75%) underwent primary tumor surgery and 7
patients (25%) had repeat craniotomy for brain tumor. Nine patients (10.6%) had ventricular opening
during tumor resection, one (3.6%) of whom had a short shunt longevity. None of those with shunt-failure
had post-craniotomy hemorrhage and only 2 patients (7.1%) had shunt infections. Nine patients (32.1%)
had more than one shunt revision procedure (Table 1).
Long-term shunt longevity

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Overall, there were 65, 60, and 57 out of 85 patients who did not have any shunt malfunction at 1 year, 5
years and 10 years, respectively, yielding VP shunt success rates of 77%, 71% and 67% (Figure 2, Table 2).
The median shunt-longevity was 20.5, 23 and 23.5 days, at 1 year, 5 years and 10 years, respectively
(Figure 2, Table 2).
Median shunt longevity was 457.5 days and 21.5 days, respectively, for those with and without pre-
craniotomy HC (Figures 3 and 4, Table 3). Patients with pre-craniotomy HC had signicantly lower risk of
shunt-failure overall in the long-term in both univariate (HR 0.3, CI [0.1 – 0.7], p < .01) and multivariate
analysis (HR 0.2, CI [0.1 – 0.5], p < .05) compared to patients without pre-craniotomy hydrocephalus
(Figures 3 and 4, Table 3).
Risk factors for reduced long-term shunt longevity
Neither age nor sex were signicantly associated with long-term shunt failure in univariate or multivariate
analysis (Table 3). Similarly, tumor location (dichotomized into supratentorial/infratentorial compartment
and intra-axial/extra-axial tumors), primary/repeat craniotomy, ventricular entry, post-craniotomy
hemorrhage, post-shunting meningitis/infection and multiple shunt revisions/failures were not
signicantly associated with reduced shunt longevity in the long-term period (Table 3).
Discussion
The innate natural history of brain tumors or their surgical interventions may lead to HC that necessitates
temporary CSF diversion procedures, such as external ventricular drainage (EVD) and/or endoscopic third
ventriculostomy (ETV), or lead to permanent CSF diversion. Although the incidence and risk factors for
development of postoperative HC leading to VP shunt dependency of patients with and without HC prior
to a craniotomy for brain tumor have been previously described [19,18], the long-term outcomes of VP
shunts in brain tumor patients are largely unknown.
In our study, a total of 85 patients in a consecutive cohort of 4204 adult patients became VP shunt
dependent after craniotomies for brain tumors (2% of patients). Of these, 28 patients (33%) had
conrmed shunt-failures during the study period of 10 years, yielding cumulative shunt success rates at
1, 5, and 10 years of 77%, 71%, and 67%, respectively (Figure 2, Table 2). In the literature, reports of long-
term shunt-failure rates in the adult population range from 11% at 1 year up to 34% at 10 years
[24,29,45,36], with the majority of these consisting of various underlying etiologies including congenital
diseases, normal pressure hydrocephalus, trauma, tumor, intracranial cysts etc. In a nationwide study on
adult HC patients, Donoho et al. [12] found that 9% of patients required a shunt revision with a median
time to shunt revision of only 41 days. However, their study included shunts due to all underlying
conditions and 45% had shunt insertions due to obstructive HC. Furthermore, the authors did not state
whether an obstructive HC was due to brain tumors and their shunt revision rates reect the rst 6
months only. In another study by Reddy et al. [36] on VP shunt complications in HC patients with
intracranial tumors, 20% and 24% of patients experienced shunt failures requiring shunt revisions within 1

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year and 5 years, respectively. Our lower shunt-failure rates might be explained by inclusion of brain
tumor patients in adults only. However, the overall median time to shunt-failure was shorter in our study
as compared to that of Donoho et al. [9], but this might be explained by tumor debris and higher protein
content in the CSF of patients with brain tumors leading to shunt blockage compared to other non-
oncological conditions.
Recently, Hosainey et al. [17] studied risk factors of early VP shunt failure after brain tumor surgery and
found that patients with pre-existing, non-treated HC prior to craniotomy had a signicantly shorter shunt-
free period before denitive shunting compared to those without pre-craniotomy HC. Interestingly, in the
current study, shunted patients with HC prior to craniotomy had signicantly longer shunt survival
(Figures 3 and 4). This indicates that in patients with distinct pathologies and profoundly deranged CSF
dynamics in the early postoperative course after brain tumor surgery, early VP shunting may serve as
‘prophylaxis’ against further CSF disturbances in the future and hence give prolonged shunt longevity due
to early ‘normalized’ hydrodynamics by shunting. The median shunt longevity was 457.5 days and 21.5
days for those with and without untreated HC pre-craniotomy, respectively (Figures 3 and 4). In the
literature, median shunt survival times range from 19 days in the short-term up to 20.1 years in the long-
term [35,29,8,24,12]. However, these studies were not limited to brain tumor patients and include a
plethora of underlying conditions. Early changes to CSF dynamics as a result of overloading venous
outow and CSF pathway obstruction caused by disease burden has been described in the literature
[40,44]. Further neuronal cell death may also ensue [10,11] if the disease process is left untreated. This
requires early VP shunt insertion in order to normalize intracranial processes and avoid brain damage
caused by a disrupted hydrocephalic state. Nonetheless, another plausible explanation may be that
although some patients with pre- and post-craniotomy HC underwent shunting in the early postoperative
course, they might have experienced spontaneous resolution of their hydrocephalic condition in the long-
term period. Therefore, a ‘silent’ shunt obstruction may have ensued, making them effectively shunt-
independent, wherefore a shunt obstruction would be unnoticed due to lack of signs and symptoms.
Neither patient age at time of shunt placement nor sex were associated with reduced shunt longevity
(Table 3). Male gender has been associated with increased risk of shunt dysfunction [29,45], but it is not
known if this was related to intracranial tumors. In a study by Reddy et al. [36] of VP shunt complications
for hydrocephalus in patients with intracranial tumors, males had signicantly lower 3- or 6-month
survival rates compared to females (p < 0.001). This is in contrast to our ndings. They also reported a
2% decrease in odds of shunt-failure with increasing age at time of shunt insertion [36]. Comparatively,
some studies have associated younger age with higher risk of shunt-failure [12,36], whereas others have
not reached this conclusion regarding age in the short-term [1,13,17] nor in the long-term period after
shunting [24].
Tumor location was not signicantly associated with reduced shunt longevity despite dichotomizations
into supratentorial/infratentorial and intra-axial/extra-axial tumor location (Table 3). Although somewhat
surprising, this is in line with previous studies that did not nd extra-axial/intra-axial tumor location to be
signicantly associated with early shunt-failure after craniotomy for brain tumor [17]. In contrast, Khan et

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al. [24] studied factors affecting shunt survival in adults and found that extra-axial tumors were more
common (13.2%) than intra-axial tumors (9.7%), but in line with our results, they reported that brain tumor
location was not a signicant risk factor of shunt failure.
With respect to tumor histology, several extra-axial tumors such as choroid plexus tumors,
craniopharyngiomas [19] and schwannomas [14], and periventricular intra-axial tumors [21] have been
reported to have increased risk of postoperative HC and shunt dependency. Additional stratied risk
analysis into those with and without pre-craniotomy HC did not reveal intra-axial/extra-axial tumors as
statistically signicant risk factors for reduced long-term shunt longevity in our study. Nonetheless,
similar reports are scarce in the literature making comparative analysis to our study dicult.
In our study, meningiomas had the highest incidence of shunt failure during follow-up (Table 1).
Interestingly, these are extra-axial tumors and not usually located in the ventricles, but they might cause
signicant CSF dynamics changes after craniotomy if the tumor volume is large, particularly in the
posterior fossa region, or if the area of resected/coagulated dura is large. Reddy et al. [36] reported that
patients with benign tumors had higher risk of shunt revision, probably because of a shorter survival rate
among patients with malignant brain tumors. In the above-mentioned study by Khan et al. [24], the effect
of brain tumor histology did not reach statistical signicance (p = 0.062). In the same vein, Rinaldo et al.
[37] found no difference in the incidence of shunt revision surgery in high grade glioma patients as
compared to NPH patients. We believe that the lower number of malignant brain tumor patients with
reduced shunt longevity in our study might be due to the short overall survival of these patients, rendering
shunt procedures futile when they present at advanced stages in the disease process. In addition to
clinical diagnosis of shunt dysfunction, these patients may also suffer from ventriculomegaly as a
consequence of radiation-induced brain atrophy, which is diagnosed radiologically. Lastly, patients with
high grade gliomas invariably see clinical deterioration due to tumor progression and a shunt dysfunction
in this context may be overlooked.
In our study, primary/secondary surgery for brain tumor was not signicantly associated with increased
risk of reduced long-term shunt longevity (Table 3). Secondary/repeat surgery has been reported as a risk
factor for postoperative HC and subsequent VP shunt dependency in patients with pre-craniotomy
hydrocephalus [19] and one would expect repeat surgical intervention for recurrent brain tumor to cause
even more CSF disturbance and shunt-failures. However, only seven patients in our study cohort
underwent repeat craniotomy for brain tumor, leaving a low statistical power and a high risk of a
statistical error type II.
Only 2 patients (7.1%) had shunt infection during the follow-up (Table 1). Although post-shunting
meningitis/infection was not signicantly associated with reduced shunt longevity (Table 3), infection
has been shown to be associated with higher risk of shunt failure in some studies [29]. Our rates of
infection lie in the upper range of published reports [1,26,29,24], which can be explained by our inclusion
criteria of adult patients with brain tumors only. However, the number of patients with infection were too
few for adequate statistical power, possibly giving rise to false negative results in our study. Most of the

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shunt revisions happened during the rst year after shunt insertion (Table 2). Whereas some have
reported shunt-failures in the rst 6 months [13,26,29,35], others have reported within the rst year [32].
Nine patients in the study cohort (32.1%) underwent multiple shunt revisions (≥ 2 revisions) (Table 1), in
keeping with other reports [45]. Korinek et al. [29] reported that previous shunt revision was an
independent risk factor for infection leading to failure and Reddy et al. [36] reported single shunt revision
procedures in 25 patients (13.4%) and multiple shunt revisions in 27 patients (14.4%) after initial shunt
placement. Reddy et al. [36] also found that odds for multiple revisions among those with shunt system
replacements were signicantly higher (OR 24.39, p < 0.01) than those without any shunt replacement.
They also showed that infection, shunt valve replacement and externalization were also signicantly
associated with multiple revisions. However, the signicance was lost when the data was adjusted for the
effects of other risk factors such as shunt system replacement and proximal shunt complication. Our
study did not nd that multiple revisions procedures (≥ 2 revision surgeries) were signicantly associated
with reduced shunt-longevity in the long-term (Table 3).
Strength And Limitations Of The Study
Our centralized neurosurgical health care center at Oslo University Hospital (Rikshospitalet and Ullevål)
has a population-based referral of patients from a well-dened geographical region of Norway with
approximately 2.8 million inhabitants. This reduces possible confounding effects of differences in
access to health care services. As there is only one main neurosurgical department performing
neurosurgical procedures from a dened geographical area, selection bias is avoided, which are
inherently present in multicenter studies. Our study is unique in that we did not nd any other large-scale
studies with focus on analysis of long-term shunt longevity and possible risks associated with shunt-
failure after craniotomies for brain tumors where all patients are included regardless of tumor histology.
There is no selection bias, as the study includes all craniotomies performed within the study period from
a histologically veriable intracranial tumor. The design of our study is a retrospective analysis of a
prospectively collected database. Additionally, by cross-linking our tumor database with the registry for
neurosurgical procedures, we have included all craniotomies leading to shunt-dependency and have been
able to perform shunt-survival and risk analysis as per our main aims of the study. Finally, no patients
have been lost to follow up and to the extent of our knowledge, this is the largest study with respect to
analyzing long-term shunt-survival and risks associated with shunt-failure in patients whom became
shunt-dependent after craniotomy for brain tumors.
The foremost limitation of this study is its retrospective analysis of prospectively collected data.
Surgeon’s preferences with regards to treating hydrocephalus and timing of shunt revision might be a
potential selection bias. Other variables such as tumor volume, shunt valve type and whether proximal or
distal catheter malfunction/block were the cause of shunt-failure were not included in our analyses. The
analysis of images with regards to shunt-failure was not performed in an automatized manner, due to
lack of comparability across the different imaging modalities in absence of age-adjusted normal values
and due to lack of comparability across the different imaging modalities. Even though CT/MRI was

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available for all patients included in the study, the presence or absence of ventriculomegaly leading to
shunt-failure and subsequent revision may have been limited by human error. Adjuvant treatments such
as radiotherapy, chemotherapy and coexisting comorbidities were not included in the analyses, which
may contribute to the risks and rates associated with reduced shunt longevity in the long-term period.
Although being a large study, the number of patients might be so low in the nal analyses giving rise to
statistical type I and II errors, thus failing to identify true prognostic factors for shunt-failures. As most
published reports in the literature are biased with limitations to certain patient groups, tumor histologies
and accounting for overall shunt-failure rates, comparative analysis to our study was dicult. Our study
was conned only to adults whom had undergone craniotomies for brain tumors.
Conclusions
The overall 10-year shunt success rate after brain tumor surgery was 67%. Median shunt longevities were
457.5 days and 21.5 days in those with and without pre-craniotomy hydrocephalus. Patients with pre-
craniotomy hydrocephalus had signicantly longer shunt longevity than those without pre-craniotomy
hydrocephalus. Early ‘prophylactic’ shunting of patient with persisting hydrocephalus after brain tumor
surgery may yield prolonged shunt longevity in the long-term. This study can serve as benchmark for
future studies.
Declarations
Funding
There are no nancial disclosures concerning the materials or methods used in this study or the ndings
specied in this paper.
Conict of interest
The authors declare that they have no conict of interest
Availability of data and material
Data may be given upon reasonable request
Code availability
Not applicable
Ethical approval

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The study has been approved by the institutional ethics committee (Personvernombudets tilrådning
2013/14574)
Consent to participate
Not applicable
Consent for publication
Not applicable
Authors’ contributions
Concept and design: Sayied Abdol Mohieb Hosainey, Torstein R Meling. Material preparation and data
collection: Sayied Abdol Mohieb Hosainey, Torstein R Meling. Data analysis: all authors. Original draft
preparation: Sayied Abdol Mohieb Hosainey. Manuscript review and editing: all authors. Supervision:
Torstein R Meling. All authors reviewed and commented on previous versions of the manuscript. All
authors read and approved the nal version of the manuscript.
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Tables
Table 1. Overview characteristics of patients with post-craniotomy VP shunt dependency and reduced
shunt longevity.

Page 15/22
 Total VP shunt dependency after
craniotomy (N/%) VP shunt
failure (N/%) No VP shunt
failure (N/%)
Total 85 28 57
Age (median yrs) 61.9 61.0 62.7
Sex
 Male
 Female

44 (51.8)
41 (48.2)

13 (46.4)
15 (53.6)

27 (47.4)
30 (52.6)
Pre-craniotomy
hydrocephalus
 No
 Yes

46 (54.1)
39 (45.9)

16 (57.2)
12 (42.8)

30 (52.6)
27 (47.4)
Tumor location
 Supratentorial
 Infratentorial

68 (80.0)
17 (20.0)

25 (89.3)
3 (10.7)

47 (82.5)
10 (17.5)
Extra-axial tumor
Intra-axial tumor
33 (38.8)
52 (61.2)
14 (50.0)
14 (50.0)
19 (33.3)
38 (66.7)
Surgery
 Primary
 Secondary

64 (75.3)
21 (24.7)

21 (75.0)
7 (25.0)

43 (75.4)
14 (24.6)
Histology
 HGG
 Meningioma
 Metastasis
 Other tumors
 Ependymoma
 Craniopharyngioma
 Schwannoma
 Choroid plexus tumor
 Pituitary adenoma
 LGG

21 (24.7)
21 (24.7)
18 (21.2)
8 (9.5)
4 (4.7)
4 (4.7)
3 (3.6)
2 (2.3)
2 (2.3)
2 (2.3)

6 (21.5)
9 (32.2)
4 (14.3)
2 (7.1)
2 (7.1)
1 (3.6)
2 (7.1)
0
0
2 (7.1)

15 (26.3)
12 (21.1)
14 (24.6)
6 (10.5)
2 (3.5)
3 (5.3)
1 (1.7)
2 (3.5)
2 (3.5)
0
Ventricular entry during 9 (10.6) 1 (3.6) 8 (14.0)

Page 16/22
craniotomy
Post-craniotomy
bleeding 8 (9.4) 0 8 (14.0)
Post-craniotomy
infection 4 (4.7) 2 (7.1) 2 (3.5)
Multiple (≥ 2) shunt
revisions – 9 (32.1) 0
Abbreviations: EVD = external ventricular drainage; ETV = endoscopic third ventriculostomy; HGG = high
grade glioma; LGG = low grade glioma; VP = ventriculoperitoneal.

Table 2. Shunt longevity time frames of selected variables after craniotomy for brain tumor.

Page 17/22
1 year post VP-
shunting 5 years post VP-
shunting 10 years post VP-
shunting
Patients with shunt-failure
(N) 20 5 3
Shunt-failure rate
(cumulative %) 23 29 33
Sex (N/%)
 Male
 Female

12 (60)
8 (40)

1 (20)
4 (80)

0
3 (100)
Shunt longevity daysa20.5 23.0 23.5
HC prior to craniotomy
(N/%)
 Yesb
 Noc

5 (25)
15 (75)

4 (80)
1 (20)

3 (100)
0
Tumor location (N/%)
 Supratentorial
 Infratentorial

18 (90)
2 (10)

4 (80)
1 (20)

3 (100)
0
Intra-axial (N/%)
Extra-axial (N/%)
9 (45)
11 (55)
3 (60)
2 (40)
2 (67)
1 (33)
Surgery (N/%)
 Primary
 Secondary

15 (75)
5 (25)

3 (60)
2 (40)

3 (100)
0
a: Time given as median unless otherwise specied
b: Cases with persisting postoperative HC (after craniotomy) requiring VP shunting
c: Cases with
de novo
(new onset) postoperative HC requiring VP shunting
Abbreviations: HC = hydrocephalus; VP = ventriculoperitoneal.

Table 3. Long-term shunt longevity and risk analysis of shunting with univariate and multivariate
proportional hazards ration model

Page 18/22
  Risk of long-term shunt-failure
 Univariate (HR, CI[95%]) Multivariate (HR, CI[95%])
Age at time of shunt failure 1.0 [0.9 – 1.1] 1.0 [0.9 – 1.1]
Sex
 Male
 Female

1
0.5 [0.2 – 1.2]

1
0.9 [0.3 – 2.8]
Pre-craniotomy HC
 No
 Yes

1
0.3 [0.1 – 0.7] a

1
0.2 [0.1 – 0.6] b
Tumor location
 Supratentorial
 Infratentorial

1
0.8 [0.2 – 2.3]

1
0.6 [0.1 – 3.7]
Intra-axial tumor
Extra-axial tumor
1
0.9 [0.4 – 2.0]
1
0.5 [0.1 – 1.6]
Surgery
 Primary
 Secondary

1
1.1 [0.4 – 2.3]

1
0.5 [0.1 – 2.1]
Ventricular opening at craniotomy
 No
 Yes

1
1.2 [0.1 – 6.1]

1
1.4 [0.1 – 12.4]
Post-craniotomy haemorrhage
 No
 Yes

–c
–c

–c
–c
Post-craniotomy meningitis/infection
 No
 Yes

1
8.5 [0.5 – 66.3]

1
–c
Multiple revisions (≥ 2 procedures)
 No
 Yes

1
1.3 [0.5 – 2.8]

1
0.4 [0.1 – 2.3]

Page 19/22
a: p < .01
b: p < .05
c: too few cases in variable parameters to determine HR for long term shunt longevity


Figures
Figure 1
Flowchart illustrating all cases leading to VP shunt dependency and subsequently VP shunt-failure within
the study period.

Page 20/22
Figure 2
Kaplan – Meier curve showing overall 10-year shunt longevity for all patients in the entire study period.

Page 21/22
Figure 3
Kaplan – Meier curves demonstrating 1-year shunt longevity. Red continuous and blue dotted lines
represent patients with and without pre-craniotomy hydrocephalus, respectively.

Page 22/22
Figure 4
Kaplan – Meier curves demonstrating 5-year shunt longevity. Red continuous and blue dotted lines
represent patients with and without pre-craniotomy hydrocephalus, respectively.