10
Članek prispel / Received
18. 8. 2020
Članek sprejet / Accepted
8. 4. 2022
Abstract
Purpose: A craniotomy is a common 
surgical procedure with complications, 
including a surgical site infection after 
craniotomy (SSI-CRAN), for which 
risk factors are ill-defined. Therefore, 
we determined the risk factors for deve-
loping an SSI-CRAN in adult patients 
at a university hospital in Maribor.
Methods: A retrospective cohort stu-
dy was conducted to compare patients 
with an SSI-CRAN (n=66) against 
a control group (n=70) from January 
2009 to August 2019. We collected 
data from patients in who elective cra-
niotomy had been performed and requi-
red surgical treatment for an infection.
Results: A total of 1192 patients 
underwent a craniotomy, of whom 66 
(5.5%) developed an SSI-CRAN. The 
most common infections were osteom-
Izvleček
Namen: Kraniotomija je osnovni ne-
vrokirurški pristop, ki je povezan z za-
pleti, med katere spada okužba kirurške 
rane, za pojav katere so dejavniki tvega-
nja še vedno nepopolno definirani. Na-
men raziskave je bil prepoznati dejav-
nike tveganja za pojav okužbe kirurške 
rane pri odraslih bolnikih, operiranih 
na Oddelku za nevrokirurgijo Univer-
zitetnega kliničnega centra v Mariboru.
Metode: Izvedli smo retrospektivno ko-
hortno študijo, v kateri smo analizirali 
podatke za obdobje od januarja 2009 
do avgusta 2019. Primerjali smo podat-
ke bolnikov, ki so razvili okužbo kirur-
ške rane, s podatki tistih, ki okužbe niso 
razvili. 66 bolnikov je razvilo okužbo 
kirurške rane, v kontrolno skupino smo 
naključno uvrstili 70 bolnikov brez ome-
njene  rane. V raziskavo smo vključili 
Ključne besede: 
kraniotomija, dejavniki tveganja, 
okužba kirurške rane
Key words: 
craniotomy, risk factors, surgical site 
infection  
Dejavniki tveganja 
za pojav okužbe po kraniotomiji: 
10-letna retrospektivna kohortna študija
Risk factors for surgical site infection following 
craniotomy: a 10-year retrospective cohort study
Avtor / Author Hojka Rowbottom1, Borut Hribernik2, Janez Ravnik1,3 
Ustanova / Institute 1Univerza v Mariboru, Medicinska fakulteta, Maribor, Slovenija; 2Splošna bolnišnica Celje, 
Travmatološki oddelek, Celje, Slovenija; 3Univerzitetni klinični center Maribor, Klinika za 
kirurgijo, Oddelek za nevrokirurgijo, Maribor, Slovenija;
1University of Maribor, Faculty of Medicine, Maribor, Slovenia; 2General and Teaching 
Hospital Celje, Department of Traumatology, Celje, Slovenia; 3University Medical Centre 
Maribor, Clinic for Surgery, Department of Neurosurgery, Maribor, Slovenia;
Klinična študija / Clinical study
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2022; 15 (1): 10–21
https://doi.org/10.18690/actabiomed.228, CC BY 4.0
© 2022 University of Maribor, University Press
11
INTRODUCTION
A craniotomy is a surgical procedure in which a 
portion of the skull (bone flap) is removed to expose 
the underlying structures of the central nervous 
system and adjacent anatomic structures. During 
surgery the bone flap is separated from the rest of 
the skull and returned to its original anatomic site 
upon completion of the surgery before the skin 
is sutured, which separates the craniotomy from 
the craniectomy. Postoperative complications of 
craniotomies include hematomas (intracerebral, 
subdural, and epidural), stroke, postoperative 
epileptic seizures, acute hydrocephalus, 
pneumocephalus, cerebral edema, osteomyelitis of 
the bone flap, and extradural abscess formation 
(1-4). Depending on the anatomic location of the 
pathologic process, which is the indication for 
surgery, different craniotomies allow the most 
optimal approach to the surgical site. Importantly, 
the approach allows for achieving the desired 
results (e.g., tumour removal) without additional 
le bolnike, ki so po opravljeni elektivni 
kraniotomiji potrebovali kirurško zdra-
vljenje okužene kirurške rane. 
Rezultati: Med 1192 bolniki, ki so v 
opazovanem obdobju imeli opravljeno 
kraniotomijo, je 66 (5,5 %) bolnikov 
razvilo okužbo kirurške rane. Najpo-
gosteje je prišlo do razvoja osteomieli-
tisa (66,7 %) in epiduralnega abscesa 
(63,6 %), najpogosteje izoliran povzro-
čitelj pa je bil Propionibacterium acnes 
(54,5 %). V raziskavi so se kot dejavni-
ki, povezani s pojavom okužbe kirurške 
rane, izkazali uporaba izdelka Surgicel® 
(p = 0,0019, Fisherjev natančni test), 
duralni nadomestki (p = 0,0028, Fis-
herjev natančni test), samolepilna dura 
(p = 0,0274, Fisherjev natančni test), 
zapiranje kože s šivi (p = 0,0001, Fis-
herjev natančni test), opravljena frontal-
na kraniotomija (p = 0,0328, Fisherjev 
natančni test) in pooperativno predpiso-
vanje glukokortikoidov (p = 0,04, Fis-
herjev natančni test).
Zaklju~ek: Z našo študijo smo pre-
poznali določene dejavnike tveganja, 
povezane s pojavi okužbe kirurške rane, 
ki jih lahko odpravimo in tako znižamo 
pojavnost tovrstnega operativnega zaple-
ta oz. zaplet hitreje prepoznamo. 
yelitis (66.7%) and epidural abscesses 
(63.6%). The most frequent causative 
organism was Propionibacterium ac-
nes (54.5%). Based on Fisher’s exact 
test, the factors associated with an 
SSI-CRAN compared to the control 
group were use of Surgicel® (89.4% vs. 
67.1%, p=0.0019), use of dural sub-
stitutes (53% vs. 27.1%, p=0.0028), 
use of adhesive dura (13.9% vs. 2.9%, 
p=0.0274), sutures used for skin clo-
sure (69.7% vs. 34.3%, p=0.0001), a 
frontal craniotomy (28.8% vs. 12.9%, 
p=0.0328), and postoperative admini-
stration of  glucocorticosteroids (73.7% 
vs. 54.4%, p=0.04).
Conclusion: We identified risk fac-
tors associated with SSIs-CRAN, for 
which alternatives exist that could re-
duce the incidence of SSIs-CRAN.
Naslov za dopisovanje /  
Correspondence
Hojka Rowbottom, dr. med.,  
Univerza v Mariboru, Medicinska 
fakulteta, Taborska ulica 8, Maribor, 
Slovenija.
Telefon: +386 31287467
E-pošta: hojka.rowbottom@gmail.com
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12
nerve damage (3,5). A surgical site infection 
after craniotomy (SSI-CRAN) is an infection 
that develops at the site of surgery and can be a 
superficial or deep incision, or an organ-space 
SSI. A superficial incision SSI is an infection of 
the skin and subcutaneous tissue. A deep incision 
SSI is an infection of the muscles and fascia. An 
organ-space SSI is an infection of any organ or 
tissue in the surgical field under the muscle layer 
(6).  An SSI-CRAN is a severe complication that 
requires timely diagnosis and treatment because 
such infections are associated with a high morbidity 
rate and the increased cost of hospital treatment. 
The predicted incidence of SSIs-CRAN is 5%, but 
ranges between 1% and 11% depending on the risk 
factors (7,8). Several risk factors for an SSI-CRAN, 
such as previous radiotherapy, previous brain 
surgery, a postoperative cerebrospinal fluid (CSF) 
leak, duration of surgery > 4 h, a body mass index 
≥40 kg/m2, preoperative glucocorticosteroid use, 
emergency surgery, intraoperative breach into the 
sinus, concomitant infection, CSF drainage, entry 
into the venous sinus, > 2 points on the American 
Society of Anesthesiologists (ASA) point score, 
male gender, an atraumatic cause of craniotomy, 
age 70+ years, absence of antibiotic prophylaxis, 
preoperative chemotherapy, use of dural substitutes, 
infratentorial or intraventricular tumour location, 
hospital admission > 1 day before craniotomy, and 
multiple failed attempts at wound closure (9-18). 
An SSI-CRAN is often detected after discharge 
from the hospital. The clinical presentation of an 
SSI-CRAN depends on the anatomic location. In 
patients with superficial SSIs, there are signs of 
cellulitis. Deep SSIs are usually recognised by the 
presence of an abscess. Organ-space SSIs may be 
clinically manifested as meningitis, ventriculitis, or 
osteomyelitis (6).
An SSI-CRAN represents a significant and 
concerning postoperative complication. Patients 
affected by an SSI-CRAN often need another 
operation for treatment, hospitalisation, long-
term antimicrobial therapy, increased costs, and 
the treatment of their primary disease may be 
delayed. In this retrospective cohort study, we 
determined risk factors for the development of an 
SSI-CRAN in patients who underwent surgery in 
the Department of Neurosurgery at the University 
Medical Centre Maribor to reduce the number of 
patients developing an SSI-CRAN.
MATERIAL AND METHODS
Study design and patients
A retrospective cohort study was conducted in the 
Department of Neurosurgery at the University 
Medical Centre in Maribor. We included patients 
who were surgically treated for an SSI-CRAN between 
January 2009 and August 2019. The study included 
patients who developed an SSI-CRAN after an elective 
neurosurgical procedure. Patients who developed 
an SSI-CRAN after an emergency craniotomy (e.g., 
head and brain injury) were not included in the 
study. We also did not include patients who required 
only conservative therapy (e.g., antibiotic treatment). 
Considering the inclusion and exclusion criteria, there 
were 66 patients with SSIs-CRAN. We also included 
70 randomly selected patients who did not develop an 
SSI-CRAN after the elective neurosurgical procedure, 
who served as the control group. 
Data collection and statistical analysis
We retrospectively reviewed the medical records of 
the patients with SSIs-CRAN and the control group. 
We considered the potential risk factors for the 
development of an SSI-CRAN. We analysed patient 
factors, such as gender, age at first surgery, smoking 
status, diabetes, arterial hypertension, liver cirrhosis, 
chronic kidney disease, and chronic obstructive 
pulmonary disease, and factors in the first surgery 
or factors related to the first surgery, such as average 
duration of hospitalisation for the first craniotomy, 
glucocorticosteroid administration before surgery 
and in the postoperative period, use of electrodes to 
control intracranial pressure, intraoperative breach 
of the sinuses, occurrence of a postoperative CSF 
leak, radiotherapy before surgery, type of craniotomy 
performed, pathohistologic diagnosis, indication for 
surgery, surgical material used, presence of infection at 
the time of hospital discharge after the first craniotomy, 
oncologic therapy after the first craniotomy, and 
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revision of the craniotomy before the onset of infection. 
The Statistical Package for Social Sciences (SPSS) for 
Windows (version 25.0.0.1) was used for statistical 
analysis of the data. Fisher's exact test was used for 
statistical analysis of the descriptive variables, and a 
t-test for independent samples was used for analysis of 
numerical variables. Statistical significance was set at a 
p <0.05. Due to the retrospective nature of this study, 
approval by the Ethics Committee was not required. 
RESULTS  
During the observation period (1 November 2009-
17 October 2019), 1192 elective craniotomies were 
performed in the Department of Neurosurgery at the 
University Medical Centre Maribor. Among the 1192 
patients, 66 developed an SSI-CRAN that required 
re-operation. Based on this data, the overall incidence 
of SSIs-CRAN was 5.5%. The average length of 
hospitalisation for the first surgical treatment of the 
SSI-CRAN was 26.37 days (SD=30.73 days) and the 
average time between the first craniotomy and the 
diagnosis of an SSI-CRAN was 58.6 days (SD=52.57 
days). Propionibacterium acnes was the most 
frequently isolated bacterium (54.5%), followed 
by coagulase-negative staphylococci (45.5%), and 
Staphylococcus aureus (39.4 %). The most common 
Gram-negative bacterium was Enterobacter cloacae 
(9.1%). Other isolated pathogens occurred in < 10% 
of patients with an SSI-CRAN; fungi were isolated 
in 3% of the patients. In the current study gender 
was not a statistically significant risk factor for the 
development of an SSI-CRAN. There were 52.9% 
men in the control group and 47% in the group 
with an SSI-CRAN (p=0.6069).  The mean age in 
the control and SSI-CRAN groups (56.85±11.55 
and 59.42±11.36 years, respectively; p=0.1767) at 
the first surgery and the duration of hospitalization 
(14.29±17 and 14.34±14.14 days, respectively; 
p=0.9852) for the first surgery did not represent 
statistically significant risk factors. The mortality 
during hospitalization was statistically higher in the 
group with an SSI-CRAN than in the control group 
(2.9% and 13.6%, respectively; p=0.0274). 
Table 1 shows that osteomyelitis (66.7%) alone or 
Table 1. Group of patients with SSI-CRAN
Group with SSI-CRAN n = number
Infection site
Epidural abscess 63.6% (n=42)
Subdural abscess 10.6% (n=7)
Intracerebral abscess 19.7% (n=13)
Subcutaneous abscess 31.8% (n=21)
Osteomyelitis 66.7% (n=44)
The number of operations required to 
treat an SSI-CRAN
1 74.2% (n=49)
2 16.7% (n=11)
3 7.6% (n=5)
4 1.5% (n=1)
Number of isolated pathogens in each 
patient
Polymicrobial infection 56.1% (n=37)
Monomicrobial infection 42.4% (n=28)
Sterile sample 1.5% (n=1)
Isolated pathogens 
Gram-positive bacteria 81.8% (n=112)
Gram-negative bacteria 16.8% (n=23)
Fungi 3% (n=2)
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with an epidural abscess (63.6%) and vice versa was/
were the most common infection sites. We identified 
the site of infection using a description given 
during the operation because imaging diagnostics 
of intracranial infections are often not completely 
reliable. Patients often developed infections at > 2 
sites, resulting in an overall total > 100%. In most 
patients with an SSI-CRAN, only 1 operation was 
required to treat the infection and 25.8% of patients 
required > 2 operations. A polymicrobial SSI-CRAN 
was the most common finding and a Gram-positive 
bacterium was isolated in most cases (81.8%). 
In the current study we determined whether 
patient characteristics were risk factors for an SSI-
CRAN. For the control and SSI-CRAN groups, 
data on smoking status and co-morbidities (arterial 
hypertension, diabetes mellitus, chronic kidney 
disease, liver cirrhosis, and chronic obstructive 
pulmonary disease [COPD]) were obtained from 
the medical records. Figure 1 shows that smoking 
status and selected associated diseases did not have a 
statistically significant association with a SSI-CRAN.
We attempted to determine whether the type of 
craniotomy, and thus the anatomic location of the 
procedure, posed a risk factor for the subsequent 
development of an SSI-CRAN. Figure 2 shows that 
frontal craniotomy was associated with the onset of an 
SSI-CRAN (p = 0.0328). Also, a pterional craniotomy 
was performed more often in the control group 
(p=0.038). The surgical procedure, such as reduction of 
the tumour or excision of metastases, was not represent 
a risk factor for development of an SSI-CRAN. We 
also showed that the histopathologic diagnosis of the 
excised lesion was not a risk factor for an SSI-CRAN. 
Moreover, the development of an SSI-CRAN was not 
influenced by the origin of the removed lesion (e.g., 
primary brain tumour or metastasis). 
Furthermore, we examined the effects of preoperative 
(green square), intraoperative (blue square), and 
postoperative (yellow square) factors on the occurrence 
of an SSI-CRAN. Preoperative administration of 
glucocorticosteroids and prior radiotherapy were Figure 1: Patients' factors 
 
Figure 2: Type of performed craniotomy 
Pa#ents' factors
COPD-control group
COPD-group with SSI-CRAN
Chronic kidney disease-control group
Chronic kidney disease-group with SSI-CRAN
Liver cirrhosis-control group
Liver cirrhosis-group with SSI-CRAN
Diabetes mellitus-control group
Diabetes mellitus-group with SSI-CRAN
Arterial hypertension-control group
Arterial hypertension-group with SSI-CRAN
Smoking-control group
Smoking-group with SSI-CRAN
0% 25% 50% 75% 100%
71%
81%
56%
63%
80%
90%
100%
100%
100%
99%
100%
100%
Yes No
Figure 1. Patients' factors.
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Figure 3: Potential risk factors compared between the groups 
Type of performed craniotomy
Temporal Suboccipital Frontal Frontoparietal Parietal Temporoparietal
1,50%
6,10%
9,10%
10,60%
3,00%
7,60%
0,00%
28,80%
7,60%
6,10%
13,60%
6,10%
0,00%
1,40%
2,90%
4,30%
10,00%
8,60%
1,40%
12,90%
1,40%
11,40%
28,60%
17,10%
Control group Group with SSI-CRAN
Figure 2. Type of performed craniotomy.
Control group Group with SSI-CRAN
not risk factors for an SSI-CRAN. One patient in 
the control group and three patients in the group 
with an SSI-CRAN had an intraoperatively breached 
frontal sinus; however, intraoperative frontal sinus 
breach was not a risk factor for an SSI-CRAN nor 
was the use of electrodes to monitor intracranial 
pressure (ICP). Two patients from the control group 
had pneumonia at the time of hospital discharge and 
two patients from the SSI-CRAN group had lower 
urinary tract infections; however, infection at the 
time of hospital discharge was not a risk factor for an 
SSI-CRAN. Figure 3 shows that the prescription of 
glucocorticosteroids at the time of hospital discharge 
had a statistically significant association with the 
development of an SSI-CRAN (p=0.04). No patient 
characteristics during the postoperative period were 
risk factors for the development of an SSI-CRAN. 
We then determined if any of the surgical materials 
used posed a risk for the subsequent development of 
an SSI-CRAN. Table 2 shows that the development 
of an SSI-CRAN was associated with the use 
of dural substitutes (p=0.0028), especially self-
adhesive dura (p=0.0274); however, there were no 
statistically significant differences amongst other 
types of dural substitutes between the groups. In the 
group of patients who developed an SSI-CRAN the 
craniotomy wound was more frequently closed with 
sutures (p=0.0001), while the surgical wound was 
more frequently closed with staples in the control 
group (p=0.0001) and the dura was more frequently 
sutured (p=0.0001). There were no statistically 
significant differences between the groups with 
respect to the use of hemostatic agents; Surgicel® 
was more frequently used in the SSI-CRAN group 
(p=0.0019) and TachoComb® was more often used 
in the control group ( =0.0241).
DISCUSSION 
This retrospective cohort study of patients treated 
at Maribor University Hospital showed that the 
overall incidence of SSI-CRAN was 5.5%, which is 
in agreement with the 1%-11% incidence reported 
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in other studies (1,8,19). Notably, a retrospective 
study reported a 0.5% incidence of SSI-CRAN over 
a 10-year period (7). It is possible that the incidence 
of SSI-CRAN in our patients was higher or that we 
operated sooner and allowed patients to continue 
with oncologic treatment as soon as possible. The 
average time of onset of an SSI-CRAN was 58.6 
days (SD=52.57 days), which is longer than the 39 
days (SD=54 days) in comparable studies (1). In 
another study, most SSIs-CRAN occurred within 
2 weeks of surgery (9). In our study most patients 
with SSIs-CRAN were diagnosed after discharge 
from the hospital, which is similar to the results of 
related studies (20,21). The most prevalent SSIs were 
osteomyelitis (66.7%) and/or epidural abscesses 
(63.6%), as previously reported (7,20,22). In most 
cases, patients with an SSI-CRAN only required 
one surgery to treat the SSI (74.2%). In 56.1% of 
patients > 1 microorganism was isolated, with 
monomicrobial infections occurring in 42.4% of 
patients.  Gram-positive bacteria were isolated in 
81.8% of SSIs, which is in agreement with other 
studies (1,7,9,10,20,21). The most commonly 
isolated bacterium was Propionibacterium acnes 
(54.5%), followed by coagulase-negative staphylococci 
(45.5%) and Staphylococcus aureus (39.4%). 
The most commonly isolated bacterial genus was 
Staphylococcus (84.85%), as reported in previous 
studies (31,33). The most commonly isolated Gram-
negative bacterium was Enterobacter cloacae (9.1%), 
as previously reported (1).
Smoking status, diabetes, arterial hypertension, liver 
cirrhosis, chronic kidney disease, and COPD were not 
shown to be risk factors for the development of SSI-
CRAN. Likewise, gender and mean age at the time 
of first surgery were not risk factors for SSI-CRAN, 
which is comparable to data from other studies 
(1,7,19); however, a meta-analysis concluded that 
male gender was a risk factor for SSI-CRAN (23). In 
the current study there was no statistically significant 
difference in the mean duration of hospitalisation 
for the first craniotomy among the groups, while 
other researchers reported that hospitalisation after 
the first surgery was longer in the group of patients 
who subsequently developed an SSI-CRAN (19). In 
addition, we showed that hospitalization of patients 
with an SSI-CRAN was greater (26.37 days) than 
hospitalization for the first surgery (14.34 days).
The most common indication for the first craniotomy 
in both groups was removal of a primary brain tumour, 
as reported by others (1,7). Revision of the craniotomy 
was not shown to be a risk factor for an SSI-CRAN, 
which is in contrast to reports that concluded revision 
of a craniotomy to be a risk factor (8,20,23).
Preoperative administration of glucocorticosteroids 
and preoperative radiotherapy were not risk factors 
for the development of an SSI-CRAN; however, one 
study did conclude that preoperative chemotherapy 
and administration of glucocorticosteroids were risk 
factors for an SSI-CRAN (22). The use of electrodes 
to control intracranial pressure was also shown not 
to be a risk factor for an SSI-CRAN, in contrast to 
the findings in one study (9).
SSI-CRAN was more frequent in patients who 
underwent a frontal craniotomy (p=0.0328 [Fisher's 
exact test]), while intraoperative breach of the 
paranasal sinus was not a risk factor for an SSI-
CRAN (p=0.3551 [Fisher's exact test]). Numerous 
studies have concluded that breach of the paranasal 
sinus is an important risk factor for an SSI-CRAN 
(24). The reason for this discrepancy is likely the 
small number of patients in our study where an 
intraoperative breach of the paranasal sinus was 
detected and documented in the medical records, 
both in the control (1.4% of patients) and SSI-
CRAN groups (4.5% of patients). Considering that 
frontal craniotomy was a risk factor for SSI-CRAN, 
unlike breach of the paranasal sinus, it is possible 
that we overlooked some of the intraoperative 
breaches. We also found that pterional craniotomy 
was more frequently performed in the control 
group (p=0.038 [Fisher’s exact test]); there were no 
statistically significant differences for the other types 
of craniotomies. We also did not demonstrate that 
the pathohistologic diagnosis of the removed lesion 
was a risk factor for the development of an SSI-
CRAN based on a comparison of the two groups. In 
one study, the authors identified surgical treatment 
of extrinsic tumours as a risk factor for SSI-CRAN 
because such tumours require a more aggressive 
approach and are therefore associated with a more 
frequent occurrence of an SSI-CRAN (1).
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Figure 3. Potential risk factors compared between the groups.
The use of dural substitutes (p=0.0028 [Fisher's exact 
test]) was a risk factor for an SSI-CRAN. Of the types 
of dural substitutes, the self-adhesive dura (p=0.0274 
[Fisher's exact test]) was more likely to be used in 
the group of patients who developed an SSI-CRAN. 
Likewise, other researchers have recognised the use 
of dural substitutes as a significant risk factor for an 
SSI-CRAN (10,19). A risk factor for the subsequent 
occurrence of an SSI-CRAN was closure of the skin 
with sutures versus staples (p=0.0001 [Fisher's exact 
test]), as reported in previous studies (25,26). We also 
found a study in which the use of staples was shown 
to be a risk factor for the occurrence of an SSI-CRAN 
(19). Taken together, we conclude that there is no 
convincing evidence regarding the safety of different 
materials with respect to the incidence of SSIs. The 
staples allow the wound to close faster, which may be 
one of the reasons for the lower incidence of SSIs. 
In addition, titanium staples are more inert than 
the materials used to make sutures (26). Moreover, 
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when using sutures the risk of infection is increased 
by the development of a biofilm, which occurs more 
frequently when using multifilament sutures, but 
may also develop on the surface of monofilament 
sutures (1). There were no statistically significant 
differences between the two groups regarding the use 
of hemostatic agents. Surgicel® was more frequently 
used in the group of patients with an SSI-CRAN 
(p=0.0019 [Fisher's exact test]); no studies have 
reported similar findings. There was a statistically 
significant increase in the use of the hemostatic 
agent, TachoComb®, in the control group.
Referral to further oncologic treatment after the first 
craniotomy was not a risk factor for an SSI-CRAN. 
The data in other studies were not available regarding 
the number of patients commencing oncologic 
treatment after the first craniotomy (1,4,7). We did 
not demonstrate that a postoperative CSF leak was a 
risk factor for an SSI-CRAN, which may reflect the 
relatively small sample of patients in our study who 
developed CSF leaks postoperatively (4 patients in 
the control group and 8 patients in the SSI-CRAN 
group). Other studies have reported the occurrence 
of postoperative CSF leaks as a statistically significant 
risk factor for an SSI-CRAN (20,23). Infection at the 
time of discharge from the hospital after the first 
craniotomy was also not shown to be a risk factor. 
A review of the literature revealed one study that 
reported infection at the time of discharge from the 
hospital as a risk factor for an SSI-CRAN (23), but 
this was not the finding in most studies (1,4,7). 
The administration of glucocorticosteroids in 
the early postoperative period was a risk factor 
for the development of an SSI-CRAN (p=0.04 
[Fisher's exact test]). Glucocorticosteroids slow the 
wound healing process, increase the risk of wound 
dehiscence and subsequent infection, and also have 
immunosuppressive effects (27). Other researchers 
have also reported the use of glucocorticoids in the 
perioperative and early postoperative periods as a 
risk factor for an SSI-CRAN (17). In the SSI-CRAN 
group, death was statistically significantly more 
frequent during hospitalisation than in the control 
group (p=0.0274 [Fisher’s exact test]). Similar 
findings have been reported other researchers (20).
Unlike other studies (1,8,19-21), a strength of our 
study was the 10-year observation period. In contrast, 
a weakness of in our study was the retrospective 
cohort design and a randomly selected control group 
because a case-control retrospective study with a 
large, carefully selected and balanced control group 
would have been a more suitable method with an 
increase in the statistical power of the result. An 
additional drawback of our study was the relatively 
small number of craniotomies performed over the 
entire period, and consequently, the small absolute 
number of patients who developed an SSI-CRAN 
compared to other studies, in which the number of 
patients varied between a few hundred and several 
thousand (1,7,19-21). A small sample was likely 
the reason that the intraoperative breach of the 
paranasal sinus and the postoperative appearance 
of the CSF leak were not considered a risk factor 
in our study, which is in contrast to other studies 
(20,23,34). Therefore, in the future, the results of our 
study should be verified in a larger group of patients 
with SSIs-CRAN at the national level. We intend 
to monitor the use of Surgicel® and TachoComb® 
in the future and the impact on the incidence of 
SSIs-CRAN as we are currently unable to explain 
these associations. Other factors (frontal craniotomy 
and administration of glucocorticosteroids in the 
postoperative period), which also appeared to be risk 
factors for an SSI-CRAN, cannot be changed, but it 
is important to recognize them nonetheless because 
this is the only way can we be more alert to patients 
with these risk factors and to recognize SSI-CRAN in 
a timely fashion. 
UNITS AND ABBREVIATIONS 
SSI-CRAN: Surgical site infection after craniotomy 
CSF: cerebrospinal fluid 
ASA: American Society of Anesthesiologists 
SPSS: Statistical Package for Social Sciences 
COPD: chronic obstructive pulmonary disease
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Table 2. The material used during the first craniotomy
The material used during the first 
craniotomy
Control group (percentage, 
number of patients)
Group with SSI-CRAN 
(percentage, number of patients) p-value
Hemostatic agents 120% (n=84) 133.3% (n=88) p=1.0
Dural substitutes 27.1% (n=19) 53% (n=35) p=0.0028
Dural suturing 95.7% (n=67) 71.2% (n=47) p=0.0001
Fibrin sealant 65.7% (n=46) 78.8% (n=52) p=0.1257
Drain located underneath the 
bone 32.9% (n=23) 31.8% (n=21) p=1.0
CranioFix® 35.7% (n=25) 24.2% (n=16) p=0.1907
Titanium bone plates and screws 57.1% (n=40) 72.7% (n=48) p=0.0729
Skin suturing 34.3% (n=24) 69.7% (n=46) p=0.0001
Skin stapling 65.7% (n=46) 30.3% (n=20) p=0.0001
Drain located under galea 50% (n=35) 39.4% (n=26) p=0.2315
Drain located epidurally 28.6% (n=20) 31.8% (n=21) p=0.7117
Subcutaneous drain location 30% (n=21) 19.7% (n=13) p=0.2343
Titanium mesh 0% (n=0) 6.1% (n=4) p=0.0529
Bone cement 0% (n=0) 1.5% (n=1) p=0.4853
Type of hemostatic agent
Surgicel® 67.1% (n=47) 89.4% (n=59) p=0.0019
TachoComb® 30% (n=21) 13.6% (n=9) p=0.0241
TachoSil® 22.9% (n=16) 30.3% (n=20) p=0.3389
Type of dural substitute 
Artificial dura 4.3% (n=3) 13.6% (n=9) p=0.0714
Self-adhesive dura 2.9% (n=2) 13.6% (n=9) p=0.0274
Bovine dura 2.9% (n=2) 0% (n=0) p=0.4967
Bovine pericardium 1.4% (n=1) 1.5% (n=1) p=1.0
Duraform® 2.9% (n=2) 3% (n=2) p=1.0
Lyophilized dura 12.9% (n=9) 21.2% (n=14) p=0.2534
20
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