Peer-Review Reports
Autologous and Acrylic Cranioplasty: A Review of 10 Years and 258 Cases
Daniel R. Klinger1, Christoper Madden1, Joseph Beshay1, Jonathan White1, Kenneth Gambrell2, Kim Rickert1
Key words
Cranioplasty
- Craniotomy/craniectomy
- Hemorrhage
- Infection
- Traumatic brain injury
-
Abbreviations and Acronyms
ICH: Intracerebral hemorrhage
SAH: Subarachnoid hemorrhage
TBI: Traumatic brain injury
From the Departments of 1Neurological Surgery
and 2Oral and Maxillofacial Surgery, University
of Texas Southwestern Medical Center, Dallas, Texas, USA
To whom correspondence should be addressed:
Daniel R. Klinger, M.D.
[E-mail: danielrklinger@gmail.com]
Citation: World Neurosurg. (2014).
http://dx.doi.org/10.1016/j.wneu.2013.08.005
Journal homepage: www.WORLDNEUROSURGERY.org
Available online: www.sciencedirect.com
1878-8750/$ - see front matter ª 2014 Elsevier Inc.
All rights reserved.
INTRODUCTION
Craniectomy has maintained a broad range
of applications to neurosurgical practice.
The reduction of malignant intracranial
pressure in the setting of traumatic brain
injury (TBI), aneurysmal subarachnoid
hemorrhage, and ischemic stroke can
often be accomplished quickly and
successfully with decompressive craniectomy (1, 3, 6, 10, 11, 13, 22, 23). Secondary
benefits may include reduction in patients’
intensive care unit time, ventilator dependence, hospital stay, and long-term
morbidity and mortality (1, 3, 6, 10, 11, 13,
19). In addition, craniectomy will always
have a role in tumor surgery in the removal
of neoplastic and nonviable bone and in
cases of significant intraoperative brain
edema (6, 10, 19). Finally, postcraniotomy
infections may require removal of the
infected cranial flap to eliminate the source
of infection. These diverse patient groups,
once recovered from the acute processes
prompting craniectomy, generally require
replacement of the bone flap or construction of a substitute to repair the cranial
defect. Cranioplasty with either the
- INTRODUCTION:
Cranioplasty is a well-accepted neurosurgical procedure
that has application to a wide range of pathologies. Given the varied need for
both autologous and synthetic cranial grafts, it is important to establish rates of
procedural complication.
- METHODS:
A retrospective review identified 282 patients undergoing cranioplasty at our institution over a 10-year period, of which 249 patients underwent 258 cranioplasties with either autologous or acrylic flaps. A database
including patient age, gender, presenting diagnosis, hospital of surgery, presence of a drain, and surgical complications was created in order to analyze the
autologous and acrylic cranioplasty data.
- RESULTS:
A total of 28 complications were noted, yielding a rate of 10.9% (28/
258). There was no statistically significant difference in infection rate between
autologous and acrylic cranioplasty (7.2% vs. 5.8%, P [ 0.80). Male patients
(P [ 0.007), tumor patients (P [ 0.02), and patients undergoing surgery at the
county hospital (P [ 0.06) sustained a statistically higher rate of infection.
Among traumatic brain injury patients, complex injuries and surgical involvement of the frontal sinus carried a significantly higher infection rate of 17% and
38.5%, respectively (P [ 0.03, P [ 0.001). Postoperative epidural hematoma
requiring reoperation occurred in 3.5% (9/258) with no difference in hematoma
rate with placement of a drain (P [ 1).
- CONCLUSIONS:
Cranioplasty carries a significant risk of infection and
postoperative hematoma. In this large series comparing autologous and acrylic
flaps, male patients, tumor patients, and those undergoing surgery at the county
hospital were at increased risk of postoperative infection. Among traumatic
brain injury cases, complex injuries and cases with surgical involvement of the
frontal sinus may portend a higher risk.
recovered bone flap or a constructed
synthetic substitute not only provides
cosmetic value to patients and their families but also provides protection to the
underlying brain. Less well known and well
described is the value of cranioplasty, if
any, in fostering further neurologic
recovery (7, 8, 21).
In many institutions, the removed craniectomy bone flap is cultured, frozen,
and stored in an institutional bone bank in
anticipation of replacement at a later time.
In the past decade, it has been the policy
at our institution to discard bone flaps
with positive cultures so as to prevent
future infection during cranioplasty. In
this regard, many patients have subsequently required cranial reconstruction
WORLD NEUROSURGERY - [-]: ---, MONTH 2014
with a nonautologous flap. A number of
studies have retrospectively reviewed the
risks of cranioplasty but have often
included an amalgam of many different
cranioplasty materials (including autologous, polymethylmethacrylate, titanium,
polyetheretherketone, and acrylic) with
little basis for direct comparison (4,
14-16). We present a single-center review
of all cranioplasty procedures completed
at two hospitals, Parkland Memorial and
University of Texas Southwestern University Hospital, and describe the largest reported comparison of autologous versus
acrylic cranial flaps. It includes a subset of
118 patients undergoing 122 cranioplasties
in the setting of TBI. We evaluate the
complication profile of each surgery as
www.WORLDNEUROSURGERY.org
1
PEER-REVIEW REPORTS
DANIEL R. KLINGER ET AL.
well as the financial costs in hopes of
deriving information that may assist with
future decision making in regards to both
craniectomy and cranioplasty.
METHODS
International Classification of Diseases
codes for cranioplasty and craniectomy at
Parkland Memorial Hospital and University of Texas Southwestern University
Hospital from June 2001 through October
2010 were collected, yielding 282 patients
who underwent a total of 293 cranioplasty
procedures. To investigate our aim of
comparing autologous and acrylic bone
flaps, we excluded 33 patients who
underwent cranioplasty with other materials such as polyetheretherketone or titanium as well as those patients for whom
the material of use could not be determined. We limited our study cases to
autologous and acrylic cranioplasty. These
criteria yielded 249 patients who underwent 258 cranioplasties. Cases in which
patients underwent a second cranioplasty—usually after the initial procedure
resulted in an infection or bone resorption
requiring flap removal—were included in
our analysis.
Data were collected to include patient’s
gender, age, presenting diagnosis, type of
graft (autologous vs. acrylic), presence of
an intraoperative drain (subgaleal or
epidural), and complications. We defined
complications as events that may significantly hamper patients’ continued
recovery from initial neurologic insult or
prevent or delay future adjuvant medical
care. We included all infections, wound
breakdowns, cases of significant bone
resorption, and symptomatic epidural
hematoma or fluid collection requiring
reoperation. Infections were defined as
surgical wound sites marked by erythema,
drainage, wound breakdown, and palpable
fluid collections, often with associated
radiographic correlates (fluid collections,
abscesses, empyemas) that required
intervention in the form of antibiotic
treatment or reoperation. Microbiology
results from surgical site wound cultures
were also recorded.
Seizures were excluded as complications
because many patients were noted to have
an underlying seizure disorder prior to
cranioplasty. On chart review, no patients’
outcomes
were
adversely
affected
2
www.SCIENCEDIRECT.com
AUTOLOGOUS AND ACRYLIC CRANIOPLASTY
secondary to perioperative epileptic events.
Assessment of follow-up included a review
of all postoperative encounters documented
in the electronic medical record and varied
from one month to several years.
Thirteen staff neurosurgeons performed
all of the cranioplasties. In select cases,
secondary to egregious soft tissue defects or
craniofacial involvement, plastic surgeons
and dedicated craniofacial surgeons assisted
with the procedures. The majority of
decompressive craniectomies performed for
TBI involved a large hemicraniectomy with
a single frontotemporoparietal bone flap
and dural opening. A similar flap was
employed for cases of malignant ischemic
infarct (cerebrovascular infarction). Several
cases included bifrontal decompressive craniectomy for malignant intracranial pressure, facial and frontal sinus pathology, and
penetrating frontal injuries. Decompressive
craniectomy for aneurysmal subarachnoid
hemorrhage (SAH) involved a smaller pterional bone flap usually removed for intraoperative brain swelling. Craniectomy for
intracerebral hemorrhage (ICH) and tumor
depended on the site of pathology; all cases
were confined to supratentorial pathology.
Tumor craniectomies were usually required
for intraoperative brain swelling or tumor
involvement of bone.
Grossly contaminated bone flaps were
discarded. All bone flaps not grossly
contaminated per institutional protocol
underwent tissue swab aerobic cultures
and were then frozen and stored in
a tissue bank (12, 17). The flaps were
frozen at 40 to 80 C in our Transfuion Services Tissue Bank. When the
patient was deemed ready for subsequent
cranioplasty by a staff neurosurgeon, the
culture results were reviewed. In all cases
of positive cultures, the native flap was
discarded and an acrylic bone flap was
constructed based on a wax model of the
patient’s skull defect. This wax model was
hand-crafted by a technician who examined the patient and his or her cranial
defect. In cases of negative cultures, the
autologous flap was recovered from
storage and thawed for replacement.
Statistical Analysis
Two-by-two contingency tables were constructed to compare infection rates and
hematoma rates of targeted populations
with the rest of the study population. Odds
ratios were then calculated for each variable
in comparison to the remaining study
population, and 95% confidence intervals
were calculated for these odds ratios. Twotailed Fisher exact probability tests were
conducted, yielding two-tailed P-values. A
two-tailed P-value of 0.05 was considered
statistically significant. Where multiple
variables reached statistical significance,
these variables were compared again using
two-by-two contingency tables and calculating a separate p1-value from two-tailed
Fisher exact probability tests to assess for
any confounding among these variables.
RESULTS
Patient Characteristics
A total of 249 patients underwent 258
procedures with either autologous or
acrylic cranioplasty. Of the nine patients
who underwent a second cranioplasty,
seven were performed in patients who
initially developed cranioplasty infection
requiring flap removal. All seven of these
second cranioplasties were acrylic. One
patient underwent a second acrylic procedure after he developed clinically significant bone resorption from an autologous
cranioplasty. One patient underwent two
separate-site cranioplasties—one autologous cranioplasty after decompressive
craniectomy for ruptured aneurysm and
later a contralateral acrylic cranioplasty
after an elective aneurysm craniotomy for
clipping became infected.
Of the 258 procedures, 138 (53%) were
autologous and 120 (47%) were acrylic.
The average age of the patients was 44.0
years with 37% of the patients less than 40
years (93 patients), 46% of the patients
between the ages of 40 and 59 years (114
patients), and 17% of the patients 60 years
or older (42 patients). In addition, 63%
(157 patients) were male, and 37% (92)
patients were female. One hundred
seventy-one of the 258 (66%) cranioplasties were performed at the county
hospital, Parkland Memorial, whereas 87
(34%) were performed at the university
hospital. Subgaleal drains to assist with
hemostasis were left in 71% (183) of cases.
All patients were admitted postoperatively
and monitored both clinically and with a
noncontrast computed tomographic head
scan after surgery.
The initial diagnosis of the patients
(Figure 1) included TBI (118 patients, 47%),
WORLD NEUROSURGERY, http://dx.doi.org/10.1016/j.wneu.2013.08.005
PEER-REVIEW REPORTS
DANIEL R. KLINGER ET AL.
AUTOLOGOUS AND ACRYLIC CRANIOPLASTY
Table 1. Complications of Cranioplasty
Number of
Complications/
Number of Complication
Complication
Cases
Rate (%)
Infection
15/258
5.8
Wound
breakdown
2/258
0.7
Bone
resorption
2/258
Epidural
hematoma
9/258
aneurysmal SAH (59 patients, 24%), ICH
(25 patients, 10%), malignant ischemic
infarct (cerebrovascular infarction, 18
patients, 7.2%), infection (11 patients,
4.4%), tumor (9 patients, 3.6%), and other
(9 patients, 3.6%). Those patients included
in the “other” category included procedures
for epilepsy (2), cosmesis (4), and postcraniotomy pain or headache (3).
Further subdividing our 118 TBI patients,
there were 85 patients who underwent
unilateral hemicraniectomy for closed head
injury (which we termed “simple” cases) and
23 patients with penetrating injuries, either
gunshot wound (15) or open depressed
skull fracture (8). Cases involving bifrontal
decompressive craniectomy (7) and repair
of frontal sinus fractures (2) were grouped
with the penetrating-injury TBI patients as
“complex” for a total of 32 cases. Mechanisms of injury included 34 motor vehicle
collisions, 20 falls, 18 aggravated assaults, 15
gunshot wounds to the head, 12 motorcycle collisions, 12 patients found down of
unknown cause, 4 motor-pedestrian collisions, 1 all-terrain vehicle accident, 1 wakeboarding accident, 1 electrical accident, and
1 bull-riding injury.
Complications
Complications (Table 1) were noted in 28
of the 258 cases (10.9%). There were no
mortalities associated with cranioplasty.
Variable
Number of
Infections/
Number of Infection
Cases
Rate (%) P-Value
Flap type
0.7
Autologous
Acrylic
Total complication rate
Figure 1. Initial diagnoses in patients
undergoing cranioplasty. Note the
percentage of patient subgroups undergoing
cranioplasty in the study population of 249
patients. Abbreviations: TBI, traumatic brain
injury; SAH, subarachnoid hemorrhage; ICH,
intracerebral hemorrhage; CVA, cerebral
ischemic infarct.
Table 2. Analysis of Variables
Associated with Infection in
Cranioplasty
3.5
Presence of
drain
10.9
Drain
Complications included infection, wound breakdown,
clinically significant bone resorption, and epidural
hematoma. Of note, the rate of bone resorption with
autologous cranioplasty is higher than that seen
above, at 1.4% or 2/138.
No drain
0.80
10/138
7.2
7/120
5.8
0.78
13/183
7.1
4/75
5.3
Age
0.30
<40 years
9/99
9.1
40 years
8/159
5.0
Gender
The complications included 15 cases of
cranioplasty infection (5.8%), 8 of which
involved autologous cases and 7 involved
acrylic. There were an additional two cases
of wound breakdown in the autologous
group (0.8% of whole, 1.4% of autologous
cohort). There were also two cases of
significant bone resorption in the autologous group (0.8% of whole, 1.4% of autologous cohort), one requiring a second
cranioplasty with acrylic. Of infected cases,
all required treatment with antibiotics,
reoperation for removal of the infected flap,
or both. In 14 of the 15 cases of infection,
organisms were isolated from surgical site
cultures. These included 4 cases of methicillin-resistant Staphylococcus aureus, 3 cases
of methicillin-sensitive S. aureus, 4 cases of
mixed organisms (Propionibacterium acnes
and S. aureus, P. acnes and methicillinsensitive S. aureus, Serratia and coagulasenegative S. aureus, and mixed flora), 1 case of
coagulase-negative S. aureus, 1 case of
Enterobacter species, and 1 case of P. acnes
species. There was no statistical difference
in the infection rate (Table 2) between
acrylic and autologous cranioplasty (P ¼ 1),
which remained true when including cases
of wound breakdown with autologous cranioplasty (P ¼ 0.80).
In our series (Table 2), young-age patients
(<40 years old) had a higher infection rate
(9/99, 9.1%), which was not statistically
significant (P ¼ 0.30). Similarly with TBI, an
insignificantly higher infection rate was
WORLD NEUROSURGERY - [-]: ---, MONTH 2014
Male
Female
0.007*
16/165
9.7
1/93
1.1
Hospital
Parkland
0.06
15/171
8.8
2/87
2.3
TBI
10/122
8.2
0.45
SAH
2/62
3.2
0.26
ICH
2/25
8.0
1.0
SAH þ ICH
4/87
4.6
0.44
Tumor
3/9
33.0
0.02*
Zale-Lipshy
Bone flap type, the presence of a drain, age, gender,
hospital, and initial diagnosis were analyzed for
association with cranioplasty infection rate.
TBI, traumatic brain injury; SAH, subarachnoid hemorrhage; ICH, intracerebral hemorrhage.
*Statistical significance.
noted (10/122, 8.2%, P ¼ 0.45). The infection
rate was clearly higher in our complex TBI
patients (17%) in comparison to the simple
TBI patients (4.7%, P ¼ 0.03) (Table 3).
Penetrating injuries (11.5% vs. 7.4%, P ¼
0.33) and surgical involvement of the frontal
sinus (38.5%, P ¼ 0.001) also carried
a higher infection rate within the subset of
TBI patients. Flap type was not a significant
predictor of infection in TBI patients. All of
the infected complex TBI cases involved
acrylic flaps, although this did not
reach statistical significance (6/21 vs. 0/14,
P ¼ 0.06).
www.WORLDNEUROSURGERY.org
3
PEER-REVIEW REPORTS
DANIEL R. KLINGER ET AL.
There were two infections in 59 SAH
patients (3.4%, P ¼ 0.26). ICH patients
had an 8% infection rate (2/25, P ¼ 1).
When combining ICH and SAH patients
into one subset, the infection rate was
4.6% (P ¼ 0.44). Male gender did carry
a significantly higher infection rate in
comparison to female (16/165, 9.7% vs.
1.1%, P ¼ 0.007). Cranioplasty for tumor,
though the case number was low, also
carried a high rate of infection (3/9, 33%,
P ¼ 0.02). In contrast, the placement of an
intraoperative drain in the subgaleal space
during cranioplasty did not significantly
increase the rate of infection (7.1 vs. 5.3%,
P ¼ 0.42). Finally, in comparing hospitals,
there was a trend toward a higher infection rate at the county hospital versus the
private hospital (15/171 vs. 2/87, 8.8% vs.
2.3%, P ¼ 0.06).
There were 9 cases of symptomatic
epidural hematoma (Table 4) requiring
reoperation (3.5%). The use of an intraoperative drain was not associated with
a significantly lower rate of symptomatic
epidural hematoma formation (6 hematomas/183 cases vs. 3 hematomas/75 cases,
3.3 vs. 4%, P ¼ 0.51). In general, there was
no discernible subgroup of patients
undergoing cranioplasty that had a significantly higher rate of symptomatic postoperative epidural hematoma.
DISCUSSION
Complications with Cranioplasty
In keeping with findings in other large
series, cranioplasty is associated with
a moderate rate of complication, 10.9%
(2, 4, 15, 16). A small subset of patients
will likely require a second procedure (or
more) to address the risks of infection and
hematoma formation. Our overall infection rate of 5.8% in 258 cases, the largest
reported neurosurgical single-institution
series, correlates with prior reports as
well. A recent meta-analysis of 17 varied
series in the literature demonstrated
a range of cranioplasty infection rates
from 0 to 21.4%, with an average rate of
7.9% (24). Including cases of wound
breakdown, our wound complication rate
reaches 6.6%.
We established no significant difference
in infection rate between autologous and
acrylic cranioplasty. In limiting our cranioplasty flap type to autologous bone and
4
www.SCIENCEDIRECT.com
AUTOLOGOUS AND ACRYLIC CRANIOPLASTY
Table 3. Analysis of Traumatic Brain
Injury Patient Subgroups and Infection
Rate in Cranioplasty
Table 4. Analysis of Variables
Associated with Epidural Hematoma
Formation After Cranioplasty
Number of
Infections/
Number of Infection
TBI Subtype
Cases Rate (%) P-Value
Variable
Flap type
Flap type
0.34
Autologous
3/56
5.4
Acrylic
765
10.8
Simple vs.
complex
0.03*
Simple
4/86
4.7
Complex
6/35
17.0
Penetrating vs.
closed
0.33
Penetrating
3/26
11.5
Closedhead injury
7/95
7.4
5/13
38.5
Frontal sinus
involvement
Number
of EDHs/
Number Rate of
of Cases EDH (%) P-Value
0.74
Autologous
4/138
2.9
Acrylic
5/120
4.2
Presence of
a drain
1
Autologous
6/183
7.2
Acrylic
3/75
5.8
Age
0.94
<40 years
6/99
6.1
40 years
3/156
1.9
Hospital
0.001*
Subgroups of TBI patients to include flap type, simple
versus complex head injuries, closed-head versus
penetrating injuries, and frontal sinus involvement
were analyzed for association with cranioplasty
infection rate.
TBI, traumatic brain injury.
*Statistical significance.
acrylic (the preferred choice at our institution) we believe the findings add validity
to the idea that cranioplasty flap source is
unlikely a significant factor in influencing
surgical infection and complication rate.
Several studies have reached similar findings but often under the comparison of
numerous types of cranioplasty materials
(4, 16, 24).
Cranioplasty and TBI
Nearly half of the patients in this series
(118 patients, 47%) underwent an initial
decompressive craniectomy for TBI and
these patients exhibited a higher infection
rate that did not reach clinical significance
(8.2%, P ¼ 0.15). The notion that infection
and complication rate of cranioplasty in
this subpopulation likely depends on the
initial injury complexity—with penetrating
injuries, complex fractures, dirty wounds,
and frontal sinus involvement incurring
higher complications later at the time of
cranial repair—seems likely.
1
Parkland
5/171
2.9
Zale-Lipshy
4/87
4.6
TBI
5/122
4.1
0.74
SAH
2/62
3.2
1
ICH
2/25
8.0
0.22
Flap type, the presence of a drain, patient age, hospital,
and initial diagnosis were analyzed for association
with EDH formation after cranioplasty.
EDH, epidural hematoma; TBI, traumatic brain injury;
SAH, subarachnoid hemorrhage; ICH, Intracerebral
hemorrhage.
The bulk of our series consisted of simple
closed head injuries (72%) predominantly
undergoing unilateral decompression, and
our most prominent mechanism of injury
was motor vehicle collision. In these 86
cases for “simple” injuries, the rate of
infection was quite low at 4.7% when
compared with other traumatic series
(9, 20) and in comparison to our remaining
study population (P ¼ 0.44). In contrast, an
infection rate of 17% (6/35) was found in our
“complex” injuries (which included penetrating injuries and those with surgical
involvement of the frontal sinus), which
was significantly higher (P ¼ 0.03) than the
“simple” TBI cases.
TBI cases involving the frontal sinus in
our study were at even higher risk of
infection (5/13, 38.5% infection rate, P ¼
0.001). These numbers may be slightly
WORLD NEUROSURGERY, http://dx.doi.org/10.1016/j.wneu.2013.08.005
PEER-REVIEW REPORTS
DANIEL R. KLINGER ET AL.
skewed by the fact that two TBI patients in
our study had two cranioplasty infections
each, and both of these patients had
frontal sinus involvement in their initial
decompressive procedures. However, even
when excluding these two additional
infections, the infection rate in frontal
sinus cases was still significantly higher
(P ¼ 0.02). Our finding that frontal sinus
injuries and bifrontal flaps are a high-risk
subpopulation may help to explain the
unfavorable outcomes data from Cooper’s
recent prospective study involving bifrontotemporoparietal craniectomy in diffuse
TBI patients (6). It has been the belief at
our institution that a bifrontal decompression in TBI is seldom justified and
that a hemicraniectomy is preferred in
almost all TBI pathologies.
Other Factors
Cranioplasty in tumor patients was associated with a significantly higher infection
rate of 33% in 9 patients (P ¼ 0.02). In
Chang’s institutional review of cranioplasty, a higher complication rate among
tumor patients was also found (38% vs.
15%, P ¼ 0.02 in their study) (4). In
further analysis, the high infection rate
among tumor patients was not explained
by confounding by another high-risk variable such as gender or hospital (p1 ¼ 1 and
0.35, respectively). Although limited by
a small number of patients within this
subgroup, these findings may highlight
a patient demographic truly at higher risk.
Only one of the nine patients in our series
underwent radiation treatment (and did
not sustain a complication), but tumor
patients also often undergo prolonged
corticosteroid treatment perioperatively
and frequently suffer from nutritional
problems and chemotherapeutic toxicities,
which place them at risk of infection and
poor wound healing (18).
As part of our analysis, we compared
rates of infection and case distribution at
our two institutional hospitals, Parkland
Memorial and the university hospital.
Parkland is a county hospital with a busy
emergency department and level-one
trauma center that provides care to a large
population of uninsured patients. The
university hospital is a tertiary referral
center with a large practice in cerebrovascular neurosurgery. The infection rate
at Parkland appeared to be higher at 8.8%
versus 2.3% at the university (P ¼ 0.06).
AUTOLOGOUS AND ACRYLIC CRANIOPLASTY
The same group of surgeons operated at
both hospitals. Further statistical analysis
comparing the variables of gender and
hospital type revealed a statistically higher
number of male patients undergoing cranioplasty at Parkland (p1 ¼ 0.0006).
Overall, 116 of 164 Parkland cranioplasty
patients were male whereas 41 of 85
university-hospital cranioplasty patients
were male. Given similar operative techniques, it is tempting to conclude that an
inherent difference in the patient population at the county hospital accounts for
a higher infection rate with cranioplasty
there. Perhaps Parkland’s cranioplasty
patients included a greater mix of
complex, male patients more prone to
subsequent cranioplasty infection.
Cranioplasty, Extraaxial Hematoma and
Drains
In 9 of 258 cases (3.5%), a postoperative
epidural hematoma after cranioplasty
required reoperation. Eight of these
patients had the cranioplasty flap replaced
at the time of hematoma evacuation, one at
a later surgery. One patient subsequently
developed a wound and flap infection, later
requiring removal of the flap, which was
finally replaced with another acrylic cranioplasty procedure once the infection was
treated. No patients had permanent
sequelae from hematoma development.
Subgaleal and subdural drains, which were
employed in 71% of all procedures, did not
result in a significantly lower rate of
hematoma formation (3.3% vs. 4% in
nondrain cranioplasties, P ¼ 0.51). Nor did
we find a significantly higher rate of infection with the use of drains (7.1% with drain
vs. 5.3% without). Clearly, a drain does
not prevent development of symptomatic
postoperative hematoma. Proving the
utility of drains in a clinical study is difficult
given that randomization of drain placement alone would not prevent a surgeon’s
bias in obtaining meticulous hemostasis
intraoperatively.
Institutional Cost of Cranioplasty
In select patients undergoing craniectomy
and in whom there is concern in regards
to the integrity of the native bone flap,
acrylic cranioplasty (and likely synthetic
cranioplasty in general) appears to be
a very reasonable and comparably safe
alternative. In addition to a similar infection rate, autologous cranioplasty in our
WORLD NEUROSURGERY - [-]: ---, MONTH 2014
series carried the additional risk of
significant bone resorption (1.4%), a longterm complication also reported in the
craniofacial literature (15). We accrued
a large series of acrylic flaps mainly
secondary to our institutional protocol to
discard all stored autologous flaps with
any positive cultures even in the absence
of frank signs of infection, accounting for
101 of the 120 total acrylic cases. It is
a separate but important question whether
these 101 acrylic cranioplasties would have
had similar results and rates of infection if
completed instead with their culturepositive autologous cranial bone flaps.
The financial cost of constructing an
acrylic flap is significant. At our institution, a craniofacial technician constructs
the acrylic flaps by hand from a wax model
designed by physical inspection of the
patient’s cranial defect. The cost amounts
to 4,000 dollars per acrylic flap (with
computed tomographyemodeled flaps
often costing two to three times as much).
If estimating the cost of storage and
harvest of an autologous flap at even
a quarter of this figure, the additional cost
of our institutional policy of utilizing
acrylic flaps in cranioplasty for asymptomatic positive bone flap cultures reaches
roughly 300,000 dollars over ten years. A
recent elegant study from Iowa found no
difference in infection rate with replacement of the native bone flap in patients
who had light bacterial growth from their
flaps (although in most of these cases, the
flaps were replaced during the patient’s
initial craniotomy procedure) (5).
Limitations
As a retrospective review of a large single
institutional experience with cranioplasty,
this study suffers from several limitations.
As described above, it is difficult to draw
broad conclusions among subpopulations
of patients that are inherently different in
their pathology. The decisions regarding
initial choice of operative craniectomy,
type of procedure, and timing of cranioplasty were subject to the attending
physician and in no way blinded. In
addition, there may have been selection
bias in that all autologous flaps with
positive swab cultures after initial craniectomy were subsequently discarded.
Complications were necessarily assessed
retrospectively from chart review. In
certain cases, follow-up was limited to
www.WORLDNEUROSURGERY.org
5
PEER-REVIEW REPORTS
DANIEL R. KLINGER ET AL.
postoperative clinic visits, and in most
subjects no long-term data on the patients
were available.
CONCLUSIONS
Cranioplasty carries a significant risk of
postoperative infection, wound breakdown, bone resorption, and hematoma
formation, often requiring reoperation in
these instances. There is likely no difference in the complication rate among
patients who undergo the procedure with
autologous bone versus acrylic substitute.
Among TBI patients in our study, complex
injuries and surgical involvement of the
frontal sinus significantly increased the
rate of infection with cranioplasty. The
implementation of safe and cost-effective
clinical and surgical strategies is necessary
to reduce the rate of complication in
patients with postsurgical cranial defects.
REFERENCES
1. Aarabi B, Hesdorffer DC, Ahn ES, Aresco C,
Scalea TM, Eisenberg HM: Outcome following
decompressive craniectomy for malignant
swelling due to severe head injury. J Neurosurg
104:469-479, 2006.
2. Aziz TZ, Mathew BG, Kirkpatrick PJ: Bone flap
replacement versus acrylic cranioplasty: a clinical
audit. Br J Neurosurg 4:417-419, 1990.
3. Bullock MR, Chestnut RM, Clifton G, Ghajar RP,
Young HF, Marion DW, Narayan RK: Management and prognosis of severe traumatic brain
injury. Part I: Guidelines for the management of
severe traumatic brain injury. J Neurotrauma 17:
449-453, 2000.
4. Chang V, Hartzfeld P, Langlois M, Mahmood A,
Seyfried D: Outcomes of cranial repair after craniectomy. J Neurosurg 112:120-124, 2010.
5. Chiang H, Steelman V, Pottinger J, Schlueter A,
Diekema D, Greenlee J, Howard M, Herwaldt L:
Clinical significance of positive cranial bone flap
cultures and associated risk of surgical site
infection after craniotomies or craniectomies.
J Neurosurg 114:1746-1754, 2011.
6. Cooper D, Rosenfeld J, Murray L, Arabi YM,
Davies AR, D’Urso P, Kossmann T, Ponsford J,
6
www.SCIENCEDIRECT.com
AUTOLOGOUS AND ACRYLIC CRANIOPLASTY
Seppelt I, Reilly P, Wolfe R: Decompressive craniectomy in diffuse traumatic brain injury. N Engl
J Med 364:1493-1502, 2011.
7. Dujovny M, Agner C, Aviles A: Syndrome of the
trephined: theory and facts. Crit Rev Neurosurg 9:
271-278, 1999.
8. Fodstad H, Love JA, Eksted J, Friden H,
Liliequist B: Effect of cranioplasty on cerebrospinal fluid hydrodynamics in patients with the
syndrome of the trephined. Acta Neurochir
(Wien) 70:21-30, 1984.
9. Gooch MR, Gin GE, Kenning TJ, German JW:
Complications of cranioplasty following decompressive craniectomy: analysis of 62 cases. Neurosurg Focus 26:E9, 2009.
10. Guresir E, Schuss P, Vatter H, Raabe A, Seifert V,
Beck J: Decompressive craniectomy in subarachnoid hemorrhage. Neurosurg Focus 26:E4, 2009.
11. Hutchinson PJ, Corteen E, Czosnyka M,
Mendelow AD, Menon DK, Mitcehll P: Decompressive craniectomy in traumatic brain injury: the
randomized multicenter RESCUE-ICP study
(www.RESCUEicp.com). Acta Neurochir Suppl 96:
17-20, 2006.
12. Iwama T, Yamada J, Imai S, Shinoda J,
Funakoshi T, Sakai N: The use of frozen autogenous bone flaps in delayed cranioplasty revisited.
Neurosurgery 52:591-596, 2003.
13. Juttler E, Schwab S, Schmiedek P, Unterberg A,
Hennerici M, Woitzik J, Witte S, Jenetzky E,
Hacke W: Decompressive Surgery for the Treatment of Malignant Infarction of the Middle Cerebral Artery (DESTINY): a randomized, controlled
trial. Stroke 38:2518-2525, 2007.
14. Lee SC, Wu CT, Lee ST, Chen PJ: Cranioplasty
using polymethyl methacrylate protheses. J Clin
Neurosci 16:56-63, 2009.
15. Matsuno A, Tanaka H, Iwamuro H, Takanashi S,
Miyawaki S, Nakashima M, Nakaguchi H,
Nagashima T: Analyses of the factors influencing
bone graft infection after delayed cranioplasty.
Acta Neurochir (Wien) 48:535-540, 2006.
16. Moreira-Gonzalez A, Jackson IT, Miyawaki T,
Barakat K, DiNick V: Clinical outcome in cranioplasty: critical review in long-term follow-up.
J Craniofac Surg 14:144-153, 2005.
18. Penel N, Lefebre D, Fournier C, Sarini J, Kara A,
Lefebvre JL: Risk factors for wound infection in
head and neck cancer: a prospective study. Head
Neck 23:447-455, 2001.
19. Smith E, Carter B, Ogilvy C: Proposed use of
prophylactic decompressive craniectomy in poorgrade aneurysmal subarachnoid hemorrhage
patients presenting with associated large sylvian
hematomas. Neurosurgery 51:117-124, 2002.
20. Stephens FL, Mossop C, Bell R, Tigno T,
Rosner M, Kumar A, Moores L, Armonda R:
Cranioplasty complications following wartime
decompressive craniectomy. J Neurosurg Focus
28:E3, 2010.
21. Stiver SI, Wintermark M, Manley GT: Reversible
monoparesis following decompressive hemicraniectomy for traumatic brain injury. J Neurosurg
109:245-254, 2009.
22. Vahedi K, Vicaut E, Mateo J, Kurtz A, Orabi M,
Guichard JP, Boutron C, Couvreur G, Rouanet F,
Touze E, Guillon B, Carpentier A, Yelnik A,
George B, Payen D, Bousser MG: Sequentialdesign multicenter randomized, controlled trial of
early decompressive craniectomy in malignant
middle cerebral artery infarction (DECIMAL Trial).
Stroke 38:2506-2517, 2007.
23. Weiner G, Lacey M, Mackenzie L, Shah D,
Frangos S, Grady MS, Kofke A, Levine J,
Schuster J, Le Roux PD: Decompressive craniectomy for elevated intracranial pressure and its
effect on cumulative ischemic burden and therapeutic intensity levels after severe traumatic brain
injury. Neurosurgery 66:1111-1118, 2010.
24. Yadla S, Campbell P, Chitale R, Maltenfort M,
Jabbour P, Sharan A: Effect of early surgery,
material and method of flap preservation on cranioplasty infections: a systematic review. Neurosurgery 68:1124-1129, 2011.
Conflict of interest statement: The authors declare that the
article content was composed in the absence of any
commercial or financial relationships that could be construed
as a potential conflict of interest.
Received 27 December 2012; accepted 9 August 2013
Citation: World Neurosurg. (2014).
http://dx.doi.org/10.1016/j.wneu.2013.08.005
Journal homepage: www.WORLDNEUROSURGERY.org
17. Osawa M, Hara H, Ichinose Y, Koyama T,
Kobayashi S: Sugita Y: Cranioplasty with a frozen
and autoclaved bone flap. Acta Neurochir (Wien)
1-2:38-41, 1990.
Available online: www.sciencedirect.com
1878-8750/$ - see front matter ª 2014 Elsevier Inc.
All rights reserved.
WORLD NEUROSURGERY, http://dx.doi.org/10.1016/j.wneu.2013.08.005