Keywords
decompressive craniectomy - cranioplasty - bone flap preservation - abdominal wall
complications - in vivo bone storage
Introduction
Decompressive craniectomy (DC) is a neurosurgical intervention made specifically to
relieve intracranial pressure in patients who suffer from conditions such as severe
traumatic brain injury (TBI), malignant middle cerebral artery infarction, and aneurysmal
subarachnoid hemorrhage.[1]
[2] DC allows expansion, and the pressure–volume curve shifts to the right after bone
removal.[1]
[3]
[4] Bleeding, new or expanded contusion, extracerebral herniation, fever, wound infection,
subdural hygroma, infarction, and hydrocephalus are all common neurosurgical complications
during and after a DC,[1]
[2]
[3] whereas trephine syndrome and bone resorption are relatively late complications.[1]
[5]
[6] After DC, the excised bone flap can be banked for subsequent reimplantation in the
form of cranioplasty; this procedure is usually performed for the protection of the
brain, hydrodynamic equilibrium, and cosmesis.[4]
[7]
[8] Though post-DC complications are under intense research, associated abdominal wall
complications are relatively less discussed. In this article, we intend to discuss
the abdominal wall complications associated with DC in this study.
Following bone flap removal, it can be stored in vivo in the subcutaneous plane of
the anterior abdominal wall or anterior thigh. Even though it needs an additional
procedure, the self-proclaimed justification for in vivo bone flap preservation in
the abdominal subcutaneous plane includes that the modality of autologous bone flap
storage is cost-effective, with no requirements for additional machinery or personnel,
which would be challenging in a high-volume center.[4]
[9] There are few studies suggesting postcranioplasty bone resorption in patients who
had their bone cryopreserved.[5]
[9]
[10]
Even though cryopreservation is being practiced more often lately, abdominal subcutaneous
preservation is still a cost-effective and accessible method, but not without its
complications, especially in high-volume or resource-poor settings. This study evaluates
the complications of the abdominal wall after the subcutaneous preservation of the
bone flaps compared with those that present concerning cryopreservation and other
in vivo methods.
Aim of the Study
This study aims to investigate the abdominal wall complications following DC with
subcutaneous bone flap preservation and to review the associated literature.
Review of Literature
For centuries, the notion of relieving intracranial pressure by surgical means was
known, but advances in neurosurgery, critical care, and neuroimaging paved the way
for the modern evolution of DC.[11]
[12] Though DC can be lifesaving, the long-term outcomes have been the subject of much
debate. Most surviving patients succumb to severe disabilities, raising ethical questions
regarding the quality of survival.[13] Current research emphasizes better patient selection criteria and improvement in
functional outcomes at the time of discharge.[14] Future developments in DC include the introduction of minimally invasive techniques,
better biomaterials for skull reconstruction, and improved neuroprotective strategies
that eliminate or reduce secondary brain injury after the procedure.
Preservation of the bone flap is important for maintaining the protective and esthetic
functions of the skull once the patient's neurological condition becomes stable and
intracranial pressure normalizes. Over the years, different techniques for bone flap
preservation have been developed and studied, each with its advantages, disadvantages,
and potential complications. Autologous bone flap preservation is still the major
option for cranioplasty due to its perceived biocompatibility and low cost.[15] Then, in the middle of the 20th century, more controlled procedures emerged for
the storage of the bone, including autologous storage and cryopreservation—whose techniques
have been perfected over time, with continuing research on the validity of effectiveness
in preventing infections, resorptions, and other complications.[4]
[9]
Today, several approaches to bone flap preservation are employed, each with unique
benefits and limitations. These techniques are broadly categorized into autologous
preservation methods and extracorporeal preservation methods.
Preservation of Autologous Bone Flap
Subcutaneous Pocket Preservation (Anterior Thigh or Abdominal)
In subcutaneous pocket preservation, the resected bone flap is placed in a subcutaneous
pocket, mainly in the abdominal wall. It has several benefits, including a reduced
chance of infection as the bone is kept in the patient's own body, and the external
contamination risk is reduced. Another benefit is biocompatibility; in most studies,
the bone stock retained its biological and structural characteristics after this storage,
significantly reducing the possibility of bone resorption upon reimplantation as there
is minimal destruction of viable osteoblasts. A study by Movassaghi et al showed that
the histology of retrieved bone at the time of cranioplasty showed portions of necrotic
bone interspersed with areas of new bone formation. Several studies demonstrate good
outcomes with abdominal preservation.[16] A very illustrative study by Schuss et al found less infection and bone flap resorption
with this method than with extracorporeal storage methods.[17] However, the abdominal preservation has some potential disadvantages, such as requiring
additional surgery to create the subcutaneous pocket, which increases the chance of
infection or other complications at the site. Some patients may experience pain or
discomfort at the storage site during recovery.
Subgaleal Preservation
In this largely obsolete technique, the bone flap is usually positioned under the
galea aponeurotica adjacent to the craniectomy incision over the opposite side of
the skull. Subgaleal storage is often argued as less invasive than abdominal storage.[18] Although no second incision is needed, it is risky compared with abdominal storage
because the bone flap is closer to the original surgical site and thus poses more
chances of infection and other wound complications. If the patient ends up having
wound complications, the clinical outcome will be worse, and it made this technique
largely obsolete.
Extracorporeal Bone Flap Preservation
Cryopreservation
Storage of bone flaps at −80°C in a deep-freeze environment is called cryopreservation
and maintains the structural integrity of the bone flap till reimplantation.[5]
[15] The procedure is widely practiced in many neurosurgical centers due to its availability
and efficiency. Key advantages include that the bone flaps can be stored for a long
time. This is of great value for patients who need a long recovery or rehabilitation
period before the cranioplasty since subcutaneously placed bone can have progressive
resorption.[19] And the bone flaps preserved by cryopreservation are available and useful for reimplantation
without further additional surgical sites, as in the case of autologous methods. It
eliminates the need for additional surgery at the time of DC and also cranioplasty.
Though rare, when the abdominal wound is opened first to check the condition of the
bone flap, cranioplasty may need to be postponed in case the bone flap happens to
be unhealthy and results in deferring the cranioplasty. Storage of an extracorporeal
flap can save such unwarranted events.
Despite these benefits, cryopreservation also carries the risk of a higher chance
of bone flap resorption after reimplantation. There is evidence that postcranioplasty
bone resorption is higher compared with autologous storage methods.[5]
[19] This results in bone fragility and poor cosmetic results after cranioplasty. In
addition, improper handling during storage and reimplantation can lead to contamination
and infection. In high-volume, low-resource settings, facilities and infrastructure
for cryopreservation and bone banks may not be available, and logistical errors can
happen.
Finally, alternatives to autologous bone flaps include polymethyl methacrylate, titanium
mesh, custom-made titanium molds, or porous polyethylene implants. They have many
advantages, such as minimizing the risk of infection and resorption, and they can
be custom-shaped with methods such as three-dimensional printing and other advanced
techniques for optimal results in cosmetics and protection. They do not, however,
offer biological integration as has been known with autologous bone flaps.
Complications and Outcomes
The most common complications associated with bone flap preservation techniques include
infection, resorption, and poor cosmetic results. However, they can occur after any
preservation technique, each carrying specific risk factors. Each has varied incidence
in various studies. A study by Corliss et al showed no significant difference in the
infection rate between in vivo-preserved and cryopreserved bone flaps.[4] Bone flap resorption is a significant problem with cryopreserved bone flaps, especially
when storage duration exceeds several months. This is due to the absence of nutritive
supply to the bone graft such as the in vivo preservation and progressive loss of
osteoblastic activity. Young age, longer duration, and fractures are other factors
that can increase bone flap resorption.[4]
[5]
[19] Cosmetic and functional outcomes have been relatively better for autologous storage
methods, especially abdominal preservation because they preserve much of the biological
characteristics of the bone tissue postcranioplasty.
Objectives
While complications associated with DC, such as hydrocephalus, wound infections, and
bone flap resorption, have been extensively studied, there remains a relative paucity
of literature addressing abdominal wall complications arising from in vivo preservation
of bone flaps in the subcutaneous plane. In our study, we aim to evaluate and analyze
abdominal wall complications following the preservation of bone flaps in the abdominal
subcutaneous tissue after DC. This study seeks to shed light on this underexplored
area, contributing to a better understanding of the associated risks and outcomes.
Our main focus for this research was to assess complications following DC and bone
flap preservation in the abdominal wall.
Materials and Methods
This study was conducted in the Department of Neurosurgery, Government Medical College.
We studied 92 patients who underwent DC, followed by cranioplasty with the preservation
of a bone flap in the abdomen after receiving clearance from the Institutional Review
Board and Institutional Ethics Committee. We conducted a record-based retrospective
study for 2 years in the Department of Neurosurgery, Government Medical College, Thrissur,
from 2022 through 2024.
Data Collection Method and Tools
Data Collection Method and Tools
Data were collected from department records and operative registers in the Department
of Neurosurgery, Government Medical College, and with phone interviews if details
were insufficient in records. We collected variables such as age, sex, indication
for DC, postoperative Glasgow coma scale, side of the surgery, difficulty while squatting,
breathing difficulty, heaviness, local pain, psychological problems, wound infection
in the abdomen, hematoma, and cosmetic concerns in our study. This is a record-based
study; hence, permission was taken from the head of the department and hospital authorities
to use details available in the medical records. If the details were not fully available
in the available clinical records, details were sought through a phone call, and in
such cases, verbal consent was obtained.
Data Analysis
The collected data were inputted on the proforma and later consolidated into the master
chart. The results were analyzed using SPSS 22.0. The charted quantitative data and
qualitative data were analyzed by descriptive statistics.
Results
During the study period, 92 patients underwent cranioplasty in our department. The
mean age of the study population was 44.5 years, with 76% of them being males. TBI
was the most common primary pathology for DC (85%), followed by infarct and intraparenchymal
hematoma. The mean interval of the cranioplasty period was 3 months ([Table 1]).
Table 1
Patient characteristics and primary pathology
|
Demographic details
|
|
Mean age (range)
|
44.5 (18–72)
|
|
Sex: male, n (%)
|
70 (76)
|
|
Primary pathology, n (%)
|
|
Trauma
|
78 (85)
|
|
Infarct
|
8 (9)
|
|
Intraparenchymal hematoma
|
4 (4)
|
|
Timing of cranioplasty, n (%)
|
|
Mean
|
5.5 mo
|
|
< 6 wk
|
1 (1)
|
|
6 wk–3 mo
|
18 (20)
|
|
3–6 mo
|
53 (58)
|
|
> 6 mo
|
20 (21)
|
Complications Associated with Abdominal Flap
The data were selected using record reviews and phone interviews with patients awaiting
cranioplasty surgery following DC. Eighteen patients had wound site pain in the immediate
postoperative period; 9 patients had wound infections in the abdominal flap site out
of which 2 bone flaps were removed and were planned for cranioplasty with exogenous
implant at a later date; 19 patients had abdominal wall heaviness at the wound site;
20 patients had cosmetic concerns regarding flap site incision; and 19 patients had
some psychological issues. Other complications are depicted in [Table 2].
Table 2
Complications associated with abdominal flap, n (%)
|
Pain
|
18 (19.5%)
|
|
Difficulty in squatting
|
19 (20%)
|
|
Breathing difficulty
|
2 (2%)
|
|
Abdominal wall heaviness
|
18 (19.5%)
|
|
Wound infection
|
9 (10%)
|
|
Psychological concerns
|
22 (24%)
|
|
Cosmetic concerns
|
20 (21.7%)
|
|
Wound hematoma
|
3 (3%)
|
Discussion
The removed bone flap after DC is stored in the subcutaneous plane in the anterior
abdomen or the thigh, or extracorporeally in the bone biobank. Even though there is
a tendency to shift to cryopreservation in recent literature, autologous preservation
still has advantages such as biocompatibility, low cost, a perfect match in terms
of fit and curvature, and immunological tolerance.[20]
[21]
[22]
[23]
[24] Even though many studies are comparing different storage techniques on the outcome
of cranioplasty in terms of infections, bone flap resorption, etc., there is a relative
paucity of literature studying abdominal wall complications following bone flap preservation.
In our study, we tried to address this lacuna. In our study group, there were no significant
complications except for wound infection in the abdominal site in nine patients. Of
which seven patients were treated conservatively. In two patients, the infected bone
flap had to be removed, and the wound was closed with a drain. The other complications
such as pain are treated successfully with conservative measures. Psychological and
cosmetic concerns were managed with counseling and reassurance.
Conclusion
As there were no significant complications following abdominal flap preservation and
comparable safety with cryopreservation, it remains a valid choice in high-volume
and resource-constrained settings due to its low cost and comparable efficacy. Additional
logistical errors and the cost of biobanks for bone preservation can also be avoided.
Even so, the need for an additional procedure and surgical site should be discussed
with patients and relatives, and options for biobanking should be offered if available.
We need further studies to evaluate the complications and outcomes of in vivo preservation
in a larger population. The bone flap resorption and new bone formation are to be
studied in subcutaneously preserved bone flaps.
