Cranioplasty in Oman: Retrospective review of cases from the National Craniofacial Center 2012-2022

Objectives

Cranioplasty is a complex craniofacial and neurosurgical procedure that aims to reinstate the architecture of the cranial vault and elevate both its aesthetic and neurological function. Several reconstructive materials have been thoroughly explored in the search for the optimal solution for cranioplasty. This study aimed to evaluate different material used for cranial reconstruction in Oman.

Methods

This retrospective study included all patients who had had cranioplasty procedures performed at Khoula Hospital, Muscat, Oman, from 2012 to 2022. Demographic information, the characteristics of the cranial defect and any complications that occurred post-operatively were analysed.

Results

A total of 47 patients were included in this study. The most common cause of cranial defects was craniectomy following traumatic head injury (70.2%) along with excision of fibrous dysplasia (10.6%). The most frequently utilised material for cranial repair was autologous bone grafts (n = 28), followed by polyetheretherketone (PEEK; n = 14). Interestingly, the replacement of bone grafts from previous craniectomy showed a notably high resorption rate (71.4%), in contrast to split calvarial grafts (0%) and other types of bone grafts (14.3%). Additionally, delayed graft infection was observed in 3.6% of the bone graft group and 7.1% of the PEEK group.

Conclusion

Patient-specific alloplastic implants such as PEEK have gained popularity for large and complex cranioplasty, as they provide excellent aesthetic outcomes and leave no donor site morbidity. In contrast, bone grafts remain the gold standard for small to medium-sized cranial defects.

Subcutaneous preservation versus cryopreservation of autologous bone grafts for cranioplasty: A systematic review and meta-analysis

BACKGROUND

Cranioplasty corrects cranial bone defects using various bone substitutes or autologous bone flaps created during a previous craniectomy surgery. These autologous bone flaps can be preserved through subcutaneous preservation (SP) or cryopreservation (CP).

AIM

We aim to compare outcomes and complications for both SP and CP techniques to enhance the current evidence about autologous bone flap preservation.

METHODS

Five electronic databases were searched to collect all relevant studies. Records were screened for eligibility. Data were extracted from the included studies independently. We categorized surgical site infection (SSI) as either due to Traumatic brain injury (TBI) or not to reveal potential variations in SSI incidence. The double-arm meta-analysis utilized risk ratios (RR) and mean differences (MD) with corresponding confidence intervals (CI) to pool categorical and continuous outcomes, respectively. Proportions with their respective 95% CIs were pooled for single-arm meta-analyses to determine outcomes related to SP technique.

RESULTS

Seventeen studies involving 1169 patients were analyzed. No significant difference in SSI rates was observed between SP and CP methods in patients with or without TBI. SP was linked to shorter hospital stays in two studies (194 patients). Single-arm analysis showed a 17% revision surgery rate across five studies (375 patients) and infection rates in 17 studies for SP. New bone formation occurred in 13.2% of patients, with 19.9% showing resorption.

CONCLUSION

SP and CP methods showed similar SSI rates post-craniectomy in TBI and non-TBI patients. SP was associated with reduced hospitalization time, low infection rates, and a moderate need for revision surgery.

Comparison of Infection Rates Following Immediate and Delayed Cranioplasty for Postcraniotomy Surgical Site Infections: Results of a Meta-Analysis

Postoperative surgical site infections (SSIs) in neurosurgery are rare. However, they pose a formidable challenge to the treating neurosurgeon and substantially worsen patient outcomes. These infections require prompt intervention in the form of débridement, including removal of craniotomy bone. Reconstruction of the craniotomy defect can be performed along with the débridement or can be performed at a later time. Although there have been concerns about performing cranioplasty at the same time as débridement, recent studies have advocated performance of cranioplasty at the same time as the débridement, as it avoids the morbidity associated with having a craniectomy defect and avoids the need for another surgical procedure. We conducted a literature review and meta-analysis to examine the data on immediate cranioplasties and delayed cranioplasties performed for postcraniotomy SSIs. We analyzed 15 articles with a total of 353 patients. Our analysis revealed that the pooled proportion of treatment failure was 10.4% (95% confidence interval [CI] 5.9%-17.8%) when an immediate cranioplasty was done and 16.1% (95% CI 7.2%-32.1%) when delayed cranioplasty was done. The pooled proportion of treatment failure was 12% (95% CI 5.9%-22.9%) when the same bone was used for cranioplasty and was 8% (95% CI 3%-20%) when prosthetic material such as titanium was used for cranial vault reconstruction. Thus, the rate of treatment failure was less when an immediate single-stage cranioplasty was done compared with a delayed cranioplasty following SSIs.

Skull Reconstruction Using a Custom-Made, Three-Dimensional-Printed, Hydroxyapatite-Titanium Cranioplasty Implant: Largest Single-Center U.S. Experience

OBJECTIVE

Although several material options, both natural and synthetic, are available for cranioplasty, the rate of implant-related complications has remained high. A relatively novel, synthetic hydroxyapatite-titanium implant, which combines biocompatibility with biomechanical resilience, has been reported to reduce tissue inflammation, infection, and explantation rates, while delivering superior cosmetic results. However, despite such promising preliminary reports, clinical data supporting its use have remained scarce.

METHODS

All the patients who had undergone cranioplasty between 2019 and 2022 using this implant were identified from a prospectively maintained database. Medical records were retrospectively reviewed and the following variables recorded: demographic data, clinical data, radiologic findings, operative details, complications (implant-related and unrelated), and outcomes.

RESULTS

A total of 18 patients (12 men and 6 women), with a mean age of 39 years (range, 20-70 years), were identified. The indications for craniectomy were traumatic brain injury (n = 13; 72.2%), hemorrhagic stroke (n = 3; 16.7%), and ischemic stroke (n = 2; 11.1%). The median time to cranioplasty was 140 days (range, 51-1717 days). The median modified Rankin scale score before cranioplasty was 4 (range, 0-5). Cranioplasty was technically successful in all 18 patients. Minor postoperative complications, none related to the implant, were managed conservatively in 3 patients (16.6%), including a small intraparenchymal hematoma in 1, an extra-axial hematoma in 1, and a seizure in 1. Of these 3 patients, 1 (5.6%) died 1 week later of a suspected pulmonary embolism. No implant-related complications occurred after a median follow-up of 6 months (range, 1-38 months). All 17 survivors exhibited some degree of neurologic improvement. The cosmetic result was good or excellent for all patients.

CONCLUSIONS

Our experience, the largest in the United States, confirms the previously reported benefits associated with the use of 3-dimensional-printed hydroxyapatite-titanium cranioplasty implants.

Evidence of linear bone flap resorption in patients undergoing autologous cranioplasty following decompressive craniectomy: A 3D Slicer segmented analysis of serial CT images

OBJECTIVES

Autologous cranioplasty (CP) following decompressive craniectomy (DC) carries risk of bone flap resorption (BFR). The current literature offers limited information regarding the natural progression of BFR, and the rate at which it occurs. We aim to characterize the progression of BFR over time and elucidate risk factors for accelerated BFR.

METHODS

A retrospective analysis was conducted on patients who underwent DC and autologous CP. Serial computed tomography (CT) images were used to quantify degree of BFR over time. Risk factors included age, diabetes, smoking status, flap fragmentation, defect size, and DC-CP time interval. Chi-square analyses and Student's t-tests were performed to examine differences between patients who experienced BFR and those who did not.

RESULTS

Overall, 82% of patients demonstrated evidence of clinically relevant resorption on CT. On average, the bone flap decreased in volume by 36.7% within the first year, with a linear loss in volume after multiple years of follow-up. Individuals who developed greater BFR were significantly younger (43 ± 17 vs. 56 ± 12, p=0.022), had a lower incidence of diabetes (5.9% vs. 43%, p=0.037), and had more bone flap fragments (1.4 ± 0.67 vs. 1.00 ± 0, p <0.001) than those who did not.

CONCLUSION

Resorption following CP with cryopreserved bone appears to progress in a fairly linear and continuous fashion over time. Using serial CT images, we found a resorption rate of 82% at our institution. We identified several possible risk factors for resorption, including flap fragmentation, younger age, and absence of diabetes.

Microbiological profile and infection potential of different cryopreserved skull flaps after decompressive hemicraniectomy. Is cryopreservation at - 80 ℃ better?

OBJECTIVE

Patterns of cryopreservation of explanted skull bone flaps have long been a matter of debate, in particular the appropriate temperature of storage. To the best of our knowledge no study to date has compared the microbiological profile and the infection potential of skull bone flaps cryostored at the same institution at disparate degrees for neurosurgical purposes. In the context of our clinical trial DRKS00023283, we performed a bacterial culture of explanted skull bone flaps, which were cryopreserved lege artis at a temperature of either - 23 °C or - 80 °C after a decompressive hemicraniectomy. In a further step, we contaminated the bone fragments in a s uspension with specific pathogens (S. aureus, S. epidermidis and C. acnes, Colony forming unit CFU 103/ml) over 24 h and conducted a second culture.

RESULTS

A total of 17 cryopreserved skull flaps (8: - 23 °C; 9: - 80 °C) explanted during decompressive hemicraniectomies performed between 2019 and 2020 as well as 2 computer-aided-designed skulls (1 vancomycin-soaked) were analyzed. Median duration of cryopreservation was 10.5 months (2-17 months). No microorganisms were detected at the normal bacterial culture. After active contamination of our skull flaps, all samples showed similar bacterial growth of above-mentioned pathogens; thus, our study did not reveal an influence of the storage temperature upon infectious dynamic of the skulls.

Decompressive hemicraniectomy and cranioplasty using subcutaneously preserved autologous bone flaps versus synthetic implants: perioperative outcomes and cost analysis

OBJECTIVE

It has not been well-elucidated whether there are advantages to preserving bone flaps in abdominal subcutaneous (SQ) tissue after decompressive hemicraniectomy (DHC), compared to discarding bone flaps. The authors aimed to compare perioperative outcomes and costs for patients undergoing autologous cranioplasty (AC) after DHC with the bone flap preserved in abdominal SQ tissue, and for patients undergoing synthetic cranioplasty (SC).

METHODS

A retrospective review was performed of all patients undergoing DHC procedures between January 2017 and July 2021 at two tertiary care institutions. Patients were divided into two groups: those with flaps preserved in SQ tissue (SQ group), and those with the flap discarded (discarded group). Additional analysis was performed between patients undergoing AC versus SC. Primary end points included postoperative and surgical site complications. Secondary endpoints included operative costs, length of stay, and blood loss.

RESULTS

A total of 248 patients who underwent DHC were included in the study, with 155 patients (62.5%) in the SQ group and 93 (37.5%) in the discarded group. Patients in the discarded group were more likely to have a diagnosis of severe TBI (57.0%), while the most prevalent diagnosis in the SQ group was malignant stroke (35.5%, p < 0.05). There were 8 (5.2%) abdominal surgical site infections and 9 (5.8%) abdominal hematomas. The AC group had a significantly higher reoperation rate (23.2% vs 12.9%, p = 0.046), with 11% attributable to abdominal reoperations. The average cost of a reoperation for an abdominal complication was $40,408.75 ± $2273. When comparing the AC group to the SC group after cranioplasty, there were no significant differences in complications or surgical site infections. There were 6 cases of significant bone resorption requiring cement supplementation or discarding of the bone flap. Increased mean operative charges were found for the SC group compared to the AC group ($72,362 vs $59,726, p < 0.001).

CONCLUSIONS

Autologous bone flaps may offer a cost-effective option compared to synthetic flaps. However, when preserved in abdominal SQ tissue, they pose the risk of resorption over time as well as abdominal surgical site complications with increased reoperation rates. Further studies and methodologies such as cryopreservation of the bone flap may be beneficial to reduce costs and eliminate complications associated with abdominal SQ storage.

Guidelines in Practice: Autologous Tissue Management

During a surgical procedure, the surgeon may remove tissue to be preserved and stored for replantation or autotransplantation on or in the same individual during a subsequent procedure. The AORN "Guideline for autologous tissue management" provides guidance to perioperative personnel for preserving and handling autologous tissue (eg, cranial bone flaps, parathyroid tissue, skin, vessels) that will be replanted or autotransplanted in the same facility in which the tissue was surgically removed. This article discusses guideline recommendations on packaging, labeling, storing, and disposing of autologous tissue. A scenario describes how an interdisciplinary team uses the AORN guideline and Guideline Essentials to identify recommendations and tools to incorporate into their policy and procedures after their facility receives a citation during a regulatory site visit. Perioperative RNs should review the entire guideline for additional information when creating and updating policies and procedures on autologous tissue management.

AK, Faujdar DS. Bony Union and Flap Resorption in Cranioplasty with Autologous Subcutaneous Pocket Preserved Bone Flap: Early Report on an Ambidirectional CT Scan-Based Study

Introduction Absence of sufficient number of prospective randomized controlled studies and comparatively small sample size and short follow-up period of most of the studies, available so far, have left ambiguity and lack of standardization of different aspects of cranioplasty.

Materials and Methods This is an early report of a computed tomography scan image-based ambidirectional study on cranioplasties performed with autologous subcutaneous pocket preserved bone flaps. Retrospective arm compared bony union and factors influencing it between cranioplasties and craniotomies. Patients with poor bony union and aseptic resorption were followed up in the prospective arm.

Results Retrospective arm of the study, followed up for five years (mean 32.2 months), comprised 42 patients as cases (Group 1) and 29 as controls (Group 2). Twenty-seven individuals (64.3%) in Group 1 had good bony union, as compared with 20 (68.9%) good unions in Group 2 out of the 29 patients. Four patients (9.5%) in Group 1 showed evidence of flap resorption, a finding absent in any patient in Group 2. Age, sex, smoking habits, superficial skin infection, and method of fixation did not appear to have any implication on bony union. Craniotomies done using Gigli saws fared better as compared with those done with pneumatic saw with lesser flap size–craniectomy size discrepancy, though it was not statistically significant. Fifteen patients have been included in the Prospective arm at the time of submission of this article.

Conclusion Ours is a study with a small sample size, unable to put its weight on any side, but can surely add some more data to help the Neurosurgeons in choosing the best for their patients.

Nerve allograft histology after banking following complicated reconstruction

Burial of nerve allografts in muscle tissue for later use is a novel technique with no prior literature discussions. This may be a safe and effective technique for short-term preservation of nerve allograft removed from a prior reconstruction.

The storage of skull bone flaps for autologous cranioplasty: literature review

The use of autologous bone flap for cranioplasty after decompressive craniectomy is a widely used strategy that allows alleviating health expenses. When the patient has recovered from the primary insult, the cranioplasty restores protection and cosmesis, recovering fluid dynamics and improving neurological status. During this time, the bone flap must be stored, but there is a lack of standardization of tissue banking practices for this aim. In this work, we have reviewed the literature on tissue processing and storage practices. Most of the published articles are focused from a strictly clinical and surgical point of view, paying less attention to issues related to tissue manipulation. When bone resorption is avoided and the risk of infection is controlled, the autograft represents the most efficient choice, with the lowest risk of complication. Otherwise, depending on the degree of involvement, the patient may have to undergo new surgery, assuming further risks and higher healthcare costs. Therefore, tissue banks must implement protocols to provide products with the highest possible clinical effectiveness, without compromising safety. With a centralised management of tissue banking practices there may be a more uniform approach, thus facilitating the standardization of procedures and guidelines.

Cranioplasty: A Comprehensive Review of the History, Materials, Surgical Aspects, and Complications

Cranioplasty is a common neurosurgical procedure performed to reconstruct cranial defects. The materials used to replace bone defects have evolved throughout history. Cranioplasty materials can be broadly divided into biological and synthetic materials. Biological materials can be further subdivided into autologous grafts, allografts, and xenografts. Allografts (bony materials and cartilage from cadavers) and xenografts (bony materials from animals) are out of favor for use in cranioplasty because of their high rates of infection, resorption, and rejection. In autologous cranioplasty, either the cranial bone itself or bones from other parts of the body of the patient are used. Synthetic bone grafts have reduced the operation time and led to better cosmetic results because of the advancement of computer-based customization and three-dimensional printing. Aluminum was the first synthetic bone graft material used, but it was found to irritate neural tissue, induce seizures, and dissolve over time. Acrylic, in the form of methyl methacrylate, is the most widely used material in cranioplasty. Hydroxyapatite is a natural component of bone and is believed to enhance bone repair, resulting in decreased tissue reactions and promoting good osteointegration. Polyetheretherketones are light and nonconductive and do not interfere with imaging modalities. The complication rates of cranioplasty are high, and surgical site infection is the most common complication. The effect of cranioplasty timing on cognitive function remains debatable. However, the timing of cranioplasty is independent of neurologic outcomes. In this article, the history, materials, complications, and evolution of current practices used in cranioplasty are comprehensively reviewed.

Subcutaneous priming of protein-functionalized chitosan scaffolds improves function following spinal cord injury

Strategies using neural stem cells (NSCs) to aid regeneration following spinal cord injury (SCI) show much promise, but challenges remain regarding implementation and efficacy. In this work, we explored the use of an NSC-seeded scaffold consisting of covalently immobilized interferon-γ and rat NSCs within a hydrogel matrix (methacrylamide chitosan). We placed the scaffolds within the subcutaneous environment of rats, allowing them to incubate for 4 weeks in order to prime them for regeneration prior to being transplanted into a right lateral hemisection SCI model in the same animal. We found that subcutaneous priming reduced the lineage commitment of encapsulated NSCs, as observed by increased nestin expression and decreased NeuN expression. When combined with intracellular σ peptide administration (which reduces inhibition from the glial scar), subcutaneous maturation improved functional outcomes, which were assessed by BBB score and quantitative gait parameters (fore and hind limb duty factor imbalance, right and left paw placement accuracy). Although we did not observe any direct reconnection of the transplanted cells with the host tissue, we did observe neurofilament fibers extending from the host tissue into the scaffold. Importantly, the mechanism for improved functional outcomes is likely an increase in trophic support from subcutaneously maturing the scaffold, which is enhanced by the administration of ISP.

Subcutaneous bone flap storage after emergency craniectomy: cost-effectiveness and rate of resorption

OBJECTIVEDecompressive craniectomy is used for uncontrolled intracranial pressure in traumatic brain injury and malignant hemispheric stroke. Subcutaneous preservation of the autologous bone flap in the abdomen is a simple, portable technique but has largely been abandoned due to perceived concerns of resorption. The authors sought to characterize their experience with subcutaneous preservation of the bone flap and cranioplasty.METHODSThe authors performed a retrospective single-institution review of subcutaneous preservation of the autologous bone flap after decompressive craniectomy from 2005 to 2015. The primary outcome was clinically significant bone resorption, defined as requiring a complete mesh implant at the time of cranioplasty, or delayed revision. The outcome also combined cases with any minor bone resorption to determine predictors of this outcome. Logistic regression modeling was used to determine the risk factors for predicting resorption. A cost comparison analysis was also used via the 2-sided t-test to compare the cost of cranioplasty using an autologous bone flap with standard custom implant costs.RESULTSA total of 193 patients with craniectomy were identified, 108 of whom received a cranioplasty. The mean time to cranioplasty was 104.31 days. Severe resorption occurred in 10 cases (9.26%): 4 were clinically significant (2 early and 2 late) and 6 demonstrated type II (severe) necrosis on CT, but did not require revision. Early resorption of any kind (mild or severe) occurred in 28 (25.93%) of 108 cases. Of the 108 patients, 26 (24.07%) required supplemental cranioplasty material. Late resorption of any kind (mild or severe) occurred in 6 (5.88%) of 102 cases. Of these, a clinically noticeable but nonoperative deformity was noted in 4 (3.92%) and minor (type I) necrosis on CT in 37 (37%) of 100. Bivariate analysis identified fragmentation of bone (OR 3.90, 95% CI 1.03-14.8), shunt-dependent hydrocephalus (OR 7.97, 95% CI 1.57-40.46), and presence of post-cranioplasty drain (OR 9.39, 95% CI 1.14-1000) to be significant risk factors for bone resorption. A binary logistic regression optimized using Fisher's scoring determined the optimal multivariable combination of factors. Fragmentation of bone (OR 5.84, 95% CI 1.38-28.78), diabetes (OR 7.61, 95% CI 1.37-44.56), and shunt-dependent hydrocephalus (OR 9.35, 95% CI 1.64-56.21) were found to be most predictive of resorption, with a C value of 0.78. Infections occurred in the subcutaneous pocket in 5 (2.60%) of the 193 cases and after cranioplasty in 10 (9.26%) of the 108 who underwent cranioplasty. The average cost of cranioplasty with autologous bone was $2156.28 ± $1144.60 (n = 15), and of a custom implant was $35,118.60 ± $2067.51 (3 different sizes; p < 0.0001).CONCLUSIONSCraniectomy with autologous bone cranioplasty using subcutaneous pocket storage is safe and compares favorably to cryopreservation in terms of resorption and favorably to a custom synthetic implant in terms of cost. While randomized data are required to definitively prove the superiority of one method, subcutaneous preservation has enough practical advantages with low risk to warrant routine use for most patients.

Predictors of Surgical Site Infection in Autologous Cranioplasty: A Retrospective Analysis of Subcutaneously Preserved Bone Flaps in Abdominal Pockets

BACKGROUND

Decompressive craniectomy (DC) is a surgical procedure performed to manage intracranial hypertension. Once performed, patients are obligated to undergo another surgical procedure known as cranioplasty to reconstruct the cranial defect. Cranioplasty still has one of the highest rates of infection. The factors contributing to the high rate of surgical site infection (SSI) after cranioplasty are not well established. This study aims to estimate the incidence of SSI and determine its possible risk factors for patients who underwent cranioplasty using bone flaps subcutaneously preserved in abdominal pockets.

METHODS

A retrospective cohort study was conducted to investigate the predictors of infection among patients who underwent cranioplasty from subcutaneously preserved bone flaps in abdominal pockets between January 2005 and December 2018 at a level l trauma center.

RESULTS

A total of 103 cases of cranioplasty from subcutaneously preserved bone flaps were included in the study. The mean age of the patients was 31.2 ± 14.8 years (range, 5-67 years). The median interval between DC and cranioplasty was 115 days. The most frequent indication for DC was traumatic brain injury (76.4%). The incidence of SSI was noted in 15.7% of patients. The most significant predictors of infection in patients requiring cranioplasty were blood glucose levels and skull defect size (P = 0.03 and P = 0.02, respectively).

CONCLUSIONS

Blood glucose levels and skull defect size were the only identifiable risk factors associated with SSI. Storing bone flaps in subcutaneous abdominal pockets is cost-efficient but carries considerable risk of infection.

Cranioplasty in Infants Less Than 24 Months of Age: A Retrospective Case Review of Pitfalls, Outcomes, and Complications

BACKGROUND

Management of pediatric skull defects after decompressive craniectomy (DC) poses unique problems, particularly in children younger than 24 months. These problems include complications such as resorption and infection as well as difficulties with plagiocephaly and reconstruction. The goal of this study was to evaluate bone resorption complications after cranioplasty in patients <24 months.

METHODS

A single-center retrospective case study was performed of all patients younger than 24 months who underwent cranioplasty after DC between 2011 and 2018. The following variables were assessed: injury cause, age at craniotomy, time to cranioplasty, craniectomy size, mode of fixation, drain use, shunt use, subdural fluid collection, resorption, need for synthetic graft revision, and plagiocephaly.

RESULTS

A total of 10 patients were identified who met inclusion criteria; 3 patients were excluded for insufficient follow-up. Ages ranged from <1 day to 19 months, with a mean of 10.7 months. Overall rate of cranioplasty resorption was 85.7%, 57.1% of which required revision with synthetic graft. There were univariate trends toward more frequent implant resorption with subdural fluid collection (P = 0.1071) and without shunt placement (P = 0.1429). These effects persisted through multivariable analysis and even reached statistical significance in the case of subdural collection when controlling for operative and demographic characteristics (P = 0.01138, P = 0.0694). In addition, univariate analysis showed a trend toward more frequent neurologic complications with greater craniotomy-to-cranioplasty intervals (P = 0.1043), which reached significance on multivariable analysis (P = 0.00518).

CONCLUSIONS

In patients younger than 24 months undergoing cranioplasty subdural collection, a lack of shunt placement and increased time to cranioplasty were associated with increased rates of resorption.

Bone resorption in autologous cryopreserved cranioplasty: quantitative evaluation, semiquantitative score and clinical significance

BACKGROUND

Changes after reimplantation of the autologous bone have been largely described. However, the rate and the extent of resorption in cranial grafts have not been clearly defined. Aim of our study is to evaluate the bone flap resorption (BFR) after cryopreservation.

METHODS

We retrospectively reviewed 27 patients, aged 18 years or older, subjected to cranioplasty (CP) adopting autologous cryopreserved flap. The BFR was derived from the percentage of decrease in flap volume (BFR%), comparing the first post-operative computed tomography (CT) and the last one available (performed at least 1 year after surgery). We also proposed a semiquantitative scoring system, based on CT, to define a clinically workable BFR classification.

RESULTS

After a mean ± SE follow-up of 32.5 ± 2.4 months, the bone flap volume decreased significantly (p < 0.0001). The mean BFR% was 31.7 ± 3.8% and correlated with CT-score (p < 0.001). Three BFR classes were described: mild (14.8% of cases) consisting in minimal bone remodelling, CT-score ≤ 6, mean BFR% = 3.5 ± 0.7%; moderate (51.9% of cases) corresponding to satisfactory cerebral protection, CT-score < 13, mean BFR% = 25.6 ± 2.2%; severe (33.3% of cases) consisting in loss of cerebral protection, CT-score ≥ 13, mean BFR% = 54.2 ± 3.9%. Females had higher BFR% than males (p = 0.022). BFR classes and new reconstructive surgery were not related (p = 0.58).

CONCLUSIONS

BFR was moderate or severe in 85.2% of re-implanted cryopreserved flaps. The proposed CT-score is an easy and reproducible tool to define resorption extent.

Subcutaneous Maturation of Neural Stem Cell-Loaded Hydrogels Forms Region-Specific Neuroepithelium

A combinatorial approach integrating stem cells and capable of exploiting available cues is likely needed to regenerate lost neural tissues and ultimately restore neurologic functions. This study investigates the effects of the subcutaneous maturation of adult-derived neural stem cell (aNSCs) seeded into biomaterial constructs on aNSC differentiation and ultimate regional neuronal identity as a first step toward a future spinal cord injury treatment. To achieve this, we encapsulated rat aNSCs in chitosan-based hydrogels functionalized with immobilized azide-tagged interferon-γ inside a chitosan conduit. Then, we implanted these constructs in the subcutaneous tissues in the backs of rats in the cervical, thoracic, and lumbar regions for 4, 6, and 8 weeks. After harvesting the scaffolds, we analyzed cell differentiation qualitatively using immunohistochemical analysis and quantitatively using RT-qPCR. Results revealed that the hydrogels supported aNSC survival and differentiation up to 4 weeks in the subcutaneous environment as marked by the expression of several neurogenesis markers. Most interesting, the aNSCs expressed region-specific Hox genes corresponding to their region of implantation. This study lays the groundwork for further translational work to recapitulate the potentially undiscovered patterning cues in the subcutaneous tissue and provide support for the conceptual premise that our bioengineering approach can form caudalized region-specific neuroepithelium.

Cranial autologous bone flap resorption after a cranioplasty: A case report

BACKGROUND

Craniectomies and cranioplasty are common neurosurgical procedures performed after brain trauma, ischemia, tumor resection, or infection. Post-cranioplasty autologous bone flap resorption may occur in patients after delayed cranial reconstruction. The occurrence is usually low when bone flaps are stored in subcutaneous abdominal tissue. We report a unique case of post-cranioplasty cranial bone flap.

CASE DESCRIPTION

We report a total autologous bone flap resorption in a 28-year-old man with a history of alcohol abuse. He was found unconscious in his bedroom with a head trauma of unknown mechanism. After an emergency room assessment, he was diagnosed with an acute subdural hematoma and underwent to emergency surgical drainage and a craniectomy. Three months later, a cranioplasty was performed and he exhibited exceptional outcomes. During a follow-up assessment, 7 months post-cranioplasty, total bone flap resorption was observed on computerized tomography image.

CONCLUSION

This case described an abnormal accelerated resorption of an autologous bone flap cranioplasty inserted after 3 months. Thus, to avoid bone flap resorption, an as early as possibly strategy may prevent this. Still, the exact mechanisms underlying bone resorption are poorly understood.

Bone Flap Resorption Following Cranioplasty with Autologous Bone: Quantitative Measurement of Bone Flap Resorption and Predictive Factors

Objective

To quantitatively measure the degree of bone flap resorption (BFR) following autologous bone cranioplasty and to investigate factors associated with BFR.

Methods

We retrospectively reviewed 29 patients who underwent decompressive craniectomy and subsequent autologous bone cranioplasty between April 2005 and October 2014. BFR was defined as: 1) decrement ratio ([the ratio of initial BF size/craniectomy size]-[the ratio of last BF/craniectomy size]) >0.1; and 2) bone flap thinning or geometrical irregularity of bone flap shape on computed tomographic scan or skull plain X-ray. The minimal interval between craniectomy and cranioplasty was one month and the minimal follow-up period was one year. Clinical factors were compared between the BFR and no-BFR groups.

Results

The time interval between craniectomy and cranioplasty was 175.7±258.2 days and the mean period of follow up was 1364±886.8 days. Among the 29 patients (mean age 48.1 years, male: female ratio 20: 9), BFR occurred in 8 patients (27.6%). In one patient, removal of the bone flap was carried out due to severe BFR. The overall rate of BFR was 0.10±0.11 over 3.7 years. Following univariate analysis, younger age (30.5±23.2 vs. 54.9±13.4) and longer follow-up period (2204.5±897.3 vs. 1044.1±655.1) were significantly associated with BFR (p=0.008 and 0.003, respectively).

Conclusion

The degree of BFR following autologous bone cranioplasty was 2.7%/year and was associated with younger age and longer follow-up period.

Cryostored autologous skull bone for cranioplasty? A study on cranial bone flaps' viability and microbial contamination after deep-frozen storage at -80°C

Craniectomy is a life-saving procedure. Subsequent cranioplasty with autologous skull bone has a bone resorption rate from 4% to 22.8% and an infection rate from 3.3% to 26%. There are concerns with their viability and the potential microbial contamination as they were explanted for a long period of time. Eighteen cranial bone flaps stored at Prince of Wales Hospital Skull Bone Bank during the period from June 2011 to March 2016 were identified. Ethics approval was obtained. Bone chips and deep bone swabs were collected for osteoblast culture and microbial culture. Skull Bone Bank was kept at -80°C under strict aseptic technique during the study period. The storage period ranged from 4months to 55months. For the osteoblast culture, all eighteen bone flaps had no viable osteoblast growth. For the bacterial culture, five had positive bacteria growth (27.8%). Three were Pasteurella multocida and two were Methicillin-resistant Staphylococcus aureus. The mean duration of storage of the infected bone flap was 32.9months (±15.1months) versus 19.9months (±17.9months) of those bone flaps with no bacterial growth (p=0.1716). The mean size of the infected versus non-infected bone flaps was 117.7cm² (±44.96cm²) versus 76.8cm² (±50.24cm²) respectively (p=0.1318). Although in this study statistical significance was not reached, it was postulated that infected bone flaps tended to be larger in size and had a longer duration of storage. In conclusion, cryostored skull bone flaps beyond four months showed no viable osteoblasts. Bacterial contamination rate of bone flaps was 27.8% in this study.

Functional investigation of bone implant viability using radiotracers in a new model of osteonecrosis

OBJECTIVES:

Conventional imaging methods are excellent for the morphological characterization of the consequences of osteonecrosis; however, only specialized techniques have been considered useful for obtaining functional information. To explore the affinity of radiotracers for severely devascularized bone, a new mouse model of isolated femur implanted in a subcutaneous abdominal pocket was devised. To maintain animal mobility and longevity, the femur was harvested from syngeneic donors. Two technetium-99m-labeled tracers targeting angiogenesis and bone matrix were selected.

METHODS:

Medronic acid and a homodimer peptide conjugated with RGDfK were radiolabeled with technetium-99m, and biodistribution was evaluated in Swiss mice. The grafted and control femurs were evaluated after 15, 30 and 60 days, including computed tomography (CT) and histological analysis.

RESULTS:

Radiolabeling achieved high (>95%) radiochemical purity. The biodistribution confirmed good blood clearance 1 hour after administration. For 99mTc-hydrazinonicotinic acid (HYNIC)-E-[c(RGDfK)2, remarkable renal excretion was observed compared to 99mTc-methylene diphosphonate (MDP), but the latter, as expected, revealed higher bone uptake. The results obtained in the control femur were equal at all time points. In the implanted femur, 99mTc-HYNIC-E-[c(RGDfK)2 uptake was highest after 15 days, consistent with early angiogenesis. Regarding 99mTc-MDP in the implant, similar uptake was documented at all time points, consistent with sustained bone viability; however, the uptake was lower than that detected in the control femur, as confirmed by histology.

CONCLUSIONS:

1) Graft viability was successfully diagnosed using radiotracers in severely ischemic bone at all time points. 2) Analogously, indirect information about angiogenesis could be gathered using 999mTc-HYNIC-E-[c(RGDfK)2. 3) These techniques appear promising and warrant further studies to determine their potential clinical applications.

Which One Is Better to Reduce the Infection Rate, Early or Late Cranioplasty?

OBJECTIVE

Decompressive craniectomy is an effective therapy to relieve high intracranial pressure after acute brain damage. However, the optimal timing for cranioplasty after decompression is still controversial. Many authors reported that early cranioplasty may contribute to improve the cerebral blood flow and brain metabolism. However, despite all the advantages, there always remains a concern that early cranioplasty may increase the chance of infection. The purpose of this retrospective study is to investigate whether the early cranioplasty increase the infection rate. We also evaluated the risk factors of infection following cranioplasty.

METHODS

We retrospectively examined the results of 131 patients who underwent cranioplasty in our institution between January 2008 and June 2015. We divided them into early (≤90 days) and late (>90 days after craniectomy) groups. We examined the risk factors of infection after cranioplasty. We analyzed the infection rate between two groups.

RESULTS

There were more male patients (62%) than female (38%). The mean age was 49 years. Infection occurred in 17 patients (13%) after cranioplasty. The infection rate of early cranioplasty was lower than that of late cranioplasty (7% vs. 20%; p=0.02). Early cranioplasty, non-metal allograft materials, re-operation before cranioplasty and younger age were the significant factors in the infection rate after cranioplasty (p<0.05). Especially allograft was a significant risk factor of infection (odds ratio, 12.4; 95% confidence interval, 3.24-47.33; p<0.01). Younger age was also a significant risk factor of infection after cranioplasty by multivariable analysis (odds ratio, 0.96; 95% confidence interval, 0.96-0.99; p=0.02).

CONCLUSION

Early cranioplasty did not increase the infection rate in this study. The use of non-metal allograft materials influenced a more important role in infection in cranioplasty. Actually, timing itself was not a significant risk factor in multivariate analysis. So the early cranioplasty may bring better outcomes in cognitive functions or wound without raising the infection rate.

A novel technique for reimplanting extruded bone fragments in open fractures

Extruded bone fragments are a rare complication of high-energy open fractures. Generally, management is thorough debridement and managing the bone defect. In the literature, there are only a few case reports where successful retention of the free bone fragment has been done. Disinfection of bone fragment is done by autoclaving or use of antiseptic/antibiotic solution. Autoclaving leads to complete loss of viable cells and antiseptic/antibiotic solutions do not disinfect completely. In this case report, authors present an innovative technique of disinfecting the bone fragment effectively with minimum compromise on biology. A 38-year-old male with compound grade III B comminuted fracture of distal femur with 2 extruding bone pieces was managed by thorough debridement, external fixator and antibiotic cement spacer. The extruded bone fragments were rinsed in saline and diluted betadine and implanted in subfascial plane in healthy soft tissues in the thigh along with a few antibiotic beads for assuring disinfection. After 1 week, when no clinical signs of infection were found, the site was opened, cement spacer removed, free fragments positioned anatomically and rigid internal fixation was done. Fracture united at 6 months with good functional outcome. At last follow-up at 1 year, the patient was mobilising freely and there were no signs of low grade infection. The key points of this procedure are:1)Viability of bone fragment maintained while achieving disinfection.2)Traumatised soft tissues healed and prepared for accepting the free bone fragment.3)Use of antibiotic cement counters any remaining chances of infection after thorough debridement.4)Faster union with maintenance of bone length and alignment with use of anatomic fragments. Extensive search of literature was done and this procedure was found to be novel. A larger case series can help in determining the utility of this technique in compound fractures.

Complications Associated with Decompressive Craniectomy: A Systematic Review

Decompressive craniectomy (DC) has been used for many years in the management of patients with elevated intracranial pressure and cerebral edema. Ongoing clinical trials are investigating the clinical and cost effectiveness of DC in trauma and stroke. While DC has demonstrable efficacy in saving life, it is accompanied by a myriad of non-trivial complications that have been inadequately highlighted in prospective clinical trials. Missing from our current understanding is a comprehensive analysis of all potential complications associated with DC. Here, we review the available literature, we tabulate all reported complications, and we calculate their frequency for specific indications. Of over 1500 records initially identified, a final total of 142 eligible records were included in our comprehensive analysis. We identified numerous complications related to DC that have not been systematically reviewed. Complications were of three major types: (1) Hemorrhagic (2) Infectious/Inflammatory, and (3) Disturbances of the CSF compartment. Complications associated with cranioplasty fell under similar major types, with additional complications relating to the bone flap. Overall, one of every ten patients undergoing DC may suffer a complication necessitating additional medical and/or neurosurgical intervention. While DC has received increased attention as a potential therapeutic option in a variety of situations, like any surgical procedure, DC is not without risk. Neurologists and neurosurgeons must be aware of all the potential complications of DC in order to properly advise their patients.

Low Incidence of Bone Flap Resorption After Native Bone Cranioplasty in Adults

OBJECTIVE

Cranioplasty via use of the patient's autologous bone is performed often after craniectomy procedures. Bone resorption remains a matter of concern in patients with native bone cranioplasty. The objective of this study was to evaluate the rate of native bone resorption in adults and review associated factors that may increase the risk of resorption.

METHODS

This is a single-center retrospective cohort study that assessed consecutive patients who had cranioplasty via use of the patient's native bone flap. A total of 114 patients were identified. Electronic medical records were reviewed for demographic and operative data.

RESULTS

The mean age was 51.2 years. The main indications for initial craniectomy included subarachnoid hemorrhage (SAH) in 50.9%, intracerebral hemorrhage in 17.5%, ischemic stroke in 14.9%, and trauma in 13.2% of patients. Mean interval between craniectomy and cranioplasty was 6 months. Mean follow-up after cranioplasty was 25 months. Bone resorption occurred in 3 patients (2.7%): at 6 months in a 30-year-old woman who presented with SAH followed by decompressive craniectomy and cranioplasty 3.5 months later; at 19 months in a 67-year-old female patient who presented with intracerebral hemorrhage followed by decompressive craniectomy and cranioplasty 6 months later; and at 9 months in a 50-year-old man who presented with SAH followed by craniectomy for clip ligation and cranioplasty 3 months later. Two of these patients underwent replacement of the native flap with synthetic material.

CONCLUSIONS

The rate of autologous bone flap resorption in adult patients undergoing cranioplasty is low even after a mean interval for cranioplasty of 6 months.

Titanium cranioplasty in children and adolescents

Full thickness calvarial defects present considerable challenges to reconstructive surgeons. In paediatric cases, the use of biomaterials as a substrate for cranioplasty rather than autologous bone is controversial. Alloplastic cranioplasty in adults is supported by several large case series however long term outcome of biomaterial use in paediatric cases is limited. Retrospective seven year analysis of departmental database and clinical records identified 22 patients aged under 18 who had undergone 23 custom made titanium cranioplasties by a single surgeon using the same technique. Data including patient demographics, reason for craniectomy and complications experienced following surgery was obtained. The mean age at operation was 12 years 9 months. The mean defect size was 44.3 cm(2). No significant complications related to the cranioplasty were recorded in the early post operative period or during long term review (average follow up 4 years 6 months). No cranioplasty implant required removal. This retrospective case series shows that custom made patient specific titanium cranioplasty is a viable alternative to autologous bone as a reconstructive material in paediatric patients under specific circumstances.

Long-term follow-up of cryopreservation with glycerol of autologous bone flaps for cranioplasty after decompressive craniectomy

BACKGROUND

Autologous bone flaps adequately preserved can be used successfully for repair of cranial bone defects with biological and economic advantages. However, the effect or advantages of cryopreservation of autologous bone flaps using cryoprotectant solutions have not been investigated. The aim of this study was to investigate the utility of autologous bone flaps frozen with glycerol in cranioplasty after decompressive craniectomy.

METHODS

We evaluated postoperative complications and clinical and aesthetic results in 40 consecutive patients who underwent delayed cranioplasty using autologous bone flaps frozen with glycerol following decompressive craniectomy between 2001 and 2010. Bone flaps removed at the time of external decompression were dipped in 20 % glycerol solution with a sterilized plastic vessel and stored at -84 °C in an ultra-low temperature freezer. The bone flaps were thawed in the vessel at room temperature for 12 h. The bone flaps were taken out of melting glycerol, replaced in their original positions, and fixed with silk sutures or titanium plates. Follow-up periods ranged from 35 to 3745 days (median, 558 days).

RESULTS

Mild resorption of the bone flap occurred in one case. However, there were no cases with local infection and no cases requiring reoperation for complications during the follow-up period.

CONCLUSIONS

Cryopreservation with glycerol is a simple and safe method for preservation of autologous bone grafts. The clinical and aesthetic results of delayed cranioplasty using autologous bone flaps frozen with glycerol solution were satisfactory.

Analysis of Factors Contributing to Infections After Cranioplasty: A Single-Institution Retrospective Chart Review

OBJECTIVE

Cranioplasty is one of the most common neurosurgical procedures, yet has one of the greatest rates of infection among cranial operations. Although studies have reported on cranioplasty complications, it is unclear what factors contribute to the high rate of infection. This study aims to determine which patient characteristics and operative factors lead to postcranioplasty infections.

METHODS

This was a retrospective chart review of 186 patients. Factors analyzed included sex, reason for cranioplasty, type of infection, medical comorbidities, and surgical factors.

RESULTS

The overall infection rate was 24%. Skin flora was the most common pathogen. Wound dehiscence and presence of a postoperative fluid collection were associated significantly with a greater rate of infection (P < 0.001), whereas the use of autologous bone flap and a state of immunosuppression trended toward statistical significance (P = 0.075 and P = 0.089, respectively). Male sex, history of previous infection, history of craniectomy for trauma, cranioplasty size, and time to cranioplasty were not found to be significant factors related to cranioplasty infection.

CONCLUSIONS

Although wound dehiscence and postoperative fluid collections were associated significantly with infection in this study, the number in each sample size was small, and further studies with a larger number of patients in each subgroup is necessary to validate our findings.

Cranioplasty complications and risk factors associated with bone flap resorption

Background

Decompressive craniectomy (DC) may be performed in patients with acutely raised intracranial pressure due to traumatic brain injury or stroke. It is later followed by a cranioplasty procedure (CP) in the surviving patients. This procedure is associated with a high frequency of post-operative complications. Identifying risk factors for these adverse events is important in order to improve the clinical outcome. This study examines possible predictive parameters for post-operative complications in CP.

Methods

Retrospective, single institution review of all patients undergoing a DC for acutely raised intracranial pressure over a 10 year period at Oslo University Hospital Ullevål, Norway. Subsequent CP using autologous bone flaps or synthetic implants were registered along with all post-operative complications. Predictors of post-operative complications were identified using uni –and multivariable regression analyses.

Results

A DC was carried out in 125 patients, of whom 33 died, 4 were lost to follow-up, and 1 (an infant) later underwent cranial remodeling. A CP was performed in the remaining 87 patients. Post-operative complications were recorded in 31 (36 %) patients of whom 22 lost their primary implant. Surgical site infection (SSI) and bone flap resorption (BFR) were the two most common complications, affecting 8 (9.2 %) and 14 (19.7 %) patients, respectively. Only BFR was associated with some of the recorded variables. Using multivariable logistic regression analysis, young age (OR = 0.94, 95 % CI 0.88-1.00, p = 0.04), bone flap fragmentation (OR = 14.3, 95 % CI 2.26-89, p = 0.005), long storage time (OR = 1.03, 95 % CI 1.00-1.04, p = 0.02) and Glasgow Outcome Scale at the time of cranioplasty (OR = 2.55, 95 % CI 1.04-6.23, p = 0.04) were found to be significant risk factors for bone flap resorption.

Conclusions

Cranioplasty after decompressive craniectomy carries a high rate of complications. In this study, SSI and BFR were the two most common complications of which predictive clinical parameters could be identified for BFR only. The results indicate that synthetic implants may be considered in pediatric patients and in cases with fragmented bone flaps or delayed time to cranioplasty. Although the rate of complications was high, 73 % had a successful reinsertion of the autologous graft at a low cost. We feel this result justifies the continued use of cryopreserved bone flaps.

Delayed Cranioplasty: Outcomes Using Frozen Autologous Bone Flaps

Reconstruction of skull defects following decompressive craniectomy is associated with a high rate of complications. Implantation of autologous cryopreserved bone has been associated with infection rates of up to 33%, resulting in considerable patient morbidity. Predisposing factors for infection and other complications are poorly understood. Patients undergoing cranioplasty between 1999 and 2009 were identified from a prospectively maintained database. Records and imaging were reviewed retrospectively. Demographics, the initial craniectomy and subsequent cranioplasty surgeries, complications, and outcomes were recorded. A total of 187 patients underwent delayed cranioplasty using autologous bone flaps cryopreserved at -30°C following decompressive craniectomy. Indications for craniectomy were trauma (77.0%), stroke (16.0%), subarachnoid hemorrhage (2.67%), tumor (2.14%), and infection (2.14%). There were 64 complications overall (34.2%), the most common being infection (11.2%) and bone resorption (5.35%). After multivariate analysis, intraoperative cerebrospinal fluid (CSF) leak was significantly associated with infection, whereas longer duration of surgery and unilateral site were associated with resorption. Cranioplasty using frozen autologous bone is associated with a high rate of infective complications. Intraoperative CSF leak is a potentially modifiable risk factor. Meticulous dissection during cranioplasty surgery to minimize the chance of breaching the dural or pseudodural plane may reduce the chance of bone flap.

Cranioplasty after decompressive craniectomy. A prospective series analyzing complications and clinical improvement

BACKGROUND

Cranioplasty is carried out for cosmetic reasons and for protection, but it may also lead to some neurological improvement after the bone flap placement. Complications of cranioplasty are more frequent than expected for a scheduled neurosurgical procedure. We tried to identify factors associated with both complications and improvement after cranioplasty.

METHODS

We prospectively studied the cranioplasties performed in our hospital from November 2009 to November 2013. Patients whose initial reason for bone removal was tumor infiltration were excluded. Demographic, clinical and radiological data were collected. The NIH Stroke Scale and Barthel Self-Care Index scores were obtained both before and within 72 h after cranioplasty. The outcome measures were the occurrences of complications and clinical improvement.

RESULTS

Fifty-five cranioplasties were performed. The material used for the cranioplasty was autologous bone in 42 cases, polyetheretherketone (PEEK) in 7 and methacrylate in 6. The average size of the bone defect was 69.5 (19.5-149.5) cm2. The time elapsed between decompressive craniectomy and cranioplasty was 309 (25-1217) days. There were 10 complications (7 severe and 3 mild), an 18.2% complication rate. Statistically significant risk factors of complications were identified as a Barthel≤70 (Odds ratio [OR] 22; 2.5-192; P=0.005), age over 45 years (OR 13.5; 1.5-115; P=0.01) and early surgery (≤85 days; OR 8; 1.69-37.03, P=0.004). After multivariate analysis, Barthel≤70 and age over 45 years remained independent predictors of complications. Twenty-two (40%) of the 55 patients showed objective improvement. Early surgery (<85 days) increased the likelihood of improvement (OR 4.67; 1.05-20.83; P=0.035). Larger bone defects seemed to be related with improvement, but differences in defect size were not statistically significant (75.3 vs 65.6 cm2; P=0.1).

CONCLUSIONS

The complication rate of cranioplasty is higher than for other elective neurosurgical procedures. Older age, poorer functional situation (worse Barthel index score) and early surgery (≤85 days) are independent risk factors for complications. However, cranioplasty produces clinical benefits beyond protection and esthetic improvement. Earlier surgery and larger bone defects seem to increase the likelihood of clinical improvement.

Materials used in cranioplasty: a history and analysis

Cranioplasty, one of the oldest surgical procedures used to repair cranial defects, has undergone many revolutions over time to find the ideal material to improve patient prognosis. Cranioplasty offers cosmetic and protective benefits for patients with cranial defects. The first primitive cranioplasty procedures date back to 7000 bc and used metal and gourds to repair cranial defects. Cranioplasty was first documented by Fallopius who described repair using gold plates; the first bone graft was documented by van Meekeren. The first significant improvement for this procedure began with experimentation involving bone grafts in the late 19th century as a more natural approach for repairing cranial defects. The next impetus for advancement came because of wartime injuries incurred during World Wars I and II and involved experimentation with synthetic materials to counter the common complications associated with bone grafts. Methyl methacrylate, hydroxyapatite, ceramics, and polyetheretherketone implants among other materials have since been researched and used. Research now has shifted toward molecular biology to improve the ability of the patient to regenerate bone using bone growth factors. This paper reviews the evolution of materials used over time in addition to the various advantages and pitfalls associated with each change. It is important for neurosurgeons to be mindful of how these techniques have evolved in order to gain a better understanding of this procedure and how it has been adapted.

Histopathology of subcutaneously preserved autologous bone flap after decompressive craniectomy: a prospective study

BACKGROUND

Limited reports are available regarding the viability of subcutaneously preserved autologous bone flaps after decompressive craniectomy. The present study was undertaken to evaluate the histopathological changes in these autologous bone flaps.

METHODS

Between January 2011 and July 2012, 50 patients were prospectively studied at the time of cranioplasty. Bone flap retrieved from the abdominal wall was subjected to histopathological examination to look for mononuclear cell infiltration into the Haversian system, presence of osteocytes, osteoblastic activity, angiogenesis and new bone formation. Microbiological culture of bone specimens was also done.

RESULTS

Of the 50 patients, there were 40 cases of trauma, 6 of aneurysmal bleed, 2 of tumor, and a single case of intracerebral hemorrhage and middle cerebral artery infarct, respectively. Mean age of the patients was 35.8 years (range, 10-64 years). Histopathological examination revealed the presence of osteocytes in 86 %, which indicates the viability of bone flaps. Osteoblastic activity was noted in 38 % and angiogenesis in 14 % of bone flaps, respectively. New bone formation was found in 6 %, and all had underlying osteoblastic activity. No significant correlation was found between the presence of osteocytes, osteoblasts, angiogenesis and duration of preservation of bone flaps. Acinetobacter species were cultured in a single patient. However, there was no evidence of clinical infection.

CONCLUSIONS

Subcutaneously preserved bone flap in the anterior abdominal wall remains viable and retains its osteogenic potential, and it is a simple, cost-effective option for storage of bone flaps during decompressive craniotomy. It has a negligible infection rate.

Autologous bone flap cranioplasty following decompressive craniectomy is combined with a high complication rate in pediatric traumatic brain injury patients

OBJECTIVE

Decompressive craniectomy (DC) is a last treatment option of refractory intracranial hypertension in traumatic brain injury (TBI) patients. Replacement of the autologous bone flap is the preferred method to cover the cranial defect after brain swelling has subsided. Long term outcomes and complications after replacement of the autologous bone flap in pediatric patients were studied in comparison to young, healthy adults.

METHODS

Medical records of 27 pediatric patients who underwent DC and subsequent replacement of the bone flap between 1998 and 2011 were reviewed retrospectively. Patients were divided into two age groups (group 1: 18 children < 15 years; group 2:9 adolescents 15-18 years). For comparative reasons, a young adult control group of 39 patients between 18 and 30 years was additionally evaluated.

RESULTS

With 81.8 % resorption of the bone flap, this was the major complication in young children. In up to 54.4 % of patients, a surgical revision of the osteolytic bone flap became necessary. However, in some pediatric patients, the osteolysis resolved spontaneously and further operations were not required. Probable enabling factors for bone flap resorption were young age (0-7 years), size of craniectomy, permanent shunt placement, and extent of dural opening/duraplasty. Other complications were bone flap infections, loosening of the re-inserted bone flap, and postoperative hematomas.

CONCLUSION

There is an unacceptably high complication rate after reimplantation of the autologous bone following DC in pediatric TBI patients, especially in young children up to seven years of age. Artificial or synthetic cranioplasties may be considered as alternatives to initial bone flap reimplantation in the growing child. Despite the fact that DC is an effective treatment in TBI with persistent intracranial hypertension, it is important to realize that DC is not only combined with replacement of the autologous bone flap but also with a high rate of additional complications especially in pediatric patients.

Cranioplasty with custom-made titanium plates--14 years experience

BACKGROUND

There is no consensus on which material is best suited for repair of cranial defects.

OBJECTIVE

To investigate the outcomes following custom-made titanium cranioplasty.

METHODS

The medical records for all patients who had titanium cranioplasty at 2 major neurosurgical centers in Western Australia were retrieved and analyzed for this retrospective cohort study.

RESULTS

Altogether, 127 custom-made titanium cranioplasties on 113 patients were included. Two patients had 3 titanium cranioplasties and 10 patients had 2. Infected bone flap (n = 61, 54%), either from previous craniotomy or autologous cranioplasty, and contaminated bone flap (n = 16, 14%) from the initial injury were the main reasons for requiring titanium cranioplasty. Complications attributed to titanium cranioplasty were common (n = 33, 29%), with infection being the most frequent complication (n = 18 patients, 16%). Complications were, on average, associated with an extra 7 days of hospital stay (interquartile range 2-17). The use of titanium as the material for the initial cranioplasty (P = .58), the presence of skull fracture(s) (P > .99) or scalp laceration(s) (P = .32) at the original surgery, and proven local infection before titanium cranioplasty (P = .78) were not significantly associated with an increased risk of infection. Infection was significantly more common after titanium cranioplasty for large defects (hemicraniectomy [39%] and bifrontal craniectomy [28%]) than after cranioplasty for small defects (P = .04).

CONCLUSION

Complications after using titanium plate for primary or secondary cranioplasty were common (29%) and associated with an increased length of hospital stay. Infection was a major complication (16%), and this suggested that more vigorous perioperative infection prophylaxis is needed for titanium plate cranioplasty.

Risk factors of aseptic bone resorption: a study after autologous bone flap reinsertion due to decompressive craniotomy

Object

In patients who have undergone decompressive craniectomy, autologous bone flap reinsertion becomes necessary whenever the cerebral situation has consolidated. However, aseptic necrosis of the bone flap remains a concern. The aim of this study was to report possible perioperative complications in patients undergoing autologous bone flap reinsertion and to identify the risk factors that may predispose the bone flap to necrosis.

Methods

All patients admitted to the authors' neurosurgical department between September 1994 and June 2011 and who received their own cryoconserved bone flap after decompressive craniectomy were studied. The grade of the bone flap necrosis was classified into 2 types. Type II bone necrosis was characterized by aseptic resorption with circumscribed or complete lysis of tabula interna and externa requiring surgical revision. To define predisposing factors, a multivariate analysis was performed using bone necrosis as the dependent variable.

Results

Among the 372 patients (mean age 48.6 years, 57.4% males) who received 414 bone flaps during the observation period, 134 (36.0%) had a diffuse traumatic brain injury, 69 (18.5%) had subarachnoid hemorrhage, 58 (15.6%) had cerebral infarction, 56 (15.1%) had extraaxial bleeding, 43 (11.6%) had intracerebral bleeding, and 12 (3.2%) had a neoplasm. Surgical relevant Type II bone flap necrosis occurred in 85 patients (22.8%) and 91 bone flaps, after a median time of 15 months (interquartile range [IQR], 10–33 months). In a multivariate analysis with Type II necrosis as the dependent variable, bone flap fragmentation with 2 (OR 3.35, 95% CI 1.59–7.01, p < 0.002) or more fragments (OR 24.00, 95% CI 10.13–56.84, p < 0.001), shunt-dependent hydrocephalus (OR 1.76, 95% CI 0.99–3.12, p = 0.04), and a younger age (OR 0.98, 95% CI 0.96–0.99, p = 0.004) was associated with a higher risk for the development of an aseptic bone flap necrosis.

Conclusions

In patients undergoing bone flap reinsertion after craniotomy, aseptic bone necrosis is an underestimated problem during long-term follow-up. Especially in younger patients with an expected good neurological recovery and a fragmented bone flap, an initial allograft should be considered because of an increased risk for aseptic bone flap necrosis.

Long-term incidence and predicting factors of cranioplasty infection after decompressive craniectomy

Objective

The predictors of cranioplasty infection after decompressive craniectomy have not yet been fully characterized. The objective of the current study was to compare the long-term incidences of surgical site infection according to the graft material and cranioplasty timing after craniectomy, and to determine the associated factors of cranioplasty infection.

Methods

A retrospective cohort study was conducted to assess graft infection in patients who underwent cranioplasty after decompressive craniectomy between 2001 and 2011 at a single-center. From a total of 197 eligible patients, 131 patients undergoing 134 cranioplasties were assessed for event-free survival according to graft material and cranioplasty timing after craniectomy. Kaplan-Meier survival analysis and Cox regression methods were employed, with cranioplasty infection identified as the primary outcome. Secondary outcomes were also evaluated, including autogenous bone resorption, epidural hematoma, subdural hematoma and brain contusion.

Results

The median follow-up duration was 454 days (range 10 to 3900 days), during which 14 (10.7%) patients suffered cranioplasty infection. There was no significant difference between the two groups for event-free survival rate for cranioplasty infection with either a cryopreserved or artificial bone graft (p=0.074). Intergroup differences according to cranioplasty time after craniectomy were also not observed (p=0.083). Poor neurologic outcome at cranioplasty significantly affected the development of cranioplasty infection (hazard ratio 5.203, 95% CI 1.075 to 25.193, p=0.04).

Conclusion

Neurologic status may influence cranioplasty infection after decompressive craniectomy. A further prospective study about predictors of cranioplasty infection including graft material and cranioplasty timing is necessary.

Optimal timing of autologous cranioplasty after decompressive craniectomy in children

OBJECT

The object of this study was to determine if early cranioplasty after decompressive craniectomy for elevated intracranial pressure in children reduces complications.

METHODS

Sixty-one consecutive cases involving pediatric patients who underwent autologous cranioplasty after decompressive craniectomy for raised intracranial pressure at a single academic children's hospital over 15 years were studied retrospectively.

RESULTS

Sixty-one patients were divided into early (< 6 weeks; 28 patients) and late (≥ 6 weeks; 33 patients) cranioplasty cohorts. The cohorts were similar except for slightly lower age in the early (8.03 years) than the late (10.8 years) cranioplasty cohort (p < 0.05). Bone resorption after cranioplasty was significantly more common in the late (42%) than the early (14%) cranioplasty cohort (p < 0.05; OR 5.4). No other complication differed in incidence between the cohorts.

CONCLUSIONS

After decompressive craniectomy for raised intracranial pressure in children, early (< 6 weeks) cranioplasty reduces the occurrence of reoperation for bone resorption, without altering the incidence of other complications.

CT of the skin and subcutaneous tissues

A broad spectrum of skin and subcutaneous (SQ) findings may be discovered in the emergency setting on CT examinations. There are some findings that are directly relevant to the reason or reasons why the patient has undergone the CT examination. However, other findings may be incidental. The skin and SQ tissues are by definition on the periphery of CT images and may be overlooked by the radiologist, although findings related to them can be of clinical importance. The purpose of this pictorial essay is to present a broad spectrum of skin and subcutaneous findings which may be identified on CT examinations in the emergency setting (and in some cases nonemergently), and to briefly review the relevant imaging literature, which surprisingly is relatively limited on this topic. Categories of cutaneous and subcutaneous abnormalities that will be covered include trauma and hemorrhage, iatrogenic findings, infection, neoplasms, calcification, and other miscellaneous entities, all of which may initially present on emergency CT examinations of the body.

Decompressive craniectomy bone flap hinged on the temporalis muscle: A new inexpensive use for an old neurosurgical technique

Background:

The neurosurgical procedure of hinge decompressive craniectomy (hDC), or hinge craniotomy (HC), as described from units in the advanced countries makes use of metallic implants, usually titanium plates and screws, which may not be economically viable in resource-limited practice settings.

Methods:

We describe our surgical techniques for performing this same procedure of hDC in a developing country using the patient's own temporalis muscle instead of any other potentially costly implants.

Results:

The technique as described appears to be successful in achieving intracranial decompression in cases of traumatic brain swelling in which it has been used. Clinical and radiological illustrations of the feasibility, and practical utility, of the procedures in four clinical scenarios of traumatic brain injury are presented. Like all other techniques of HC, this new surgical technique of hDC temporalis saves the survivors the added imperative of future cranioplasty of the usual postcraniectomy skull defect. Unlike the others, the procedure eliminates the added cost of the metallic implants needed to perform the former techniques.

Conclusions:

The procedure of hDC temporalis appears to be a viable option for performing the surgical procedure of HC and has added cost-cutting economic benefits for resource-limited practice settings.