Cranioplasty with autologous cryopreserved bone after decompressive craniectomy: complications and risk factors for developing surgical site infection

Subgaleal drains may be associated with decreased infection following autologous cranioplasty: a retrospective analysis

BACKGROUND

Autologous bone is often the first choice in cranioplasty following a decompressive craniectomy. However, infection is a common complication, with reported rates up to 25%. While the incidence and management of infection are well documented, the risk factors associated with infection remain less clear. The current study aims to identify predictors of infection risk following autologous cranioplasty.

METHODS

A retrospective analysis was conducted on patients who underwent decompressive craniectomy and cranioplasty using cryopreserved autologous bone flaps between 2010 and 2020. Patient demographics and factors related to both surgeries and infection rates were recorded from patient records. Logistic regressions were conducted to determine which factors were implicated in the development of infection.

RESULTS

In our cohort, 126 patients underwent autologous cranioplasty. A total of 10 patients (7.9%) developed an infection following reconstruction, with half resulting in implant failure. We did not identify any significant risk factors for infection. Regression analysis identified placement of subgaleal drain following cranioplasty as a protective factor against the development of infection (OR: 0.16, p = 0.007). On average, drains remained in for 3 days, with no difference between the length of drains for those with infection vs. those without (p = 0.757).

CONCLUSIONS

The current study demonstrates an infection rate of 7.9% in patients who receive an autologous cranioplasty following decompressive craniectomy, which is consistent with previous data. Half (4%) of patients who experienced an infection ultimately required removal of the implant. While it is common practice for neurosurgeons to use drains to prevent hematomas and fluid collections, we found that subgaleal drain placement following cranioplasty was associated with decreased infection, thus demonstrating another benefit of a commonly used tool.

Bone graft absorption complication following cranioplasty: A retrospective institutional study

The aim of the present retrospective study was to confer the factors that are related to bone graft absorption and affect the outcomes of patients following cranioplasty (CPL). The present retrospective study includes cases of patients that underwent CPL between February, 2013 and December, 2022. All participants had a follow-up period of 1 to 10 years from the day of discharge from the hospital. In total, 116 (62.3%) of the 186 patients that underwent decompressive craniectomy (DC) were enrolled in the present study for CPL. A total of 109 (93.9%) patients were included in group A, and 7 (6.0%) patients were included in group B. On the whole, the results of the present study suggest that a CPL after 2.5-7.7 months of DC increases the possibility of bone absorption.

Excessive Heat Generation by Power-Driven Craniotomy Tools: A Possible Cause of Autologous Bone Flap Resorption Observed in an Ex Vivo Simulation

BACKGROUND

Bone flap resorption is an issue after autologous cranioplasty. Critical temperatures above 50°C generated by power-driven craniotomy tools may lead to thermal osteonecrosis, a possible factor in resorption. This ex vivo study examined whether the tools produced excessive heat resulting in bone flap resorption.

METHODS

Using swine scapulae maintained at body temperature, burr holes, straight and curved cuts, and wire-pass holes were made with power-driven craniotomy tools. Drilling was at the conventional feed rate (FR) plus irrigation (FR-I+), at a high FR plus irrigation (hFR-I+), and at high FR without irrigation (hFR-I-). The temperature in each trial was recorded by an infrared thermographic camera.

RESULTS

With FR-I+, the maximum temperature at the burr holes, the cuts, and the wire-pass holes was 69.0°C, 56.7°C, and 46.2°C, respectively. With hFR-I+, these temperatures were 53.1°C, 52.1°C, and 46.0°C, with hFR-I- they were 56.0°C, 66.5°C, and 50.0°C; hFR-I- burr hole- and cutting procedures resulted in the highest incidence of bone temperatures above 50°C followed by FR-I+, and hFR-I+. At the site of wire-pass holes, only hFR-I- drilling produced this temperature.

CONCLUSIONS

Except during prolonged procedures in thick bones, most drilling with irrigation did not reach the critical temperature. Drilling without irrigation risked generating the critical temperature. Knowing those characteristics may be a help to perform craniotomy with less thermal bone damage.

An update on a persisting challenge: A systematic review and meta-analysis of the risk factors for surgical site infection post craniotomy

BACKGROUND

Surgical site infections (SSIs) postcraniotomy continue to impose a significant burden on health care systems and patient outcomes. It is, therefore, important to understand their risk factors in order to promote effective preventative measures. This meta-analysis aims to provide a comprehensive, up-to-date analysis of the risk factors associated with SSIs in neurosurgical procedures.

METHODS

A systematic review was conducted as per preferred reporting items for systematic reviews and meta-analysis guidelines to explore existing primary evidence on the risk factors for SSIs postcraniotomy. A comprehensive search of MEDLINE, EMBASE, and Pubmed was performed from database inception up to June 2023. 43 studies were included in the meta-analysis, encompassing a total of 68,881 patients.

RESULTS

The strongest predictor for SSIs was found to be cerebrospinal fluid (CSF) leak (OR: 8.91, CI: 4.30-18.44). Other significant factors included infratentorial surgery (OR: 0.43, CI: 0.31-0.61), emergency surgery (OR: 1.41, CI: 1.05-1.91), reintervention (OR: 3.19, CI: 1.77-5.75), prolonged operative time (mean difference: 33.25; CI: 18.83-47.67), hospital length of stay (mean difference: 0.60; CI: 0.23-0.98) and intracranial pressure monitor (ICPM) insertion (OR: 1.81; CI: 1.06-3.11). Contrarily, sex, body mass index (BMI), diabetes, antibiotic prophylaxis, immunosuppressive agents, trauma, use of artificial implants did not demonstrate statistical significance.

CONCLUSIONS

This meta-analysis provides an up-to-date and comprehensive evaluation of risk factors for SSIs postcraniotomy. It emphasizes the need for preventive strategies, particularly against CSF leaks, and calls for further research to elucidate the intricate relationships between these factors.

Perioperative risk factors for major complications after bone replacement in decompressive craniectomy

INTRODUCTION

Bone flap replacement after a decompressive craniectomy is a low complexity procedure, but with complications that can negatively impact the patient's outcome. A better knowledge of the risk factors for these complications could reduce their incidence.

PATIENTS AND METHODS

A retrospective review of a series of 50 patients who underwent bone replacement after decompressive craniectomy at a tertiary center over a 10-year period was performed. Those clinical variables related to complications after replacement were recorded and their risk factors were analyzed.

RESULTS

A total of 18 patients (36%) presented complications after bone flap replacement, of which 10 (55.5%) required a new surgery for their treatment. Most of the replacements (95%) were performed in the first 90 days after the craniectomy, with a tendency to present more complications compared to the subsequent period (37.8% vs 20%, p > 0.05). The most frequent complication was subdural hygroma, which appeared later than infection, the second most frequent complication. The need for ventricular drainage or tracheostomy and the mean time on mechanical ventilation, ICU admission, or waiting until bone replacement were greater in patients who presented post-replacement complications. Previous infections outside the nervous system or the surgical wound was the only risk factor for post-bone flap replacement complications (p = 0.031).

CONCLUSIONS

Postoperative complications were recorded in more than a third of the patients who underwent cranial bone flap replacement, and at least half of them required a new surgery. A specific protocol aimed at controlling previous infections could reduce the risk of complications and help establish the optimal time for cranial bone flap replacement.

A meta-analysis of the risk factors for neurosurgical surgical site infection following craniotomy

The purpose of the meta-analysis was to evaluate and compare the risk factors for neurosurgical surgical site infection (SSI) after craniotomy. Using dichotomous or contentious random or fixed effect models, the odds ratio (OR) and mean difference (MD) with 95% confidence intervals (CIs) were computed based on the examination of the meta-analysis results. Eighteen analyses, covering 11 068 craniotomies between 2001 and 2023, were included in the current meta-analysis. Subjects with SSIs had a significantly younger age (MD, -2.49; 95% CI, -2.95 to -2.04, p < 0.001), longer operation duration (MD, 10.21; 95% CI, 6.49-13.94, p < 0.001) and longer length of postoperative hospital stay (MD, 1.52; 95% CI, 0.45-2.60, p = 0.006) compared to subjects with no SSI with craniotomy. However, no significant difference was found between craniotomy subjects with SSIs and with no SSI in gender (OR, 0.90; 95% CI, 0.76-1.07, p = 0.23), and combination with other infection (OR, 3.93; 95% CI, 0.28-56.01, p = 0.31). The data that were looked at showed that younger age, longer operation duration and longer length of postoperative hospital stay can be considered as risk factors of SSI in subjects with craniotomy; however, gender and combination with other infections are not. Nonetheless, consideration should be given to their values because several studies only involved a small number of patients, and there are not many studies available for some comparisons.

Lowering Cranioplasty Infection Incidence with Novel Bone Flap Storage Protocol: A Retrospective Cohort Study

BACKGROUND

After craniectomy, autologous bone flaps may be stored using wet or dry cryopreservation. After brain edema subsides, they are replaced during an operation termed cranioplasty. Cranioplasty is associated with 15% infection incidence.

METHODS

We conducted a retrospective comparison of infection outcomes between wet and dry cryopreservation of cranioplasty bone flaps. Historically, bone flaps were stored utilizing wet cryopreservation-bone flap storage in 1 L of lactated Ringer's solution containing 80 mg gentamicin and 2 g nafcillin in a sterile plastic container secured in an unsterile plastic bag. Our newer dry cryopreservation protocol involved storage in gauze soaked in 80 mg gentamicin and 2 g nafcillin within a 3-layer sterile bag system.

RESULTS

A total of 119 autologous bone flaps were included, with median follow-up of 3.9 months from cranioplasty. Overall, 10.9% became infected, requiring subsequent surgery; 18.4% of 49 bone flaps stored using wet cryopreservation became infected compared with only 5.7% of 70 dry cryopreservation bone flaps (P = 0.038; relative risk [RR] 0.311; absolute risk reduction 12.7%). Tobacco use (P = 0.076; RR 3.17) was not associated with increased infection risk. Infection incidence was similar for traumatic craniectomy indications compared to the other indications (12.0% trauma vs. 10.1% other; P = 0.750). On average, infected cranioplasty patients spent 8.5 more days hospitalized and faced increased risk of additional complications.

CONCLUSIONS

Dry cryopreservation significantly decreases infection after cranioplasty when compared with wet cryopreservation, and this mitigates additional morbidity, mortality, and costs attributable to cranioplasty infection. Other nonmodifiable risk factors for cranioplasty infection were identified.

Autologous Cranioplasty with Bone Flap Preserved in Conventional Freezers: An Adequate Option in Low Resource Settings

BACKGROUND

Autologous cranioplasty has been used for decades and is the gold standard treatment in patients who underwent decompressive craniectomy (DC). One of the most common methods to store the cranial bone flap is cryopreservation at very low temperatures (-70 to -80°). The only way to achieve these low temperatures is by using special freezers which are not always available in all medical facilities, especially in low-resource centers. This paper describes our experience with the storage of cranial bone flaps in freezers of conventional refrigerators.

METHODS

This retrospective study included patients treated with autologous cranioplasty, operated between 2015 and 2020. The cranial bone flap was stored at -18°C in the freezer of conventional refrigerators. Complications and outcomes were analyzed and compared with reports of patients in whom ultra-low temperature freezers were used for bone flap preservation.

RESULTS

Twenty-five patients were included. The average follow-up period was 33 months. Trauma was the most common cause of DC, followed by stroke. The mean age was 36.7. Aseptic bone flap resorption was observed in 4 cases (16%). No cases of infection were observed.

CONCLUSIONS

The use of freezers from conventional refrigerators may be an acceptable alternative for the preservation of the cranial bone flap in facilities where special freezers are not available. The rate of aseptic bone necrosis and infections observed in this paper was similar to the incidence of these complications reported in studies where ultra-low temperatures were used.

Two-Stage Anatomic Myocutaneous Flap Dissection in Cranioplasty: Technical Nuances and Single-Surgeon Experience

BACKGROUND AND OBJECTIVES

Temporalis muscle management remains one of the most challenging aspects of cranioplasty, which accounts for considerable rates of dissection-related complications. Since 2019, the senior author has developed and consistently used a methodical, two-stage anatomic dissection technique to separate the scalp and temporalis muscle from the underlying brain. This technique is believed to facilitate dissection and minimize the risk of brain injury, while optimizing cosmetic outcomes.

METHODS

All patients who underwent cranioplasty between January 2019 and February 2023 were identified from a prospectively maintained database. Charts were retrospectively reviewed. Demographic, clinical, and procedural data were extracted and analyzed.

RESULTS

Twenty-nine patients, 20 men and 9 women with a median age of 37 years (range 17-72), were identified. Indications for craniectomy were traumatic brain injury in 18 (62.1%), hemorrhagic stroke in five (17.2%), ischemic stroke in four (13.8%), and aneurysmal subarachnoid hemorrhage in two (6.9%). Median precranioplasty modified Rankin Scale and Glasgow Coma Scale scores were 5 (range in series: 0-5) and 14 (range in series: 3-15), respectively. The median time to cranioplasty was 131 days (32-1717). Cranioplasty was technically successful in all patients, with a median operative time of 106 minutes (62-182). There were no intraoperative complications. Postoperative complications occurred in three patients (10.3%): hemorrhagic brain contusion (n = 1), meningitis (n = 1), and seizure (n = 1). Of those, one patient (3.4%) died 2 weeks after surgery from suspected pulmonary embolism. After a median follow-up of 4 months (1-44), all 28 survivors have either remained clinically stable or exhibited neurological improvement. Cosmetic results were good or excellent in 27 (96.4%) and fair in one (3.6%).

CONCLUSION

Two-stage anatomic dissection of the scalp and temporalis muscle during cranioplasty can maximize surgical efficiency and result in excellent outcomes. Cranioplasty should be considered a low-risk, low-complexity neurosurgical procedure. Safe and efficient management of the temporalis muscle is key.

Intrawound Vancomycin Powder Application for Preventing Surgical Site Infection Following Cranioplasty

OBJECTIVE

Surgical site infection is the most detrimental complication following cranioplasty. In other surgical fields, intrawound vancomycin powder application has been introduced to prevent surgical site infection and is widely used based on results in multiple studies. This study evaluated the effect of intrawound vancomycin powder in cranioplasty compared with the conventional method without topical antibiotics.

METHODS

This retrospective study included 580 patients with skull defects who underwent cranioplasty between August 1, 1998 and December 31, 2021. The conventional method was used in 475 (81.9%; conventional group) and vancomycin powder (1 g) was applied on the dura mater and bone flap in 105 patients (18.1%; vancomycin powder group). Surgical site infection was defined as infection of the incision, organ, or space that occurred after cranioplasty. Surgical site infection within 1-year surveillance period was compared between the conventional and vancomycin powder groups with logistic regression analysis. Penalized likelihood estimation method was used in logistic regression to deal with zero events. All local and systemic adverse events associated with topical vancomycin application were also evaluated.

RESULTS

Surgical site infection occurred in 31 patients (5.3%) and all were observed in the conventional group. The median time between cranioplasty and detection of surgical site infection was 13 days (range, 4-333). Staphylococci were the most common organisms and identified in 25 (80.6%) of 31 cases with surgical site infections. The surgical site infection rate in the vancomycin powder group (0/105, 0.0%) was significantly lower than that in the conventional group (31/475, 6.5%; crude odds ratio [OR], 0.067; 95% confidence interval [CI], 0.006-0.762; adjusted OR, 0.068; 95% CI, 0.006-0.731; p=0.026). No adverse events associated with intrawound vancomycin powder were observed during the follow-up.

CONCLUSION

Intrawound vancomycin powder effectively prevented surgical site infections following cranioplasty without local or systemic adverse events. Our results suggest that intrawound vancomycin powder is an effective and safe strategy for patients undergoing cranioplasty.

Current and emerging applications of saccharide-modified chitosan: a critical review

Chitin, as the main component of the exoskeleton of Arthropoda, is a highly available natural polymer that can be processed into various value-added products. Its most important derivative, i.e., chitosan, comprising β-1,4-linked 2-amino-2-deoxy-β-d-glucose (deacetylated d-glucosamine) and N-acetyl-d-glucosamine units, can be prepared via alkaline deacetylation process. Chitosan has been used as a biodegradable, biocompatible, non-antigenic, and nontoxic polymer in some in-vitro applications, but the recently found potentials of chitosan for in-vivo applications based on its biological activities, especially antimicrobial, antioxidant, and anticancer activities, have upgraded the chitosan roles in biomaterials. Chitosan approval, generally recognized as a safe compound by the United States Food and Drug Administration, has attracted much attention toward its possible applications in diverse fields, especially biomedicine and agriculture. Even with some favorable characteristics, the chitosan's structure should be customized for advanced applications, especially due to its drawbacks, such as low drug-load capacity, low solubility, high viscosity, lack of elastic properties, and pH sensitivity. In this context, derivatization with relatively inexpensive and highly available mono- and di-saccharides to soluble branched chitosan has been considered a "game changer". This review critically reviews the emerging technologies based on the synthesis and application of lactose- and galactose-modified chitosan as two important chitosan derivatives. Some characteristics of chitosan derivatives and biological activities have been detailed first to understand the value of these natural polymers. Second, the saccharide modification of chitosan has been discussed briefly. Finally, the applications of lactose- and galactose-modified chitosan have been scrutinized and compared to native chitosan to provide an insight into the current state-of-the research for stimulating new ideas with the potential of filling research gaps.

Cranioplasty in Brain Tumor Surgery: A Single-Center Retrospective Study Investigating Cranioplasty Failure and Tumor Recurrence

OBJECTIVE

Cranioplasty with synthetic implant can be performed to restore function and form of the skull after resection of malignancy infiltrating the bone. The aim of this study was to examine the rate of implant failure and tumor recurrence in patients undergoing nonautologous cranioplasty and tumor resection.

METHODS

In this retrospective single-center study, 48 patients were identified who had undergone cranioplasty with synthetic implants after tumor resection between 2010 and 2020. The medical records were analyzed to investigate patient demographics, surgery data, cranioplasty failure rates, and rate of tumor recurrence.

RESULTS

Cranioplasty failed in 8 patients. The median time to implant failure was 220 days with most failures occurring within 1 year (5 of 8). There was no significant difference in rate or time to failure between the different cranioplasty materials (P = 0.39). Low body mass index (P < 0.05), previous craniectomy/cranioplasty (P < 0.05), previous radiation therapy to the brain/skull (P < 0.05), and skin closure with sutures (P < 0.05) were associated with an increased risk of implant failure. Tumors recurred in 15 patients.

CONCLUSIONS

Cranioplasty surgery with synthetic implants carries a relatively high risk of failure, regardless of type of cranioplasty material used. Skin closure with staples may be beneficial in these patients.

A multicenter cohort study of early complications after cranioplasty: results of the German Cranial Reconstruction Registry

OBJECTIVE

Cranioplasty (CP) is a crucial procedure after decompressive craniectomy and has a significant impact on neurological improvement. Although CP is considered a standard neurosurgical procedure, inconsistent data on surgery-related complications after CP are available. To address this topic, the authors analyzed 502 patients in a prospective multicenter database (German Cranial Reconstruction Registry) with regard to early surgery-related complications.

METHODS

Early complications within 30 days, medical history, mortality rates, and neurological outcome at discharge according to the modified Rankin Scale (mRS) were evaluated. The primary endpoint was death or surgical revision within the first 30 days after CP. Independent factors for the occurrence of complications with or without surgical revision were identified using a logistic regression model.

RESULTS

Traumatic brain injury (TBI) and ischemic stroke were the most common underlying diagnoses that required CP. In 230 patients (45.8%), an autologous bone flap was utilized for CP; the most common engineered materials were titanium (80 patients [15.9%]), polyetheretherketone (57 [11.4%]), and polymethylmethacrylate (57 [11.4%]). Surgical revision was necessary in 45 patients (9.0%), and the overall mortality rate was 0.8% (4 patients). The cause of death was related to ischemia in 2 patients, diffuse intraparenchymal hemorrhage in 1 patient, and cardiac complications in 1 patient. The most frequent causes of surgical revision were epidural hematoma (40.0% of all revisions), new hydrocephalus (22.0%), and subdural hematoma (13.3%). Preoperatively increased mRS score (OR 1.46, 95% CI 1.08-1.97, p = 0.014) and American Society of Anesthesiologists Physical Status Classification System score (OR 2.89, 95% CI 1.42-5.89, p = 0.003) were independent predictors of surgical revision. Ischemic stroke, as the underlying diagnosis, was associated with a minor rate of revisions compared with TBI (OR 0.18, 95% CI 0.06-0.57, p = 0.004).

CONCLUSIONS

The authors have presented class II evidence-based data on surgery-related complications after CP and have identified specific preexisting risk factors. These results may provide additional guidance for optimized treatment of these patients.

The utility of routine autologous bone-flap swab cultures in predicting post-cranioplasty infection

Objective:

To evaluate the utility of autologous bone-flap swab cultures performed at the time of cranioplasty in predicting postcranioplasty surgical site infection (SSI).

Design:

Retrospective cohort study.

Participants:

Patients undergoing craniectomy (with bone-flap storage in tissue bank), followed by delayed autologous bone-flap replacement cranioplasty between January 1, 2010, and November 30, 2020.

Setting:

Tertiary-care academic hospital.

Methods:

We framed the bone-flap swab culture taken at the time of cranioplasty as a diagnostic test for predicting postcranioplasty SSI. We calculated, sensitivity, specificity, positive and negative predictive values, and positive and negative likelihood ratios.

Results:

Among 282 unique eligible cases, 16 (5.6%) developed SSI after cranioplasty. A high percentage of bone-flap swab cultures were positive at the time of craniectomy (66.7%) and cranioplasty (59.5%). Most organisms from bone-flap swab cultures were Cutibacterium acnes or coagulase-negative staphylococci (76%–85%), and most SSI pathogens were methicillin-susceptible Staphylococcus aureus (38%). Bone-flap swab culture had poor sensitivity (0.07; 95% CI, 0.01–0.31), specificity (0.4; 95% CI, 0.34–0.45), and positive likelihood ratio (0.12) for predicting postcranioplasty SSI.

Conclusion:

Overall, autologous bone-flap swab cultures performed at the time of cranioplasty have poor utility in predicting postcranioplasty SSI. Eliminating this low-value practice would result in significant workload reductions and associated healthcare costs.

Cryopreservation of autologous bone flaps following decompressive craniectomy: A new method reduced positive cultures without increase in post-cranioplasty infection rate

Introduction

Cranioplasty (CP) after decompressive craniectomy (DC) is a common neurosurgical procedure. Implementation of European Union (EU) directives recommending bacterial cultures before cryopreservation, lead to increased number of autologous bone flaps being discarded due to positive cultures. A new method for handling bone flaps prior to cryopreservation, including the use of pulsed lavage, was developed.

Research question

The aim was to evaluate the effect of a new method on proportion of positive bacterial cultures and surgical site infection (SSI) following CP surgery.

Material and methods

Sixty-one bone flaps from 53 consecutive DC surgery patients were retrospectively included and the study period was divided into before and after method implementation. Patient demographics, laboratory and culture results, type of CP and occurrence of SSI were analyzed.

Results

Twenty-six and 18 bone flaps were available for analysis during the first and second period, respectively. The proportion of positive bacterial cultures was higher in the first period compared to the second (n ​= ​9(35%) vs 0(0%); p ​= ​0.001), and thus the use of custom made implants was considerably higher in the first study period (p ​= ​0.001). There was no difference in the frequency of post-cranioplasty SSI between the first and second study period (n ​= ​3 (11.5%) vs 1 (4.8%), p ​= ​0.408).

Discussion and conclusion

The new method for handling bone flaps resulted in a lower frequency of positive bacterial cultures, without increased frequency of post-cranioplasty SSI, thus demonstrating it is safe to use, allows compliance with the EU-directives, and may reduce unnecessary discarding of bone flaps.

•

New method of bone flap handling and preservation reduced positive bacterial cultures from 35% to 0%.

•

The new method used pulsed lavage of bone flap with saline solution and subsequent swab culture.

•

There was no increase in post-cranioplasty surgical site infection following introduction of the new method.

[Features of modeling a polymer implant for closing a defect after decompressive craniotomy]

BACKGROUND

Individual polymer implants are widespread for bone reconstruction after decompressive craniectomy. Despite the availability of customized titanium products, various specialists and hospitals prefer polymer implants.

OBJECTIVE

To compare the methods of modeling and manufacturing the polymethylmethacrylate implants and identify the features affecting the quality of reconstruction.

MATERIAL AND METHODS

We analyzed 14 patients with extensive skull defects after installation of polymethyl methacrylate implants. Software used for modeling of individual implants by different specialists was compared.

RESULTS

Satisfactory reconstruction result was obtained in all cases. There were no infectious complications. The authors outlined certain important aspects for modeling of individual polymer products: local use of anatomical thickness of the implant, leaving safe spaces, prevention of temporal retraction, template-based resection before reconstruction.

CONCLUSION

To date, skull defect closure with polymeric materials remains relevant, and even has certain advantages over customized titanium products.

Two-center validation of the Oulu resorption score for bone flap resorption after autologous cranioplasty

OBJECTIVE

Autologous bone has been the gold standard of cranioplasty materials for decades. Unique to autologous cranioplasty, bone flap resorption is a poorly understood and unclearly defined complication. Even further, it has been unclear, whether the resorption process eventually stabilizes over time. Thus, the sufficient follow-up period after autologous cranioplasty is unknown. The Oulu Resorption Score (ORS) is a straight-forward classification system for the radiological interpretation of bone flap resorption. The aims of the present study were to evaluate the reliability of the ORS using intra-class correlation coefficient (ICC) and to assess the temporal progression of the resorption process.

METHODS

We identified 108 consecutive autologous cranioplasty patients treated between 2005 and 2018 in two tertiary referral centers. All 365 head CT scans the patients had undergone were evaluated using the ORS in a blinded, independent two-center setting. Intra- and inter-observer reliabilities were calculated. The ORS was applied to study the temporal progression of the resorption process.

RESULTS

The intra-observer reliability of the ORS was excellent (ICC 0.94, 95%CI 0.93-0.95). Inter-observer reliability was good-to-excellent (ICCs 0.87 and 0.89, 95%CIs 0.84-0.89 and 0.87-0.91, respectively). In scatterplot smoothing analyses, the progression of bone flap resorption appeared to stabilize 12-24 months after cranioplasty.

CONCLUSIONS

ORS is the only validated radiological tool for the standardized analysis of bone flap resorption after autologous cranioplasty. Evaluated using the ORS, the resorption process seemed to stabilize during the first two postoperative years after cranioplasty, suggesting that the sufficient follow-up time after autologous cranioplasty is two years.

Predictive Value of Swab Cultures for Cryopreserved Flaps During Delayed Cranioplasties

OBJECTIVE

To assess the predictive value of swab cultures of cryopreserved skull flaps during cranioplasties for surgical site infections (SSIs).

METHODS

A retrospective review was conducted of consecutive patients who underwent delayed cranioplasties with cryopreserved autografts between 2009 and 2017. The results of cultures obtained from swabs and infected surgical sites were assessed. The accuracy, sensitivity, and specificity of swab cultures for SSIs were evaluated.

RESULTS

The study included 422 patients categorized into two groups, swab and nonswab, depending on whether swab cultures were implemented during cranioplasties. The overall infection rate was 7.58%. No difference was seen in infection rates between groups. There were 18 false-positive and no true-positive swab culture results. All bacteria between swab cultures and SSI cultures were discordant. Meanwhile, there were 19 false-negative swab cultures. The results showed high specificity but low sensitivity for swab cultures to predict SSI occurrence and the pathogens.

CONCLUSIONS

Owing to low accuracy and sensitivity, swab cultures of cryopreserved autografts should not be routinely performed during delayed cranioplasties.

Decompressive Craniectomy and Risk of Wound Infection After Microsurgical Treatment of Ruptured Aneurysms

BACKGROUND

Owing to prolonged hospitalization and the complexity of care required for patients with aneurysmal subarachnoid hemorrhage (aSAH), these patients have a high risk of complications. The risk for wound infection after microsurgical treatment for aSAH was analyzed.

METHODS

All patients who underwent microsurgical treatment for aSAH between August 1, 2007, and July 31, 2019, and were recorded in the Post-Barrow Ruptured Aneurysm Trial database were retrospectively reviewed. The patients were analyzed for risk factors for wound infection after treatment.

RESULTS

Of 594 patients who underwent microsurgical treatment for aSAH, 23 (3.9%) had wound infections. There was no significant difference in age between patients with wound infection and patients without infection (mean, 52.6 ± 12.2 years vs. 54.2 ± 4.0 years; P = 0.45). The presence of multiple comorbidities (including diabetes, tobacco use, and obesity), external ventricular drain, ventriculoperitoneal shunt, pneumonia, or urinary tract infection was not associated with an increased risk for wound infection. Furthermore, there was no significant difference in mean operative time between patients with wound infection and those without infection (280 ± 112 minutes vs. 260 ± 92 minutes; P = 0.38). Patients who required decompressive craniectomy (DC) were at increased risk of wound infection (odds ratio, 5.0; 95% confidence interval, 1.8-14.1; P = 0.002). Among the 23 total infections, 9 were diagnosed following cranioplasty after DC.

CONCLUSIONS

Microsurgical treatment for aSAH is associated with a relatively low risk of wound infection. However, patients undergoing DC may be at an increased risk for infection. Additional attention and comprehensive wound care are warranted for these patients.

Treatment of Osteomyelitic Bone Following Cranial Vault Reconstruction With Delayed Reimplantation of Sterilized Autologous Bone: A Novel Technique for Cranial Reconstruction in the Pediatric Patient

ABSTRACT

Craniosynostosis, a deformity of the skull caused by premature fusion of ≥1 cranial sutures, is treated surgically via endoscopic approaches or cranial vault remodeling. Postoperative infection is rare. Management of postoperative surgical site infections often involves culture-directed intravenous antibiotics and debridement, with removal of osteomyelitic bone and hardware in refractory cases. Removal of autologous bone in a pediatric patient presents a reconstructive challenge, as alloplastic options are not optimal in a growing child, especially in the setting of infection. Moreover, infants and small children have limited autologous bone options for reconstruction. We present our case of a young child who developed an infectious complication following cranial vault remodeling. The patient's demographic information, clinical presentation and postoperative course, radiologic features, surgical interventions, and treatment outcomes were reviewed. In our case, autologous osteomyelitic bone underwent tissue processing to eradicate the infection and complete skull reconstruction using the patient's own processed autologous bone was performed in a delayed fashion. The patient is now 1 year postoperative with no recurrence of infection. We present this case as a novel technique to eradicate infection in autologous bone, allowing for delayed autologous cranial reconstruction.

Complications of cranioplasty in relationship to traumatic brain injury: a systematic review and meta-analysis

Despite being a common procedure, cranioplasty (CP) is associated with a variety of serious, at times lethal, complications. This study explored the relationship between the initial injury leading to decompressive craniectomy (DC) and the rates and types of complications after subsequent CP. It specifically compared between traumatic brain injury (TBI) patients and patients undergoing CP after DC for other indications.A comprehensive search of PubMed, Scopus, and the Cochrane Library databases using PRISMA guidelines was performed to include case-control studies, cohorts, and clinical trials reporting complication data for CP after DC. Information about the patients' characteristics and the rates of overall and specific complications in TBI and non-TBI patients was extracted, summarized, and analyzed.A total of 59 studies, including the authors' institutional experience, encompassing 9264 patients (4671 TBI vs. 4593 non-TBI) met the inclusion criteria; this total also included 149 cases from our institutional series. The results of the analysis of the published series are shown both with and without our series 23 studies reported overall complications, 40 reported infections, 10 reported new-onset seizures, 13 reported bone flap resorption (BFR), 5 reported post-CP hydrocephalus, 10 reported intracranial hemorrhage (ICH), and 8 reported extra-axial fluid collections (EFC). TBI was associated with increased odds of BFR (odds ratio [OR] 1.76, p < 0.01) and infection (OR 1.38, p = 0.02). No difference was detected in the odds of overall complications, seizures, hydrocephalus, ICH, or EFC.Awareness of increased risks of BFR and infection after CP in TBI patients promotes the implementation of new strategies to prevent these complications especially in this category of patients.

An altered posterior question-mark incision is associated with a reduced infection rate of cranioplasty after decompressive hemicraniectomy

OBJECTIVE

Performing a cranioplasty (CP) after decompressive craniotomy is a straightforward neurosurgical procedure, but it remains associated with a high complication rate. Surgical site infection (SSI), aseptic bone resorption (aBR), and need for a secondary CP are the most common complications. This observational study aimed to identify modifiable risk factors to prevent CP failure.

METHODS

A retrospective analysis was performed of all patients who underwent CP following decompressive hemicraniectomy (DHC) between 2010 and 2018 at a single institution. Predictors of SSI, aBR, and need for allograft CP were evaluated in a univariate analysis and multivariate logistic regression model.

RESULTS

One hundred eighty-six patients treated with CP after DHC were included. The diagnoses leading to a DHC were as follows: stroke (83 patients, 44.6%), traumatic brain injury (55 patients, 29.6%), subarachnoid hemorrhage (33 patients, 17.7%), and intracerebral hemorrhage (15 patients, 8.1%). Post-CP SSI occurred in 25 patients (13.4%), whereas aBR occurred in 32 cases (17.2%). An altered posterior question-mark incision, ending behind the ear, was associated with a significantly lower infection rate and CP failure, compared to the classic question-mark incision (6.3% vs 18.4%; p = 0.021). The only significant predictor of aBR was patient age, in which those developing resorption were on average 16 years younger than those without aBR (p < 0.001).

CONCLUSIONS

The primary goal of this retrospective cohort analysis was to identify adjustable risk factors to prevent post-CP complications. In this analysis, a posterior question-mark incision proved beneficial regarding infection and CP failure. The authors believe that these findings are caused by the better vascularized skin flap due to preservation of the superficial temporal artery and partial preservation of the occipital artery. In this trial, the posterior question-mark incision was identified as an easily and costless adaptable technique to reduce CP failure rates.

Complications Following Decompressive Craniectomy

BACKGROUND

 Decompressive craniectomy (DC) has become the definitive surgical procedure to manage a medically intractable rise in intracranial pressure. DC is a life-saving procedure resulting in lower mortality but also higher rates of severe disability. Although technically straightforward, DC is accompanied by many complications. It has been reported that complications are associated with worse outcome. We reviewed a series of patients who underwent DC at our department to establish the incidence and types of complications.

METHODS

 We retrospectively evaluated the incidence of complications after DC performed in 135 patients during the time period from January 2013 to December 2018. Postoperative complications were evaluated using clinical status and CT during 6 months of follow-up. In addition, the impact of potential risk factors on the incidence of complications and the impact of complications on outcome were assessed.

RESULTS

 DC was performed in 135 patients, 93 of these for trauma, 22 for subarachnoid hemorrhage, 13 for malignant middle cerebral artery infarction, and 7 for intracerebral hemorrhage. Primary DC was performed in 120 patients and secondary DC in 15 patients. At least 1 complication occurred in each of 100 patients (74%), of which 22 patients (22%) were treated surgically. The following complications were found: edema or hematoma of the temporal muscle (34 times), extracerebral hematoma (33 times), extra-axial fluid collection (31 times), hemorrhagic progression of contusions (19 times), hydrocephalus (12 times), intraoperative malignant brain edema (10 times), temporal muscle atrophy (7 times), significant intraoperative blood loss (6 times), epileptic seizures (5 times), and skin necrosis (4 times). Trauma (p = 0.0006), coagulopathy (p = 0.0099), and primary DC (p = 0.0252) were identified as risk factors for complications. There was no significant impact of complications on outcome.

CONCLUSIONS

 The incidence of complications following DC is high. However, we did not confirm a significant impact of complications on outcome. We emphasize that some phenomena are so frequent that they can be considered a consequence of primary injury or natural sequelae of the DC rather than its direct complication.

Consensus statement from the international consensus meeting on post-traumatic cranioplasty

Background

Due to the lack of high-quality evidence which has hindered the development of evidence-based guidelines, there is a need to provide general guidance on cranioplasty (CP) following traumatic brain injury (TBI), as well as identify areas of ongoing uncertainty via a consensus-based approach.

Methods

The international consensus meeting on post-traumatic CP was held during the International Conference on Recent Advances in Neurotraumatology (ICRAN), in Naples, Italy, in June 2018. This meeting was endorsed by the Neurotrauma Committee of the World Federation of Neurosurgical Societies (WFNS), the NIHR Global Health Research Group on Neurotrauma, and several other neurotrauma organizations. Discussions and voting were organized around 5 pre-specified themes: (1) indications and technique, (2) materials, (3) timing, (4) hydrocephalus, and (5) paediatric CP.

Results

The participants discussed published evidence on each topic and proposed consensus statements, which were subject to ratification using anonymous real-time voting. Statements required an agreement threshold of more than 70% for inclusion in the final recommendations.

Conclusions

This document is the first set of practical consensus-based clinical recommendations on post-traumatic CP, focusing on timing, materials, complications, and surgical procedures. Future research directions are also presented.

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.

Reduction in the infection rate of cranioplasty with a tailored antibiotic prophylaxis: a nonrandomized study

BACKGROUND

Cranioplasty carries a high risk of surgical site infections (SSIs) for a scheduled procedure, particularly with antibiotic-resistant bacteria.

METHODS

The goal of this retrospective study was to measure the effect of tailored antibiotic prophylaxis on SSIs resulting from cranioplasties. The authors collected a prospective database of cranioplasties from 2009 to 2018. Risk factors for SSI were registered, as well as infection occurring during the first year postoperatively. A new protocol was initiated in 2016 consisting of antibiotic prophylaxis tailored to the colonizing flora of the skin of the scalp and decolonization of patients who were nasal carriers of methicillin-resistant S. aureus (MRSA); infection rates were compared.

RESULTS

One hundred nine cranioplasties were identified, 64 in the old protocol and 45 in the new protocol. Of the 109 cranioplasties, 16 (14.7%) suffered an infection, 14 (21.9%) in the old protocol group and 2 (4.4%) in the new protocol group (OR for the new protocol 0.166, 95% CI 0.036-0.772). Multiple surgeries (OR 3.44), Barthel ≤ 70 (OR 3.53), and previous infection (OR 3.9) were risk factors for SSI. Of the bacteria identified in the skin of the scalp, 22.2% were resistant to routine prophylaxis (cefazoline). Only one patient was identified as a nasal carrier of MRSA and was decolonized.

CONCLUSIONS

A high percentage of bacteria resistant to routine prophylaxis (cefazoline) was identified in the skin of these patients' scalps. The use of tailored antibiotic prophylaxis reduced significantly the infection rate in this particular set of patients.

Comparison of Postoperative Surgical-Site Infection and Symptomatic Intracranial Hemorrhage between Staged and Simultaneous Cranioplasty with Ventriculoperitoneal Shunt Placement: A Meta-Analysis

Objective

Consensus about the sequence of cranioplasty and ventriculoperitoneal shunt placement to reduce postoperative complications has not been established. This meta-analysis investigated and collated further evidence to determine whether staged cranioplasty with ventriculoperitoneal shunt placement would significantly reduce the risk of postoperative surgical-site infection (SSI) and symptomatic intracranial hemorrhage.

Methods

Two independent reviewers identified articles and extracted the data of patients who underwent cranioplasty and ventriculoperitoneal shunt placement from PubMed, Embase, and Cochrane Central Register of Controlled Trials. A random effects model was used to compare the complication rates using odd ratios (ORs) and 95% confidence intervals (CIs). A meta-regression analysis for traumatic brain injury (TBI) was additionally performed.

Results

Data from 7 studies with 391 patients were consecutively included. The meta-analysis revealed that staged surgery was significantly associated with lower rates of SSI after decompressive craniectomy (staged group vs. simultaneous group: 6.2% vs. 23.7%, OR: 2.72, 95% CI: 1.46–5.06, I²=2.4%, p=0.407). Pooled analysis did not indicate a statistically significant difference between the 2 groups for symptomatic intracranial hemorrhage (staged group vs. simultaneous group: 10.4% vs. 23.0%, OR: 1.66, 95% CI: 0.74–3.73, I²=0.0%, p=0.407). The meta-regression analysis did not indicate any modifying effect of TBI on postoperative SSI development (p=0.987).

Conclusion

This meta-analysis indicated that staged surgery is significantly associated with a lower rate of postoperative SSI as compared with simultaneous surgery, but there is no difference in symptomatic intracranial hemorrhage. Additionally, there is no modifying effect of TBI on SSI.

Establishment and Characteristic Analysis of a Dog Model for Autologous Homologous Cranioplasty

Objective

The aim of this study is to establish a large animal (dog) model that can be referred clinically for autologous homologous cranioplasty.

Methods

Our large skull defect dog model was established by emulating the decompressive craniectomy with 22 adult beagle dogs. The autologous bones were taken out from the dogs and divided into two groups, the freeze-drying (FD) group and the single freezing (SF) group. They were then stored in the bone bank at -20°C after being irradiated with 25 KGy. Three months later, the bones were reimplanted. After operation, we closely watch the experimental objects for four more months examining the infection and survival of the bone graft.

Results

Through macroscopic observation, it was found that, among 44 cranial flaps (bilateral) from the rest of the 22 dogs, grade A cranial flaps accounted for 86.4% (19/22) in the SF group and only 31.8% (7/22) in the FD group. Although osteogenic osteoclast, Harvard tube, neovascularization, and angiogenic factors were found through the pathological results, including an electron microscope and calmodulin tracer, it could be verified by using X-CT and micro-CT that early bone resorption could be still found even in grade A bone flap.

Conclusion

By using the common clinical method to preserve the cranial flaps, we established an experimental dog model of autologous cranioplasty for a large area of cranial defect. It was proved that this model could reproduce the infections and bone resorption which typically happened in clinical autologous homologous cranioplasty. As a conclusion, the established model can be used as an effective experimental tool for further research to improve the success rate of autologous homologous cranioplasty.

Cranioplasty Following Decompressive Craniectomy

Cranioplasty (CP) after decompressive craniectomy (DC) for trauma is a neurosurgical procedure that aims to restore esthesis, improve cerebrospinal fluid (CSF) dynamics, and provide cerebral protection. In turn, this can facilitate neurological rehabilitation and potentially enhance neurological recovery. However, CP can be associated with significant morbidity. Multiple aspects of CP must be considered to optimize its outcomes. Those aspects range from the intricacies of the surgical dissection/reconstruction during the procedure of CP, the types of materials used for the reconstruction, as well as the timing of the CP in relation to the DC. This article is a narrative mini-review that discusses the current evidence base and suggests that no consensus has been reached about several issues, such as an agreement on the best material for use in CP, the appropriate timing of CP after DC, and the optimal management of hydrocephalus in patients who need cranial reconstruction. Moreover, the protocol-driven standards of care for traumatic brain injury (TBI) patients in high-resource settings are virtually out of reach for low-income countries, including those pertaining to CP. Thus, there is a need to design appropriate prospective studies to provide context-specific solid recommendations regarding this topic.

Autogenous Bone Cranioplasty: Review of a 42-Year Experience by a Single Surgeon

BACKGROUND

Autogenous bone is frequently espoused as the gold standard material for cranioplasty procedures, yet alloplastic cranioplasty continues to persist in the search, presumably, for a simpler technique. Although short-term outcomes can be successful using foreign materials, long-term follow-up in these patients often demonstrates increased rates of failure because of exposure or late infection. Autogenous bone grafts, however, integrate and revascularize, and are thus more resistant to infection than alloplastic materials.

METHODS

This is a retrospective review of all patients that underwent reconstructive cranioplasty for full-thickness defects, as performed by the senior author (S.A.W.) between 1975 and 2018. All procedures were performed with autogenous bone.

RESULTS

One hundred fifty-four patients met criteria for inclusion in the report. Cranioplasties were performed for both congenital and secondary indications. Split calvaria was used in 115 patients (74.7 percent), rib graft was used in 12 patients (7.8 percent), iliac crest graft was used in 10 patients (6.5 percent), and combinations of donor-site grafts were used in 17 patients (11.0 percent). In the entire series, none of the patients suffered from complications related to infection of either the donor site or transferred bone graft. None of the patients required secondary operations to fill in defects created by the postoperative resorption.

CONCLUSIONS

Although autologous bone is widely considered the gold standard material for cranioplasty procedures, some argue against its use, mainly citing unpredictable resorption as the purported disadvantage. However, it is less susceptible to infection, and results in fewer long-term complications than alloplastic materials. There is no alloplastic material that has matched these outcomes, and thus autogenous bone should be considered as the primary option for cranioplasty procedures.

CLINICAL QUESTION/LEVEL OF EVIDENCE

Therapeutic, IV.

Is Three-Dimensional Virtual Planning in Cranial Reconstruction for Advanced Cutaneous Squamous Cell Carcinoma of the Skull a Feasible Option?

BACKGROUND

Cutaneous squamous cell carcinoma (cSCC) is a common type of malignant skin disorder. An uncommon feature is local bony invasion, as can rarely be seen in lesions on the scalp. The optimal treatment strategy in these rare cases is still under debate.

OBJECTIVE

The aim of this case report is to present a 1-stage three-dimensional planned surgical resection and reconstruction of a cSCC with bony invasion into the scalp and to discuss the alternative options and potential pitfalls.

MATERIALS AND METHODS

A patient diagnosed with rT4N0M0 cSCC of the scalp underwent a cranial resection and reconstruction in 1 stage. With the use of computer-assisted design and computer-assisted manufacturing a patient-specific implant (PSI) of poly (ether ether ketone) was manufactured. After the PSI was inserted, it was covered with a latissimus dorsi muscle and a split-thickness skin graft.

RESULTS

Intraoperatively the resection template generated an accurate resection and accurate and fast placement of the PSI. The reconstruction had a clinical satisfactory esthetic result, but was hampered by the development of a small wound dehiscence was observed over the postoperative course.

CONCLUSION

Three-dimensional planned resection and reconstruction for composite defects of the skull after resection of a cSCC of the scalp with bony invasion may lead to an accurate and predictable resection and accurate and fast placement of the PSI. However, patient specific characteristics should be considered to assess potential risks and benefits before opting for this one-stage treatment strategy.

Early autologous cranioplasty: complications and identification of risk factors using virtual reality visualisation technique

Background: Cranioplasty (CP) of autologous bone flap after decompressive craniectomy (DC) is known to be associated with a high complication rate, particularly bone flap resorption (BFR). In a retrospective study, we used a novel virtual reality (VR) visualisation technique to identify and evaluate risk factors associated with CP.Method: Twenty-five patients underwent early autologous CP. All complications were recorded. Cranial computed tomography scans were visualised via the VR software to access the fitting accuracy of the bone flap (bone flap size, gap width at trepanation cutting edge, extent of osteoclastic extension).Results: An overall complication rate of 44% was seen, and BFR was the most common (36%). Only 'osteoclastic extension of trepanation' (p = .04) was a significant risk factor for BFR. The factors 'indication for DC' (p = .09) and 'size of bone flap' (p = .09) had a tendency towards influencing the rate of BFR, while 'age' (p = .68), 'time interval between DC and CP' (p = 1.00), and 'gap width' (p = .50) were not considered to influence the BFR rate.Conclusions: DC and subsequent CP is a complication-prone procedure. Therefore, it is relevant to identify and quantify probable risk factors for the most common complications, such as BFR. Here, we found that the extent of osteoclastic extension may impair the patient's healing process. Our investigation was made considerably easier by using the novel VR visualisation technique, which allows parallax free measurements of distances in 3D space.

Cranioplasty Using Autoclaved Autologous Skull Bone Flaps Preserved at Ambient Temperature

Context

Decompressive craniectomy followed by cranioplasty (CP) uses autologous craniectomy flaps or synthetic materials like titanium. Sterilization and preservation methods for the autologous bone flaps continue to be the surgeon's choice.

Aim

This study aimed to assess the short-term as well as long-term clinical outcomes of CP using autoclaved autologous bone grafts.

Settings and Design

This retrospective observational study was performed on patients admitted in a tertiary care teaching neurosurgery department.

Patients and Methods

Seventy-two patients who underwent CP with autoclaved autologous skull flaps preserved under ambient conditions with strict aseptic precautions were included in the study.

Statistical Analysis Used

Frequencies and percentages of the various characteristics before and after the surgery were tabulated. Continuous variables were summarized as means and standard deviations.

Results

The primary CP had a satisfactory clinical outcome in 62 cases (86.11%). Osteomyelitis was observed in four patients (5.56%) nearly 2 months after the surgery. Radiologically significant bone resorption was noted in a single patient (1.39%) after 1 year. Five patients (6.94%) developed bone fragmentation or fracture, and the mean time taken for this was about 36 months. In all these ten cases, secondary CP was successfully done using a prefabricated, patient-specific titanium mesh.

Conclusions

The efficacy and safety of the studied craniectomy flaps used for cranial reconstruction showed a good patient outcome. Further retrospective studies with larger cohorts and prospective case-control studies are essential so as to issue standard guidelines for sterilization and preservation of autologous bone flaps.

Consensus statement from the International Consensus Meeting on the Role of Decompressive Craniectomy in the Management of Traumatic Brain Injury : Consensus statement

BACKGROUND

Two randomised trials assessing the effectiveness of decompressive craniectomy (DC) following traumatic brain injury (TBI) were published in recent years: DECRA in 2011 and RESCUEicp in 2016. As the results have generated debate amongst clinicians and researchers working in the field of TBI worldwide, it was felt necessary to provide general guidance on the use of DC following TBI and identify areas of ongoing uncertainty via a consensus-based approach.

METHODS

The International Consensus Meeting on the Role of Decompressive Craniectomy in the Management of Traumatic Brain Injury took place in Cambridge, UK, on the 28th and 29th September 2017. The meeting was jointly organised by the World Federation of Neurosurgical Societies (WFNS), AO/Global Neuro and the NIHR Global Health Research Group on Neurotrauma. Discussions and voting were organised around six pre-specified themes: (1) primary DC for mass lesions, (2) secondary DC for intracranial hypertension, (3) peri-operative care, (4) surgical technique, (5) cranial reconstruction and (6) DC in low- and middle-income countries.

RESULTS

The invited participants discussed existing published evidence and proposed consensus statements. Statements required an agreement threshold of more than 70% by blinded voting for approval.

CONCLUSIONS

In this manuscript, we present the final consensus-based recommendations. We have also identified areas of uncertainty, where further research is required, including the role of primary DC, the role of hinge craniotomy and the optimal timing and material for skull reconstruction.

Gentamicin loading of calcium phosphate implants: implications for cranioplasty

Background

Surgical site infections (SSI) are a significant risk in cranioplasty, with reported rates of around 8–9%. The most common bacteria associated with these nosocomial infections are of the Staphylococcus species, which have the ability to form biofilm. The possibility to deliver antibiotics, such as gentamicin, locally rather than systemically could potentially lower the early postoperative SSI. Various antibiotic dosages are being applied clinically, without any true consensus on the effectiveness.

Methods

Drug release from calcium phosphate (CaP), polyetheretherketone (PEEK), and titanium (Ti) samples was evaluated. Microbiological studies with Staphylococcus aureus (SA) and Staphylococcus epidermidis (SE) including strains from clinical infection were used to establish clinically relevant concentrations.

Results

The CaP samples were able to retain and release gentamicin overtime, whereas the Ti and PEEK samples did not show any drug uptake or release. A gentamicin loading concentration of 400 μg/ml was shown to be effective in in vitro microbiological studies with both SA and SE.

Conclusions

Out of the three materials studied, only CaP could be loaded with gentamicin. An initial loading concentration of 400 μg/ml appears to establish an effective gentamicin concentration, possibly translating into a clinical benefit in cranioplasty.

Predictors of primary autograft cranioplasty survival and resorption after craniectomy

OBJECTIVE

Craniectomy is a common neurosurgical procedure that reduces intracranial pressure, but survival necessitates cranioplasty at a later stage, after recovery from the primary insult. Complications such as infection and resorption of the autologous bone flap are common. The risk factors for complications and subsequent bone flap removal are unclear. The aim of this multicenter, retrospective study was to evaluate the factors affecting the outcome of primary autologous cranioplasty, with special emphasis on bone flap resorption.

METHODS

The authors identified all patients who underwent primary autologous cranioplasty at 3 tertiary-level university hospitals between 2002 and 2015. Patients underwent follow-up until bone flap removal, death, or December 31, 2015.

RESULTS

The cohort comprised 207 patients with a mean follow-up period of 3.7 years (SD 2.7 years). The overall complication rate was 39.6% (82/207), the bone flap removal rate was 19.3% (40/207), and 11 patients (5.3%) died during the follow-up period. Smoking (OR 3.23, 95% CI 1.50-6.95; p = 0.003) and age younger than 45 years (OR 2.29, 95% CI 1.07-4.89; p = 0.032) were found to independently predict subsequent autograft removal, while age younger than 30 years was found to independently predict clinically relevant bone flap resorption (OR 4.59, 95% CI 1.15-18.34; p = 0.03). The interval between craniectomy and cranioplasty was not found to predict either bone flap removal or resorption.

CONCLUSIONS

In this large, multicenter cohort of patients with autologous cranioplasty, smoking and younger age predicted complications leading to bone flap removal. Very young age predicted bone flap resorption. The authors recommend that physicians extensively inform their patients of the pronounced risks of smoking before cranioplasty.

Reconstruction of a Calvarial Wound Complicated by Infection: Comparing the Effects of Biopatterned Bone Morphogenetic Protein 2 and Vascular Endothelial Growth Factor

Bone morphogenetic protein 2 (BMP2) bioprinted on biological matrix induces osseous regeneration in large calvarial defects in rabbits, both uncomplicated and scarred. Healing in unfavorable defects scarred from previous infection is decreased due in part to the lack of vascularity. This impedes the access of mesenchymal stem cells, key to osseous regeneration and the efficacy of BMP2, to the wound bed. The authors hypothesized that bioprinted vascular endothelial growth factor (VEGF) would augment the osseous regeneration achieved with low dose biopatterned BMP2 alone. Thirteen New Zealand white rabbits underwent subtotal calvariectomy using a dental cutting burr. Care was taken to preserve the underlying dura. A 15 mm × 15 mm flap of bone was cut away and incubated in a 1 × 108 cfu/mL planktonic solution of S aureus before reimplantation. After 2 weeks of subsequent infection the flap was removed and the surgical wound debrided followed by 10 days of antibiotic treatment. On postoperative day 42 the calvarial defects were treated with acellular dermal matrix bioprinted with nothing (control), VEGF, BMP2, BMP2/VEGF combined. Bone growth was analyzed with serial CT and postmortem histology. Defects treated with BMP2 (BMP2 alone and BMP2/VEGF combination) showed significantly greater healing than control and VEGF treated defect (P < 0.5). Vascular endothelial growth factor treated defect demonstrated less healing than control and VEGF/BMP2 combination treatments achieved less healing than BMP2 alone though these differences were nonsignificant. Low dose BMP2-patterned acellular dermal matrix improves healing of scarred calvarial defects. Vascular endothelial growth factor at the doses applied in this study failed to increase healing.

Factors related to failure of autologous cranial reconstructions after decompressive craniectomy

PURPOSE

Cranioplasty is customary after decompressive craniectomy. Many different materials have been developed and used for this procedure. The ideal material does not yet exist, while complication rates in cranioplasties remain high. This study aimed to determine factors related to autologous bone flap failure.

MATERIALS AND METHODS

In this two-center retrospective cohort study, 276 patients underwent autologous bone cranioplasty after initial decompressive craniectomy between 2004 and 2014. Medical records were reviewed regarding patient characteristics and factors potentially related to bone flap failure. Data were analyzed using univariable and multivariable regression analysis.

RESULTS

Independent factors related to overall bone flap failure were: duration of hospitalization after decompressive craniectomy [OR: 1.012 (95%CI: 1.003-1.022); p = 0.012], time interval between decompressive craniectomy and cranioplasty [OR: 1.018 (95%CI: 1.004-1.032); p = 0.013], and follow-up duration [OR: 1.034 (95%CI: 1.020-1.047); p < 0.001]. In patients with bone flap infection, neoplasm as initial diagnosis occurred significantly more often (29.2% vs. 7.8%; RD 21.3%; 95%CI 8.4 -38.3%; NNH 5; 95%CI 3 -12) and duration of hospitalization after decompressive craniectomy tended to be longer (means 54 vs. 28 days, MD 26.2 days, 95%CI -8.6 to 60.9 days). Patients with bone flap resorption were significantly younger (35 vs. 43 years, MD 7.7 years, 95%CI 0.8-14.6 years) and their cranial defect size tended to be wider than in patients without bone flap resorption (mean circumference 39 vs. 37 cm; MD 2.4 cm, 95% CI -0.43-5.2 cm) and follow-up duration was significantly longer (44 vs. 14 months, MD 29 months, 95%CI 17-42 months).

CONCLUSION

A neoplasm as initial diagnosis, longer hospitalization after decompressive craniectomy, larger time interval between decompressive craniectomy and cranioplasty, and longer follow-up duration are associated with a higher risk of failure of autologous bone flaps for cranioplasty. Patients with these risk factors may be better served with an early recovery program after decompressive surgery or an alloplastic material for cranioplasty.

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.

A polycaprolactone-β-tricalcium phosphate-heparan sulphate device for cranioplasty

BACKGROUND

Cranioplasty is a surgical procedure used to treat a bone defect or deformity in the skull. To date, there is little consensus on the standard-of-care for graft materials used in such a procedure. Graft materials must have sufficient mechanical strength to protect the underlying brain as well as the ability to integrate and support new bone growth. Also, the ideal graft material should be individually customized to the contours of the defect to ensure a suitable aesthetic outcome for the patient.

PURPOSE

Customized 3D-printed scaffolds comprising of polycaprolactone-β-tricalcium phosphate (PCL-TCP) have been developed with mechanical properties suitable for cranioplasty. Osteostimulation of PCL-TCP was enhanced through the addition of a bone matrix-mimicking heparan sulphate glycosaminoglycan (HS3) with increased affinity for bone morphogenetic protein-2 (BMP-2). Efficacy of this PCL-TCP/HS3 combination device was assessed in a rat critical-sized calvarial defect model.

METHOD

Critical-sized defects (5 mm) were created in both parietal bones of 19 Sprague Dawley rats (Male, 450-550 g). Each cranial defect was randomly assigned to 1 of 4 treatment groups: (1) A control group consisting of PCL-TCP/Fibrin alone (n = 5); (2) PCL-TCP/Fibrin-HSft (30 μg) (n = 6) (HSft is the flow-through during HS3 isolation that has reduced affinity for BMP-2); (3) PCL-TCP/Fibrin-HS3 (5 μg) (n = 6); (4) PCL-TCP/Fibrin-HS3 (30 μg) (n = 6). Scaffold integration and bone formation was evaluated 12-weeks post implantation by μCT and histology.

RESULTS

Treatment with PCL-TCP/Fibrin alone (control) resulted in 23.7% ± 1.55% (BV/TV) of the calvarial defect being filled with new bone, a result similar to treatment with PCL-TCP/Fibrin scaffolds containing either HSft or HS3 (5 μg). At increased amounts of HS3 (30 μg), enhanced bone formation was evident (BV/TV = 38.6% ± 9.38%), a result 1.6-fold higher than control. Further assessment by 2D μCT and histology confirmed the presence of enhanced bone formation and scaffold integration with surrounding host bone only when scaffolds contained sufficient bone matrix-mimicking HS3.

CONCLUSION

Enhancing the biomimicry of devices using a heparan sulphate with increased affinity to BMP-2 can serve to improve the performance of PCL-TCP scaffolds and provides a suitable treatment for cranioplasty.

Reconstruction of composite defects of the scalp and neurocranium-a treatment algorithm from local flaps to combined AV loop free flap reconstruction

Background

Reconstruction of cranial composite defects, including all layers of the scalp and the neurocranium, poses an interdisciplinary challenge. Especially after multiple previous operations and/or radiation therapy, sufficient reconstruction is often only possible using microsurgical free flap transplantation. The aim of this study was to analyze the therapy of interdisciplinary cases with composite defects including the scalp and neurocranium.

Methods

From 2009 to 2017, 23 patients with 18 free flaps and 10 pedicled/local flaps were analyzed. First choices for free flaps were muscle flaps followed by fasciocutaneous flaps.

Results

Except for four patients, a stable coverage could be reached in the first operation. Three of these patients received a local scalp rotation flap in the first operation and needed an additional free flap because the local flap was no longer sufficient for coverage after wound healing deficiency or tumor relapse. The superficial temporal artery or external carotid artery served as recipient vessels. In special cases, venous grafts or an arteriovenous loop (AV loop) were used as extensions for the recipient vessels.

Conclusions

In summary, an interdisciplinary approach with radical debridement of infected or necrotic tissue and the reconstruction of the dura mater are essential to reach a stable, long-lasting reconstructive result. Based on our experience, free flaps seem to be the first choice for patients after multiple previous operations and/or radiation therapy.

Cranioplasty Using Autologous Bone versus Porous Polyethylene versus Custom-Made Titanium Mesh : A Retrospective Review of 108 Patients

Objective

The purpose of this study was to compare the cosmetic outcome and complications after cranioplasty (CP) due to three different implant materials, and analyze the mean implant survival and cumulative survival rate based on these results.

Methods

We reviewed 108 patients retrospectively who underwent CP between January 2014 and November 2016. Autologous bone (AB; 45 patients) and synthetic materials with porous polyethylene (PP; 32 patients) and custom-made 3-dimensional printed titanium mesh (CT; 31 patients) were used as implants.

Results

Regardless of implanted materials, more than 89.8% of the CP patients were satisfied with the cosmetic outcome. No statistically significant difference was observed among the three groups. The overall postoperative complication rates of each group were 31.1% in the AB group, 15.6% in the PP group and 3.2% in the CT group. The CT group showed lower complication rates compared with AB and PP groups (χ²-test : AB vs. PP, p=0.34; AB vs. CT, p=0.00; PP vs. CT, p=0.03). The AB and PP groups demonstrated a higher post-CP infection rate (11.1% and 6.3%) than the CT group (3.2%). However, no significant difference in the incidence of post-CP infection was observed among the three groups. The PP and CT groups demonstrated a higher mean implant survival time and cumulative survival rate than the AB group at the last follow-up (p<0.05).

Conclusion

In comparison with AB and PP, cranioplasty with CT shows benefits in terms of lower post-CP complication, less intraoperative bleeding loss, shorter operation time and in-hospital stay. The PP and CT groups showed higher implant survival time and cumulative survival rate compared with the AB group.

Efficacy of immediate replacement of cranial bone graft following drainage of intracranial empyema

OBJECTIVE Intracranial empyema is a life-threatening condition associated with a high mortality rate and residual deleterious neurological effects if not diagnosed and managed promptly. The authors present their institutional experience with immediate reimplantation of the craniotomy flap and clarify the success of this method in terms of cranial integrity, risk of recurrent infection, and need for secondary procedures. METHODS A retrospective analysis of patients admitted for management of intracranial empyema during a 19-year period (1997-2016) identified 33 patients who underwent emergency drainage and decompression with a follow-up duration longer than 6 months, 23 of whom received immediate bone replacement. Medical records were analyzed for demographic information, extent and location of the infection, bone flap size, fixation method, need for further operative intervention, and duration of intravenous antibiotics. RESULTS The mean patient age at surgery was 8.7 ± 5.7 years and the infections were largely secondary to sinusitis (52.8%), with the most common location being the frontal/temporal region (61.3%). Operative intervention involved removal of a total of 31 bone flaps with a mean surface area of 22.8 ± 26.9 cm². Nearly all (96.8%) of the bone flaps replaced at the time of the initial surgery were viable over the long term. Eighteen patients (78.3%) required a single craniotomy in conjunction with antibiotic therapy to address the infection, whereas the remaining 21.7% required more than 1 surgery. Partial bone flap resorption was noted in only 1 (3.2%) of the 31 successfully replaced bone flaps. This patient eventually had his bone flap removed and received a split-calvaria bone graft. Twenty-one patients (91.3%) received postoperative CT scans to evaluate bone integrity. The mean follow-up duration of the cohort was 43.9 ± 54.0 months. CONCLUSIONS The results of our investigation suggest that immediate replacement and stabilization of the bone flap after craniectomy for drainage of intracranial empyemas has a low risk of recurrent infection and is a safe and effective way to restore bone integrity in most patients.

Bone Flap Conservation in the Scalp After Decompressive Craniectomy

BACKGROUND

Decompressive craniectomy may be used as a primary or secondary treatment for intracranial hypertension and is clearly associated with reduced mortality. The removed bone flap is usually preserved in the abdominal subcutaneous tissue or in the bone bank. The aim of this study was to describe an option for preserving the bone flap after decompressive craniectomy using bone flap preservation in the skull subcutaneous tissue in subgaleal space over the pericranium contralateral to the craniectomy site.

METHODS

This was a multicenter retrospective study including patients with severe traumatic brain injury from 2014 to 2016. There were 23 patients who had their bone fragments preserved below the scalp in the subcutaneous tissue for analysis. The following results were analyzed: surgical site infection, bone flap resorption during the period of preservation, and patient discomfort.

RESULTS

Five patients died of systemic infectious complications, and the remaining patients underwent cranioplasty a mean 118 days after craniectomy. There were no surgical wound infections, macroscopically evident bone absorption, or site discomfort in any of the patients during a period of 18 months.

CONCLUSIONS

This variant of the bone flap preservation technique has been shown to be satisfactory as an option for routine use.