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

Comprehensive analysis of risk factors and pathogenetic characteristics associated with surgical site infections following craniotomy procedures

Craniotomies are intricate neurosurgical procedures susceptible to post-operative complications, among which surgical site infections (SSIs) are particularly concerning. This study sought to elucidate the potential risk factors and pathogenetic characteristics associated with SSIs following craniotomy procedures in a clinical setting. A retrospective study was conducted from May 2020 to May 2023, examining patients subjected to elective or emergency craniotomies. The cohort underwent post-operative surveillance for SSIs, facilitating patient classification into SSI and Non-SSI groups based on infection occurrence. Data collection encapsulated demographic and clinical parameters, including American Society of Anesthesiologists (ASA) classifications, and operative factors. SSIs were diagnosed via an integrated approach combining clinical symptoms, microbiological culture findings and pertinent laboratory tests. A rigorous statistical methodology employing IBM's SPSS version 27.0 was utilised for data analysis. In a univariate analysis, significant risk factors for post-craniotomy SSIs were identified, with patients aged over 60 displaying a pronounced susceptibility. Moreover, surgeries exceeding a duration of 4 h heightened infection risks. Elevated ASA grades denoted an increased prevalence of SSIs, as did emergency procedures and higher National Nosocomial Infections Surveillance scores. Multivariate analysis pinpointed epidural/subdural drainage as a protective measure against SSIs, whereas emergency surgeries, operative times beyond 4 h and subsequent surgeries within the hospital stay amplified infection risks. Notably, coagulase-negative Staphylococcus dominated the identified pathogens at 28.09%, followed by Escherichia coli (17.98%), Klebsiella pneumoniae (10.11%) and Staphylococcus aureus (11.24%), underscoring the need for diverse prophylactic measures. SSIs following craniotomies present a multifaceted challenge influenced by a confluence of patient-related, operative and post-operative determinants. Understanding these risk factors is paramount in refining surgical protocols and post-operative care strategies to mitigate SSI incidence.

Risk Factor Analysis of Cryopreserved Autologous Bone Flap Resorption in Adult Patients Undergoing Cranioplasty with Volumetry Measurement Using Conventional Statistics and Machine-Learning Technique

OBJECTIVE

Decompressive craniectomy (DC) with duroplasty is one of the common surgical treatments for life-threatening increased intracranial pressure (ICP). Once ICP is controlled, cranioplasty (CP) with reinsertion of the cryopreserved autologous bone flap or a synthetic implant is considered for protection and esthetics. Although with the risk of autologous bone flap resorption (BFR), cryopreserved autologous bone flap for CP is one of the important material due to its cost effectiveness. In this article, we performed conventional statistical analysis and the machine learning technique understand the risk factors for BFR.

METHODS

Patients aged >18 years who underwent autologous bone CP between January 2015 and December 2021 were reviewed. Demographic data, medical records, and volumetric measurements of the autologous bone flap volume from 94 patients were collected. BFR was defined with absolute quantitative method (BFR-A) and relative quantitative method (BFR%). Conventional statistical analysis and random forest with hyper-ensemble approach (RF with HEA) was performed. And overlapped partial dependence plots (PDP) were generated.

RESULTS

Conventional statistical analysis showed that only the initial autologous bone flap volume was statistically significant on BFR-A. RF with HEA showed that the initial autologous bone flap volume, interval between DC and CP, and bone quality were the factors with most contribution to BFR-A, while, trauma, bone quality, and initial autologous bone flap volume were the factors with most contribution to BFR%. Overlapped PDPs of the initial autologous bone flap volume on the BRF-A crossed at approximately 60 mL, and a relatively clear separation was found between the non-BFR and BFR groups. Therefore, the initial autologous bone flap of over 60 mL could be a possible risk factor for BFR.

CONCLUSION

From the present study, BFR in patients who underwent CP with autologous bone flap might be inevitable. However, the degree of BFR may differ from one to another. Therefore, considering artificial bone flaps as implants for patients with large DC could be reasonable. Still, the risk factors for BFR are not clearly understood. Therefore, chronological analysis and pathophysiologic studies are needed.

Analysis of craniectomy bone flaps stored in a neurosurgical cryopreservation freezer: microorganism culture results and reimplantation rates

BACKGROUND

Cryopreservation of bone flaps after decompressive craniectomies is a common practice. A frequent complication after bone flap reimplantation is postoperative infection, so culturing of frozen craniectomy bone flaps is a crucial practice that can prevent patient morbidity and mortality. Although many studies report on infection rates after cranioplasty, no study reports on the results of bone flaps stored in a cryopreservation freezer, reimplanted or otherwise. We sought to analyze the flaps in our medical center's bone bank freezer, including microorganism culture results and reimplantation rates of cryopreserved bone flaps.

METHODS

Patients who underwent craniectomy and had bone flaps cryopreserved between January 1, 2016, and July 1, 2022, were included in this retrospective study. Information about bone flap cultures and reimplantation or discard was obtained from a prospectively maintained cryopreservation database. Information including infection rates and mortality was acquired from a retrospective review of patient records. Culture results were obtained for all flaps immediately before cryopreservation and again at the time of reimplantation at the operator's discretion.

RESULTS

There were 148 bone flaps obtained from 145 patients (3 craniectomies were bilateral) stored in our center's freezer. Positive culture results were seen in 79 (53.4%) flaps. The most common microorganism genus was Propionibacterium with 47 positive flaps, 46 (97.9%) of which were P. acnes. Staphylococcus was the second most common with 23 positive flaps, of which 8 (34.8%) tested positive for S. epidermidis. Of the 148 flaps, 25 (16.9%) were reimplanted, 116 (78.4%) were discarded, and 7 (4.7%) are still being stored in the freezer. Postcranioplasty infections were seen in 3 (12%) patients who had flap reimplantation.

CONCLUSIONS

Considering the substantial number of positive cultures and limited reimplantation rate, we have reservations about the logistical efficiency of cryopreservation for flap storage. Future multicenter studies analyzing reimplantation predictors could help to reduce unnecessary freezing and culturing.

Effect of microorganisms isolated by preoperative osseous sampling on surgical site infection after autologous cranioplasty: A single-center experience

PURPOSE

The most frequent postoperative complication in autologous cranioplasty (AC) is infection. European recommendations include osseous sampling before cryogenic storage of a bone flap. We evaluated the clinical impact of this sampling.

METHODS

All patients who underwent decompressive craniectomy (DC) and AC in our center between November 2010 and September 2021 were reviewed. The main outcome was the rate of reoperation for infection of the cranioplasty. We evaluated risk factors for bone flap infection, rate of reoperation for any reason (hematoma, skin erosion, cosmetic request, or bone resorption), and radiological evidence of bone flap resorption.

RESULTS

A total of 195 patients with a median age of 50 (interquartile range: 38.0-57.0) years underwent DC and AC between 2010 and 2021. Of the 195 bone flaps, 54 (27.7%) had a positive culture, including 48 (88.9%) with Cutibacterium acnes. Of the 14 patients who underwent reoperation for bone flap re-removal for infection, 5 and 9 had positive and negative bacteriological cultures, respectively. Of patients who did not have bone flap infection, 49 and 132 had positive and negative bacteriological cultures, respectively. There were no significant differences between patients with and without positive bacteriological culture of bone flaps in the rates of late bone necrosis and reoperation for bone flap infection.

CONCLUSIONS

A positive culture of intraoperative osseous sampling during DC is not associated with a higher risk of re-intervention after AC.