Cranioplasty Following Decompressive Craniectomy

Efficacy of decompressive craniectomy: A retrospective case series study with 321 patients and an update on controversies

Decompressive craniectomy (DC) is considered a cornerstone in the management of refractory intracranial hypertension. For decades, DC was known as an occasionally lifesaving procedure; however, it was associated with numerous severe complications. The present study is a single-center retrospective case series study on with 321 patients who underwent DC between January, 2010 and December, 2020. All patients were divided into four groups as follows: Group A included patients who suffered from a space-occupying middle cerebral artery (MCA) ischemic event; group B included individuals who developed intracerebral hemorrhage; group C included patients admitted for traumatic brain injury; and group D included patients with other neurosurgical entities that underwent DC, such as subarachnoid hemorrhage, tumors, brain abscess and cerebral ventricular sinus thrombosis events. The present study enrolled a total of 321 patients who underwent DC. Group A included 52 out of the 321 (16.1%) patients, group B included 51 (15.8%) patients, group C included 164 (51.0%) patients, and group D included 54 (16.8%) patients. Of the 321 patients, 235 (73.2%) were males, and the median age was 53.7 years. Multivariate analysis revealed that only the group A parameter was an independent factor associated with a Glasgow outcome scale score >2 during follow-up (P<0.05). On the whole, the results of the present study suggest that among patients who underwent DC with different neurological entities, those who had experienced MCA events had more favorable outcomes.

Template Routed Patient-Specific Implant for 1-Stage Cranioplasty

BACKGROUND AND OBJECTIVES

Cranial reconstruction presents a significant challenge in cases involving pathologies with skull invasion, and various techniques have been used, including the intraoperative shaping of titanium mesh and the manual sculpting of bone cement serving as surrogates for the excised bone graft. In the context of prefabricated patient-specific implants (PSIs) for cranioplasty, precise surgical execution of craniotomies is paramount. This ensures optimal congruity between the implant and the defect created during the craniotomy, leading to a successful single-stage procedure encompassing both bone removal and reconstruction. This article presents a meticulous method for achieving such high-fidelity craniotomy and subsequent cranioplasty using PSIs in a single-stage surgery.

METHODS

The procedure was implemented for 2 cases of meningiomas with osseous invasion. Through meticulous preoperative planning, the craniotomy template and implant were designed using computer-assisted design and manufactured on a 3-dimensional printer using the patient's computed tomography scans. Intraoperative fabrication of sterile polymethyl methacrylate replicas was achieved through the creation of silicone molds and subsequent injection molding techniques. Predesignated screw holes facilitated neuronavigation-assisted positioning of the template, aligning it accurately with the target site using registration points. Mini-screws firmly secured the template to the skull. Guided by the template, a craniotomy router performed the bone resection. On completion, the implant was affixed into place using plates and screws.

RESULTS

This technique demonstrably facilitated a cost-effective, streamlined and precise application of prefabricated PSIs within a single-stage craniotomy-cranioplasty procedure. Subjective patient reports indicated high levels of satisfaction with the outcome.

CONCLUSION

The template routed patient-specific implant 1-stage cranioplasty technique refines previous approaches through precise template localization on the skull, enabling an accurate craniotomy to match a prefabricated PSI. This single-stage procedure rivals hand-shaped methods in aesthetics and compares with the outcomes of 2-stage PSI cranioplasties. Additional studies are needed to validate our results.

Basic study on cryopreservation of rat calvarial osteoblasts with different cryoprotectants

Cryopreservation is a method adopted for storage of autologous skulls. Herein, this current research sought to explore the effects of different cryoprotectants on the biological characteristics of rat calvarial osteoblasts after cryopreservation. Neonatal Sprague-Dawley rats were selected and their skull tissues were isolated. The skull tissues were allocated into the refrigerating-3M, refrigerating-6M, M199-3M, M199-6M, povidone iodine-3M, and povidone iodine-6M groups according to the usage of cryoprotectants and treatment time (month) and the fresh group. Osteoblasts were isolated from skull tissues in each group through digestion. The histomorphology of the skull was evaluated by H&E staining and cell morphology was observed by microscopy. The viability, proliferation, apoptosis, and osteogenic activity of osteoblasts were assessed by trypan blue staining, MTT, flow cytometry, and alkaline phosphatase (ALP) staining. The skull histomorphology and osteoblast morphology were similar between the fresh and refrigerating groups. Osteoblast viability was weakened after cryopreservation. The longer the refrigeration time, the lower the number of living cells and the higher the apoptosis rate. However, cryopreservation using different cryoprotectants did not evidently affect osteoblast proliferation and ALP activity. Different cryoprotectants show no apparent effect on the osteogenic activity of rat calvarial osteoblasts after cryopreservation.

Analysis of Causes of Complications and Prognostic Factors After Titanium Mesh Ultra-Early Cranioplasty Following Decompressive Craniectomy for Craniocerebral Trauma

OBJECTIVE

Craniocerebral trauma is one of the main causes of death and disability worldwide. Decompressive craniectomy is a common emergency measure in the treatment of craniocerebral trauma, aimed at relieving intracranial pressure. However, cranial bone reconstruction (CP) following this surgery is crucial for the patient's long-term recovery. Despite this, research on complications and prognostic factors after ultra-early cranioplasty remains limited. Therefore, this study aims to explore the complications of ultra-early cranioplasty with titanium mesh and its impact on prognosis.

METHODS

From January 2020 to November 2022, 44 patients with craniocerebral trauma who needed ultra-early CP after decompressive craniectomy were collected. The basic data of the National Institutes of Health Stroke Scale (NIHSS), Glasgow Coma Scale, modified Rankin Scale, and Montreal Cognitive Assessment scores of patients were collected, and the complications and prognosis of patients 3 months after operation were collected. Multivariate logistic regression was used to analyze the prognostic factors.

RESULTS

Compared with preoperative, the postoperative NIHSS score of patients with ultra-early CP decreased, the postoperative Glasgow Coma Scale score increased, the postoperative modified Rankin Scale score decreased (P < 0.05), and the postoperative Montreal Cognitive Assessment score was higher. Postoperative complications occurred in 42 patients with ultra-early CP. There were 37 complications, including 7 cases of hydroaccumulation, 18 cases of hematocele, 11 cases of pneumatosis, 3 cases of scalp swelling, 2 cases of epilepsy, 10 cases of hydrocephalus, and 1 case of intracranial infection, and no incision infection occurred. Age and postoperative NIHSS score were related factors affecting the poor prognosis of ultra-early CP patients (P < 0.05).

CONCLUSIONS

Ultra-early CP can promote the recovery of neurological function, reduce the disturbance of consciousness, improve daily living ability, and improve cognitive function in patients with craniocerebral trauma, but there is a high risk of postoperative complications. In addition, age and postoperative NIHSS score are related factors affecting the poor prognosis of ultra-early CP patients.

Decompressive craniectomy in trauma: What you need to know

ABSTRACT

Decompressive craniectomy (DC) is a surgical procedure in which a large section of the skull is removed, and the underlying dura mater is opened widely. After evacuating a traumatic acute subdural hematoma, a primary DC is typically performed if the brain is bulging or if brain swelling is expected over the next several days. However, a recent randomized trial found similar 12-month outcomes when primary DC was compared with craniotomy for acute subdural hematoma. Secondary removal of the bone flap was performed in 9% of the craniotomy group, but more wound complications occurred in the craniectomy group. Two further multicenter trials found that, whereas early neuroprotective bifrontal DC for mild to moderate intracranial hypertension is not superior to medical management, DC as a last-tier therapy for refractory intracranial hypertension leads to reduced mortality. Patients undergoing secondary last-tier DC are more likely to improve over time than those in the standard medical management group. The overall conclusion from the most up-to-date evidence is that secondary DC has a role in the management of intracranial hypertension following traumatic brain injury but is not a panacea. Therefore, the decision to offer this operation should be made on a case-by-case basis. Following DC, cranioplasty is warranted but not always feasible, especially in low- and middle-income countries. Consequently, a decompressive craniotomy, where the bone flap is allowed to "hinge" or "float," is sometimes used. Decompressive craniotomy is also an option in a subgroup of traumatic brain injury patients undergoing primary surgical evacuation when the brain is neither bulging nor relaxed. However, a high-quality randomized controlled trial is needed to delineate the specific indications and the type of decompressive craniotomy in appropriate patients.

Early Challenges in the Implementation of Automated CranialRebuild Freeware for Generation of Patient-Specific Cranial Implant Using Additive Manufacturing: A Pilot Project in Review

Traumatic Brain Injury (TBI) is a significant global health concern, particularly in low- and middle-income countries (LMICs) where access to medical resources is limited. Decompressive craniectomy (DHC) is a common procedure to alleviate elevated intracranial pressure (ICP) following TBI, but the cost of subsequent cranioplasty can be prohibitive, especially in resource-constrained settings. We describe challenges encountered during the beta-testing phase of CranialRebuild 1.0, an automated software program tasked with creating patient-specific cranial implants (PSCIs) from CT images. Two pilot clinical teams in the Philippines and Ukraine tested the software, providing feedback on its functionality and challenges encountered. The constructive feedback from the Philippine and Ukrainian teams highlighted challenges related to CT scan parameters, DICOM file arrays, software limitations, and the need for further software improvements. CranialRebuild 1.0 shows promise in addressing the need for affordable PSCIs in LMICs. Challenges and improvement suggestions identified throughout the beta-testing phase will shape the development of CranialRebuild 2.0, with the aim of enhancing its functionality and usability. Further research is needed to validate the software's efficacy in a clinical setting and assess its cost-effectiveness.

Decompressive Craniectomy: From Ancient Practices to Modern Neurosurgery

Decompressive craniectomy (DC) is a neurosurgical strategy that expels a parcel of the cranium to relieve pressure on a swollen or herniating brain. This review article explores the history of DC, from its ancient roots in trepanning to its contemporary applications. It then examines the mechanisms by which DC reduces intracranial pressure (ICP) and improves cerebral blood flow. The article highlights the efficacy of DC in treating patients with severe traumatic brain injury (TBI), stroke, and other conditions that cause increased ICP. However, it also acknowledges the potential complications of DC, such as infection and bleeding. The ethical considerations surrounding DC are explored in detail, particularly the challenging decision-making process for patients who are unable to give consent. A specific focus is given to the use of DC in pediatric patients, where the developing brain is especially vulnerable to pressure changes.

Optimal Timing of Cranioplasty After Decompressive Craniectomy: Timing or Collapse Ratio

BACKGROUND AND OBJECTIVES

Although cranioplasty (CP) is a relatively straightforward surgical procedure, it is associated with a high complication rate. The optimal timing for this surgery remains undetermined. This study aimed to identify the most suitable timing for CP to minimize postoperative complications.

METHODS

We conducted a retrospective analysis of all CP cases performed in our department from August 2015 to March 2022. Data were gathered through case statistics and categorized based on the occurrence of complications. The collapse ratio was determined using 3-dimensional Slicer software.

RESULTS

In our retrospective study of 266 patients, 51 experienced postoperative complications, including hydrocephalus, epidural effusion, subdural hematoma, epilepsy, and subcutaneous infection. Logistic regression analysis identified independent predictors of postcranioplasty complications, and a nomogram was developed. The predictive value of the logistic regression model, collapse ratio, and decompression craniotomy-CP operation interval for post-skull repair complications was assessed using receiver operating characteristic curve analysis. No significant differences were observed in postoperative complications and decompression craniotomy-CP intervals between the groups (P = .07, P > .05). However, significant differences were noted in postoperative collapse ratios and CP complications between the groups (P = .023, P < .05). Logistic regression revealed that the collapse ratio (odds ratio = 1.486; 95% CI: 1.001-2.008; P = .01) and CP operation time (odds ratio = 1.017; 95% CI: 1.008-1.025, P < .001) were independent risk factors for postoperative complications. Receiver operating characteristic curve analysis indicated that the collapse ratio could predict CP postoperative complications, with a cutoff value of 0.274, an area under the curve of 0.621, a sensitivity of 62.75%, and a specificity of 63.26%.

CONCLUSION

The post-skull repair collapse ratio is a significant predictor of postoperative complications. It is advisable to base the timing of surgery on the extent of brain tissue collapse, rather than solely on the duration between cranial decompression and CP.

Functional ultrasound imaging of human brain activity through an acoustically transparent cranial window

Visualization of human brain activity is crucial for understanding normal and aberrant brain function. Currently available neural activity recording methods are highly invasive, have low sensitivity, and cannot be conducted outside of an operating room. Functional ultrasound imaging (fUSI) is an emerging technique that offers sensitive, large-scale, high-resolution neural imaging; however, fUSI cannot be performed through the adult human skull. Here, we used a polymeric skull replacement material to create an acoustic window compatible with fUSI to monitor adult human brain activity in a single individual. Using an in vitro cerebrovascular phantom to mimic brain vasculature and an in vivo rodent cranial defect model, first, we evaluated the fUSI signal intensity and signal-to-noise ratio through polymethyl methacrylate (PMMA) cranial implants of different thicknesses or a titanium mesh implant. We found that rat brain neural activity could be recorded with high sensitivity through a PMMA implant using a dedicated fUSI pulse sequence. We then designed a custom ultrasound-transparent cranial window implant for an adult patient undergoing reconstructive skull surgery after traumatic brain injury. We showed that fUSI could record brain activity in an awake human outside of the operating room. In a video game "connect the dots" task, we demonstrated mapping and decoding of task-modulated cortical activity in this individual. In a guitar-strumming task, we mapped additional task-specific cortical responses. Our proof-of-principle study shows that fUSI can be used as a high-resolution (200 μm) functional imaging modality for measuring adult human brain activity through an acoustically transparent cranial window.

Digitalization in Cranial Reconstruction: Revolutionizing Precision and Innovation

Cranioplasty for cranial defects can be complex and challenging in composite defects. The intricate 3D structure of the craniofacial skeleton poses various difficulties encountered in surgical reconstruction. The continuous progress in computer-aided design and computer-aided manufacturing design, and fabrication technology has led to a growing array of applications for visual analog scale and 3D printing in craniofacial surgery, encompassing preoperative assessment, the creation of cutting guides, and the development of custom implants and stereolithographic models. Within this review, the authors detail the present and developing applications of virtual surgical planning, 3D bioprinting, augmented reality, and virtual reality in craniofacial reconstruction.

Experimental Modeling of Cranial Injury and Defect Reconstruction Using Superconstructive Polymers (PEEK)

Experimental model of resection craniotomy with subsequent reconstruction of the defect with a polymer implant enables comprehensive assessment of functional and ultrastructural changes during replacement of the damaged tissue. Reconstruction of a skull defect was accompanied by transient motor disturbance in the acute period and did not cause functional disorders and neurological deficits in a delayed period. Histological examination of osteal and brain tissue revealed no pathological reactions that could be associated with the response to the chemical components of the implant.

A Modern Approach to the Treatment of Traumatic Brain Injury

Background: Traumatic brain injury manifests itself in various forms, ranging from mild impairment of consciousness to severe coma and death. Traumatic brain injury remains one of the leading causes of morbidity and mortality. Currently, there is no therapy to reverse the effects associated with traumatic brain injury. New neuroprotective treatments for severe traumatic brain injury have not achieved significant clinical success. Methods: A literature review was performed to summarize the recent interdisciplinary findings on management of traumatic brain injury from both clinical and experimental perspective. Results: In the present review, we discuss the concepts of traditional and new approaches to treatment of traumatic brain injury. The recent development of different drug delivery approaches to the central nervous system is also discussed. Conclusions: The management of traumatic brain injury could be aimed either at the pathological mechanisms initiating the secondary brain injury or alleviating the symptoms accompanying the injury. In many cases, however, the treatment should be complex and include a variety of medical interventions and combination therapy.

Comprehensive functional outcome analysis and importance of bone remodelling on personalized cranioplasty treatment using Poly(methyl methacrylate) bone flaps

Cranioplasty involves the surgical reconstruction of cranial defects arising as a result of various factors, including decompressive craniectomy, cranial malformations, and brain injury due to road traffic accidents. Most of the modern decompressive craniectomies (DC) warrant a future cranioplasty surgery within 6-36 months. The conventional process of capturing the defect impression and polymethyl methacrylate (PMMA) flap fabrication results in a misfit or misalignment at the site of implantation. Equally, the intra-operative graft preparation is arduous and can result in a longer surgical time, which may compromise the functional and aesthetic outcomes. As part of a multicentric pilot clinical study, we recently conducted a cohort study on ten human subjects during 2019-2022, following the human ethics committee approvals from the participating institutes. In the current study, an important aspect of measuring the extent of bone remodelling during the time gap between decompressive craniectomy and cranioplasty was successfully evaluated. The sterilised PMMA bone flaps were implanted at the defect area during the cranioplasty surgery using titanium mini plates and screws. The mean surgery time was 90 ± 20 min, comparable to the other clinical studies on cranioplasty. No signs of intra-operative and post-operative complications, such as cerebrospinal fluid leakage, hematoma, or local and systemic infection, were clinically recorded. Importantly, aesthetic outcomes were excellent for all the patients, except in a few clinical cases, wherein the PMMA bone flap was to be carefully customized due to the remodelling of the native skull bone. The extent of physiological remodelling was evaluated by superimposing the pre-operative and post-operative CT scan data after converting the defect morphology into a 3D model. This study further establishes the safety and efficacy of a technologically better approach to fabricate patient-specific acrylic bone flaps with improved surgical outcomes. More importantly, the study outcome further demonstrates the strategy to address bone remodelling during the patient-specific implant design.

Cranioplasty Outcomes from a Tertiary Hospital in a Developing Country

BACKGROUND

Decompressive craniectomy (DC) is a surgical procedure to treat refractory increase in intracranial pressure. DC is frequently succeeded by cranioplasty (CP), a reconstructive procedure to protect the underlying brain and maintain cerebrospinal fluid flow dynamics. However, complications such as seizures, fluid collections, infections, and hydrocephalus can arise from CP. Our aim is to investigate these complications and their possible risk factors and to discuss whether early or late CP has any effect on the outcome.

MATERIALS AND METHODS

A single-center retrospective cohort study was performed, including patients who underwent CP after DC between January 2014 and January 2022. Relevant information was collected such as demographics, type of brain injury, materials used in CP, timing between DC and CP, and postoperative complications. Ultimately, 63 patients were included in our study. We also compared the complication rate between patients who underwent late CP after DC (>90 days) against patients who underwent early CP (<90 days).

RESULTS

Most patients were male (78%). The sample median age was 29 years, with pediatric patients, accounting for 36% of the samples. Overall complication rate was 57% and they were seizure/epilepsy in 50% of the patients, fluid collection (28%), infections (25%), posttraumatic hydrocephalus (17%), and bone defect/resorption (3%). Twenty-two percent of patients with complications required reoperation and underwent a second CP. The median (interquartile range) duration between the craniotomy and the CP was 56 (27-102) days, with an early (≤3 months) percentage of 68%. We found no significant difference between early (≤3 months) and late (>3 months) CP regarding complication rates.

CONCLUSION

Despite CP being a simple procedure, it has a considerable rate of complications. Therefore, it is important that surgeons possess adequate knowledge about such complications to navigate these challenges more effectively.

Customised pre-operative cranioplasty to achieve maximal surgical resection of tumours with osseous involvement-a case series

PURPOSE

Surgical resection with bony margins would be the treatment of choice for tumours with osseous involvement such as meningiomas and metastasis. By developing and designing pre-operative customised 3D modelled implants, the patient can undergo resection of meningioma and repair of bone defect in the same operation. We present a generalisable method for designing pre-operative cranioplasty in patients to repair the bone defect after the resection of tumours.

MATERIALS AND METHODS

We included six patients who presented with a tumour that was associated with overlying bone involvement. They underwent placement of customised cranioplasty in the same setting. A customised implant using a pre-operative imaging was designed with a 2-cm margin to allow for any intra-operative requirements for extending the craniectomy.

RESULTS

Six patients were evaluated in this case series. Four patients had meningiomas, 1 patient had metastatic breast cancer on final histology, and 1 patient was found to have an intra-osseous arteriovenous malformation. Craniectomy based on margins provided by a cutting guide was fashioned. After tumour removal and haemostasis, the cranioplasty was then placed. All patients recovered well post-operatively with satisfactory cosmetic results. No wound infection was reported in our series.

CONCLUSION

Our series demonstrate the feasibility of utilising pre-designed cranioplasty for meningiomas and other tumours with osseous involvement. Following strict infection protocols, minimal intra-operative handling/modification of the implant, and close follow-up has resulted in good cosmetic outcomes with no implant-related infections.

Functional outcome after late cranioplasty after decompressive craniectomy: a single-center retrospective study

OBJECTIVE

The best time for cranioplasty (CP) after decompressive craniectomy (DC) is controversial, and there are no authoritative guidelines yet. Both complications as well as outcome may depend on the timing of CP. The aim of this single-center study was to evaluate the impact of late CP on procedural safety as well as on patient outcome.

METHODS

All patients receiving CP at a tertiary university medical center between 01/2015 and 12/2022 were included retrospectively. Patients' conditions were assessed according to the modified Rankin Scale (mRS) prior to CP and 6 months after. Baseline characteristics, indication for DC, time from DC to CP, and postoperative complications according to the Landriel Ibañez Classification were analyzed.

RESULTS

CP was performed in 271 patients who previously underwent DC due to traumatic brain injury (25.5%), ischemic stroke (29.5%), aneurysmal subarachnoid hemorrhage (26.9%), or intracerebral hemorrhage (18.1%). The median interval between DC and CP was 143 days (interquartile range 112-184 days). Receiver operating characteristic analysis revealed a cut-off of 149 days, where CP performed within 149 days after DC led to an improvement on mRS after CP (p = 0.001). In multivariate analysis, additional rehabilitation after and better mRS before CP were independently associated with improvement of outcome. The rate of complications was similar between early and late CP (24.8% and 25.4%, respectively, p = 0.562).

CONCLUSIONS

Late cranioplasty is a safe procedure. The outcome was improved when additional rehabilitation was performed after cranioplasty and was not associated with the timing of cranioplasty.

Personalized 3D-printed cranial implants for complex cranioplasty using open-source software

Background

Cranioplasty is a routine neurosurgery treatment used to correct cranial vault abnormalities. Utilization of 3D printing technology in the field of cranioplasty involving the reconstruction of cranial defects emerged as an advanced possibility of anatomical reshaping. The transformative impact of patient-specific 3D printed implants, focuses on their remarkable accuracy, customization capabilities, and enhanced biocompatibility.

Methods

The precise adaptation of implants to patient-specific anatomies, even in complex cases we presented, result in improved aesthetic outcomes and reduced surgical complications. The ability to create highly customized implants addresses the functional aspects of cranial defects and considers the psychological impact on patients.

Results

By combining technological innovation with personalized patient care, 3D printed cranioplasty emerges as a transformative avenue in cranial reconstruction, ultimately redefining the standards of success in neurosurgery.

Conclusion

3D printing allows an excellent cranioplasty cosmesis achieved at a reasonable price without sacrificing patient outcomes. Wider implementation of this strategy can lead to significant healthcare cost savings.

Exploring complications following cranioplasty after decompressive hemicraniectomy: A retrospective bicenter assessment of autologous, PMMA and CAD implants

Cranioplasty (CP) after decompressive hemicraniectomy (DHC) is a common neurosurgical procedure with a high complication rate. The best material for the repair of large cranial defects is unclear. The aim of this study was to evaluate different implant materials regarding surgery related complications after CP. Type of materials include the autologous bone flap (ABF), polymethylmethacrylate (PMMA), calcium phosphate reinforced with titanium mesh (CaP-Ti), polyetheretherketone (PEEK) and hydroxyapatite (HA). A retrospective, descriptive, observational bicenter study was performed, medical data of all patients who underwent CP after DHC between January 1st, 2016 and December 31st, 2022 were analyzed. Follow-up was until December 31st, 2023. 139 consecutive patients with a median age of 54 years who received either PMMA (56/139; 40.3%), PEEK (35/139; 25.2%), CaP-Ti (21/139; 15.1%), ABF (25/139; 18.0%) or HA (2/139; 1.4%) cranial implant after DHC were included in the study. Median time from DHC to CP was 117 days and median follow-up period was 43 months. Surgical site infection was the most frequent surgery-related complication (13.7%; 19/139). PEEK implants were mostly affected (28.6%; 10/35), followed by ABF (20%; 5/25), CaP-Ti implants (9.5%; 2/21) and PMMA implants (1.7%, 1/56). Explantation was necessary for 9 PEEK implants (25.7%; 9/35), 6 ABFs (24.0%; 6/25), 3 CaP-Ti implants (14.3%; 3/21) and 4 PMMA implants (7.1%; 4/56). Besides infection, a postoperative hematoma was the most common cause. Median surgical time was 106 min, neither longer surgical time nor use of anticoagulation were significantly related to higher infection rates (p = 0.547; p = 0.152 respectively). Ventriculoperitoneal shunt implantation prior to CP was noted in 33.8% (47/139) and not significantly associated with surgical related complications. Perioperative lumbar drainage, due to bulging brain, inserted in 38 patients (27.3%; 38/139) before surgery was protective when it comes to explantation of the implant (p = 0.035). Based on our results, CP is still related to a relatively high number of infections and further complications. Implant material seems to have a high effect on postoperative infections, since surgical time, anticoagulation therapy and hydrocephalus did not show a statistically significant effect on postoperative complications in this study. PEEK implants and ABFs seem to possess higher risk of postoperative infection. More biocompatible implants such as CaP-Ti might be beneficial. Further, prospective studies are necessary to answer this question.

Dehydrated human amnion/chorion membrane use in emergent craniectomies shows minimal dural adhesions

Decompressive craniectomies (DCs) are routinely performed neurosurgical procedures to emergently treat increased intracranial pressure secondary to multiple aetiologies, such as subdural haematoma, epidural haematoma, or malignant oedema in the setting of acute infarction. The DC procedure typically induces epidural fibrosis post-cranial resection, resulting in adherence of the dura to both the brain internally and skin flap externally. This becomes especially problematic in the setting of skull flap replacement for cranioplasty as adherences can lead to bridging vein tear, damage to the underlying brain cortex, and other postoperative complications. Dural adjuvants, which can contribute to decreased rate of adherence formation, can thereby reduce both postoperative cranioplasty complications and operative duration. Dehydrated human amnion/chorion membrane (DHACM) allografts (AMNIOFIX, MIMEDX Group Inc., US) have been shown to reduce the rate of dural scar tissue formation in re-exploration of posterior lumbar interbody fusion operations which require entry into the epidural space. The purpose of this study was to evaluate whether or not the use of DHACM in the setting of emergent craniectomies decreased the rate of dural adhesion formation and subsequent cranioplasty complications. Patients (n=7) who underwent emergent craniectomy and intraoperative placement of DHACM were evaluated during replacement of either an autologous skull cap or a custom-made implant, at which point the degree of adhesions was qualitatively assessed. Placement of DHACM below and on top of the dura resulted in negligible adhesion being found during the defect exposure, and there were no intraoperative complications during cranioplasties. Reported estimated blood loss across the seven patients averaged 64.2ml, total operative time averaged 79.2 minutes, and time dedicated to exposing defect for bone flap placement was <3 minutes.

Quantitative Analysis of Brain Swelling Resolution With Regard to Cranioplasty After Decompressive Craniectomy

OBJECTIVE

Adequate brain swelling resolution prior to cranioplasty (CP) is an important yet loosely defined issue. Despite efforts to balance timely CP and patient safety, heterogeneous study methodologies have led to conflicting results. This study aims to standardize this issue through quantifying degree of brain swelling resolution using a proposed Visual CP Scale.

METHODS

The proposed Visual CP Scale is validated through a 2-pronged approach. The first prong involves a national survey in Taiwan, where neurosurgeons were surveyed to determine what constitutes a patient's readiness for CP. The second prong involves a large retrospective cohort, where the correlations between timing, degree of brain swelling resolution, and post-CP complication rates, are evaluated.

RESULTS

In the national Taiwan CP Survey, 124 out of 772 neurosurgeons (17.2%) completed the survey. Respondents who chose higher grades on the Visual CP Scale preferred later CP timings. In the retrospective data, 378 out of 770 (49.1%) patients had pre-CP brain images, allowing for the utilization of the Visual CP Scale. A Visual CP Scale score of greater than or equal to 4 was associated with fewer complications after CP.

CONCLUSIONS

The timing of CP should be determined by the degree of brain swelling resolution, not vice versa. The proposed Visual CP Scale offers an objective method for assessing brain swelling resolution, making it an adjuvant tool for clinical decision-making and future research related to CP.

Low-Cost 3-D-Printer-Assisted Personalized Cranioplasty Treatment: A Case Series of 14 Consecutive Patients

OBJECTIVE

The current study used polylactic acid molds [developed locally using three-dimensional printers and our software] and polymethyl methacrylate (PMMA) to perform cranioplasty of bone defects in technically demanding areas of the skull while ensuring ideal cosmetic results and functional recovery. The overall aim was to identify the ideal method for standard cranioplasty procedures METHODS: Polylactic acid duplicates of the skull defects were created for eligible patients, after which a two-part negative mold composed of plaster and silicone was used to form artificial bone with PMMA. Thereafter, cranioplasty was performed and the treatment success was assessed by evaluating the percentage of similarity objectively and the body image scale subjectively.

RESULTS

No surgical complications were seen to occur in the 14 patients included in the current study. Furthermore, the subjective and objective evaluation revealed a significant improvement in outcomes (p < 0.05). No postoperative complications were observed over a follow-up period of 6 months, except in 1 patient who exhibited late infection.

CONCLUSIONS

Cranioplasty operations were performed at an economical price of approximately US$50 dollars, suggesting that this method can be applied widely. Furthermore, preoperative preparation of the PMMA models can help reduce the duration of anesthesia and surgery which, in turn, will minimize the risk of surgical complications. Based on current knowledge in the field, we believe that this method represents the ideal technique.

Functional outcome in patients with traumatic or hemorrhagic brain injuries undergoing decompressive craniectomy versus craniotomy and 6-month rehabilitation

Decompressive craniectomy (DC) and craniotomy (CT) to treat increased intracranial pressure after brain injury are common but controversial choices in clinical practice. Studying a large cohort of patients with traumatic brain injury (TBI) and hemorrhagic stroke (HS) on rehabilitation pathways, we aimed to determine the impact of DC and CT on functional outcome/mortality, and on seizures occurrence. This observational retrospective study included patients with either TBI, or HS, who underwent DC or CT, consecutively admitted to our unit for 6-month neurorehabilitation programs between January 1, 2009 and December 31, 2018. Neurological status using Glasgow Coma Scale (GCS), and rehabilitation outcome with Functional Independence Measure, both assessed at baseline and on discharge, post-DC cranioplasty, prophylactic antiepileptic drug use, occurrence of early/late seizures, infectious complications, and death during hospitalization were evaluated and analyzed with linear and logistic regression models. Among 278 patients, DC was performed in 98 (66.2%) with HS, and in 98 (75.4%) with TBI, whilst CT in 50 (33.8%) with HS, and in 32 (24.6%) with TBI. On admission, GCS scores were lower in patients treated with CT than in those with DC (HS, p = 0.016; TBI, p = 0.024). Severity of brain injury and older age were the main factors affecting functional outcome, without between-group differences, but DC associated with worse functional outcome, independently from severity or type of brain injury. Unprovoked seizures occurred post-DC cranioplasty more frequently after HS (OR = 5.142, 95% CI 1.026-25.784, p = 0.047). DC and CT shared similar risk of mortality, which associated with sepsis (OR = 16.846, 95% CI 5.663-50.109, p < 0.0001), or acute symptomatic seizures (OR = 4.282, 95% CI 1.276-14.370, p = 0.019), independently from the neurosurgery procedures. Among CT and DC, the latter neurosurgical procedure is at major risk of worse functional outcome in patients with mild-to-severe TBI, or HS undergoing an intensive rehabilitation program. Complications with sepsis or acute symptomatic seizures increase the risk of death.

A window to the brain: ultrasound imaging of human neural activity through a permanent acoustic window

Recording human brain activity is crucial for understanding normal and aberrant brain function. However, available recording methods are either highly invasive or have relatively low sensitivity. Functional ultrasound imaging (fUSI) is an emerging technique that offers sensitive, large-scale, high-resolution neural imaging. However, fUSI cannot be performed through adult human skull. Here, we use a polymeric skull replacement material to create an acoustic window allowing ultrasound to monitor brain activity in fully intact adult humans. We design the window through experiments in phantoms and rodents, then implement it in a participant undergoing reconstructive skull surgery. Subsequently, we demonstrate fully non-invasive mapping and decoding of cortical responses to finger movement, marking the first instance of high-resolution (200 μm) and large-scale (50 mmx38 mm) brain imaging through a permanent acoustic window.

Infection-related failure of autologous versus allogenic cranioplasty after decompressive hemicraniectomy - A systematic review and meta-analysis

Introduction

Cranioplasty is required after decompressive craniectomy (DC) to restore brain protection and cosmetic appearance, as well as to optimize rehabilitation potential from underlying disease. Although the procedure is straightforward, complications either caused by bone flap resorption (BFR) or graft infection (GI), contribute to relevant comorbidity and increasing health care cost. Synthetic calvarial implants (allogenic cranioplasty) are not susceptible to resorption and cumulative failure rates (BFR and GI) tend therefore to be lower in comparison with autologous bone. The aim of this review and meta-analysis is to pool existing evidence of infection-related cranioplasty failure in autologous versus allogenic cranioplasty, when bone resorption is removed from the equation.

Materials and methods

A systematic literature search in PubMed, EMBASE, and ISI Web of Science medical databases was performed on three time points (2018, 2020 and 2022). All clinical studies published between January 2010 and December 2022, in which autologous and allogenic cranioplasty was performed after DC, were considered for inclusion. Studies including non-DC cranioplasty and cranioplasty in children were excluded. The cranioplasty failure rate based on GI in both autologous and allogenic groups was noted. Data were extracted by means of standardized tables and all included studies were subjected to a risk of bias (RoB) assessment using the Newcastle-Ottawa assessment tool.

Results

A total of 411 articles were identified and screened. After duplicate removal, 106 full-texts were analyzed. Eventually, 14 studies fulfilled the defined inclusion criteria including one randomized controlled trial, one prospective and 12 retrospective cohort studies. All but one study were rated as of poor quality based on the RoB analysis, mainly due to lacking disclosure why which material (autologous vs. allogenic) was chosen and how GI was defined. The infection-related cranioplasty failure rate was 6.9% (125/1808) for autologous and 8.3% (63/761) for allogenic implants resulting in an OR 0.81, 95% CI 0.58 to 1.13 (Z ​= ​1.24; p ​= ​0.22).

Conclusion

In respect to infection-related cranioplasty failure, autologous cranioplasty after decompressive craniectomy does not underperform compared to synthetic implants. This result must be interpreted in light of limitations of existing studies. Risk of graft infection does not seem a valid argument to prefer one implant material over the other. Offering an economically superior, biocompatible and perfect fitting cranioplasty implant, autologous cranioplasty can still have a role as the first option in patients with low risk of developing osteolysis or for whom BFR might not be of major concern.

Trial registration

This systematic review was registered in the international prospective register of systematic reviews. PROSPERO: CRD42018081720.

Titanium Versus Autologous Bone-Based Cranioplasty: A Systematic Review and Meta-Analysis

At present, there is no gold standard when looking at reconstructive evidence for cranioplasty with the use of autologous bone as well as other synthetic materials. Titanium has been considered recently as a good option due to its unique properties such as strength and biocompatibility. Numerous studies have previously compared titanium with autologous bone for cranioplasty yet no meta-analysis has been performed within the literature to provide guidelines for craniofacial surgeons. A systematic review and meta-analysis were performed as per the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines. A search of electronic information was conducted to identify all comparative studies of autologous bone vs. titanium implants in cranioplasty following a craniectomy. The primary outcomes were measured as re-operation rates and cosmesis, the secondary outcome measures included the incidence of complications, for example, bone resorption and infection. Five studies were selected, enrolling 323 cases. A high reoperation rate (p > 0.007) was seen in autologous cranioplasty using bone due to the significantly high resorption rate reported in this group. Cosmetic outcomes demonstrated no significant difference between the two groups examined. Finally, costs and infection rates (p > 0.18) were found to be comparable. Overall, titanium implants used in cranioplasty offer lower re-operation rates in comparison to autologous bone grafts whilst there was no major increase in adverse outcomes such as postoperative cost or rates.

Malignant cerebral edema after cranioplasty: a case report and literature review

BACKGROUND

Cranioplasty is a common surgery in the neurosurgery for patients with skull defects following decompression craniectomy. Concomitant rare complications are increasingly reported, such as malignant cerebral edema after cranioplasty.

CASE REPORT

A 45-year-old man underwent decompression craniectomy due to traumatic brain injury. At 3 months after the decompression craniectomy, the patient developed refractory subdural hydrogen and received ipsilateral refractory subdural effusion capsule resection, but no significant relief was seen. Therefore, the cranioplasty was decided to treat subdural hydrogen and restore the normal appearance of the skull. After the successful cranioplasty surgery and the expected anesthesia recovery period, the pupils of the patients were continued to be dilated and fixed, without light reflection and spontaneous breathing. The Computed Tomography of the patient 1 hour after surgery showed malignant cerebral edema.

CONCLUSIONS

Malignant cerebral edema is a rare and lethal complication after cranioplasty. Negative pressure drainage and deregulation of cerebral blood flow at the end of cranioplasty may partially explain the malignant cerebral after cranioplasty. In addition, patients with epileptic seizures, no spontaneous breathing, dilated pupils without reflection, and hypotension within a short period after cranioplasty may show the occurrence of malignant cerebral.

Impact of Cranioplasty on Rehabilitation Course of Patients with Traumatic or Hemorrhagic Brain Injury

BACKGROUND

Some authors have hypothesized that cranioplasty after decompressive craniectomy (DC) could positively influence functional recovery through several mechanisms. However, only a few studies with small sample sizes have investigated the effects of cranioplasty on functional recovery. Our study aims at evaluating the role of post-DC cranioplasty in influencing the functional recovery in a large cohort of patients with different etiologies of acquired brain injury (ABI).

METHODS

This retrospective study consecutively enrolled 253 patients with ABI, consisting of 108 adults who underwent post-DC cranioplasty and 145 adults who did not. All the subjects underwent a 6-month individual rehabilitation program. Demographic data, etiology, classification and anatomical site of brain injury, neurological and functional assessment at baseline and on discharge, and number of deaths during hospitalization were recorded.

RESULTS

In our cohort, 145 patients (57.3%) and 108 patients (42.7%) had, respectively, a hemorrhagic stroke (HS) and a traumatic brain injury (TBI). Only in the patients with TBI cranioplasty emerged as an independent predictor of better functional outcome in terms of the Functional Independence Measure (FIM) total score at discharge (β = 0.217, p = 0.001) and of the FIM variation during rehabilitation (ΔFIM) (β = 0.315, p = 0.001). Conversely, in the case of HS, no associations were found between post-DC cranioplasty and functional recovery.

CONCLUSIONS

Post-DC cranioplasty was associated with better functional recovery six months after TBI but not in the patients with HS. Although the pathophysiological mechanisms underlying HS are different from those of TBI and possibly play a role in the different outcomes between the two groups, further studies are needed to investigate the mechanisms underlying the observed differences.

Analysis of PMMA versus CaP titanium-enhanced implants for cranioplasty after decompressive craniectomy: a retrospective observational cohort study

Numerous materials of implants used for cranioplasty after decompressive craniectomy (DC) have been investigated to meet certain demanded key features, such as stability, applicability, and biocompatibility. We aimed to evaluate the feasibility and safety of biocompatible calcium-phosphate (CaP) implants for cranioplasty compared to polymethylmethacrylate (PMMA) implants. In this retrospective observational cohort study, the medical records of all patients who underwent cranioplasty between January 1st, 2015, and January 1st, 2022, were reviewed. Demographic, clinical, and diagnostic data were collected. Eighty-two consecutive patients with a mean age of 52 years (range 22-72 years) who received either a PMMA (43/82; 52.4%) or CaP (39/82; 47.6%) cranial implant after DC were included in the study. Indications for DC were equally distributed in both groups. Time from DC to cranioplasty was 143.8 ± 17.5 days (PMMA) versus 98.5 ± 10.4 days (CaP). The mean follow-up period was 34.9 ± 27.1 months. Postoperative complications occurred in 13 patients with PMMA and 6 in those with CaP implants (13/43 [30.2%] vs. 6/39 [15.4%]; p = 0.115). Revision surgery with implant removal was necessary for 9 PMMA patients and in 1 with a CaP implant (9/43 [20.9%] vs. 1/39 [2.6%]; p = 0.0336); 6 PMMA implants were removed due to surgical site infection (SSI) (PMMA 6/43 [14%] vs. CaP 0/39 [0%]; p = 0.012). In this study, a biocompatible CaP implant seems to be superior to a PMMA implant in terms of SSI and postoperative complications. The absence of SSI supports the idea of the biocompatible implant material with its ability for osseointegration.

Paradigm Shift in Materials for Skull Reconstruction Facilitated by Science and Technological Integration

The surgical repair of a bone deficiency in the skull caused by a prior procedure or accident is known as cranioplasty. There are various types of cranioplasties, but the majority entail raising the scalp and reshaping the skull using either the original piece of bone from the skull or a specially molded graft created from Titanium (plate or mesh), artificial bone in place of, a stable biomaterial (prefabricated customized implant to match the exact contour and shape of the skull). Cranioplasty, one of the oldest surgical treatments for cranial abnormalities, has undergone several changes throughout the years to discover the best material to improve patient outcomes. Various materials have been utilized in cranioplasty throughout history. As biomedical technology progresses, surgeons will have access to new materials. There is still no agreement on the optimum material, and research into biologic and nonbiologic alternatives is ongoing in the hopes of finding the finest reconstruction material. The materials and techniques used in cranioplasty are covered in this article.

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.

Low-Cost Cranioplasty-A Systematic Review of 3D Printing in Medicine

The high cost of biofabricated titanium mesh plates can make them out of reach for hospitals in low-income countries. To increase the availability of cranioplasty, the authors of this work investigated the production of polymer-based endoprostheses. Recently, cheap, popular desktop 3D printers have generated sufficient opportunities to provide patients with on-demand and on-site help. This study also examines the technologies of 3D printing, including SLM, SLS, FFF, DLP, and SLA. The authors focused their interest on the materials in fabrication, which include PLA, ABS, PET-G, PEEK, and PMMA. Three-dimensional printed prostheses are modeled using widely available CAD software with the help of patient-specific DICOM files. Even though the topic is insufficiently researched, it can be perceived as a relatively safe procedure with a minimal complication rate. There have also been some initial studies on the costs and legal regulations. Early case studies provide information on dozens of patients living with self-made prostheses and who are experiencing significant improvements in their quality of life. Budget 3D-printed endoprostheses are reliable and are reported to be significantly cheaper than the popular counterparts manufactured from polypropylene polyester.

Effects of Cranioplasty on Contralateral Subdural Effusion After Decompressive Craniectomy: A Literature Review

BACKGROUND

Contralateral subdural effusion(CSE) after decompressive craniectomy (CSEDC) is occasionally observed. Cranioplasty is routinely performed for reconstruction and has recently been associated with improving contralateral subdural effusion .

OBJECTIVE

To systematically review all available literature and evaluate the effectiveness of cranioplasty for CSE.

METHODS

A PubMed, Web of Science, and Google Scholar search was conducted for preferred reporting items following the guidelines of systematic review and meta-analysis, including studies reporting patients who underwent cranioplasty because of CSEDC.

RESULTS

The search yielded eight articles. A total of 56 patients ranging in age from 21 to 71 years, developed CSEDC. Of them, 32 patients underwent cranioplasty. Eighteen cases with symptomatic CSE underwent cranioplasty alone, two cases received Ommaya drainage later because of a a recurrence of CDC, and one case underwent a ventriculoperitoneal shunt because the CSE did not resolve completely and the ventricle was dilated again. The symptoms of 14 cases lessened without recurrence after simultaneous cranioplasty and drainage or a shunt. The total success rate(CSE disappeared without recurrence) was 90.6% for patients who underwent cranioplasty; however, the total incidence of hydrocephalus was 40.1%.

CONCLUSIONS

This review suggests that cranioplasty is effective for the treatment of CSEDC, particularly intractable cases, but early cranioplasty may be more effective. In addition, hydrocephalus is fairly common after cranioplasty and requires further treatment.

Single-stage cranioplasty with customized polyetheretherketone implant after tumor resection using virtual reality and augmented reality for precise implant customization and placement: illustrative case

BACKGROUND

Cranioplasties are routinely performed to restore cosmesis and to protect intracranial contents after trauma, resection of tumors, or other pathologies. Traditionally done as a second-stage procedure, new single-stage cranioplasty protocols have been developed to minimize recovery periods, decrease complications, and improve patient satisfaction. These protocols, however, still require the use of larger than planned implants or use larger than ideal incisions to accommodate three-dimensional (3D) templates, which may not be optimal in regions with complex bony anatomy.

OBSERVATIONS

A 50-year-old woman with a painful and progressively enlarging hemangioma of the left frontal bone underwent a single-stage resection followed by custom cranioplasty using a new extended reality (XR)-based workflow. Excellent cosmetic results, decreased operative time, and a feasible workflow were achieved.

LESSONS

The use of an XR-based visualization platform allows the surgeon to treat lesions and perform custom cranioplasties in one session while avoiding common pitfalls of current single-stage workflows, such as increased operative times for tailoring implants, as well as minimizing the use of 3D overlay models, which may not appropriately conform to complex regional bony anatomy intraoperatively.

Customized alloplastic cranioplasty of large bone defects by 3D-printed prefabricated mold template after posttraumatic decompressive craniectomy: A technical note

Background

Manufacturing of customized three-dimensional (3D)-printed cranioplastic implant after decompressive craniectomy has been introduced to overcome the difficulties of intraoperative implant molding. The authors present and discuss the technique, which consists of the prefabrication of silicone implant mold using additive manufacturing, also known as 3D printing, and polymethyl methacrylate (PMMA) implant casting.

Methods

To reconstruct a large bone defect sustained after decompressive craniectomy due to traumatic brain injury (TBI), a 3D-printed prefabricated mold template was used to create a customized PMMA implant for cranial vault repair in five consecutive patients.

Results

A superb restoration of the symmetrical contours and curvature of the cranium was achieved in all patients. The outcome was clinically and cosmetically favorable in all of them.

Conclusion

Customized alloplastic cranioplasty using 3D-printed prefabricated mold for casting PMMA implant is easy to perform technique for the restoration of cranial vault after a decompressive craniectomy following moderate-to-severe TBI. It is a valuable and modern technique to advance manufacturing of personalized prefabricated cranioplastic implants used for the reconstruction of large skull defects having complex geometry. It is a safe and cost-effective procedure having an excellent cosmetic outcome, which may considerably decrease expenses and time needed for cranial reconstructive surgery.

The "springform" technique in cranioplasty: custom made 3D-printed templates for intraoperative modelling of polymethylmethacrylate cranial implants

Background

Manual moulding of cranioplasty implants after craniectomy is feasible, but does not always yield satisfying cosmetic results. In contrast, 3D printing can provide precise templates for intraoperative moulding of polymethylmethacrylate (PMMA) implants in cranioplasty. Here, we present a novel and easily implementable 3D printing workflow to produce patient-specific, sterilisable templates for PMMA implant moulding in cranioplastic neurosurgery.

Methods

3D printable templates of patients with large skull defects before and after craniectomy were designed virtually from cranial CT scans. Both templates — a mould to reconstruct the outer skull shape and a ring representing the craniectomy defect margins — were printed on a desktop 3D printer with biocompatible photopolymer resins and sterilised after curing. Implant moulding and implantation were then performed intraoperatively using the templates. Clinical and radiological data were retrospectively analysed.

Results

Sixteen PMMA implants were performed on 14 consecutive patients within a time span of 10 months. The median defect size was 83.4 cm² (range 57.8–120.1 cm²). Median age was 51 (range 21–80) years, and median operating time was 82.5 (range 52–152) min. No intraoperative complications occurred; PMMA moulding was uneventful and all implants fitted well into craniectomy defects. Excellent skull reconstruction could be confirmed in all postoperative computed tomography (CT) scans. In three (21.4%) patients with distinct risk factors for postoperative haematoma, revision surgery for epidural haematoma had to be performed. No surgery-related mortality or new and permanent neurologic deficits were recorded.

Conclusion

Our novel 3D printing-aided moulding workflow for elective cranioplasty with patient-specific PMMA implants proved to be an easily implementable alternative to solely manual implant moulding. The “springform” principle, focusing on reconstruction of the precraniectomy skull shape and perfect closure of the craniectomy defect, was feasible and showed excellent cosmetic results. The proposed method combines the precision and cosmetic advantages of computer-aided design (CAD) implants with the cost-effectiveness of manually moulded PMMA implants.

Supplementary Information

The online version contains supplementary material available at 10.1007/s00701-021-05077-7.

Clinical efficacy and prognosis of standard large trauma craniotomy for patients with severe frontotemporal craniocerebral injury

OBJECTIVE

To observe the clinical efficacy, incidence of postoperative complications, and the quality of life in patients with severe craniocerebral injury undergoing standard large trauma craniotomy.

METHODS

Seventy-eight patients with severe craniocerebral injury who had been admitted to Hubei Hanchuan People's Hospital were selected retrospectively and assigned into an observation group and control group according to the treatment received, with 39 patients in each group. Patients in the control group were treated with conventional decompressive craniotomy and those in the observation group with standard large trauma craniotomy. The prognosis (GOS score), intracranial pressure before and after surgery, neurological functions (NIHSS score), cerebral hemodynamics (Vm, Vs, PI), quality of life (SF-36 score) and postoperative complications were compared.

RESULTS

The number of patients whose GOS scores were graded 5 was markedly higher in the observation group than that in the control group (P<0.05). The postoperative intracranial pressure and NIHSS scores in the observation group were lower than those in the control group (P<0.001). The postoperative Vm, Vs and PI were lower in the observation group than those in the control group, respectively (P<0.001). There was no statistical difference in the incidence of complications in the two groups (P>0.05). The SF-36 scores in the observation group were higher than those of the control group (P<0.01).

CONCLUSION

Standard large trauma craniotomy is effective in treating patients with severe frontotemporal craniocerebral injury. It decreases intracranial pressure, improves neurological function and quality of life and results in a good prognosis.

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.

Different materials of cranioplasty for patients undergoing decompressive craniectomy: A protocol for systematic review and network meta-analysis

BACKGROUND

Cranioplasty is widely applied on patients who has undergone decompress craniectomy (DC) due to intractable increased intracranial pressure and the cranioplasty materials have been on the bleeding edge of biomolecular and material science. This systematic review and network meta-analysis (NMA) will be conducted to comprehensively evaluate the safety and efficacy of different cranial implants for patients with cranial defects due to various reasons.

METHODS AND ANALYSIS

This protocol has been reported following the Preferred Reporting Items for Systematic Review and Meta-Analysis Protocols. The following electronic databases will be searched from the date of database establishment to September 1, 2020: PubMed, Embase, Cochrane Library, Web of Science, China National Knowledge Infrastructure, VIP, and Wanfang. Randomized controlled trials and non-randomized prospective studies focus on cranial implants will be included. Quality assessment will be conducted using Cochrane Collaboration's tool or risk of bias in nonrandomized studies of interventions based on their study designs. The primary outcome will be postoperative early mortality and implant failure while various complications for secondary outcomes. Pairwise and network meta-analysis will be conducted using STATA V.14 (StataCorp, College Station, Texas, USA). Subgroup analyses and sensitivity analyses will be conducted to assess the robustness of the results.

ETHICS AND DISSEMINATION

This systematic review does not require an ethics approval or the need to obtain informed consent. The results will be published in a peer-reviewed scientific journal.

PROTOCOL REGISTRATION NUMBER

INPLASY 202110001.

Change of Levels of NGF, ACTH, and AVP in the Cerebrospinal Fluid after Decompressive Craniectomy of Craniocerebral Injury and Their Relationship with Communicating Hydrocephalus

In recent years, the incidence of craniocerebral trauma has increased, making it one of the important causes of death and disability in neurosurgery patients. The decompressive craniectomy (DC) after severe craniocerebral injury has become the preferred treatment for patients with severe craniocerebral injury, but the incidence of postoperative hydrocephalus has become a difficult problem in clinical treatment. This study observed the changes of nerve growth factor (NGF), adrenocorticotropic hormone (ACTH), and arginine vasopressin (AVP) levels in the CSF after DC in patients with craniocerebral injury and analyzed the relationship between the three indicators and communicating hydrocephalus. The results showed that the levels of NGF, ACTH, and AVP in patients with cranial injury after DC were significantly higher than those in healthy subjects, and subdural effusion, traumatic subarachnoid hemorrhage (tSAH), and the levels of NGF, ACTH, and AVP in the CSF were independent risk factors for communicating hydrocephalus. Monitoring the levels of NGF, ACTH, and AVP is of great significance for clinicians to judge the occurrence of traffic hydrocephalus, evaluate the prognosis of patients with craniocerebral injury after DC, and guide clinical treatment.

Cranioplasty Following Severe Traumatic Brain Injury: Role in Neurorecovery

PURPOSE OF REVIEW

Decompressive craniectomy (DC) is a life-saving procedure performed in refractory intracranial pressure increase and mass lesion due to severe traumatic brain injury (TBI). Cranioplasty primarily intends to maintain cerebral protection and reconstruct aesthetic appearance. Also, cranioplasty can enable neurological rehabilitation and potentially augment neurological recovery. This article reviews recent studies on the effect of cranioplasty on neurological recovery in severe TBI.

RECENT FINDINGS

Recent findings suggested that cranioplasty has the potential to enhance neurological recovery after severe TBI. Cranioplasty may alleviate cognitive and functional deficits by reinstating the regular cerebrospinal fluid dynamics and improving brain perfusion. Analyses on the effects of cranioplasty timing on neurological recovery likely favor early cranioplasty. Also, materials used during cranioplasty, autologous and exogenous, were suggested to have similar effects in recovery. Although neurological therapy of TBI patients is still a serious challenge, recent findings represent the possible enhancing effect of cranioplasty on neurological recovery.

First Report of a Multicenter Prospective Registry of Cranioplasty in the United Kingdom and Ireland

BACKGROUND

There are many questions that remain unanswered regarding outcomes following cranioplasty including the timing of cranioplasty following craniectomy as well as the material used.

OBJECTIVE

To establish and evaluate 30-d outcomes for all cranial reconstruction procedures in the United Kingdom (UK) and Ireland through a prospective multicenter cohort study.

METHODS

Patients undergoing cranioplasty insertion or revision between June 1, 2019 and November 30, 2019 in 25 neurosurgical units were included. Data collected include demographics, craniectomy date and indication, cranioplasty material and date, and 30-d outcome.

RESULTS

In total, 313 operations were included, consisting of 255 new cranioplasty insertions and 58 revisions. Of the new insertions, the most common indications for craniectomy were traumatic brain injury (n = 110, 43%), cerebral infarct (n = 38, 15%), and aneurysmal subarachnoid hemorrhage (n = 30, 12%). The most common material was titanium (n = 163, 64%). Median time to cranioplasty was 244 d (interquartile range 144-385), with 37 new insertions (15%) within or equal to 90 d. In 30-d follow-up, there were no mortalities. There were 14 readmissions, with 10 patients sustaining a wound infection within 30 d (4%). Of the 58 revisions, the most common reason was due to infection (n = 33, 59%) and skin breakdown (n = 13, 23%). In 41 (71%) cases, the plate was removed during the revision surgery.

CONCLUSION

This study is the largest prospective study of cranioplasty representing the first results from the UK Cranial Reconstruction Registry, a first national registry focused on cranioplasty with the potential to address outstanding research questions for this procedure.

Cranioplasty with Autologous Bone Flaps Cryopreserved with Dimethylsulphoxide: Does Tissue Processing Matter

OBJECTIVE

The aim of this article was to study the outcome of patients who underwent cranioplasty with cryopreserved autologous bone after decompressive craniectomy.

METHODS

Data from 74 patients were retrospectively analyzed. They were divided into groups according to the storage time and the age at cranioplasty. To assess the predictive potential for complication, factors were related to successive stages (preoperative, craniectomy, tissue processing, cranioplasty, and postoperative). Cooling and warming rates applied on bone flap were calculated. The ability to inhibit microbial growth was determined exposing bone fragments to a panel of microorganisms. The concentration of antibiotics eluted from the bone was also determined. A bone explant culture method was used to detect living cells in the thawed cranial bone.

RESULTS

Hydrocephalus was significantly more frequent in pediatric patients (26.7%) than in adults (5.1%). The overall rate of bone flap resorption was 21.6% (43.7% of which required reoperation). Surgical site infection after cranioplasty was detected in 6.8% of patients. There was no correlation between infection as a postoperative complication and previous microbiological-positive culture during processing. The cause of craniectomy did not influence the risk of bone flap contamination. Vancomycin was the only antibiotic detected in the supernatant where the bone was incubated. Outgrowth from bone explants was observed in 36.8% of thawed skulls. An early start of bone flap processing at the tissue bank had a positive effect on cell viability.

CONCLUSIONS

The outcome after autologous cranioplasty is a multifactorial process, which is modulated by patient-related, surgery-related, and bone-related factors.

Escalate and De-Escalate Therapies for Intracranial Pressure Control in Traumatic Brain Injury

Severe traumatic brain injury (TBI) is frequently associated with an elevation of intracranial pressure (ICP), followed by cerebral perfusion pressure (CPP) reduction. Invasive monitoring of ICP is recommended to guide a step-by-step “staircase approach” which aims to normalize ICP values and reduce the risks of secondary damage. However, if such monitoring is not available clinical examination and radiological criteria should be used. A major concern is how to taper the therapies employed for ICP control. The aim of this manuscript is to review the criteria for escalating and withdrawing therapies in TBI patients. Each step of the staircase approach carries a risk of adverse effects related to the duration of treatment. Tapering of barbiturates should start once ICP control has been achieved for at least 24 h, although a period of 2–12 days is often required. Administration of hyperosmolar fluids should be avoided if ICP is normal. Sedation should be reduced after at least 24 h of controlled ICP to allow neurological examination. Removal of invasive ICP monitoring is suggested after 72 h of normal ICP. For patients who have undergone surgical decompression, cranioplasty represents the final step, and an earlier cranioplasty (15–90 days after decompression) seems to reduce the rate of infection, seizures, and hydrocephalus.

Ultrasound-Guided Ventricular Puncture During Cranioplasty

BACKGROUND

In patients with brain parenchyma extending beyond the craniectomy defect, cerebrospinal fluid diversion may be necessary to facilitate proper bone flap replacement during cranioplasty. In this study, we present our case series of patients who underwent ultrasound-guided ventricular puncture during cranioplasty and report periprocedural metrics and clinical outcomes.

METHODS

A retrospective study of patients who presented for cranioplasty that required ultrasound-guided ventricular puncture was performed. We also describe our operative technique for safely and accurately performing ultrasound-guided ventricular puncture.

RESULTS

Ten consecutive patients were included in the overall patient cohort, all of whom required intraoperative ventricular puncture to achieve brain relaxation. The mean time between decompressive hemicraniectomy and cranioplasty was 145.4 days (range 19-419). The mean duration of cranioplasty operation was 146 minutes (range 74-193). All patients underwent ultrasound-guided ventricular puncture, and 5 patients had an external ventricular drain left in place for postoperative intracranial pressure monitoring and possible cerebrospinal fluid drainage. There were no instances of pericatheter hemorrhage. One patient presented postoperatively with wound infection, and this same patient was the only one in the cohort who required subsequent ventriculoperitoneal shunt for symptomatic hydrocephalus.

CONCLUSIONS

Ultrasound-guided ventricular puncture is safe, feasible, and efficacious for use during cranioplasty to help facilitate bone flap replacement in patients with "full" brains, with an overall low rate of associated periprocedural complications. Although further studies are needed in a larger patient cohort, this technique should be considered to help reduce the morbidity associated with cranioplasty.

Postural neurologic deficits after decompressive craniectomy: A case series of sinking skin flap syndrome in traumatic brain injury

BACKGROUND

Hemicraniectomy to manage raised intracranial pressure following traumatic brain injury (TBI) has improved survival but may increase the incidence of Sinking Skin Flap Syndrome (SSFS). SSFS is a clinical syndrome in which patients with craniectomy develop objective neurologic abnormalities due to the pressure of the atmosphere on the unprotected brain, often presenting with postural headaches and neurologic deficits that localize to the craniectomy site. Previously thought to be a rare complication of craniectomy after TBI, evidence suggests SSFS is under-recognized.

OBJECTIVE

To describe the clinical and radiographic features leading to diagnosis and the impact of temporizing and definitive management of SSFS on outcomes in inpatients with moderate/severe TBI.

METHODS

Two patients' symptoms, qualitative behaviour observation, physical and cognitive outcome measures, and neuroimaging pre- and post-temporizing measures and cranioplasty are presented.

RESULTS

Both patients demonstrated partial improvements with temporizing measures and substantial improvements in functional, cognitive, physical, and rehabilitation outcomes from the cranioplasty and resolution of SSFS.

CONCLUSIONS

Rehabilitation care providers are critical to the timely diagnosis and management of SSFS, including the use of temporizing measures and advocacy for definitive treatment with cranioplasty. These cases highlight the diverse clinical presentations and importance of SSFS diagnosis to improve patient outcomes.

Cranial bone flap resorption-pathological features and their implications for clinical treatment

Cranioplasty following decompressive craniectomy (DC) has a primary complication when using the autologous bone: aseptic bone resorption (ABR). So far, risk factors such as age, number of fragments, and hydrocephalus have been identified but a thorough understanding of the underlying pathophysiology is still missing. The aim of this osteopathological investigation was to gain a better understanding of the underlying processes. Clinical data of patients who underwent surgical revision due to ABR was collected. Demographics, the time interval between craniectomy and cranioplasty, and endocrine serum parameters affecting bone metabolism were collected. Removed specimens underwent qualitative and quantitative histological examination. Two grafts without ABR were examined as controls. Compared to the controls, the typical layering of the cortical and cancellous bone was largely eliminated in the grafts. Histological investigations revealed the coexistence of osteolytic and osteoblastic activity within the necrosis. Bone appositions were distributed over the entire graft area. Remaining marrow spaces were predominantly fibrotic or necrotic. In areas with marrow cavity fibrosis, hardly any new bone tissue was found in the adjacent bone, while there were increased signs of osteoclastic resorption. Insufficient reintegration of the flap may be due to residual fatty bone marrow contained in the bone flap which seems to act as a barrier for osteogenesis. This may obstruct the reorganization of the bone structure, inducing aseptic bone necrosis. Following a path already taken in orthopedic surgery, thorough lavage of the implant to remove the bone marrow may be a possibility, but will need further investigation.