Effects of Cranioplasty on Cerebral Blood Flow Following Decompressive Craniectomy: A Systematic Review of the Literature

Consensus on the prevention and repair of titanium mesh exposed wound after cranioplasty (2024 edition)

Titanium mesh exposure after cranioplasty is the most serious complication of this procedure. Although some clinical experience has been gradually accumulated over the years in the diagnosis and treatment of titanium mesh exposure, the treatment is often not standardized and it is difficult to achieve satisfactory repair results due to insufficient understanding of its pathogenesis and concurrent infections. To normalize the diagnosis and treatment of titanium mesh exposed wounds after cranioplasty and improve the therapeutic effect and the quality of life of patients, the Wound Repair Professional Committee of Chinese Medical Doctor Association organized an expert discussion based on the literature and current diagnosis and treatment status of titanium mesh exposed wounds after cranioplasty at home and abroad, and reached a consensus on the pathogenesis, preventive measures, and diagnosis and treatment strategies of titanium mesh exposed wounds after cranioplasty to provide reference for relevant clinicians.

Large Amount of Epidural Effusion Outside the Dura After Percutaneous Puncture and Suction Treatment

Epidural fluid collection is commonly seen as a low-density accumulation beneath the dura on postoperative computed tomography scans. It is discussed less in the literature because, in most cases, the fluid amount is small, self-absorbing, and typically does not cause neurological deficits, so intervention is usually unnecessary. However, when a significant amount of fluid accumulates, patients may experience symptoms such as altered consciousness and even coma. In such cases, treatment is necessary to reduce intracranial pressure, preventing further deterioration of consciousness and potentially life-threatening situations. The authors report a case of a large epidural fluid collection following cranioplasty, resulting in progressive deterioration of consciousness in the patient. Computed tomography scans indicated brain herniation. Subsequently, percutaneous puncture and suction treatment were performed, followed by appropriate pressure dressing. The patient gradually recovered from a shallow coma to clear consciousness and was discharged after rehabilitation.

Three-dimensional personalized porous polyethylen cranioplasty in patients at increased risk of surgical site infection

BACKGROUND

Surgical site infection (SSI) is the most consistently reported complication of cranioplasty. No material showed a categorical superiority in the incidence of infection. Porous polyethylene (PE) is considered a low risk material regarding SSI. However, the literature data are very limited. Thus, our objective was to verify the assumed low incidence of SSI after PE cranioplasty in patients at high risk of SSI. The primary objective was the infection rate, while secondary objectives were implant exposure, revision and cosmetic results.

METHOD

Patients who underwent three-dimensional (3D) personalized PE cranioplasty in the period 2014-2023 were evaluated prospectively. Only patients with an increased risk of SSI, and a satisfactory clinical conditions were included in the study.

RESULTS

Thirty procedures were performed in 30 patients. Cranioplasty was performed 23 times after hemispheric decompressive craniectomy, five times after limited size craniotomy and two times after bifrontal decompressive craniectomy. Risk factors for the development of infection were 18 previous SSIs, 16 previous repeated revision surgeries, four intraoperatively opened frontal sinuses and two times radiotherapy. Neither infection nor implant exposure was detected in any patient. All patients were satisfied with the aesthetic result. In two cases, a revision was performed due to postoperative epidural hematoma.

CONCLUSIONS

Three-dimensional personalized PE cranioplasty is associated with an extremely low incidence of SSI even in high-risk patients. However, our conclusions can only be confirmed in larger studies.

Three-Pillar Expansive Craniotomy in Children with Acute Ruptured Supratentorial Brain Arteriovenous Malformations

OBJECTIVE

Acute rupture and hemorrhage of pediatric brain arteriovenous malformations (AVMs) may lead to cerebral herniation or intractable intracranial hypertension, necessitating emerging surgical interventions to alleviate intracranial pressure. However, there is still controversy regarding the timing of treatment for ruptured AVMs. This study aimed to assess the feasibility of utilizing three-pillar expansive craniotomy (3PEC) at different times during the treatment of pediatric ruptured supratentorial AVMs.

METHODS

A retrospective analysis was conducted on all consecutive cases of acute rupture in supratentorial AVM children who underwent 3PEC at a single institution from 2020 to 2022. General information, clinical characteristics, radiological data, and prognosis were reviewed and analyzed.

RESULTS

Thirteen children were included in the analysis. The intracranial pressure of all patients decreased to below 15 mmHg within 10 days. The expansion volume of the cranial cavity of the patients increased by 18.3 cm3 (95% confidence interval, 10.2-26.3; P < 0.001) compared to the hematoma volume. None of the patients required decompressive craniectomy due to intractable intracranial hypertension caused by cerebral swelling. The median waiting period for patients with delayed AVMs treatment was 8 days, during which no rebleeding occurred.

CONCLUSIONS

Emergency intervention with 3PEC in children experiencing acutely ruptured supratentorial AVMs appears to be feasible. For children requiring delayed management of the AVMs, 3PEC may diminish the risk of rebleeding during the waiting period and shorten the waiting period.

Neurocognitive outcome post cranioplasty: The role of cerebral hemodynamics and cerebrospinal fluid dynamics

Background

Cranioplasty has been useful in treating the symptoms associated with the "Sunken skin flap syndrome" post decompressive craniectomy, for which various mechanisms have been proposed. In this study, we aim to assess the changes in the cerebral blood flow and intracranial cerebrospinal fluid (CSF) dynamics post cranioplasty and correlate with the improvement in the neurocognitive status.

Methods

Computed tomography perfusion and cine magnetic resonance imaging studies were done to study the changes in cerebral perfusion and CSF flow dynamics postcranioplasty. The cognitive status was assessed using Montreal cognitive assessment, mini-mental state examination, and frontal assessment battery scores in the preoperative period and at 1 and 6 months follow-up.

Results

There was a significant change in cognitive status postcranioplasty, both at 1 and 6 months follow-up, which was associated with a significant improvement in cerebral blood flow, decreased mean transit time, and improvement in the mean and peak CSF flow velocities at the foramen of Magendie and aqueduct of Sylvius.

Conclusion

Cranioplasty leads to a marked improvement in cerebral hemodynamics, which is more significant on the ipsilateral side. It also leads to increased CSF turnover and improved CSF circulation. Improved cerebral perfusion and, more importantly, CSF dynamics may be responsible for the demonstrable improvement in the neurocognition in the postcranioplasty period.

Cranioplasty is not required in the reconstruction of small combined scalp and calvarial defects

BACKGROUND

Treatment of scalp malignancies may include the need for craniectomy. The decision to perform cranioplasty is not straightforward and is frequently subjective. The purpose of this study was to assess the clinical outcomes after reconstruction of complex scalp and calvarial defects by comparing patients with and without cranioplasty.

METHODS

Retrospective review of the clinical records of a consecutive series of patients who underwent scalp soft tissue reconstruction after craniectomy for malignancy or osteoradionecrosis between 2014 and 2022 at Royal Melbourne Hospital was conducted. Demographics, previous treatments, surgical details, and post-operative complications were assessed. Traumatic injuries and decompressive craniectomies were excluded. Minimum follow-up of 6 months.

RESULTS

Thirty-seven patients were included in the study. Indications for surgery included skin malignancies, osteoradionecrosis, or both. There was one reconstructive failure (in the non-cranioplasty group). Infection and metalware exposure were common complications in patients who underwent cranioplasty (38.5%). No patient developed neurological symptoms subsequent to craniectomy. One patient needed revision surgery due to esthetic reasons (cranioplasty group). Transposition flaps were associated with more complications and revision procedures.

CONCLUSION

Combined scalp and calvarial defects pose a difficult reconstructive challenge. Stable soft tissue coverage is more reliably achieved with free flap reconstruction. Cranioplasty is not always mandatory and should be reserved for cases with a very large bony defect or when the defect is located in a cosmetically sensitive area.

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.

A comprehensive systematic review and meta-analysis study in comparing decompressive craniectomy versus craniotomy in patients with acute subdural hematoma

There are two controversial surgery methods which are traditionally used: craniotomy and decompressive craniectomy. The aim of this study was to evaluate the efficacy and complications of DC versus craniotomy for surgical management in patients with acute subdural hemorrhage (SDH) following traumatic brain injury (TBI). We conducted a comprehensive search on PubMed, Scopus, Web of Science, and Embase up to July 30, 2023, using the Preferred Reporting Items for Systematic Reviews and Meta-Analyses checklist. Relevant articles were reviewed, with a focus on studies comparing decompressive craniectomy to craniotomy techniques in patients with SDH following TBI. Ten studies in 2401 patients were reviewed. A total of 1170 patients had a craniotomy, and 1231 had decompressive craniectomy. The mortality rate was not significantly different between the two groups (OR: 0.46 [95% CI: 0.42-0.5] P-value: 0.07). The rate of revision surgery was insignificantly different between the two groups (OR: 0.59 [95% CI: 0.49-0.69] P-value: 0.08). No significant difference was found between craniotomy and decompressive craniectomy regarding unilateral mydriasis (OR: 0.46 [95% CI: 0.35-0.57] P-value < 0.001). However, the craniotomy group had significantly lower rates of non-pupil reactivity (OR: 0.27 [95% CI: 0.17-0.41] P-value < 0.001) and bilateral mydriasis (OR: 0.59 [95% CI: 0.5-0.66] P-value: 0.04). There was also no significant difference in extracranial injury between the two groups, although the odds ratio of significant extracranial injury was lower in the craniotomy group (OR: 0.58 [95% CI: 0.45-0.7] P-value: 0.22). Our findings showed that non-pupil and bilateral-pupil reactivity were significantly more present in decompressive craniectomy. However, there was no significant difference between the two groups regarding mortality rate, extracranial injury, revision surgery, and one-pupil reactivity.

Risk Factors for Seizures After Titanium Cranioplasty: Five-Year Experience from a Single Institution

OBJECTIVE

Seizures are one of the complications that can occur after cranioplasty (CP). In some regions, titanium mesh remains the material of choice for CP. However, risk factors for seizures after titanium CP have been less studied. The purpose of this study was to identify potential risk factors for early seizures (≤7 days) and late seizures (>8 days) after titanium CP in a single institution.

METHODS

A retrospective review was conducted of 241 consecutive patients who received titanium CP at the First Affiliated Hospital of Harbin Medical University from January 2016 to December 2020. Univariate and multivariable logistic regression analyses were performed to determine the independent risk factors for new-onset seizures after titanium CP.

RESULTS

Fifteen patients (6.22%) experienced early post-CP seizures, and late post-CP seizures were observed in 81 patients (33.61%). A flaccid concave cranial defect (P = 0.042) was associated with early post-CP seizures, whereas hypertension (P < 0.001) was the only significant predictor for late seizures after titanium CP.

CONCLUSIONS

Seizure is a common complication after titanium CP, especially in patients who do not receive prophylactic antiepileptic drugs before the procedure. Risk factors for new-onset seizures at different periods after titanium CP were found to be different. In addition, radiologic factors before titanium CP may play a role in early new-onset seizures after titanium CP and should not be ignored.

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.

Toward Highly Matching the Dura Mater: A Polyurethane Integrating Biocompatible, Leak-Proof, and Self-Healing Properties

The dura mater is the final barrier against cerebrospinal fluid leakage and plays a crucial role in protecting and supporting the brain and spinal cord. Head trauma, tumor resection and other traumas damage it, requiring artificial dura mater for repair.  However, surgical tears are often unavoidable. To address these issues, the ideal artificial dura mater should have biocompatibility, anti-leakage, and self-healing properties. Herein, this work has used biocompatible polycaprolactone diol as the soft segment and introduced dynamic disulfide bonds into the hard segment, achieving a multifunctional polyurethane (LSPU-2), which integrated the above mentioned properties required in surgery. In particular, LSPU-2 matches the mechanical properties of the dura mater and the biocompatibility tests with neuronal cells demonstrate extremely low cytotoxicity and do not cause any negative skin lesions. In addition, the anti-leakage properties of the LSPU-2 are confirmed by the water permeability tester and the 900 mm H2 O static pressure test with artificial cerebrospinal fluid. Due to the disulfide bond exchange and molecular chain mobility, LSPU-2 could be completely self-healed within 115 min at human body temperature. Thus, LSPU-2 comprises one of the most promising potential artificial dura materials, which is essential for the advancement of artificial dura mater and brain surgery.

Earlier cranioplasty following posttraumatic craniectomy is associated with better neurological outcomes at one-year follow-up: a two-centre retrospective cohort study

PURPOSE

Cranioplasty (CP) after decompressive craniectomy (DC) is routinely performed for reconstructive purposes and improves rehabilitation. However, the optimal timing of CP remains controversial. This study aimed to assess differences in clinical outcomes following different timings of CP in patients with traumatic brain injury.

MATERIALS AND METHODS

Patients with traumatic brain injury who underwent CP after DC in Zhongnan Hospital of Wuhan University from 1 January 2010 to 1 May 2017, and in Affiliated Hospital of Guizhou Medical University from 1 January 2015, to 1 May 2017, were retrospectively reviewed. According to the timing of CP, patients were divided into an 'early group' (3-6 months) and a 'late group' (6-12 months). The clinical characteristics of patients and postoperative complications occurred within 1-year follow-up were analysed. The neurological function was assessed with Barthel Index (BI).

RESULTS

A total of 100 patients (58 cases in early group and 42 cases in late group) were included. The median interval between DC and CP was 135 days and 225 days in the early and late CP groups, respectively. The overall complication rate after CP was 16%, and no significant difference in complication rate was observed between the early and late CP groups (17.2% vs.14.3%, p = 0.69). The neurological function was improved in early CP group (pre-CP 85.77 ± 11.61 vs. post-CP 95.34 ± 9.02, p < 0.001, but not in late CP group (pre-CP 82.74 ± 22.82 vs. post-CP 88.93 ± 22.86, p = 0.22). In addition, a significantly higher proportion of patients in the early CP group showed neurological functional improvement in comparison with the late CP group (early vs. late: 74.1% vs. 57.1%, p = 0.04). Multivariate analysis further demonstrated that the timing of CP is an independent predictor for neurological outcomes (OR = 0.32, 95% CI 0.13-0.82, p = 0.02).

CONCLUSION

Early CP (3-6 months) following posttraumatic DC was associated with better neurological outcomes than late CP (>6 months).

Comparative effectiveness of decompressive craniectomy versus craniotomy for traumatic acute subdural hematoma (CENTER-TBI): an observational cohort study

Background

Limited evidence existed on the comparative effectiveness of decompressive craniectomy (DC) versus craniotomy for evacuation of traumatic acute subdural hematoma (ASDH) until the recently published randomised clinical trial RESCUE-ASDH. In this study, that ran concurrently, we aimed to determine current practice patterns and compare outcomes of primary DC versus craniotomy.

Methods

We conducted an analysis of centre treatment preference within the prospective, multicentre, observational Collaborative European NeuroTrauma Effectiveness Research in Traumatic Brain Injury (known as CENTER-TBI) and NeuroTraumatology Quality Registry (known as Net-QuRe) studies, which enrolled patients throughout Europe and Israel (2014-2020). We included patients with an ASDH who underwent acute neurosurgical evacuation. Patients with severe pre-existing neurological disorders were excluded. In an instrumental variable analysis, we compared outcomes between centres according to treatment preference, measured by the case-mix adjusted proportion DC per centre. The primary outcome was functional outcome rated by the 6-months Glasgow Outcome Scale Extended, estimated with ordinal regression as a common odds ratio (OR), adjusted for prespecified confounders. Variation in centre preference was quantified with the median odds ratio (MOR). CENTER-TBI is registered with ClinicalTrials.gov, number NCT02210221, and the Resource Identification Portal (Research Resource Identifier SCR_015582).

Findings

Between December 19, 2014 and December 17, 2017, 4559 patients with traumatic brain injury were enrolled in CENTER-TBI of whom 336 (7%) underwent acute surgery for ASDH evacuation; 91 (27%) underwent DC and 245 (63%) craniotomy. The proportion primary DC within total acute surgery cases ranged from 6 to 67% with an interquartile range (IQR) of 12-26% among 46 centres; the odds of receiving a DC for prognostically similar patients in one centre versus another randomly selected centre were trebled (adjusted median odds ratio 2.7, p < 0.0001). Higher centre preference for DC over craniotomy was not associated with better functional outcome (adjusted common odds ratio (OR) per 14% [IQR increase] more DC in a centre = 0.9 [95% CI 0.7-1.1], n = 200). Primary DC was associated with more follow-on surgeries and complications [secondary cranial surgery 27% vs. 18%; shunts 11 vs. 5%]; and similar odds of in-hospital mortality (adjusted OR per 14% IQR more primary DC 1.3 [95% CI (1.0-3.4), n = 200]).

Interpretation

We found substantial practice variation in the employment of DC over craniotomy for ASDH. This variation in treatment strategy did not result in different functional outcome. These findings suggest that primary DC should be restricted to salvageable patients in whom immediate replacement of the bone flap is not possible due to intraoperative brain swelling.

Funding

Hersenstichting Nederland for the Dutch NeuroTraumatology Quality Registry and the European Union Seventh Framework Program.

A 2-Year Prospective Study of Complication Rates After Cranioplasty: Is 8 Weeks' Interval Associated with Increased Complications?

BACKGROUND

The commonly observed complications after cranioplasty include infections, intracranial hemorrhage, and seizures. The timing of cranioplasty after decompressive craniectomy (DC) is still under debate, with literature available for both early and delayed cranioplasties. The objectives of this study were to note the overall complication rates and more specifically compare complications between 2 different time intervals.

METHODS

This was a 24-month, single-center, prospective study. Since timing is the most debated variable, the study cohort was divided into 2 groups (≤8 weeks and >8 weeks). Furthermore, other variables such as age, gender, etiology of DC, neurologic condition, and blood loss were correlated with complications.

RESULTS

A total of 104 cases were analyzed. Two thirds were traumatic etiology. The mean and median DC-cranioplasty intervals were 11.3 weeks (range 4-52 weeks) and 9 weeks, respectively. Seven complications (6.7%) were observed in 6 patients. There was no statistical difference observed between any of the variables and complications.

CONCLUSIONS

We observed that performing cranioplasty within 8 weeks of the initial DC surgery is safe and noninferior to cranioplasty performed after 8 weeks. Therefore if the general condition of the patient is satisfactory, we are of the opinion that an interval of 6-8 weeks from the primary DC is safe and a reasonable time frame for performing cranioplasty.

Optimal Timing of Cranioplasty and Predictors of Overall Complications After Cranioplasty: The Impact of Brain Collapse

BACKGROUND

The optimal timing of cranioplasty (CP) and predictors of overall postoperative complications are still controversial.

OBJECTIVE

To determine the optimal timing of CP.

METHODS

Patients were divided into collapsed group and noncollapsed group based on brain collapse or not, respectively. Brain collapse volume was calculated in a 3-dimensional way. The primary outcomes were overall complications and outcomes at the 12-month follow-up after CP.

RESULTS

Of the 102 patients in this retrospective observation cohort study, 56 were in the collapsed group, and 46 were in the noncollapsed group. Complications were noted in 30.4% (n = 31), 24 (42.9%) patients in the collapsed group and 7 (15.2%) patients in the noncollapsed group, with a significant difference ( P = .003). Thirty-three (58.9%) patients had good outcomes (modified Rankin Scale 0-3) in the collapsed group, and 34 (73.9%) patients had good outcomes in the noncollapsed group without a statistically significant difference ( P = .113). Brain collapse ( P = .005) and Karnofsky Performance Status score at the time of CP ( P = .025) were significantly associated with overall postoperative complications. The cut-off value for brain collapse volume was determined as 11.26 cm 3 in the receiver operating characteristic curve. The DC-CP interval was not related to brain collapse volume or postoperative complications.

CONCLUSION

Brain collapse and lower Karnofsky Performance Status score at the time of CP were independent predictors of overall complications after CP. The optimal timing of CP may be determined by tissue window based on brain collapse volume instead of time window based on the decompressive craniectomy-CP interval.

Effects of cranioplasty in cerebral blood perfusion using quantification with 99m-Tc HMPAO SPECT-CT

BACKGROUND AND PURPOSE

Syndrome of the trephined or sinking skin flap syndrome is an underdiagnosed condition of craniectomized patients that usually improves after cranioplasty. Among the pathophysiological theories proposed, the changes of cerebral blood perfusion (CBP) caused by cranial defects might have a role in the neurological deficiencies observed. We aim to assess the regional cortex changes in CBP after cranioplasty with Technetium 99m hexamethylpropylene-amine oxime (99mTc-HMPAO) SPECT-CT.

METHODS

Twenty-eight craniectomized patients subject to cranioplasty were studied with 99mTc-HMPAO SPECT-CT in three different times, before cranioplasty, a week, and 3 months after. The images were processed with quantification software comparing CBP of 24 cortical areas with a reference area, and with a database of controls. A mixed effects model and T-Student were used.

RESULTS

CBP increased significantly in both hemispheres after cranioplasty, either using ratio (β = .019, p-value = .030 first postsurgical SPECT-CT and β = .021, p-value = .015 in the second study, vs. presurgical) or Z-score (β = .220, p-value = .026 and β = .279, p-value = .005, respectively). Nine areas of the damaged side had a significant lower CBP ratio and Z-score than the undamaged. Posterior cingulate showed an increased CBP ratio (p-value = .034) and Z-score (p-value = .028) in the first postsurgical SPECT-CT. These posterior cingulate changes represent a 4.83% increase in ratio and 91.04% in Z-Score (p-value = .035 and .040, respectively).

CONCLUSION

CBP changes significantly in specific cortical areas after cranioplasty. Posterior cingulate changes might explain some improvements in attention impairments. SPECT-CT could be a useful tool to assess CBP changes in these patients and might be helpful in their clinical management.

Tissue Expanders in Staged Calvarial Reconstruction: A Systematic Review

Cranioplasties are common procedures in plastic surgery. The use of tissue expansion (TE) in staged cranioplasties is less common. We present two cases of cranioplasties with TE and systematically review literature describing the use of TE in staged cranioplasties and postoperative outcomes. A systematic review was performed by querying multiple databases. Eligible articles include published case series, retrospective reviews, and systematic reviews that described use of TE for staged bony cranioplasty. Data regarding study size, patient demographics, preoperative characteristics, staged procedure characteristics, and postoperative outcomes were collected. Of 755 identified publications, 26 met inclusion criteria. 85 patients underwent a staged cranioplasty with TE. Average defect size was 122 cm ² , and 30.9% of patients received a previous reconstruction. Average expansion period was 14.2 weeks. The most common soft tissue closures were performed with skin expansion only (75.3%), free/pedicled flap (20.1%), and skin graft (4.7%). The mean postoperative follow-up time was 23.9 months. Overall infection and local complication rates were 3.53 and 9.41%, respectively. The most common complications were cerebrospinal fluid leak (7.1%), hematoma (7.1%), implant exposure (3.5%), and infection (3.5%). Factors associated with higher complication rates include the following: use of alloplastic calvarial implants and defects of congenital etiology ( p  = 0.023 and 0.035, respectively). This is the first comprehensive review to describe current practices and outcomes in staged cranioplasty with TE. Adequate soft tissue coverage contributes to successful cranioplasties and TE can play a safe and effective role in selected cases.

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.

Systematic Review of Syndrome of the Trephined and Reconstructive Implications

Syndrome of the trephined (SoT) is a severe complication following decompressive craniectomy resulting in neurological decline which can progress to aphasia, catatonia, and even death. While cranioplasty can reverse neurological symptoms of SoT, awareness of SoT is poor outside of the neurosurgery community. The authors performed a systematic review of the literature on SoT with a focus on reconstructive implications. Search terms "syndrome of the trephined" and "sunken flap syndrome" were applied to PubMed to identify primary studies through October 2021. Full-text review yielded 11 articles discussing SoT and reconstructive techniques or implications with 56 patients undergoing cranial reconstruction. Average age of the patients was 41.8±9.5 years. Sixty-three percent of the patients were male. The most common indication for craniectomy was traumatic brain injury (43%), followed by tumor resection (23%), intracerebral hemorrhage (11%), and aneurysmal subarachnoid hemorrhage (2%). Patients most commonly suffered from motor deficits (52%), decreased wakefulness (30%), depression or anxiety (21%), speech deficits (16%), headache (16%), and cognitive difficulties (2%). Time until presentation of symptoms following decompression was 4.4±8.9 months. Patients typically underwent cranioplasty with polyetheretherketone (48%), titanium mesh (21%), split thickness calvarial bone (16%), full thickness calvarial bone (14%), or split thickness rib graft (4%). Eight percent of patients required free tissue transfer for soft tissue coverage. Traumatic Brain Injury (TBI) was a risk factor for development of SoT when adjusting for age and sex (odds ratio: 8.2, 95% confidence interval: 1.2-8.9). No difference significant difference was observed between length until initial improvement of neurological symptoms following autologous versus allograft reconstruction (P=0.47). SoT can be a neurologically devastating complication of decompressive craniectomy which can resolve following urgent cranioplasty. Familiarity with this syndrome and its reconstructive implications is critical for the plastic surgery provider, who may be called upon to assist with these urgent cases.

Ultra-Early Cranioplasty versus Conventional Cranioplasty: A Retrospective Cohort Study at an Academic Level 1 Trauma Center

The goal of this study was to ascertain the efficacy, safety, and comparability of ultra-early cranioplasty (CP; defined here as <30 days from the original craniectomy) to conventional cranioplasty (defined here as >30 days from the original craniectomy). A retrospective review of CPs performed at our institution between January 2016 and July 2020 was performed. Craniectomies initially performed at other institutions were excluded. Seventy-seven CPs were included in our study. Ultra-early CP was defined as CP performed within 30 days of craniectomy whereas conventional CP occurred after 30 days. Post-operative wound infection rates, rate of return to the operating room (OR) with or without bone flap removal, operative length, and rate of post-CP hydrocephalus were compared between the two groups. Thirty-nine and 38 patients were included in the ultra-early and conventional CP groups, respectively. The average number of days to CP in the ultra-early group was 17.70 ± 7.75 days compared to 95.70 ± 65.60 days in the conventional group. The mean Glasgow Coma Scale upon arrival to the emergency room was 7.28 ± 3.90 and 6.92 ± 4.14 for the ultra-early and conventional groups, respectively. The operative time was shorter in the ultra-early cohort than that in the conventional cohort (ultra-early, 2.40 ± 0.71 h; conventional, 3.00 ± 1.63 h; p = 0.0336). The incidence of post-CP hydrocephalus was also lower in the ultra-early cohort (ultra-early, 10.3%; conventional, 31.6%; p = 0.026). No statistically significant differences were observed regarding post-operative infection, return to the OR, or bone flap removal. Our study shows that ultra-early CP can significantly reduce the rate of post-CP hydrocephalus, as well as operative time in comparison to conventional CP. However, the timing of CP post-DC should remain a patient-centered consideration.

Hydrocephalus and the neuro-intensivist: CSF hydrodynamics at the bedside

Hydrocephalus (HCP) is far more complicated than a simple disorder of cerebrospinal fluid (CSF) circulation. HCP is a common complication in patients with subarachnoid hemorrhage (SAH) and after craniectomy. Clinical measurement in HCP is mainly related to intracranial pressure (ICP) and cerebral blood flow. The ability to obtain quantitative variables that describe CSF dynamics at the bedside before potential shunting may support clinical intuition with a description of CSF dysfunction and differentiation between normal pressure hydrocephalus and brain atrophy. This review discusses the advanced research on HCP and how CSF is generated, stored and absorbed within the context of a mathematical model developed by Marmarou. Then, we proceed to explain the main quantification analysis of CSF dynamics using infusion techniques for deciding on definitive treatment. We consider that such descriptions of multiple parameters of measurements need to be significantly appreciated by the caring neuro-intensivist, for better understanding of the complex pathophysiology and clinical management and finally, improve of the prognosis of these patients with HCP.

In this review article, we present current and novel theories of CSF circulation and pathophysiology of hydrocephalus, along with results from infusion studies for evaluating CSF dynamics at the bedside.

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

OBJECTIVE

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

METHODS

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

RESULTS

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

CONCLUSIONS

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

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.

Bifrontal Osteoplastic Flap: An Option to Decrease Infection in Bifrontal Craniotomies with Skull Base Osteotomies

Infection can be a common complication following bifrontal craniotomy with skull base osteotomies given the potential violation of sinuses and entry into the nasal structures. Our objective was to examine our series of patients who underwent a bifrontal craniotomy with skull base osteotomies and describe the infection rate. We propose the bifrontal osteoplastic flap as an adjunct to infection prevention. A retrospective single-center study of a patient database was performed. Twenty patients were identified. Fifty-five percent were male. The mean age was 55.7 ± 13.9 years. The most common indications for surgery were esthesioneuroblastomas (35%) and anterior skull base meningiomas (30%). Six patients (30%) developed an infection, 1 patient (5%) developed a CSF leak, and no patients developed a mucocele. All 6 infected cases had nasal pathology with intracranial extension, they all received chemoradiation post-operatively and were all combined cases with otorhinolaryngology. Eighty-three percent of these patients required a craniectomy and all of them required long-term IV antibiotics. Infection is not uncommon after a bifrontal craniotomy with skull base osteotomies and the use of the bifrontal osteoplastic flap in cases where the risk of infection is high, i.e., esthesioneuroblastomas surgery, may help reduce said risk and lead to better patient outcomes.

Multiple Cerebral Hemorrhages Caused by Paradoxical Reperfusion Injury After Cranioplasty

Cranioplasty-related reperfusion injury has rarely been reported. Although there are several hypotheses, particularly regarding the mechanisms of the event, clear evidence is lacking. Here, we report the case of an 84-year-old man with traumatic intracranial hemorrhage and subdural hematoma who underwent decompressive craniectomy and hematoma evacuation in the right hemisphere. After 45 days, cranioplasty was performed using titanium. A preoperative perfusion study with 99m-Tc-HMPAO brain single-photon emission tomography revealed diffuse hypoperfusion in the left cerebral hemisphere with decreased vascular reserve. After cranioplasty, multiple cerebral hemorrhages were observed on immediate postoperative computed tomography. Cerebral hemorrhage eventually improved without surgery. Here, we report a case with findings revealed through perfusion studies before and after surgery.

Can Cranioplasty Be Considered a Tool to Improve Cognitive Recovery Following Traumatic Brain Injury? A 5-Years Retrospective Study

Cranioplasty (CP) is a neurosurgical intervention of skull repairing following a decompressive craniectomy. Unfortunately, the impact of cranioplasty on cognitive and motor function is still controversial. Fifteen TBI subjects aged 26–54 years with CP after decompressive craniectomy were selected in this observational retrospective study. As per routine clinical practice, a neuropsychological evaluation carried out immediately before the cranioplasty (Pre CP) and one month after the cranioplasty (T0) was used to measure changes due to CP surgery. This assessment was performed each year for 5 years after discharge in order to investigate long-term cognitive changes (T1-T5). Before cranioplasty, about 53.3% of subjects presented a mild to severe cognitive impairment and about 40.0% a normal cognition. After CP, we found a significant improvement in all neuropsychological test scores. The more significant differences in cognitive recovery were detected after four years from CP. Notably, we found significant differences between T4 and T0-T1, as well as between T5 and T0-T1-T2 in all battery tests. This retrospective study further suggests the importance of CP in the complex management of patients with TBI showing how these patients might improve their cognitive function over a long period after the surgical procedure.

Predictive Factors of Surgical Site Infection Following Cranioplasty: A Study Including 3D Printed Implants

In patients who have undergone decompressive craniectomy (DC), subsequent cranioplasty is required to reconstruct cranial defects. Surgical site infection (SSI) following cranioplasty is a devastating complication that can lead to cranioplasty failure. The aim of the present study, therefore, was to identify predictive factors for SSI following cranioplasty by reviewing procedures performed over a 10-year period. A retrospective analysis was performed for all patients who underwent cranioplasty following DC between 2010 and 2020 at a single institution. The patients were divided into two groups, non-SSI and SSI, in order to identify clinical variables that are significantly correlated with SSI following cranioplasty. Cox proportional hazards regression analyses were then performed to identify predictive factors associated with SSI following cranioplasty. A total of 172 patients who underwent cranioplasty, including 48 who received customized three-dimensional (3D) printed implants, were enrolled in the present study. SSI occurred in 17 patients (9.9%). Statistically significant differences were detected between the non-SSI and SSI groups with respect to presence of fluid collections on CT scans before and after cranioplasty. Presence of fluid collections on computed tomography (CT) scan before (p = 0.0114) and after cranioplasty (p < 0.0000) showed significant association with event-free survival rate for SSI. In a univariate analysis, significant predictors for SSI were fluid collection before (p = 0.0172) and after (p < 0.0001) cranioplasty. In a multivariate analysis, only the presence of fluid collection after cranioplasty was significantly associated with the occurrence of SSI (p < 0.0001). The present study investigated predictive factors that may help identify patients at risk of SSI following cranioplasty and provide guidelines associated with the procedure. Based on the results of the present study, only the presence of fluid collection on CT scan after cranioplasty was significantly associated with the occurrence of SSI. Further investigation with long-term follow-up and large-scale prospective studies are needed to confirm our conclusions.

Clinical improvement after cranioplasty and its relation to body position and cerebral hemodynamics

Cranioplasty after decompressive craniectomy (DC) has been found to improve the neurological condition. The underlying mechanisms are still unknown. The aim of this study is to investigate the roles of the postural changes and atmospheric pressure (AP) in the brain hemodynamics and their relationship with clinical improvement. Seventy-eight patients were studied before and 72 h after cranioplasty with cervical and transcranial color Doppler ultrasound (TCCS) in the sitting and supine positions. Craniectomy size, shape, and force exerted by the AP (torque) were calculated. Neurological condition was assessed with the National Institutes of Health Stroke Scale (NIHSS) and the Barthel index. Twenty-eight patients improved after cranioplasty. Their time elapsed from the DC was shorter (214 vs 324 days), preoperative Barthel was worse (54 vs 77), internal carotid artery (ICA) mean velocity of the defect side was lower while sitting (14.4 vs 20.9 cm/s), and torque over the craniectomy was greater (2480.3 vs 1464.3 N*cm). Multivariate binary logistic regression showed the consistency of these changes. TCCS findings were no longer present postoperatively. Lower ICA (defect side) velocity in the sitting position correlates significantly with clinical improvement. Greater torque exerted by the AP might explain different susceptibilities to postural changes, corrected by cranioplasty.

Improvement in neurological outcome and brain hemodynamics after late cranioplasty

BACKGROUND

Early cranioplasty has been encouraged after decompressive craniectomy (DC), aiming to reduce consequences of atmospheric pressure over the opened skull. However, this practice may not be often available in low-middle-income countries (LMICs). We evaluated clinical improvement, hemodynamic changes in each hemisphere, and the hemodynamic balance between hemispheres after late cranioplasty in a LMIC, as the institution's routine resources allowed.

METHODS

Prospective cohort study included patients with bone defects after DC evaluated with perfusion tomography (PCT) and transcranial Doppler (TCD) and performed neurological examinations with prognostic scales (mRS, MMSE, and Barthel Index) before and 6 months after surgery.

RESULTS

A final sample of 26 patients was analyzed. Satisfactory improvement of neurological outcome was observed, as well as significant improvement in the mRS (p = 0.005), MMSE (p < 0.001), and Barthel Index (p = 0.002). Outpatient waiting time for cranioplasty was 15.23 (SD 17.66) months. PCT showed a significant decrease in the mean transit time (MTT) and cerebral blood volume (CBV) only on the operated side. Although most previous studies have shown an increase in cerebral blood flow (CBF), we noticed a slight and nonsignificant decrease, despite a significant increase in the middle cerebral artery flow velocity in both hemispheres on TCD. There was a moderate correlation between the MTT and contralateral muscle strength (r =  - 0.4; p = 0.034), as well as between TCD and neurological outcomes ipsilateral (MMSE; r = 0.54, p = 0.03) and contralateral (MRS; p = 0.031, r =  - 0.48) to the operated side.

CONCLUSION

Even 1 year after DC, cranioplasty may improve cerebral perfusion and neurological outcomes and should be encouraged.

The use of free myocutaneous flap and implant reinsertion for staged cranial reconstruction in patients with titanium mesh exposure and large skull defects with soft tissue infection after cranioplasty: Report of 19 cases

BACKGROUND

Management of cranial defects following failed cranioplasty due to titanium mesh exposure and infection is challenging. The purpose of this report is to describe a modified technique using a free myocutaneous flap transfer for primary soft tissue reconstruction, and titanium mesh reinsertion for cranioplasty revision.

METHODS

Nineteen patients with titanium mesh exposure and infection following cranioplasty were treated from January 2012 to January 2019. The average patient age was 41.89 years and the average size of the cranial defect was 7.74 × 13.92 cm. The reasons for craniotomy were craniocerebral trauma (n = 17), cerebrovascular disease (n = 1), and brain tumor (n = 1). The mean duration between implant exposure and current procedure was 7.16 months. Implant was removed and a free myocutaneous flap was designed to cover both scalp and cranium defects. After a mean duration of 12.32 months, implants were re-inserted in a vascularized pocket at the second stage by elevating a plane between the previously transferred fascia layer and muscle layer.

RESULTS

The average sizes of the muscle flaps and skin paddles were 7.74 × 13.92 cm and 4.97 × 8.97 cm. The average size of the implants was 8.24 × 14.42 cm. All flaps survived completely with no complication. After an average follow-up of 48.16 months there were no cranioplasty failures. Functional coverage of craniectomy defect sites with normalized head contour was achieved.

CONCLUSIONS

The use of free myocutaneous flap and implant reinsertion achieved durable cranial and scalp defect reconstruction and aesthetic outcomes. The myocutaneous flap increases blood supply to the scalp, which may reduce the chances of infection and implant re-exposure.

Decision-Making in Adult Cranial Vault Reconstruction

LEARNING OBJECTIVES

After studying this article, the participant should be able to: 1. Define and classify different types of cranial defects 2. Compare both autologous and alloplastic options for reconstruction 3. Develop an optimal approach for cranial vault reconstruction in various clinical scenarios.

SUMMARY

Defects of the cranium result from various causes, including traumatic loss, neurosurgical intervention, skull tumors, and infection. Cranial vault reconstruction aims to restore both the structural integrity and surface morphology of the skull. To ensure a successful outcome, the choice of appropriate cranioplasty reconstruction will vary primarily based on the cause, location, and size of the defect. Other relevant factors that must be considered include adequacy of soft-tissue coverage, presence of infection, and previous or planned radiation therapy. This article presents an algorithm for the reconstruction of various cranial defects using both autologous and alloplastic techniques, with a comparison of their advantages and disadvantages.

Bone Flap Resorption in Pediatric Patients Following Autologous Cranioplasty

Following a decompressive craniectomy, the autologous bone flap is generally considered the reconstructive material of choice in pediatric patients. Replacement of the original bone flap takes advantage of its natural biocompatibility and the associated low risk of rejection, as well as the potential to reintegrate with the adjacent bone and subsequently grow with the patient. However, despite these advantages and unlike adult patients, the replaced calvarial bone is more likely to undergo delayed bone resorption in pediatric patients, ultimately requiring revision surgery. In this review, we describe the materials that are currently available for pediatric cranioplasty, the advantages and disadvantages of autologous calvarial replacement, the incidence and classification of bone resorption, and the clinical risk factors for bone flap resorption that have been identified to date.

Complications of Cranioplasty in Relation to Material: Systematic Review, Network Meta-Analysis and Meta-Regression

BACKGROUND

Cranioplasty is a ubiquitous neurosurgical procedure consisting of reconstruction of a pre-existing calvarial defect. Many materials are available, including polymethylmethacrylate in hand-moulded (hPMMA) and prefabricated (pPMMA) form, hydroxyapatite (HA), polyetheretherketone (PEEK) and titanium (Ti).

OBJECTIVE

To perform a network meta-analysis (NMA) to assess the relationship between materials and complications of cranioplasty.

METHODS

PubMed/MEDLINE, Google Scholar, EMBASE, Scopus, and The Cochrane Library were searched from January 1, 1990 to February 14, 2021. Studies detailing rates of any of infections, implant exposure, or revision surgery were included. A frequentist NMA was performed for each complication. Risk ratios (RRs) with 95% CIs were calculated for each material pair.

RESULTS

A total of 3620 abstracts were screened and 31 full papers were included. Surgical revision was reported in 18 studies and occurred in 316/2032 cases (14%; 95% CI 11-17). PEEK had the lowest risk of re-operation with a rate of 8/157 (5%; 95% CI 0-11) in 5 studies, superior to autografts (RR 0.20; 95% CI 0.07-0.57), hPMMA (RR 0.20; 95% CI 0.07-0.60), Ti (RR 0.39; 95% CI 0.17-0.92), and pPMMA (RR 0.14; 95% CI 0.04-0.51). Revision rate was 131/684 (19%; 95% CI 13-25; 10 studies) in autografts, 61/317 (18%; 95%CI 9-28; 7 studies) in hPMMA, 84/599 (13%; 95% CI 7-19; 11 studies) in Ti, 7/59 (9%; 95% CI 1-23; 3 studies) in pPMMA, and 25/216 (12%; 95% CI 4-24; 4 studies) in HA. Infection occurred in 463/4667 (8%; 95% CI 6-11) and implant exposure in 120/1651 (6%; 95% CI 4-9).

CONCLUSION

PEEK appears to have the lowest risk of cranioplasty revision, but further research is required to determine the optimal material.

Effects of Cranioplasty After Decompressive Craniectomy on Neurological Function and Cerebral Hemodynamics in Traumatic Versus Nontraumatic Brain Injury

After decompressive craniectomy (DC), cranioplasty (CP) can help to normalize vascular and cerebrospinal fluid circulation besides improving the patient's neurological status. The aim of this study was to investigate the effects of CP on cerebral hemodynamics and on cognitive and functional outcomes in patients with and without a traumatic brain injury (TBI). Over a period of 3 years, 51 patients were included in the study: 37 TBI patients and 14 non-TBI patients. The TBI group was younger (28.86 ± 9.71 versus 45.64 ± 9.55 years, P = 0.0001), with a greater proportion of men than the non-TBI group (31 versus 6, P = 0.011). Both groups had improved cognitive outcomes (as assessed by the Mini-Mental State Examination) and functional outcomes (as assessed by the Barthel Index and Modified Rankin Scale) 90 days after CP. In the TBI group, the mean velocity of blood flow in the middle cerebral artery ipsilateral to the cranial defect increased between the time point before CP and 90 days after CP (34.24 ± 11.02 versus 42.14 ± 10.19 cm/s, P = 0.0001). In conclusion, CP improved the neurological status in TBI and non-TBI patients, but an increment in cerebral blood flow velocity after CP occurred only in TBI patients.

Decompressive Craniectomy in Pregnant Women

Malignant middle cerebral artery (MCA) infarction warranting decompressive craniectomy (DC) is unusual in the population younger than 40 years. Specifically, only a few cases affecting pregnant women have been described in the literature. We present the case of a 39-year-old woman in the 24th week of pregnancy who suffered a right malignant MCA infarction that eventually required DC. The patient delivered a healthy baby and underwent a second surgery for cranioplasty 7 months later. We present both this case and a review of the literature, including all cases of DC in pregnant women published to date.

Complications of cranioplasty following decompressive craniectomy for traumatic brain injury: systematic review and meta-analysis

BACKGROUND

Decompressive craniectomy (DC) is a common neurosurgical intervention for severe traumatic brain injury (TBI), as well as malignant stroke, malignancy and infection. DC necessitates subsequent cranioplasty. There are significant demographic differences between TBI and non-TBI patients undergoing cranioplasty, which may influence their relative risk profiles for infection, aseptic bone flap resorption (aBFR) and re-operation.

OBJECTIVE

Perform a meta-analysis to determine the relative infection, aBFR and re-operation risk profiles of TBI patients as compared to other indications for DC.

METHODS

A systematic review and meta-analysis was performed in accordance with the PRISMA guidelines. PubMed, MEDLINE, EMBASE and Google Scholar were searched until 26/11/2020. Studies detailing rates of infection, re-operation and/or aBFR in specific materials and the post-TBI population were included, while studies in paediatrics or craniosynostosis repair were excluded.

RESULTS

Twenty-six studies were included. There was no difference in relative risk of infection between TBI and non-TBI cohorts (RR 0.81, 95% CI 0.57-1.17), with insignificant heterogeneity (I² = 33%). TBI was a risk factor for aBFR (RR 1.54, 95% CI 1.25-1.89), with no significant heterogeneity (I² = 13%). TBI was a risk factor for re-operation in the autologous sub-group (RR 1.49, 95% CI 1.05-2.11) but not in the alloplastic sub-group (RR = 0.86, 95% CI 0.34-2.18). Heterogeneity was insignificant (I² = 11%).

CONCLUSION

TBI is a risk factor for aBFR and re-operation following cranioplasty. Use of an alloplastic graft for primary cranioplasty in these patients may partially mitigate this increased risk.

Changes in the prefronto-thalamic tract following cranioplasty: Case reports

RATIONALE

The prefrontothalamic tract (PTT) injury is associated with various neuropsychological impairments including cognitive impairment. We report on three women with hemorrhagic stroke who showed changes in the PTT following cranioplasty (C/P) using diffusion tensor tractography (DTT) images.

PATIENT CONCERNS

The 3 women with hemorrhagic stroke showed reductions of cognitive impairment following C/P. Mini-Mental State Examination scores (MMSE) were increased by 7-, 8-, and 5-point in patient 1, 2, and 3, respectively, after C/P compared with the patients' pre-C/P MMSE scores.

DIAGNOSIS

Three patients were diagnosed with spontaneous intracerebral hemorrhage. Three patients underwent C/P using auto-bone at 7 (patient 1 and 3) and 13 (patient 2) weeks after onset.

INTERVENTIONS

Diffusion tensor imaging data were acquired within 3 days before and 21 days after C/P.

OUTCOMES

The pre-C/P DTT results showed non-reconstruction of the dorsolateral prefrontal cortex (DLPFC; patient 2 and 3) on the contralateral operation (contra-OP) side and orbitofrontal cortex (OFC; patient 3) on both sides, but those were reconstructed on post-C/P DTT. Except for the contra-OP side OFC of patient 2, all fractional anisotropy values decreased on post-C/P DTT compared with pre-C/P DTT. The mean diffusivity values of the VLPFC and OFC were higher on post-C/P DTT except for the contra-OP side VLPFC of patient 1 and contra-OP side OFC of patient 2. The voxel numbers also increased except for the contra-OP side VLPFC of patient 1.

LESSONS

We demonstrated structural changes in the PTT along with concomitant reductions of cognitive impairments following C/P in 3 women with hemorrhagic stroke using DTT. The DTT changes suggest that C/P can affect the state of the PTT on both the OP and contra-OP sides. However, the limitation that DTT analysis may underestimate or overestimate fiber tract status due to regions of fiber complexity and crossing fiber should be considered.

Scenario for the use of effusion-peritoneal shunt necessary against subdural effusion secondary to decompressive craniectomy

OBJECTIVES

This study aimed to summarize the surgical strategies for subdural effusion secondary to decompressive craniectomy (SESDC) and discuss the applicable scenarios of effusion-peritoneal shunt (EP shunt).

METHODS

A total of 53 consecutive patients with SESDC were screened out of 7569 cases. The SESDC was divided into five types, and the treatment methods of each type were analyzed and compared. According to the implementation strategy of cranioplasty (CP), patients were divided into CP-first and delayed-CP groups. The differences in surgical methods were compared between the two groups.

RESULTS

All patients with SESDC in this cohort had undergone cranioplasty. Subcutaneous puncture and aspiration (SPAA) proved ineffective. Only 2/30 patients in the CP-first group used EP shunt, while 6/19 patients in the delayed-CP group used EP shunt; the difference was statistically significant (P = 0.03). A significant difference was found in the use of EP shunt among type 1, type 2, and type 5 SESDC (χ² = 6.778, P = 0.034).

CONCLUSIONS

CP combined with other treatments could cure most SESDC. EP shunt should be used preferentially in some specific scenarios in which CP cannot be performed first, rather than as a backup measure that can only be used when other preceding treatments fail.

Decompressive Craniectomy in Traumatic Brain Injury-Craniectomy-Related and Cranioplasty-Related Complications in a Single Center

OBJECTIVE

Decompressive craniectomy (DC) relieves intracranial hypertension after severe traumatic brain injury (TBI), but it has been associated with poor clinical outcome in 2 recent randomized controlled trials. In this study, we investigated the incidence and explanatory variables for DC-related and cranioplasty (CP)-related complications after TBI.

METHODS

In this retrospective study, we identified 61 patients with TBI who were treated with DC in the neurointensive care unit, Uppsala University Hospital, Sweden, between 2008 and 2018. Demography, admission status, radiology, and clinical outcome were analyzed.

RESULTS

Eleven patients (18%) were reoperated because of postoperative hemorrhage after DC. Six (10%) developed postoperative infection during neurointensive care. Twenty-eight (46%) developed subdural hygromas and 10 (16%) received a permanent cerebrospinal fluid shunt. Sixteen patients (26%) died before CP. Median time to CP was 7 months (range, 2-19 months) and 32 (71%) were operated on with autologous bone and 13 (29%) with synthetic material primarily. In 9 patients with autologous bone (29%), the CP had to be replaced because of bone resorption/infection, whereas this did not occur after synthetic material (P = 0.04). However, all 4 postoperative hemorrhages after CP occurred when synthetic material was used (P = 0.005).

CONCLUSIONS

DC and CP surgery have a high risk for complications, leading to additional neurosurgery in about one third of cases. Synthetic CP materials may decrease the risk of reoperation, but special care with hemostasis is required because of increased risk of postoperative hemorrhage. Future trials need to address these topics to further improve the outcome for these patients.

Does Impaired Glymphatic Drainage Cause Glymphedema? A Review Tailored to Neurocritical Care and Neurosurgery

Research into the glymphatic system reached an inflection point with steep trajectory in 2012 when it was formally recognized and named, but the historical roots for it are solid and deep, dating back to pioneers such as Cushing, Weed, and Dandy. We provide an overview of key discoveries of the glymphatic system, which promotes bulk flow of fluid and solutes throughout the brain parenchyma. We also discuss the lymphatic drainage of the central nervous system. Evidence is building that failure of the glymphatic system causes glymphedema in patients commonly managed by neurocritical care and neurosurgery specialists. We review research supporting this for decompressive craniectomy, subarachnoid hemorrhage, and normal-pressure hydrocephalus. We argue that it is time for a paradigm shift from the traditional model of cerebrospinal fluid circulation to a revised model that incorporates the glymphatic pathway and lymphatic clearance. These recent breakthroughs will inspire new therapeutic approaches to recognize, reverse, and restore glymphatic dysfunction and to leverage this pathway to deliver brain-wide therapeutics.

[Skull defect repair in children using a 3D-printing technology]

Currently, 3D-printing technologies are increasingly used in neurosurgery. Active development of this approach is valuable to improve preoperative planning, intraoperative navigation, and manufacturing of realistic training models. In this manuscript, the authors report an experience of the pediatric neurosurgical department of the Almazov National Medical Research Center regarding 3D-printing technologies in manufacturing of individual implants for skull defect closure. The main aspects of this technology, advantages and disadvantages are considered. Moreover, the authors describe several cases of creating individual implants for children with skull defects of various origins, dimensions and complexity.

"Eppur si muove" - Clinical case: evolutionary "saga" during the last 6 years: posttraumatic subdural hematoma, decompressive craniectomy, right hemiplegia and aphasia, cranioplasty, hydrocephalus and porencephaly, post-traumatic encephalopathy - in remission

The case reports a 59-year-old male patient who suffered a severe head injury (affirmative by accidental fall from 3 m) with multiple hemorrhagic lesions (bifrontal, bioccipital, biparieto-temporal) and left cerebral subdural hematoma, requiring a large fronto- temporo-parietal decompressive craniotomy for the mass lesion evacuation. Cranioplasty was performed after 6 months. The paper synthesizes the evolution over six years of follow-up (12 in-patient admissions and 4 out-patient evaluations), like in a neurorehabilitation cinematographic “saga”. The posttraumatic encephalopathy had a peculiar evolution, sugestively compared with the humps of a camel: the brain injury (determined coma, right hemiplegia and mixed aphasia, intense psycho-motor agitation, severe dysphagia for solids and liquids, neurogenic bladder, anemia), was followed by a slowly progressive favorable neuro-psychological evolution (after the decompressive craniectomy). A brutal neurological fall-down was noticed after the cranioplasty, and finally a gradually favorable ascending trend, towards a global neuro-psichological stabilization (with an almost imperceptible sequelary ataxic hemiparesis). The paper discusses the pathophisiological aspects focused on the decompressive craniectomy and cranioplasty, correlated to the patient’s evolution. Complications of each neurosurgical procedures are succinctly depicted. The traumatic encephalopathy was complicated with post-traumatic seizures (therapeutically controlled) and active internal hydrocephalus with interstitial edema and an ischemic lesion. Finally it was a "happyend", with favorable clinical evolution, towards a stable and stationary normotensive asymmetric hydrocephalus, with a gigantic and deforming porencephaly. The paper advocates for a carefully follow-up and prompt intervention in order to prevent recurrences and/ or complications (secondary and tertiary prophylaxis). Keywords: traumatic brain injury, subdural hematoma, decompressive craniectomy; cranioplasty; internal hydrocephalus; post-traumatic encephalopathy; seizures; neurorehabilitation,

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.

Super early cranial repair improves the prognosis of patients with craniocerebral injury

Objective

Craniocerebral injury has high disability and mortality rates. The timing of cranioplasty has an important impact on patients’ prognosis. This study was performed to compare the functional prognosis between super early repair and conventional repair.

Methods

This observational study included 60 patients who underwent cranioplasty after surgical treatment of severe craniocerebral trauma. The patients were divided into two groups according to the time of cranial repair after the surgical treatment of craniocerebral injury: the super early group and the conventional repair group. Sex, age, Karnofsky performance status (KPS) score, Zubrod performance status (ZPS) score, psychological function score, quality of life score, and complications were recorded.

Results

The KPS score, ZPS score, psychological function score, and quality of life score were significantly related to the intervention period. Each of these scores had a clear correlation with the performance of super early treatment.

Conclusion

Super early cranial repair does not increase the incidence of surgical complications, and it can improve the postoperative KPS, ZPS, and quality of life scores.

Endoscopic-assisted surgery for skull defects with subdural effusion

Introduction

Subdural effusion is a common complication that occurs after decompressive craniectomy. According to the endoscopy results, the formation mechanism of subdural effusion after decompressive craniectomy was discussed.

Aim

The morphological structure of subdural effusion in skull defects was observed with endoscopy, and endoscopic-assisted surgery was performed for subdural effusion.

Material and methods

From January 2018 to March 2020, 19 cases of skull repair and treatment of subdural effusion were performed. The external wall of the capsule was kept intact during the operation, subdural effusion and surgical procedure of the subdural effusion under an endoscope could be observed, and the results of endoscopic observation were described and recorded. A hemostasis gauze was placed between the two layers of the subdural effusion cavity. Another 13 cases of skull defects with subdural effusion treated without endoscopy during the same time period were enrolled in the study as the control group. The postoperative disappearance of effusion and the incidence of postoperative complications were compared between the two groups.

Results

Analysis with an endoscope revealed that all cases of subdural effusion in skull defects presented capsules. The main structures included the outer wall, boundary, inner wall, and fistula. The outer wall was made up of new tissue that had formed after removing the bone flap under the skin flap by artificial peeling under the condition of keeping the whole cavity. The inner wall consisted of thickened arachnoid, dura, and artificial dura. It presented with neovascularization networks, which showed a tendency to form new membrane structures through mutual adhesion and fusion. The inner and outer wall of the skull had fused to form the boundary of the cavity. Cerebrospinal fluid fistulas were detected in 31.6% of the internal walls. Subdural effusion was effectively treated in both the experimental group and the control group. Compared with the control group, complications in the experimental group were significantly reduced.

Conclusions

The effusion cavity can be divided into three types based on its structural characteristics: fistula type, membrane type, and closed type. In this study, the formation mechanism of skull defects combined with subdural effusion was explored. This represents a new method for treating subdural effusion in which hemostasis gauze is placed between the two layers of the effusion cavity and cerebrospinal fluid fistula under an endoscope, which can effectively reduce the incidence of postoperative complications.

Recurrent Syndrome of the Trephined in the Setting of Multiple Craniectomy and Cranioplasty

Decompressive craniectomy is an increasingly implemented intervention for relief of intracranial hypertension refractory to medical therapy. Despite its therapeutic benefit, a myriad of short and long-term complications may arise when the once fixed-volume cranial vault remains decompressed. The authors present a case of recurrent Syndrome of the Trephined in a patient undergoing repeated craniectomy and cranioplasty.A 70-year old male with history significant for smoking and chronic obstructive pulmonary disease presented with frontoparietal subdural hematoma with midline shift following a ground level fall necessitating craniotomy and hematoma evacuation. Three months postoperatively, the patient developed an infection of his craniotomy bone flap necessitating craniectomy without cranioplasty. Six weeks post-craniectomy the patient began demonstrating right sided sensorimotor deficits with word finding difficulties. Alloplastic cranioplasty was performed following resolution of infection, with resolution of neurologic symptoms 6 weeks post cranioplasty. Due to recurrent cranioplasty infections, multiple alloplastic cranioplasties were performed, each with reliable re-demonstration of neurologic symptoms with craniectomy, and subsequent resolution following each cranioplasty. Final cranioplasty was successfully performed using a new alloplastic implant in combination with latissimus muscle flap, with subsequent return of neurologic function.Decompressive craniectomy is a life-saving procedure, but carries many short- and long-term complications, including the Syndrome of the Trephined. Our case is the first published report, to our knowledge, to demonstrate recurrent Syndrome of the Trephined as a complication of craniectomy, with reliable resolution of the syndrome with restoration of the cranial vault.

Long-Term Effect of Decompressive Craniectomy on Intracranial Pressure and Possible Implications for Intracranial Fluid Movements

BACKGROUND

Decompressive craniectomy (DC) is used in cases of severe intracranial hypertension or impending intracranial herniation. DC effectively lowers intracranial pressure (ICP) but carries a risk of severe complications related to abnormal ICP and/or cerebrospinal fluid (CSF) circulation, eg, hygroma formation, hydrocephalus, and "syndrome of the trephined."

OBJECTIVE

To study the long-term effect of DC on ICP, postural ICP regulation, and intracranial pulse wave amplitude (PWA).

METHODS

Prospective observational study including patients undergoing DC during a 12-mo period. Telemetric ICP sensors (Neurovent-P-tel; Raumedic, Helmbrechts, Germany) were implanted in all patients. Following discharge from the neuro intensive care unit (NICU), scheduled weekly ICP monitoring sessions were performed during the rehabilitation phase.

RESULTS

A total of 16 patients (traumatic brain injury: 7, stroke: 9) were included (median age: 55 yr, range: 19-71 yr). Median time from NICU discharge to cranioplasty was 48 d (range: 16-98 d) and during this period, mean ICP gradually decreased from 7.8 ± 2.0 mm Hg to -1.8 ± 3.3 mm Hg (P = .02). The most pronounced decrease occurred during the first month. Normal postural ICP change was abolished after DC for the entire follow-up period, ie, there was no difference between ICP in supine and sitting position (P = .67). PWA was markedly reduced and decreased from initially 1.2 ± 0.7 mm Hg to 0.4 ± 0.3 mm Hg (P = .05).

CONCLUSION

Following NICU discharge, ICP decreases to negative values within 4 wk, normal postural ICP regulation is lost and intracranial PWA is diminished significantly. These abnormalities might have implications for intracranial fluid movements (eg, CSF and/or glymphatic flow) following DC and warrants further investigations.