Double collagen matrix grafting for dural closure in microvascular decompression: an alternative use of autologous fascial grafting

Dura Closure Tactics to Prevent CSF Leakage in Microvascular Decompression Surgery

(1) Background: Achieving a complete and secure dural closure to prevent cerebrospinal fluid (CSF) leakage is a critical concern in microvascular decompression (MVD). Proper dural closure minimizes complications, such as infections caused by CSF leakage. This study introduces a novel three-step dural suturing method, termed the "triple-layer closing technique". (2) Methods: From September 2020 to March 2023, a total of 475 patients underwent MVD surgery at our institution, all of whom received dural closure using the triple-layer closing technique. This technique incorporates three layers: Duragen® (synthetic dura, Integra Lifesciences), TachoSil® (collagen matrix, Nycomed), and polymethyl methacrylate (PMMC) bone cement. Postoperative complications, including CSF leakage and infections, were retrospectively analyzed. (3) Results: CSF leakage was observed in five patients (1.1%), all of whom presented with CSF rhinorrhea and radiological evidence of effusion within the mastoid air cells. These patients were successfully treated with lumbar drainage, and none required reoperation. No other postoperative infections or complications were reported. (4) Conclusions: The triple-layer closing technique, utilizing Duragen®, TachoSil®, and PMMC bone cement, is an effective and reliable method for dural closure. This technique significantly reduces the risk of CSF leakage and surgical site infections, enhancing postoperative outcomes in MVD procedures.

Histopathological analysis of duragen collagen matrix over time in humans

DuraGen is a widely used type I collagen matrix derived from bovine Achilles tendon that promotes fibroblast ingrowth and neovascularization. However, it remains unknown the time required for dura regeneration and reabsorption of the graft. We evaluate the histopathological characteristics of implanted DuraGen in humans across multiple time points. Patients who underwent a decompressive craniectomy and duraplasty with DuraGen at our institution between January 2020 and September 2021 were prospectively enrolled. At the time of the subsequent surgery, including cranioplasty, DuraGen and associated tissues removed from patients were sent for histopathological analysis. For each patient, time from index surgery to subsequent surgery was categorized into three groups: early (0-20 days), intermediate (21-30 days), and late (> 30 days). Baseline characteristics, primary disease, operative time, complication rate, and histopathological findings were compared between groups. A total of 28 patients were enrolled in the study. Seven specimens (25.0%) were collected within 20 days after craniectomy, 9 specimens (35.7%) between 21 and 30 days, and 12 specimens (39.3%) over 31 days. Histopathologically, implanted collagen matrix, erythrocyte infiltration, and fibrin layer decreased over time, whereas fibroblasts and endogenous collagen increased. Receiver operating characteristic analysis showed that the cut-off time post-implantation for presence of endogenous collagen was 34 days after DuraGen implantation (area under the curve = 0.810). We found that DuraGen was replaced by fibroblast-derived endogenous collagen as early as 34 days post-implantation. Although certain findings remain to be further validated, the present study substantiates DuraGen as a reliable substitute, with findings derived from clinical outcomes and histopathological changes.

Bone cement versus bone flap replacement: A comparative meta-analysis of posterior fossa craniotomy complications

Background

Posterior fossa surgeries are often performed to treat infratentorial pathologies, such as tumors that increase intracranial pressure. Posterior fossa craniotomy has been shown to decrease the incidence of postoperative complications and morbidity compared to craniectomy. More recently, the use of bone cement in posterior fossa craniotomies has been implemented, but there is limited comparative postoperative data of this technique to more commonly used bone flap replacement. This study aims to address this information gap through a meta-analysis comparing the incidence of postoperative cerebrospinal fluid leakage and other complications when utilizing bone cement versus bone flap replacement in posterior fossa craniotomies.

Methods

Following a literature review, search parameters for a systematic review were identified and relevant studies were sorted based on selection criteria to be included in the meta-analysis. Data analysis was performed in R studio and Microsoft Excel software. Targeted complications for analysis include cerebrospinal fluid (CSF) leakage, pseudomeningocele formation, and infection. Pooled estimates and odds ratios for dichotomous outcomes were calculated with corresponding 95% confidence intervals, and findings were translated into illustrative tables and figures.

Results

Twenty-one articles were included in a systematic review, nine studies using bone cement and thirteen using bone flap (two studies reported data for both groups). With bone flap replacement, CSF leakage was 8.36% (95% confidence interval [CI] 5.89-10.86%), pseudomeningocele formation was 9.22% (95% CI 4.82-13.62%), and infection was 6.85% (95% CI 4.05-9.65%). With bone cement usage, CSF leakage was 3.47% (95% CI 2.37-4.57%), pseudomeningocele formation was 2.43% (95% CI 1.23-3.63%), and infection was 1.85% (95% CI 0.75-2.95%). The odds ratio of CSF leak, pseudomeningocele formation, and infection was 0.39 (95% CI 0.229-0.559), 0.25 (95% CI 0.137-0.353), and 0.26 (95% CI 0.149-0.363), respectively, with the use of bone cement compared to craniotomy.

Conclusion

Outcomes demonstrated in this meta-analysis revealed an overall decreased incidence of postoperative complications rates of CSF leak, pseudomeningocele formation, and infection when using bone cement compared to bone flap in posterior fossa craniotomies. Our study suggests that bone cement use is safe and effective in posterior fossa surgery. Future studies should further assess the comparative outcomes of these techniques.

A Keyhole Approach for Intracranial Hematoma Removal Using ORBEYE

OBJECTIVE

By maximizing the advantages of exoscopy, we developed a keyhole approach for intracranial hematoma removal. Herein, we validated the utility of this procedure, and compared it with conventional microscopic hematoma removal and endoscopic hematoma removal in our institution.

METHODS

We included 12 consecutive patients who underwent this procedure from June 2022 to March 2024. A 4-cm-long skin incision was made, and a keyhole craniotomy (diameter, 2.5 cm) was performed. An assistant manipulated a spatula, and an operator performed hematoma removal and hemostasis using typical microsurgical techniques under an exoscope. The dura mater was reconstructed without sutures using collagen matrix and fibrin glue. The outcomes of this series were compared with those of 12 consecutive endoscopic hematoma removals and 19 consecutive conventional microscopic hematoma removals from October 2018 to March 2024.

RESULTS

The mean age was 72±10 years, and 7 (58%) patients were men. Hematoma location was the putamen in 5 patients and subcortical in 7 patients. The mean operative time was 122±34 min, the mean hematoma removal rate was 95%±8%, and the mortality rate was 0%. Although the preoperative hematoma volume was similar between the 3 groups, the operative time and total time in the operating room was significantly shorter in the exoscope group than in the microscope group (P<0.0001).

CONCLUSIONS

This procedure may be simpler and faster than conventional microscopic hematoma removal, and comparable to endoscopic hematoma removal.

Potential reasons for failure and recurrence in microvascular decompression for hemifacial spasm

BACKGROUND

To examine the factors contributing to persistent and recurrent hemifacial spasms (HFS) following a microvascular decompression (MVD) procedure and to suggest technical improvements to prevent such failures.

METHODS

A retrospective review was conducted on fifty-two cases of repeat surgery. The extent of the previous craniotomy and the location of neurovascular compression (NVC) were investigated. The operative findings were categorized into two groups: "Missing Compression" and "Teflon Contact". The analysis included long-term outcomes and operative complications after repeat MVD procedures.

RESULTS

Missing compression was identified in 29 patients (56%), while Teflon contact was observed in 23 patients (44%). Patients with missing compression were more likely to experience improper craniotomy (66%) compared to those with Teflon contact (48%). Medially located NVC was a frequent finding in both groups, mainly due to compression by the anterior inferior cerebellar artery. In the missing compression group, during the repeat MVD, Teflon sling retraction was utilized in 79% of cases, while in the Teflon contact group, the most common procedure involved removing the Teflon in contact (65%). After the repeat MVD procedure, immediate spasm relief was achieved in 42 patients (81%), with six (12%) experiencing delayed relief. After a median follow-up of 54 months, 96% of patients were free from spasms. Delayed facial palsy, facial weakness, and hearing impairment were more frequently observed in the Teflon contact group.

CONCLUSIONS

A proper craniotomy that provides adequate exposure around the REZ is crucial to prevent missing the culprit vessel during the initial MVD procedure. Teflon contact on the REZ should be avoided, as it poses a potential risk of procedure failure and recurrence.

Trends in CSF Leakage Associated with Duraplasty in Infratentorial Procedures over the Last 20 Years: A Systematic Review

Cerebrospinal fluid (CSF) leakage is a common postoperative complication of neurosurgical procedures, with iatrogenic causes accounting for 16% of CSF leakages. This complication increases healthcare costs and patient morbidity. The focus of this review is to analyze the rates of CSF leakage of some of the most commonly used xenogeneic and synthetic dural substitutes following surgeries in the infratentorial region of the brain where surgical repair can be most challenging. A systematic literature search was conducted using studies detailing duraplasty procedures performed with nonautologous grafts in the infratentorial region in PubMed. Studies were identified using the following search terms: "posterior fossa" or "infratentorial" were used in combination with "CSF leak," "CSF leakage," "cerebrospinal fluid leakage," "duraplasty" or "dura graft." The outcome of interest was a measure of the prevalence of CSF leakage rates following posterior fossa neurosurgery. Studies that contributed data to this review were published between 2006 and 2021. The dural graft materials utilized included: bovine collagen, acellular dermis, equine collagen, bovine pericardium, collagen matrix, and expanded polytetrafluoroethylene (ePTFE). The number of subjects in studies on each of these grafts ranged from 6 to 225. CSF leak rates ranged from 0% to 25% with the predominance of studies reporting between 3% and 15%. The studies that utilize bovine collagen, equine collagen, and acellular dermis reported higher CSF leakage rates; whereas studies that utilized ePTFE, bovine pericardium, and collagen matrix reported lower CSF leakage rates. Due to the heterogeneity of methodologies used across these studies, it is difficult to draw a direct correlation between the dural patch products used and CSF leaks. Larger prospective controlled studies that evaluate various products in a head-to-head fashion, using the same methods and animal models, are needed to conclude the relative efficacy of these dural patch products.

Indication for a skull base approach in microvascular decompression for hemifacial spasm

BACKGROUND

A thorough observation of the root exit zone (REZ) and secure transposition of the offending arteries is crucial for a successful microvascular decompression (MVD) for hemifacial spasm (HFS). Decompression procedures are not always feasible in a narrow operative field through a retrosigmoid approach. In such instances, extending the craniectomy laterally is useful in accomplishing the procedure safely. This study aims to introduce the benefits of a skull base approach in MVD for HFS.

METHODS

The skull base approach was performed in twenty-eight patients among 335 consecutive MVDs for HFS. The site of the neurovascular compression (NVC), the size of the flocculus, and the location of the sigmoid sinus are measured factors in the imaging studies. The indication for a skull base approach is evaluated and verified retrospectively in comparison with the conventional retrosigmoid approach. Operative outcomes and long-term results were analyzed retrospectively.

RESULTS

The extended retrosigmoid approach was used for 27 patients and the retrolabyrinthine presigmoid approach was used in one patient. The measurement value including the site of NVC, the size of the flocculus, and the location of the sigmoid sinus represents well the indication of the skull base approach, which is significantly different from the conventional retrosigmoid approach. The skull base approach is useful for patients with medially located NVC, a large flocculus, or repeat MVD cases. The long-term result demonstrated favorable outcomes in patients with the skull base approach applied.

CONCLUSIONS

Preoperative evaluation for lateral expansion of the craniectomy contributes to a safe and secure MVD.

Association study of the pneumatization degree of mastoid air cells and postoperative complications after microvascular decompression in hemifacial spasm

BACKGROUND

This study aimed to analyse the association between the degree of pneumatization of mastoid air cells (MACs) and postoperative complications after microvascular decompression in hemifacial spasm.

METHODS

We retrospectively reviewed 308 patients with hemifacial spasm who underwent surgery at our institute between January 2017 and March 2021. The degree of pneumatization of MACs was classified into four grades (grades 1, 2, 3, and 4) according to method of Han et al. The clinical data of the four grades were analysed and statistically examined.

RESULTS

There were no statistically significant differences between the four grades in terms of the operative time, intraoperative blood loss, and postoperative hospital stay (all, P > 0.05). The incidence of hearing loss was higher in grade 4 MACs (26.56%) than in grades 1 and 2 MACs (5.41% and 2.89%, respectively; P < 0.05). The incidence of facial paralysis was higher in grade 4 MACs (28.13%) than in grades 1 and 2 MACs (5.41% and 9.18%, respectively; P < 0.001). The incidence of intracranial infection was higher in grade 3 MACs (17.65%) than in grade 2 MACs (3.89%) (P < 0.05). All four patients with cerebrospinal fluid leakage belonged to grade 4 MACs. The incidence of cerebrospinal fluid leakage was higher in grade 4 MACs (5.13%) than in grade 2 MACs (P < 0.05).

CONCLUSIONS

This study found that the degree of pneumatization of MACs was closely related to the postoperative complications after MVD surgeries. Well-pneumatized MACs increase the risk of cerebrospinal fluid leakage and intracranial infection. However, insufficient exposure increases the risk of facial paralysis and hearing loss. For patients with well-pneumatized MACs, sufficient surgical exposure is the top priority when locating the bone hole. For those who may have a latent MAC opening, preventive occlusion should be considered.

A Multilayered Dural Repair Technique Using Duragen for Early Cranioplasty Following Decompressive Craniotomy

Decompressive craniotomy is a neurosurgical emergency procedure in which a large skull bone is removed and the dura matter is extensively opened. Duraplasty is required to avoid cerebrospinal fluid (CSF) leakage during the decompressive craniotomy. DuraGen® is a safe and effective type I collagen matrix graft, which is frequently used in decompressive craniotomy procedures. Since DuraGen® does not require labor-intensive suturing, the operative time is shortened by DuraGen® closure with sufficient tightness preventing CSF leakage. Recently, early cranioplasty is preferred to achieve efficient rehabilitation after decompressive craniotomy. Although evidence of efficacy and safety of DuraGen® has been increasing in the management of duraplasty, no reports have previously discussed the condition of DuraGen® during the second surgery (cranioplasty) at this early timing. DuraGen®-derived neodura develops a mature dura 1 year post its placement, and the neodura remain fragile at this early time point. A deconstructed fragile neodura may result in postoperative CSF leakage. Here, we illustrated a multilayered dural repair technique with DuraGen® to avoid disruption of the fragile neodura during early cranioplasty.