Reconstruction of cranial base defects using the medpor titan implant: Cranioplasty applications in acoustic neuroma surgery

Skull Base Repair following Resection of Vestibular Schwannoma: A Systematic Review (Part 2: The Translabyrinthine Approach)

Objectives  Despite advances in skull base reconstruction techniques, cerebrospinal fluid (CSF) leaks remain a relatively common complication after translabyrinthine (TL) vestibular schwannoma (VS) surgery. We conducted a systematic review to synthesize the repair techniques and materials used in TL VS surgery to prevent CSF leaks. Design  A systematic review of studies published since 2000 reporting techniques to prevent CSF leaks during adult TL VS surgery was conducted. A narrative synthesis of primary repair protocols was produced, and a taxonomy was established. Additionally, the advantages, disadvantages, and associated CSF leak rates of different repair protocols were extracted. Results  All 43 studies were case series, and 39 were retrospective. Repair strategies included heterogeneous combinations of autografts, xenografts, and synthetic materials. A taxonomy was produced, classifying repairs into seven distinct stages, including approaches to the dura, middle ear cleft, air cells, TL bony defect, extra-cranial soft tissue, postoperative dressings, and CSF diversion. The median postoperative incidence of CSF leaks was 6% (interquartile range: 0-10%). Conclusions  This systematic review reveals substantial inter-institutional heterogeneity in intraoperative strategies to prevent CSF leaks following TL VS surgery. However, comparing these techniques is challenging due to the multiple predictive factors for CSF leaks and their inconsistent reporting. We propose a taxonomy of seven stages to classify operative techniques and materials aimed at preventing CSF leaks. We recommend that future evaluations should adopt a prospective approach encompassing data collection strategies that considers all operative stages described by our taxonomy.

Skull Base Repair following Resection of Vestibular Schwannoma: A Systematic Review (Part 1: The Retrosigmoid Approach)

Objective  Despite advances in skull-base reconstruction techniques, cerebrospinal fluid (CSF) leaks remain a common complication following retrosigmoid (RS) vestibular schwannoma (VS) surgery. We aimed to review and classify the available strategies used to prevent CSF leaks following RS VS surgery. Methods  A systematic review, including studies of adults undergoing RS VS surgery since 2000, was conducted. Repair protocols were synthesized into a narrative summary, and a taxonomic classification of techniques and materials was produced. Additionally, the advantages, disadvantages, and associated CSF leak rates of different repair protocols were described. Results  All 42 studies were case series, of which 34 were retrospective, and eight were prospective. Repair strategies included heterogeneous combinations of autografts, xenografts, and synthetic materials. A repair taxonomy was produced considering seven distinct stages to CSF leak prevention, including intraoperative approaches to the dura, internal auditory canal (IAC), air cells, RS bony defect, extracranial soft tissue, postoperative dressings, and CSF diversion. Notably, there was significant heterogeneity among institutions, particularly in the dural and IAC stages. The median postoperative incidence of CSF leaks was 6.3% (IQR: 1.3-8.44%). Conclusions  The intraoperative strategies used to prevent CSF leaks during RS VS surgery vary between and within institutions. As a result of this heterogeneity and inconsistent reporting of CSF leak predictive factors, a meaningful comparative analysis of repair protocols was not feasible. Instead, we propose the development of a prospective multicenter observational evaluation designed to accurately capture a comprehensive dataset of potential CSF risk factors, including all stages of the operative repair protocol.

High-Density Porous Polyethylene Implant Cranioplasty: A Systematic Review of Outcomes

Porous polyethylene has been widely used in craniofacial reconstruction due to its biomechanical properties and ease of handling. The objective of this study was to perform a systematic review of the literature to summarize outcomes utilizing high-density porous polyethylene (HDPP) implants in cranioplasty. A literature search of PubMed, Cochrane Library, and Scopus databases was conducted to identify original studies with HDPP cranioplasty from inception to March 2023. Non-English articles, commentaries, absent indications or outcomes, and nonclinical studies were excluded. Data on patient demographics, indications, defect size and location, outcomes, and patient satisfaction were extracted. Summary statistics were calculated using weighted averages based on the available reported data. A total of 1089 patients involving 1104 cranioplasty procedures with HDPP were identified. Patients' mean age was 44.0 years (range 2 to 83 y). The mean follow-up duration was 32.0 months (range 2 wk to 8 y). Two studies comprising 17 patients (1.6%) included only pediatric patients. Alloplastic cranioplasty was required after treatment of cerebrovascular diseases (50.9%), tumor excision (32.0%), trauma (11.4%), trigeminal neuralgia/epilepsy (3.4%), and others such as abscesses/cysts (1.4%). The size of the defect ranged from 3 to 340 cm 2 . An overall postoperative complication rate of 2.3% was identified, especially in patients who had previously undergone surgery at the same site. When data were available, contour improvement and high patient satisfaction were reported in 98.8% and 98.3% of the patients. HDPP implants exhibit favorable outcomes for reconstruction of skull defects. Higher complication rates may be anticipated in secondary cranioplasty cases.

Dispersed Bone Spicules as a Cause of Postoperative Headache after Retrosigmoid Vestibular Schwannoma Surgery: A Myth?

Objectives  Dispersion of bone dust in the posterior fossa during retrosigmoid craniectomy for vestibular schwannoma (VS) resection could be a source of meningeal irritation and lead to development of persistent postoperative headaches (POH). We aim to determine risk factors, including whether the presence of bone spicules that influence POH after retrosigmoid VS resection. Design  Present study is a retrospective case series. Setting  The study was conducted at a tertiary skull-base referral center. Participants  Adult patients undergoing VS resection via a retrosigmoid approach between November 2017 and February 2020 were included for this study. Main Outcome Measures  Development of POH lasting ≥ 3 months is the primary outcome of this study. Results  Of 64 patients undergoing surgery, 49 had complete data (mean age, 49 years; 53% female). Mean follow-up time was 2.4 years. At latest follow up, 16 (33%) had no headaches, 14 (29%) experienced headaches lasting <3 months, 19 (39%) reported POH lasting ≥3 months. Twenty-seven (55%) patients had posterior fossa bone spicules detectable on postoperative computed tomography (CT). Age, gender, body mass index, length of stay, tumor diameter, size of craniectomy, the presence of bone spicules, or the amount of posterior petrous temporal bone removed from drilling did not differ significantly between patients with POH and those without. On multivariate logistic regression, patients with POH were less likely to have preoperative brainstem compression by the tumor (odds ratio [OR] = 0.21, p  = 0.028) and more likely to have higher opioid requirements during hospitalization (OR = 1.023, p  = 0.045). Conclusion  The presence of bone spicules in the posterior fossa on postoperative CT did not contribute to headaches following retrosigmoid craniectomy approach for VS resection.

Comprehensive consideration and design with the virtual surgical planning-assisted treatment for hemifacial microsomia in adult patients

PURPOSE

Hemifacial microsomia (HFM) is a frequently encountered congenital malformation syndrome involving both hard and soft tissue. Various surgical methods have been described to correct the deformities of HFM in the literature. This study aims to evaluate the therapeutic efficacy for HFM with the assistance of virtual surgical planning (VSP) and 3-dimensionally printed surgical templates.

MATERIALS AND METHODS

From January 2010 to January 2016, a total of 46 patients were referred to the study. Different surgical procedures under the guidance of VSP and 3-dimensionally printed surgical templates combined with orthodontic treatment were used to correct the deformities. Clinical outcomes were evaluated by comparing the differences of affected-side ramus height, occlusal cant degrees and chin point deviation between the preoperative VSP and postoperative surgical results.

RESULTS

Satisfactory facial contour and occlusion were achieved with the combination of orthognathic and orthodontic treatment. Postoperative examination results showed that VSP was accurately transferred into actual surgery. The difference between the preoperative design and the postoperative outcome was not statistically significant.

CONCLUSION

VSP and 3-dimensionally printed surgical templates serve as a reliable method and show great value in improving the accuracy and efficacy of surgical treatment of HFM.

Postoperative headache following treatment of vestibular schwannoma: A literature review

Vestibular schwannoma (VS) is a brain tumour arising from Schwann cells that is typically closely associated with the vestibulocochlear nerve. Post-operative headaches (POH) are a potentially common complication of surgery for VS. Greatly differing rates of POH have previously been reported, particularly with different surgical approaches. The aim of this review is to identify and summarise the available peer-reviewed evidence on rates of POH following operative (or radiosurgery) treatment for VS, in addition to information about the treatment and prognosis of POH in these patients. A systematic search was conducted of Pubmed, Medline, Scopus and EMBASE in April 2017 using the medical subject headings (acoustic neuroma OR vestibular schwannoma) AND headache. Eligibility determination and data extraction were performed in duplicate with standardised forms. POH is common following surgery for VS. Differing rates of POH have been reported with different management approaches, patient age and tumour size. There are relatively few studies that have directly compared the rates of POH with different surgical approaches. The retrosigmoid approach with craniotomy appears to have lower rates of POH than when the retrosigmoid approach is performed with craniectomy. Patients under the age of 65 and with tumours <1.5 cm in size appear to have a higher risk of POH. The most commonly documented management of POH involves simple analgesia, although the majority of patients report this treatment is of only minimal benefit. Further prospective studies comparing rates of POH following different surgical approaches and radiosurgery are required.

"Inverted Gull Wing" Dural Closure and Middle Fossa Floor Reconstruction After Transzygomatic Infratemporal Fossa Approach

BACKGROUND

Ineffective closure of complex skull base approaches leads to wound complications and cerebrospinal fluid (CSF) leak. This can result in protracted hospital stays, additional procedures, delayed postoperative recovery, and increased cost of care. Removal of large middle fossa-infratemporal fossa tumors are particularly problematic as they result in a large dead space with gravity-facilitated CSF leakage into the cavity. In this report we describe the use of a novel technique, the "inverted gull wing" titanium mesh reconstruction.

METHODS

Attempts to address this problem have focused primarily on closure and the use of myocutaneous flaps. Patients who have had multiple prior treatments are often afflicted with significant tissue attenuation that preclude dural closure or the use of local flaps. Although vascularized free flaps are an effective option in this scenario, they can add significant operative time and often yield suboptimal cosmetic results. We describe the use of the inverted gull wing titanium mesh reconstruction in the closure of 2 patients who underwent complex transzygomatic infratemporal fossa approaches for tumor with dural and sinonasal transgression.

RESULTS

Postoperatively, there were no pseudomeningoceles, CSF leaks, or technique-related morbidities.

CONCLUSIONS

The inverted gull wing technique represents a simple, fast, and effective closure for complex transzygomatic infratemporal fossa approaches.

The Recent Revolution in the Design and Manufacture of Cranial Implants: Modern Advancements and Future Directions

Large format (i.e., >25 cm) cranioplasty is a challenging procedure not only from a cosmesis standpoint, but also in terms of ensuring that the patient's brain will be well-protected from direct trauma. Until recently, when a patient's own cranial flap was unavailable, these goals were unattainable. Recent advances in implant computer-aided design and 3-dimensional (3-D) printing are leveraging other advances in regenerative medicine. It is now possible to 3-D-print patient-specific implants from a variety of polymer, ceramic, or metal components. A skull template may be used to design the external shape of an implant that will become well integrated in the skull, while also providing beneficial distribution of mechanical force in the event of trauma. Furthermore, an internal pore geometry can be utilized to facilitate the seeding of banked allograft cells. Implants may be cultured in a bioreactor along with recombinant growth factors to produce implants coated with bone progenitor cells and extracellular matrix that appear to the body as a graft, albeit a tissue-engineered graft. The growth factors would be left behind in the bioreactor and the graft would resorb as new host bone invades the space and is remodeled into strong bone. As we describe in this review, such advancements will lead to optimal replacement of cranial defects that are both patient-specific and regenerative.

Sellar Floor Reconstruction with the Medpor Implant Versus Autologous Bone After Transnasal Transsphenoidal Surgery: Outcome in 200 Consecutive Patients

OBJECTIVE

The Medpor porous polyethylene implant provides benefits to perform sellar floor reconstruction when indicated. This material has been used for cranioplasty and reconstruction of skull base defects and facial fractures. We present the most extensive use of this implant for sellar floor reconstruction and document the safety and benefits provided by this unique implant.

METHODS

The medical charts for 200 consecutive patients undergoing endonasal transsphenoidal surgery from April 2008 through December 2011 were reviewed. Material used for sellar floor reconstruction, pathologic diagnosis, immediate inpatient complications, and long-term complications were documented and analyzed. Outpatient follow-up was documented for a minimum of 1-year duration, extending in some patients up to 5 years.

RESULTS

Of the 200 consecutive patients, 136 received sellar floor cranioplasty using the Medpor implant. Postoperative complications included 6 complaints of sinus irritation or drainage, 1 postoperative cerebrospinal fluid leak requiring operative re-exploration, 1 event of tension pneumocephalus requiring operative decompression, 1 case of aseptic meningitis, 1 subdural hematoma, and 1 case of epistaxis. The incidence of these complications did not differ from the autologous nasal bone group in a statistically significant manner.

CONCLUSIONS

Sellar floor reconstruction remains an important part of transsphenoidal surgery to prevent postoperative complications. Various autologous and synthetic options are available to reconstruct the sellar floor, and the Medpor implant is a safe and effective option. The complication rate after surgery is equivalent to or less frequent than other methods of reconstruction and the implant is readily incorporated into host tissue after implantation, minimizing infectious risk.

Reconstruction after retrosigmoid approaches using autologous fat graft-assisted Medpor Titan cranioplasty: assessment of postoperative cerebrospinal fluid leaks and headaches in 60 cases

BACKGROUND

Postoperative cerebrospinal fluid (CSF) leaks and headaches remain potential complications after retrosigmoid approaches for lesions in the posterior fossa and cerebellopontine angle. The authors describe a simple repair technique with an autologous fat graft-assisted Medpor Titan cranioplasty and investigate the incidence of postoperative CSF leaks and headaches using this technique.

METHODS

A retrospective chart review was conducted on all cases (n = 60) of retrosigmoid craniectomy from September 2009 to May 2014 in patients who underwent fat graft-assisted cranioplasty. After obtaining a watertight dural closure and sealing off any visible mastoid air cells with bone wax, an autologous fat graft was placed over the dural suture line and up against the waxed-off air cells. The fat graft filled the retrosigmoid cranial defect and was then bolstered with a Medpor Titan (titanium mesh embedded in porous polyethylene) cranioplasty. A postoperative mastoid pressure dressing was applied for 48 h, and prophylactic lumbar drainage was not used. Factors examined in this study included postoperative CSF leak (incisional, rhinorrhea, otorrhea), pseudomeningocele formation, incidence and severity of postoperative headache, length of hospital stay, and length of follow-up.

RESULTS

No patients developed postoperative CSF leaks (0 %), pseudomeningoceles (0 %), or new-onset postoperative headaches (0 %) with the described repair technique. There were no cases of graft site morbidity such as hematoma or wound infection. Mean duration of postoperative hospital stay was 3.8 days (range 2-10 days). Mean postoperative follow-up was 12.4 months (range 2.0-41.1 months).

CONCLUSIONS

Our multilayer repair technique with a fat graft-assisted Medpor Titan cranioplasty appears effective in preventing postoperative CSF leaks and new-onset postoperative headaches after retrosigmoid approaches. Postoperative lumbar drainage may not be necessary.