Origami-inspired soft fluidic actuation for minimally invasive large-area electrocorticography.

Electrocorticography is an established neural interfacing technique wherein an array of electrodes enables large-area recording from the cortical surface. Electrocorticography is commonly used for seizure mapping however the implantation of large-area electrocorticography arrays is a highly invasive procedure, requiring a craniotomy larger than the implant area to place the device. In this work, flexible thin-film electrode arrays are combined with concepts from soft robotics, to realize a large-area electrocorticography device that can change shape via integrated fluidic actuators. We show that the 32-electrode device can be packaged using origami-inspired folding into a compressed state and implanted through a small burr-hole craniotomy, then expanded on the surface of the brain for large-area cortical coverage. The implantation, expansion, and recording functionality of the device is confirmed in-vitro and in porcine in-vivo models. The integration of shape actuation into neural implants provides a clinically viable pathway to realize large-area neural interfaces via minimally invasive surgical techniques.

Raney clip left behind the titanium mesh after cranial surgery: Case report.

RATIONALE: Raney clips are commonly used in neurosurgical procedures to hold the scalp in place and stop bleeding during surgery. The removal of Raney clips is often the last process during cranial surgery prior to the closure of skin incision. Thus, a Raney clip found underneath the titanium mesh resulting in fever is a very rare occurrence. PATIENT CONCERNS: An 18-year-old male patient underwent cranial surgery due to intracranial abscess in the frontal lobe and subsequently underwent frontal skull repair using titanium mesh during which a Raney clip was unintentional left underneath the titanium mesh resulting in fever. DIAGNOSIS: A thin-slice computed tomography (CT) scan was used to identify the Raney clip. INTERVENTION: A third surgery was performed to remove the Raney clip. OUTCOMES: The patient fever total resolved after the third surgery with no further neurological deficits and 2-years follow-up revealed the patient is well and go about his daily activities. LESSONS: It is crucial to ensure that all foreign objects are removed after the surgery by counting all instruments used at and after each step during the operation, including all Raney clips. This will help prevent complications and ensure the safety as well as the well-being of the patient.

Template Routed Patient-Specific Implant for 1-Stage Cranioplasty.

BACKGROUND AND OBJECTIVES: Cranial reconstruction presents a significant challenge in cases involving pathologies with skull invasion, and various techniques have been used, including the intraoperative shaping of titanium mesh and the manual sculpting of bone cement serving as surrogates for the excised bone graft. In the context of prefabricated patient-specific implants (PSIs) for cranioplasty, precise surgical execution of craniotomies is paramount. This ensures optimal congruity between the implant and the defect created during the craniotomy, leading to a successful single-stage procedure encompassing both bone removal and reconstruction. This article presents a meticulous method for achieving such high-fidelity craniotomy and subsequent cranioplasty using PSIs in a single-stage surgery. METHODS: The procedure was implemented for 2 cases of meningiomas with osseous invasion. Through meticulous preoperative planning, the craniotomy template and implant were designed using computer-assisted design and manufactured on a 3-dimensional printer using the patient's computed tomography scans. Intraoperative fabrication of sterile polymethyl methacrylate replicas was achieved through the creation of silicone molds and subsequent injection molding techniques. Predesignated screw holes facilitated neuronavigation-assisted positioning of the template, aligning it accurately with the target site using registration points. Mini-screws firmly secured the template to the skull. Guided by the template, a craniotomy router performed the bone resection. On completion, the implant was affixed into place using plates and screws. RESULTS: This technique demonstrably facilitated a cost-effective, streamlined and precise application of prefabricated PSIs within a single-stage craniotomy-cranioplasty procedure. Subjective patient reports indicated high levels of satisfaction with the outcome. CONCLUSION: The template routed patient-specific implant 1-stage cranioplasty technique refines previous approaches through precise template localization on the skull, enabling an accurate craniotomy to match a prefabricated PSI. This single-stage procedure rivals hand-shaped methods in aesthetics and compares with the outcomes of 2-stage PSI cranioplasties. Additional studies are needed to validate our results.

Intraoperative lateral rectus electromyographic recordings optimized by deep intraorbital needle electrodes.

OBJECTIVE: We demonstrate the advantages and safety of long, intraorbitally-placed needle electrodes, compared to standard-length subdermal electrodes, when recording lateral rectus electromyography (EMG) during intracranial surgeries. METHODS: Insulated 25 mm and uninsulated 13 mm needle electrodes, aimed at the lateral rectus muscle, were placed in parallel during 10 intracranial surgeries, examining spontaneous and stimulation-induced EMG activities. Postoperative complications in these patients were reviewed, alongside additional patients who underwent long electrode placement in the lateral rectus. RESULTS: In 40 stimulation-induced recordings from 10 patients, the 25 mm electrodes recorded 6- to 26-fold greater amplitude EMG waveforms than the 13 mm electrodes. The 13 mm electrodes detected greater unwanted volume conduction upon facial nerve stimulation, typically exceeding the amplitude of abducens nerve stimulation. Except for one case with lateral canthus ecchymosis, no clinical or radiographic complications occurred in 36 patients (41 lateral rectus muscles) following needle placement. CONCLUSIONS: Intramuscular recordings from long electrode in the lateral rectus offers more reliable EMG monitoring than 13 mm needles, with excellent discrimination between abducens and facial nerve stimulations, and without significant complications from needle placement. SIGNIFICANCE: Long intramuscular electrode within the orbit for lateral rectus EMG recording is practical and reliable for abducens nerve monitoring.

Evaluation of a Wearable AR Platform for Guiding Complex Craniotomies in Neurosurgery.

Today, neuronavigation is widely used in daily clinical routine to perform safe and efficient surgery. Augmented reality (AR) interfaces can provide anatomical models and preoperative planning contextually blended with the real surgical scenario, overcoming the limitations of traditional neuronavigators. This study aims to demonstrate the reliability of a new-concept AR headset in navigating complex craniotomies. Moreover, we aim to prove the efficacy of a patient-specific template-based methodology for fast, non-invasive, and fully automatic planning-to-patient registration. The AR platform navigation performance was assessed with an in-vitro study whose goal was twofold: to measure the real-to-virtual 3D target visualization error (TVE), and assess the navigation accuracy through a user study involving 10 subjects in tracing a complex craniotomy. The feasibility of the template-based registration was preliminarily tested on a volunteer. The TVE mean and standard deviation were 1.3 and 0.6 mm. The results of the user study, over 30 traced craniotomies, showed that 97% of the trajectory length was traced within an error margin of 1.5 mm, and 92% within a margin of 1 mm. The in-vivo test confirmed the feasibility and reliability of the patient-specific template for registration. The proposed AR headset allows ergonomic and intuitive fruition of preoperative planning, and it can represent a valid option to support neurosurgical tasks.

Burr-Hole Evacuation of an Acute Epidural Hematoma using the Artemis Neuroevacuation Device With Flexible Endoscopic Visualization: 2-Dimensional Operative Video.

Minimally invasive (MIS) endoscopic burr-hole evacuation of both acute and subacute subdural hematomas (SDHs) has been demonstrated as a way to avoid large craniotomies and additional morbidity, particularly for patients who are poor surgical candidates.1,2 Although generally safe and effective, there are risks of complications including SDH recurrence or new hemorrhage including epidural hematoma (EDH).3,4 Acute intraparenchymal hemorrhage has also been successfully treated using MIS endoscopic techniques with the assistance of aspiration devices; however, acute EDHs generally still necessitate a craniotomy for evacuation, nullifying many of the advantages of burr-hole craniostomy.5,6 In this surgical video, we demonstrate-to our knowledge-the first case of endoscopic burr-hole evacuation of an acute EDH using an Artemis Neuro Evacuation device (Penumbra, Alameda, CA). We present the case of a 40 year-old man with a left anterior middle cranial fossa arachnoid cyst who developed a traumatic left subacute SDH and hemorrhage into the cyst. He underwent burr-hole craniostomy for endoscopic evacuation of subacute SDH, evacuation of hemorrhage within the cyst, and fenestration of arachnoid cyst. On postoperative day 2, he developed an acute left EDH with midline shift. An Artemis device was inserted into 1 of the pre-existing burr-holes and used to evacuate the acute EDH with direct visualization from a flexible endoscope inserted into the second burr-hole. The patient did well, was discharged 2 days later, and demonstrated complete resolution of hemorrhage 5 weeks post-procedure. The video also provides a brief background on arachnoid cysts, their association with hemorrhage, and MIS techniques for hemorrhage evacuation.7-12 There is no identifying information in the video. The patient provided informed consent for both procedures (Video 1).

A Preliminary Study on Animal Experiments of Robot-Assisted Craniotomy.

BACKGROUND: Traditional craniotomy relies on the surgeon's experience and can be complicated owing to excessive skull bone removal, undesirable brain tissue penetration, or severe bleeding. For craniotomy, we developed a robot system based on intraoperative cone-beam computed tomography image guidance and human-robot cooperative interaction, aiming to improve the safety and accuracy of surgery and reduce the labor-intensiveness of the procedure. METHODS: Intraoperative cone-beam computed tomography image guidance was adopt to improve the accuracy in our experiment. Craniotomy was performed using an interactive method based on human-robot collaboration, which could achieve a natural interactive method in accordance with surgeons' operating habits. The frequency-based method of contact distinction and the method of torque estimation were used to improve the safety of the designed robot. RESULTS: An animal experiment was conducted to verify the effectiveness of the robot system. During the drilling process, the position error was 0.92 ± 0.17 mm (upper surface) and 0.97 ± 0.11 mm (lower surface), and the angle error was 3.37 ± 1.43°. During the milling process, the position error was 1.06 ± 0.13 mm (upper surface) and 1.09 ± 0.09 mm (lower surface). The results showed that the system had sufficient precision and could better complete craniotomy with human-robot collaboration. In addition, with the feedback of multisensor information, the robot system could achieve a sufficient level of safety. CONCLUSIONS: The robot system can achieve accurate positioning and safe user-friendly human-robot interaction, which solves problems encountered in the drilling and milling of craniotomy, meets clinical needs, and provides a new method for robot-assisted craniotomy.

Long-Term Neurocognitive Outcomes of Spring-Assisted Surgery versus Cranial Vault Remodeling for Sagittal Synostosis.

BACKGROUND: A long-term neurocognitive comparison of patients with sagittal synostosis who underwent spring-assisted surgery or cranial vault remodeling has not been performed. METHODS: Patients with sagittal synostosis who underwent spring-assisted surgery or cranial vault remodeling were recruited from Wake Forest School of Medicine and Yale School of Medicine, respectively. Cognitive tests administered included an abbreviated intelligence quotient, academic achievement, and visuomotor integration. An analysis of covariance model compared cohorts controlling for demographic variables. RESULTS: Thirty-nine spring-assisted surgery and 36 cranial vault remodeling patients were included in the study. No significant differences between cohorts were found with respect to age at surgery, sex, race, birth weight, family income, or parental education. The cranial vault cohort had significantly older parental age (p < 0.001), and mean age at testing for the spring cohort was significantly higher (p = 0.001). After adjusting for covariates, the cranial vault cohort had significantly higher verbal intelligence quotient (116.5 versus 104.3; p = 0.0024), performance intelligence quotient (109.2 versus 101.5; p = 0.041), and full-scale intelligence quotient (114.3 versus 103.2; p = 0.0032). When included patients were limited to intelligence quotients from 80 to 120, the cranial vault cohort maintained higher verbal (108.0 versus 100.4; p = 0.036), performance (104.5 versus 97.7; p = 0.016), and full-scale (107.6 versus 101.5; p = 0.038) intelligence quotients. The cranial vault cohort had higher visuomotor integration scores than the surgery group (111.1 versus 98.1; p < 0.001). There were no significant differences in academic achievement. CONCLUSIONS: Sagittal synostosis patients who underwent cranial vault remodeling had higher intelligence quotient and visuomotor integration scores. There were no differences in academic achievement. Both cohorts had intelligence quotient scores at or above the normal range. Further studies are warranted to identify factors that may contribute to cognitive outcome differences. CLINICAL QUESTION/LEVEL OF EVIDENCE: Therapeutic, II.

Complications following titanium cranioplasty compared with nontitanium implants cranioplasty: A systematic review and meta-analysis.

Decompressive craniectomy is widely used to treat medically refractory intracranial hypertension. There were still few studies focusing on the complications between titanium cranioplasty with non-titanium materials cranioplasty. Our systematic review and meta-analysis aimed to assess the complications following titanium cranioplasty and to make a comparison with nontitanium materials. A systematic review was used to review titanium cranioplasty characters in recent articles. A systematic literature review and meta-analysis were performed by using PubMed/MEDLINE, Scopus, the Cochrane databases and Embase for studies reporting on cranioplasty procedures that compared complication outcomes between titanium with non-titanium materials. The final 15 studies met inclusion criteria and represented 2258 cranioplasty procedures (896 titanium, 1362 nontitanium materials). Overall complications included surgical site infection, hematoma, implant exposure, seizure, cerebrospinal fluid leak, imprecise fitting. Titanium cranioplasty was associated with a significant decrease in overall complications rate (OR, 0.72; P = 0.007), hematoma rate (OR, 0.31; P = 0.0003) and imprecise fitting rate (OR, 0.35; P = 0.04). However, it also suggested that titanium cranioplasty can be greatly increased implant exposure rate (OR, 4.11; P < 0.00001). Our results confirmed the advantages of titanium cranioplasty in reducing complications including hematoma, imprecise fitting, and also suggested that clinicians should pay more attention to postoperative implant exposure. With new synthetic materials emerging, it would also be interesting to study the cost-effect and functional outcomes associated with cranioplasty materials.

Flexible endoscopic assistance in the surgical management of vestibular schwannomas.

Endoscopic-assisted techniques have extensively been applied to vestibular schwannoma (VS) surgery allowing to increase the extent of resection, minimize complications, and preserve facial nerve and auditory functions. In this paper, we retrospectively analyze the effectiveness of flexible endoscope in the endoscopic-assisted retrosigmoid approach for the surgical management of VS of various sizes. The authors conducted a retrospective analysis on 32 patients who underwent combined microscopic and flexible endoscopic resection of VS of various sizes over a period of 16 months. Flexible endoscopic-assisted retrosigmoid approach was performed in all cases, and in 6 cases, flexible and rigid endoscopic control were used in combination to evaluate the differences between the two surgical instruments. The surgical results were additionally compared with a previous case series of 141 patients operated for VS of various sizes without endoscopic assistance. Gross-total resection was achieved in 84% of the cases and near-total resection was accomplished in the rest of them. Excellent or good facial nerve function was observed in all except one case with a preoperative severe facial palsy. Hearing preservation surgery (HPS) was attempted in 11 cases and accomplished in 9 (81.8%). A tumor remnant was endoscopically identified in the fundus of the IAC in all cases (100%). Endoscopic assistance increased the rate of total removal and no intrameatal residual tumor was seen at radiological follow-up. Comparative analysis with a surgical cohort of patients operated with the sole microsurgical technique showed a significative association between endoscopic assistance and intracanalicular extent of resection. Combined microsurgical and flexible endoscopic assistance provides remarkable advantages in the pursuit of maximal safe resection of VS and preservation of facial nerve and auditory functions, minimizing the risk of post-operative complications.

A simple and effective modified technique of twist drill craniostomy for bedside drainage and irrigation of chronic subdural hematoma: Technical and clinical study.

OBJECTIVE: Chronic subdural hematoma (CSDH) is an important health problem observed mostly in elderly population. Here, we aimed to describe and validate a simple modified technique of twist-drill craniostomy (TDC) using easily accessible tools for effective and safe bedside CSDH drainage. METHODS: A detailed description of the new modified TDC technique which allows for sequential drainage and irrigation under physiological conditions is provided. Clinical and radiological characteristics as well as surgical results of the patients undergoing this procedure are also presented. RESULTS: A total of 55 patients (30 M, 25 F) underwent this modified TDC. Mean age was 61.7 ±â€¯12.3 years. Medical comorbidities were common (76.4 %). Subdural hematoma was mostly unilateral (83.6 %). Maximum width of hematoma was 21 ±â€¯4 mm on average (range: 9-38 mm). In total, patients underwent 1.6 ±â€¯0.9 subdural tappings on average (median: 1, range: 1-5). Repeat tappings were performed in 43.6 % of the patients. No mortality, serious morbidity or infectious complications were noted. Pneumocephalus was either absent or minimal in most cases (96.4 %). Mean length of hospital stay was 4.9 ±â€¯4.0 days (median: 3; range: 2-20 days). The clinical outcomes were favorable in 92.7 % of the patients (no craniotomy required and no symptomatic recurrence detected). CONCLUSION: This modified technique of TDC utilizes easily available tools, yields satisfactory radiological and clinical results, allows repeated tappings even in outpatient settings and can thus be readily applied in every neurosurgical unit across the world. It can be an effective alternative to existing procedures for patients with multiple co-morbidities and/or high anesthesia risk, in emergency conditions and busy neurosurgical centers.

Assembly and operation of an open-source, computer numerical controlled (CNC) robot for performing cranial microsurgical procedures.

Cranial microsurgery is an essential procedure for accessing the brain through the skull that can be used to introduce neural probes that measure and manipulate neural activity. Neuroscientists have typically used tools such as high-speed drills adapted from dentistry to perform these procedures. As the number of technologies available for neuroscientists has increased, the corresponding cranial microsurgery procedures to deploy them have become more complex. Using a robotic tool that automatically performs these procedures could standardize cranial microsurgeries across neuroscience laboratories and democratize the more challenging procedures. We have recently engineered a robotic surgery platform that utilizes principles of computer numerical control (CNC) machining to perform a wide variety of automated cranial procedures. Here, we describe how to adapt, configure and use an inexpensive desktop CNC mill equipped with a custom-built surface profiler for performing CNC-guided microsurgery on mice. Detailed instructions are provided to utilize this 'Craniobot' for performing circular craniotomies for coverslip implantation, large craniotomies for implanting transparent polymer skulls for cortex-wide imaging access and skull thinning for intact skull imaging. The Craniobot can be set up in <2 weeks using parts that cost <$1,500, and we anticipate that the Craniobot could be easily adapted for use in other small animals.

Comparative anatomical study on the role of zygomatic osteotomy in the extradural subtemporal approach to the clival region, when less is more.

PURPOSE: A great concern in performing the extradural subtemporal approach (ESTA) is the evaluation of the actual advantage provided by zygomatic osteotomy (ZO). Complications related to zygomatic dissection have been widely reported in the literature, making it of paramount importance to balance the actual need to perform it, against the risk of maneuver-related morbidity. Authors comparatively analyze the putative advantage provided by ZO in the ESTA in terms of anatomic exposure and surgical operability. Technical limits and potentials are critically revised and discussed. METHODS: A comparative microanatomical laboratory investigation was conducted. The operability score (OS) was applied for quantitative analysis of surgical operability. RESULTS: ZO was found to provide a weakly significant improvement in the surgical angle of attack (p value 0.01) (mean increase 3°). Maneuverability arch (MAC) increase related to ZO did not reach statistical significance (p value 0.09) (mean increase 2°). The variations provided by MAC increase on the conizing effect (CE) did not lead to an actual advantage in the real surgical scenario, modifying the vision area (VA) in terms of reduction of central vision area (CA) in favor of an increase of peripheral vision area (PA) only in the most caudal part of the surgical field. Ultimately, ZO did not influence the overall OS, scoring both ESTA-ZO+ and ESTA-ZO- 2 out of 3. CONCLUSION: In the ESTA, ZO does not provide an actual significant advantage in terms of surgical operability on clival and paraclival areas.

A Retrospective Comparative Analysis of Titanium Mesh and Custom Implants for Cranioplasty.

BACKGROUND: Autologous bone removed during craniectomy is often the material of choice in cranioplasty procedures. However, when the patient's own bone is not appropriate (infection and resorption), an alloplastic graft must be utilized. Common options include titanium mesh and polyetheretherketone (PEEK)-based custom flaps. Often, neurosurgeons must decide whether to use a titanium or custom implant, with limited direction from the literature. OBJECTIVE: To compare surgical outcomes of synthetic cranioplasties performed with titanium or vs custom implants. METHODS: Ten-year retrospective comparison of patients undergoing synthetic cranioplasty with titanium or custom implants. RESULTS: A total of 82 patients were identified for review, 61 (74.4%) receiving titanium cranioplasty and 21 (25.6%) receiving custom implants. Baseline demographics and comorbidities of the 2 groups did not differ significantly, although multiple surgical characteristics did (size of defect, indication for craniotomy) and were controlled for via a 2:1 mesh-to-custom propensity matching scheme in which 36 titanium cranioplasty patients were compared to 18 custom implant patients. The cranioplasty infection rate of the custom group (27.8%) was significantly greater (P = .005) than that of the titanium group (0.0%). None of the other differences in measured complications reached significance. Discomfort, a common cause of reoperation in the titanium group, did not result in reoperation in any of the patients receiving custom implants. CONCLUSION: Infection rates are higher among patients receiving custom implants compared to those receiving titanium meshes. The latter should be informed of potential postsurgical discomfort, which can be managed nonsurgically and is not associated with return to the operating room.

Ambroise Paré: His Contribution to the Future Advancement of Neurosurgery and the Hardships of His Times Affecting His Life and Brilliant Career.

Ambroise Paré was celebrated surgeon of the 16th century whose practical accomplishments, books, and ideas transformed surgery and was a precursor for the later development of neurosurgery. He developed many surgical innovations related to wound management, arterial ligation for the prevention of hemorrhage during limb amputations, and the treatment of war-related head and spine injuries. He maintained that a surgeon should operate gently to reduce pain and improve outcome, and he dedicated his career to the wounded, sick, and poor. He also served 4 consecutive French monarchs-Henri II and his 3 sons François II, Charles IX, and Henri III. As a Huguenot (a Reformed Protestant) by faith, he lived in an environment dominated by Catholicism. Hence, his practice and life were sometimes hindered by political circumstances and religious prejudice. In this historical vignette, we will discuss the professional accomplishments of Ambroise Paré that influenced the future development of neurosurgery, including his descriptions of phantom-limb pain and peripheral nerve injury, his innovations in neurotraumatology, and the saws he invented for use in skull surgery. We will also highlight Paré's broad neurosurgical contributions to the field. Finally, we will discuss his personal life during the difficult and dangerous political circumstances of 16th century France.

Distance Control and Virtual Drilling Improves Anatomical Orientation During Anterior Petrosectomy.

BACKGROUND: A combined drill distance control and virtual drilling image guidance feedback method was developed. OBJECTIVE: To investigate whether first-time usage of the proposed method, during anterior petrosectomy (AP), improves surgical orientation and surgical performance. The accuracy of virtual drilling and the clinical practicability of the method were also investigated. METHODS: In a simulated surgical setting using human cadavers, a trial was conducted with 5 expert skull base surgeons from 3 different hospitals. They performed 10 AP approaches, using either the feedback method or standard image guidance. Damage to critical structures was assessed. Operating time, drill cavity sizes, and proximity of postoperative drill cavities to the cochlea and the acoustic meatus, were measured. Questionnaires were obtained postoperatively. Errors in the virtual drill cavities as compared with actual postoperative cavities were calculated. In a clinical setup, the method was used during AP. RESULTS: Surgeons rated their intraoperative orientation significantly better with the feedback method compared with standard image guidance. During the cadaver trial, the cochlea was harmed on 1 occasion in the control group, while surgeons drilled closer to the cochlea and meatus without injuring them in the group using feedback. Virtual drilling under- and overestimation errors were 2.2 ± 0.2 and -3.0 ± 0.6 mm on average. The method functioned properly during the clinical setup. CONCLUSION: The proposed feedback method improves orientation and surgical performance in an experimental setting. Errors in virtual drilling reflect spatial errors of the image guidance system. The feedback method is clinically practicable during AP.

Treatment of very large cranial defects with individually shaped polypropylene polyester knitwear prostheses: a series of 11 cases.

BACKGROUND: Very large cranial defects are not very common in neurosurgical practice and there is not any widely acknowledged standard of their treatment. One of the useful methods in such cases is individual forming of polypropylene-polyester knitwear. Such material was used in the past but before 2008 it was available only as standardized plates. Currently, it can be also produced as individually-shaped implants. The authors give their definition of very large cranial defects and present their experience with this cranioplastic method in such defects. METHODS: The authors collected data on 11 cases of patients with very large cranial defects, from a total of 156 cases, operated on in 5 Polish neurosurgical departments. The necessary implants were prepared for individual patients according to the data provided by a computed tomography examination and with the use of computer aided machining. RESULTS: All defects were larger than 120 cm2 (129 to 178 cm2) and exceeded 1/4 of the calvaria area. Patients were operated between 2008 to 2012. In all patients, a very good aesthetic result and correct skull reconstruction was achieved. The follow-up time in all cases exceeded 1 year and reached 4 years in one case. No complications were observed. CONCLUSIONS: Individually pre-shaped polypropylene-polyester knitwear prostheses are a good alternative to the existing cranioplasty methods, particularly in very large cranial defects.

Demineralized Bone Matrix and Resorbable Mesh Bilaminate Cranioplasty Is Ineffective for Secondary Reconstruction of Large Pediatric Cranial Defects.

Replacement of the autologous bone flap after decompressive craniectomy can be complicated by significant osteolysis or infection with large defects over scarred dura. Demineralized bone matrix is an alternative to autologous reconstruction, effective when reconstructing large defects using a resorbable mesh bilaminate technique in primary cranioplasty, but this technique has not been studied for revision cranioplasty and the setting of scarred dura. Retrospective review was performed of patients receiving demineralized bone matrix and resorbable mesh bilaminate cranioplasty for postdecompressive craniectomy defects. Seven patients (mean age, 4.2 years) were identified with a mean follow-up of 4.0 years. Computed tomography before the demineralized bone matrix and resorbable mesh bilaminate cranioplasty and at least 1 year postoperatively were compared. Defects were characterized and need for revision was assessed. All patients had craniectomy with associated hemidural scarring. Five patients had autologous bone flap cranioplasty associated with nearly total osteolysis, and two patients had deferral of bone flap before demineralized bone matrix and resorbable mesh bilaminate cranioplasty. Demineralized bone matrix and resorbable mesh bilaminate cranioplasty demonstrated unpredictable and poor ossification, with bony coverage unchanged at postoperative follow-up. All patients required major revision cranioplasty at a mean time of 2.5 years. Porous polyethylene was successfully used in six of the revisions, whereas exchange cranioplasty was used in the remaining patient, with a mean follow-up of 1.4 years. Although demineralized bone matrix and resorbable mesh bilaminate is appropriate for primary cranioplasty, it should be avoided in the setting of scarred or infected dura in favor of synthetic materials or exchange cranioplasty. CLINICAL QUESTION/LEVEL OF EVIDENCE:: Therapeutic, IV.