Caustics and wavefronts produced by multiple refraction-reflections through plane-parallel plates.

We study the formation of caustics and wavefronts produced by multiple refraction-reflections through a plane-parallel transparent plate, assuming a point source placed at an arbitrary position along the optical axis. The caustic surfaces are obtained by using the envelope's method. Subsequently, the wavefronts are directly related to the involutes, which are associated with the envelopes for all the rays. Hence by using the Malus-Dupin theorem, we obtain their respective wavefronts produced by multiple refraction-reflections through a plane-parallel transparent plate. On the other hand, we implement Huygens' principle to obtain the wavefronts leaving the plate after undergoing multiple reflections inside the plate, which we have called zero-distance phase wavefronts. Finally, we establish the correspondence between the wavefronts obtained by Huygens' principle and the involutes associated with caustic surfaces; they are brought in coincidence assuming parallel curves from each other.

Approach for designing thick cemented doublet lenses based on the caustic surface.

A new, to the best of our knowledge, method for designing a thick-lens achromatic doublet based on the concept of a caustic surface to correct both third- and fifth-order spherical aberration is presented. We consider two different wavelengths brought into coincidence at the back focal length instead of the effective focal length as it is usually done, to calculate the radii of curvature assuming predefined values for axial thicknesses and their indices of refraction for both lenses. Alternatively, we apply Taylor's series around the optical axis, and to vanish the approximate caustic surface, we obtain the values for the conic constants, which reduce at third- and fifth-order spherical aberration. Two designs for cemented doublets are provided assuming that the lenses are cemented. Finally, we propose a method to qualitatively test doublet lenses by using null screens, considering to place the detection plane at arbitrary positions.

Special Considerations in Face Transplantation: A Systematic Review.

ABSTRACT: Vascularized composite allotransplantation of the face is an exceedingly complex procedure, requiring extensive planning and surgical precision in order to successfully manage patients with facial disfigurements. This review aims to present an overview of the salient anatomic considerations in facial transplantation, as well as give attention to unique patient populations and special considerations.A literature review was performed in search of articles pertaining to considerations in facial transplantation using the databases PubMed, Web of Science, and Cochrane. Articles selected for further review included full-text articles with an emphasis on specific anatomic defects and how they were addressed in the transplant process, as well as management of special patient populations undergoing facial transplantation. In total, 19 articles were deemed appropriate for inclusion.The use of computer-assisted technologies for the planning portion of the procedure, as well as intraoperative efficiency, has yielded favorable results and can be considered as part of the operative plan. The ultimate outcome is dependent upon the synchronization of subunits of the allograft and the desired functional outcomes, including osseous, ocular, oral, and otologic considerations. Management of specific pathology and subgroups of patients are critical aspects. Although pediatric face transplantation has not yet been performed, it is a likely a future step in the evolution of this procedure.When performing a face transplantation, many components must be considered pre-, intra-, and post-operatively. This systematic review presents specific anatomic considerations, as well as information about special patient populations within this crosssection of multidisciplinary microsurgery, psychiatry, and transplant immunology.

Cranioplasty Outcomes From 500 Consecutive Neuroplastic Surgery Patients.

BACKGROUND: Cranioplasty is critical to cerebral protection and restoring intracranial physiology, yet this procedure is fraught with a high risk of complications. The field of neuroplastic surgery was created to improve skull and scalp reconstruction outcomes in adult neurosurgical patients, with the hypothesis that a multidisciplinary team approach could help decrease complications. OBJECTIVE: To determine outcomes from a cohort of cranioplasty surgeries performed by a neuroplastic surgery team using a consistent surgical technique and approach. METHODS: The authors reviewed 500 consecutive adult neuroplastic surgery cranioplasties that were performed between January 2012 and September 2020. Data were abstracted from a prospectively maintained database. Univariate analysis was performed to determine association between demographic, medical, and surgical factors and odds of revision surgery. RESULTS: Patients were followed for an average of 24 months. Overall, there was a reoperation rate of 15.2% (n = 76), with the most frequent complications being infection (7.8%, n = 39), epidural hematoma (2.2%, n = 11), and wound dehiscence (1.8%, n = 9). New onset seizures occurred in 6 (1.2%) patients.Several variables were associated with increased odds of revision surgery, including lower body mass ratio, 2 or more cranial surgeries, presence of hydrocephalus shunts, scalp tissue defects, large-sized skull defect, and autologous bone flaps. importantly, implants with embedded neurotechnology were not associated with increased odds of reoperation. CONCLUSIONS: These results allow for comparison of multiple factors that impact risk of complications after cranioplasty and lay the foundation for development of a cranioplasty risk stratification scheme. Further research in neuroplastic surgery is warranted to examine how designated centers concentrating on adult neuro-cranial reconstruction and multidisciplinary collaboration may lead to improved cranioplasty outcomes and decreased risks of complications in neurosurgical patients.

Ronchi-Hartmann type null screens for testing a plano-freeform surface with a detection plane inside a caustic surface.

We have implemented an exact ray trace through a plano-freeform surface for an incident plane wavefront. We obtain two caustic surfaces and provide the critical points related to the ray tracing process. Additionally, we study the propagation of the refracted wavefronts through the plane-curved surface. Finally, by using the Ronchi-Hartmann type null screen and placing the detection plane within the caustic region, we have evaluated the shape of a plano-freeform optical surface under test, obtaining an RMS difference in sagitta value of 6.3 µm.

Neuroplastic Surgery Aboard USNS Comfort During the COVID-19 Pandemic in New York City.

In December of 2019, a novel virus known as severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) produced a cluster of viral pneumonia cases in Wuhan, China. In the United States (US), New York City was particularly devastated, with the volume and acuity of patients placing an unprecedented strain on the hospital system and health care workers. In response to this crisis, USNS Comfort (T-AH 20) was deployed to New York City with a 1100 member medical team to augment local hospitals. Comfort's mission to New York City was dynamic, and required special adaptation to care for both COVID positive and COVID negative patients. Neuroplastic surgery procedures were indicated in both COVID positive and COVID negative patients, and lessons learned with regard to performance of complex surgery in an unfamiliar environment consisted of developing a thorough understanding of ones capabilities, and working with a highly skilled team of Navy surgeons, anesthesiologists, and surgical support staff, in order to provide high quality care in a deployment platform.

Airway Management of COVID-19 Positive Patients Aboard USNS COMFORT Mission to New York City.

During the USNS Comfort mobilization to New York City in response to the pandemic, the ship's medical team cared for over 35 mechanically ventilated corona virus disease 2019 (COVID-19) infected patients. Due to the better than expected mortality rates of these patients, tracheotomy for prolonged intubation or other indicated interventional bronchoscopies were performed on 7 COVID positive patients, as well as 2 with negative screening tests. No member of the health care team subsequently became symptomatic or tested positive for COVID-19. This was in part due to the formation of a dedicated surgical airway team, use of standardized procedural techniques and personal protective equipment (PPE), and construction of a negative pressure operating room within the COVID-19 isolation ward on the ship. This experience shows that tracheotomies and other aerosolizing procedures can be performed with due concern for patient and provider safety, regardless of patient's COVID status.

Risk of Complications in Primary Versus Revision-Type Cranioplasty.

INTRODUCTION: Cranioplasty (CP) is a multifaceted procedure in a heterogenous patient population, with a high risk for complication. However, no previous large-scale studies have compared outcomes in primary (ie, first attempt) CP versus revision CP (ie, following previous attempts). The authors, therefore, analyzed long-term outcomes of 506 consecutive primary and revision CPs, performed by a single surgeon. METHODS: All CPs performed between 2012 and 2019 were analyzed under IRB protocol approval. Surgeries were categorized as either primary (no previous CP; n = 279) or revision CP (at least one previous CP; n = 227). Complications were defined as either major or minor. Subgroup analyses investigated whether or not CP complication risk directly correlated with the number of previous neuro-cranial surgeries and/or CP attempts. RESULTS: The primary CP group experienced a major complication rate of 9% (26/279). In comparison, the revision CP group demonstrated a major complication rate of 32% (73/227). For the revision CP group, the rate of major complications rose with each additional surgery, from 4% (1 prior surgery) to 17% (2 prior surgeries) to 39% (3-4 prior surgeries) to 47% (≥5 prior surgeries). CONCLUSION: In a review of 506 consecutive cases, patients undergoing revision CP had a 3-fold increase in incidence of major complications, as compared to those undergoing primary CP. These results provide critical insight into overall CP risk stratification and may guide preoperative risk-benefit discussions. Furthermore, these findings may support a center-of-excellence care model, particularly for those patients with a history of previous neuro-cranial surgeries and/or CP attempts.

Sagittal and tangential foci produced by tilted plane wavefronts refracted through simple lenses.

We study the formation of caustic and wavefront surfaces produced by a tilted plane wavefront propagating through spherical positive lenses. The shape of the caustic surface is a function of the indices of refraction, the geometrical parameters of the lens involved in the process of refraction, and the obliquity angle with respect to the optical axis, as we expect. We provide exact and approximate analytic equations for tangential and sagittal focal surfaces and also for Petzval field curvature considering arbitrary lenses.

Dural Reconstruction With Autologous Rectus Fascia: A New Technique for Addressing Large-Sized Defects During Cranioplasty.

INTRODUCTION: Patients requiring cranioplasty reconstruction with customized cranial implants may unexpectedly present with cerebrospinal fluid (CSF) leaks and durotomies following previous neurosurgical procedures. As such, multiple factors influence the type of dural reconstruction chosen at this time, which are essential for achieving long-term success. Overall, the most common material used for duraplasty is currently an "off-the-shelf" xenograft construct. However, some believe that they are not suitable for large-sized defects and accompany a higher incident of complications. Therefore, based on our success and experience with scalp augmentation using rectus fascia grafts, the authors herein present our preliminary experience with duraplasty using autologous rectus fascia grafts (ARFGs). METHODS: A retrospective review of our database, consisting of 437 cranial reconstructions from 2012 to 2017, was performed under institutional review board approval. Selection criteria included all adult patients (n = 6) requiring dural reconstruction (duraplasty) with ARF grafting for an active CFS leak with concomitant skull defect. Cadaver study and patient illustrations are also presented to demonstrate clinical applicability. All outcomes, including complications, were reviewed and are presented here. RESULTS: A total of 6 patients underwent autologous duraplasty with either unilateral or bilateral ARFGs. All patients (6/6) of large-sized (>3 cm) defect repair with ARFGs were indicated for repair of secondary CSF leaks following previous craniotomy by neurosurgery. To date, none have demonstrated recurrent leaking and/or dura-related complications. At this time, all 6 patients were reconstructed using customized cranial implants with a mean follow-up of 10 months. CONCLUSION: Based on our preliminary experience presented here, the use of rectus fascia grafts for autologous dural reconstruction appears to be both safe and reliable. This new technique adds another tool to the neurosurgical armamentarium by reducing the additional risk of "off-the-shelf" dural substitutes.

Adult Cranioplasty.

OBJECTIVES: After reading this article, the participant should be able to: Understand the etiology of cranial defects. Understand the anatomy of the cranium. Understand the importance of the preoperative workup in the cranial reconstruction decision-making process. Describe the options available for calvarial reconstruction including autologous and alloplastic materials. Describe the basic differences between available alloplastic materials. Understand the intraoperative and postoperative complications that may arise during cranioplasty. SUMMARY: Cranial defects can arise from a variety of causes, yielding a diverse group of patients who require cranioplasty. The goals of calvarial reconstruction are to protect the underlying brain, to restore the aesthetic contour of the calvarium, and/or to treat postcraniectomy cerebrospinal fluid circulation abnormalities that may be symptomatic. Options for calvarial reconstruction include the autogenous bone flap that was removed for access, autologous bone grafting, and a variety of alloplastic materials such as titanium, hydroxyapatite, polymethylmethacrylate, polyether ether ketone, and high-density porous polyethylene. A detailed preoperative workup and discussion with the patient is important to choosing the appropriate reconstructive path.

Full-Thickness Skin Grafting for Local Defect Coverage Following Scalp Adjacent Tissue Transfer in the Setting of Cranioplasty.

INTRODUCTION: Numerous techniques have been described to overcome scalp deficiency and high-tension closure at time of cranioplasty. However, there is an existing controversy, over when and if a free flap is needed during complex skull reconstruction (ie, cranioplasty). As such the authors present here our experience using full-thickness skin grafts (FTSGs) to cover local defects following scalp adjacent tissue transfer in the setting of cranioplasty. METHODS: By way of an institutional review board-approved database, the authors identified patients treated over a 3-year period spanning January 2015 to December 2017, who underwent scalp reconstruction using the technique presented here. Patient demographics, clinical characteristics, technical details, outcomes, and long-term follow up were statistically analyzed for the purpose of this study. RESULTS: Thirty-three patients, who underwent combined cranioplasty and scalp reconstruction using an FTSG for local donor site coverage, were identified. Twenty-five (75%) patients were considered to have "high complexity" scalp defects prior to reconstruction. Of them, 12 patients (36%) were large-sized and 20 (60%) medium-sized; 21 (64%) grafts were inset over vascularized muscle or pericranium while the remaining grafts were placed over bare calvarial bone. In total, the authors found 94% (31/33) success for all FTSGs in this cohort. Two of the skin grafts failed due to unsuccessful take. Owing to the high rate of success in this series, none of the patient's risk factors were found to correlate with graft failure. In addition, the success rate did not differ whether the graft was placed over bone verses over vascularized muscle/pericranium. CONCLUSION: In contrary to previous studies that have reported inconsistent success with full-thickness skin grafting in this setting, the authors present a simple technique with consistent results-as compared to other more complex reconstructive methods-even in the setting of highly complex scalp reconstruction and simultaneous cranioplasty.

Class-Switch Recombination in the Absence of the IgH 3' Regulatory Region.

The ∼28-kb 3' regulatory region (3'RR), which is located at the most distal 3' region of the Ig H chain locus, has multiple regulatory functions that control IgH expression, class-switch recombination (CSR), and somatic hypermutation. In this article, we report that deletion of the entire 3'RR in a mouse B cell line that is capable of robust cytokine-dependent CSR to IgA results in reduced, but not abolished, CSR. These data suggest that 3'RR is not absolutely required for CSR and, thus, is not essential for targeting activation-induced cytidine deaminase to S regions, as was suggested. Moreover, replacing 3'RR with a DNA fragment including only its four DNase I hypersensitive sites (lacking the large spacer regions) restores CSR to a level equivalent to or even higher than in wild-type cells, suggesting that the four hypersensitive sites contain most of the CSR-promoting functions of 3'RR. Stimulated cells express abundant germline transcripts, with the presence or absence of 3'RR, providing evidence that 3'RR has a role in promoting CSR that is unique from enhancing S region transcription.

Comparative Cost Analysis of Single and Mutli-Stage Temporal Deformity Correction Following Neurosurgical Procedures.

PURPOSE: Temporal hollowing deformity (THD) is a visible concavity/convexity in the temporal fossa; a complication often seen following neurosurgical/craniofacial procedures. Although numerous techniques have been described, no study to date has shown the healthcare costs associated with temporal hollowing correction surgery. Thus, the purpose here is to compare and contrast the direct costs related to temporal cranioplasty using various methods including: liquid poly-methyl-methacrylate (PMMA) implants with screw fixation, prebent, modified titanium mesh implants, and customized cranial implants (CCIs) with dual-purpose design. Understanding the financial implications related to this frequently encountered complication will help to motivate surgeons/healthcare facilities to better prevent and manage THD. METHODS: This is a single-surgeon, single-institution retrospective review of 23 THD patients randomly selected from between 2008 and 2015. Cost analysis variables include length of hospital stay, facility/professional fees, implant material fees, payer information, reimbursement rate, and net revenue. RESULTS: Of the 23 patients, ages ranged from 23 to 68 years with a mean of 48.3 years (SD 11.6). Within this cohort, 39.1% received dual-purpose PMMA CCIs (CCI PLUS), 17.4% received modified titanium mesh implants, and 43.5% received hand-molded, liquid PMMA implants with screw fixation. Total facility and/or professional charges ranged from $1978.00 to $126478.00. Average total facility charges per patient with dual-purpose CCIs were $34775.89 (SD ±â€Š$22205.09) versus $35826.00 (SD ±â€Š$23509.93) for modified titanium mesh implants and $46547.90 (SD ±â€Š81061.70) for liquid PMMA implants with screws. Mean length of inpatient stay was 5.7 days (SD = 8.1), and did not differ between implant types (P = 0.387). CONCLUSION: Temporal hollowing deformity is an expensive complication post-neurosurgery, and in the most severe form, requires a revision surgery for definitive correction. Therefore, surgeons should take further initiatives to employ reconstructive methods capable of minimizing risk for costly revision surgery, reducing morbidity related to visible deformity and accompanying social stigmata, and improving overall patient satisfaction.

Introducing the Rectus Fascia Scalp Augmentation Technique: A New Method for Improving Scalp Durability in Cranioplasty Reconstruction.

OBJECTIVE: Patients with cranioplasty in need of skull reconstruction are at increased risk of complications when presenting with abnormally thin scalps. As such, the authors sought to develop and investigate a new technique for scalp augmentation using autologous rectus fascia grafts (ARFGs) for prevention of implant extrusion and long-term scalp durability. METHODS: A retrospective review of our database, consisting of 450 consecutive cranial reconstructions from 2012 to 2017, was performed under institutional review board approval. Selection criteria included all adult patients requiring implant-based cranioplasty reconstruction and concomitant scalp augmentation using ARFGs. All long-term outcomes were reviewed for scalp-related complications and are presented here. RESULTS: In total, 12 consecutive patients receiving ARFGs were identified. Average follow-up was 10 months (range = 2-17 months). Average graft size and dimension was 82 cm (range = 12-360 cm). All patients (n = 12) underwent concomitant cranioplasty reconstruction and had a history of at least 5 or greater previous neurocranial operations. Six patients had radiation therapy prior to cranioplasty. Two major complications (2/12, 17%) were identified related to deep, recurrent intracranial infections. More importantly, none of the patients (n = 12) in this study cohort developed scalp breakdown and/or implant extrusion in the areas of rectus fascia scalp augmentation. CONCLUSION: The use of ARFGs for underlay scalp augmentation appears to be both safe and reliable based on our preliminary experience. This new approach is extremely valuable when performing large-size cranioplasty reconstruction in patients with abnormally thin scalps, an extensive neurosurgical history, and/or suboptimal tissue quality. Furthermore, this method has been successful in avoiding free tissue transfer and/or staged tissue expansion as first-line surgery in our complicated cranioplasty population.

Improving Postoperative Nasal Airway Patency in Le Fort-Based, Maxillofacial Trauma Patients Via a Modified Nasal Packing Technique.

INTRODUCTION: Combined mid-face and nasal apparatus trauma injuries pose a significant challenge to airway patency (AW), in the immediate postoperative setting following fracture reduction. As such, the authors describe a modified technique with the goal of maintaining a patent nasal AW, while at the same time, minimizing nasopharyngeal bleeding and nasal AW edema-which can complicate patients requiring intermaxillary fixation (IMF) in the setting of pan-facial trauma. METHODS: A modified technique was devised to assist the reconstruction surgeon in avoiding the risks associated with tracheostomy placement. In an effort to avoid surgical AW complications and improve nasal AW patency in the setting of concurrent IMF and nasal trauma, the authors developed a 2-stage technique drawing upon knowledge from the literature and the authors' own experiences. TECHNIQUE: Following safe extubation, the authors insert open lumen nasal splints in both the nostrils, and suture them together to the nasal septum. If additional inner nasal support is required, polyvinyl alcohol nonabsorbable nasal packing dressing is covered with antibiotic ointment, and then placed within the nasal cavity lateral to the open lumen splints-as a way to further bolster the internal valve and mid-vault anatomy. DISCUSSION: Given the fact that traditional nasal packing with merocele/gauze dressing in concomitant to IMF reduced patients ability to ventilate, the authors felt that a modified technique should be applied. The authors' preferred materials in such patients are open lumen splint, which provides nasal AW patency along with some septum support accompanied by merocele dressing. The authors feel that by applying this technique they achieve dual objectives by supporting the traumatized nose and maintaining nasal AW patency.

Post-Neurosurgical Temporal Deformities: Various Techniques for Correction and Associated Complications.

INTRODUCTION: An irregular craniofacial contour along the temporal fossa, known commonly as 'temporal hollowing deformity,' (THD) can arise from multiple etiologies. In fact, up to half of all patients who undergo neurosurgical pterional dissections develop some form of temporal contour deformities. Unfortunately, temporal hollowing correction remains surgically challenging with many techniques resulting in high rates of failure and/or morbidity. METHODS: Herein, we describe anatomy contributing to postsurgical temporal deformity as well as time-tested prevention and surgical correction techniques. In addition, a review of 25 articles summarizing various techniques and complication profiles associated with temporal hollowing correction are presented. RESULTS: Complications included infection, implant malposition, revision surgery, pain, and implant removal because of implant-related complications Augmentation with either autologous fat or dermal filler is associated with the highest number of reported complications, including catastrophic events such as stroke, pulmonary embolism, and death. No such complications were reported with use of alloplastic material, use of autologous bone, or free tissue transfer. Furthermore, careful attention to adequate temporalis muscle resuspension and position remain paramount for stable restoration of craniofacial symmetry. CONCLUSIONS: Catastrophic complications were associated with injection augmentation of both fat and dermal filler in the temporal region. In contrast, use of alloplastic materials was not found to be associated with any catastrophic complications. As such, for the most severe cases of THD, we prefer to employ alloplastic reconstruction.

Adult Cranioplasty Reconstruction With Customized Cranial Implants: Preferred Technique, Timing, and Biomaterials.

INTRODUCTION: Complex cranial defects requiring delayed reconstruction present numerous challenges. Delayed cranioplasties accompany frequent complications approaching an incidence of 35 to 40%. Therefore, the authors sought to collate their experience in hopes of sharing their perspective on several topics including technique, timing, and preferred biomaterials. METHODS: The authors' 5-year consecutive experience over 430 customized cranial implants is described herein. Since its inception in 2012, the authors' team has employed the pericranial-onlay cranioplasty technique instead of the standard epidural approach. Optimal timing for cranioplasty is determined using objective criteria such as scalp healing and parenchymal edema, close collaboration with neuroplastic surgery, conversion from autologous bone to sterile implant in instances of questionable viability/storage, and the first-line use of solid poly(methylmethacrylate) implants for uncomplicated, delayed cases, first-line porous polyethylene (MEDPOR) implants for single-stage cranioplasty, and first-line polyether-ether-ketone implants for cases with short notice. Furthermore, the use of the pterional design algorithm with temporal bulking for all customized implants has helped to correct and/or prevent temporal hollowing deformities. RESULTS: The authors' team has observed a three-fold reduction in reported complications as compared with the existing literature, with a major complication rate of 11%. The multidisciplinary center has provided an optimal stage for synergy and improved outcomes versus standard cranioplasty techniques. CONCLUSION: Secondary cranial reconstruction, or cranioplasty, can be challenging due to numerous reasons. These best practices, developed in collaboration with neuroplastic surgery and neurosurgery, appear to encompass the largest published experience to date. The authors find this approach to be both safe and reliable.

Design of Hartmann type null screens for testing a plano-convex aspheric lens with a CCD sensor inside the caustic.

A new method to design Hartmann type null screens to test either qualitatively or quantitatively fast plano-convex aspherical lenses is presented. We design both radial and square null screens that produce arrays of circular spots uniformly distributed at predefined planes, considering that the CCD sensor is solely placed inside the caustic region. The designs of these null screens are based on knowledge of the caustic by refraction and on exact ray tracing. The null screens also serve to improve the alignment in optical systems.

Algorithmic Approach to Overcome Scalp Deficiency in the Setting of Secondary Cranial Reconstruction.

BACKGROUND: Multidisciplinary approaches have shown improved outcomes in secondary cranial reconstruction, however, scalp deficiency remains a common obstacle for tension-free scalp closure during cranioplasty. Therefore, our objective was to create an algorithmic approach using a novel concept of "component separation" to help minimize potential complications. METHODS: The authors tested the hypothesis of achieving greater scalp mobility by way of "component separation" in a half-scalp, bilateral cadaver study, and describe within 2 clinical examples. Pterional-sized (N = 2) and hemicraniectomy-sized (N = 2) scalp flaps were dissected on 2 cadaveric heads using an internal control for each scenario. All flaps (N = 4) were created with (experimental group) and without (control group) "retaining ligament release." Total amounts of scalp mobility were measured bilaterally and compared accordingly. RESULTS: Scalp flap mobility was calculated from the sagittal midline using identical arcs of rotation. With zero tension, we observed an increased distance of movement equaling 1 cm for the "experimental" pterional flap, compared with the contralateral "control." Similarly, we found an increase of additional 2 cm in scalp mobility for the "experimental" hemicraniectomy-sized flap. CONCLUSIONS: Tension free scalp closure is most critical for achieving improved outcomes in secondary cranial reconstruction. In this study, we show that a range of 1 to 2 additional centimeters may be gained through a component separation, which is of critical value during scalp closure following cranioplasty. Therefore, based on our high volume cranioplasty experience and cadaver study presented, we offer some new insight on methods to overcome scalp deficiency accompanying secondary cranial reconstruction.