Creating high-resolution 3D cranial implant geometry using deep learning techniques.

Creating a personalized implant for cranioplasty can be costly and aesthetically challenging, particularly for comminuted fractures that affect a wide area. Despite significant advances in deep learning techniques for 2D image completion, generating a 3D shape inpainting remains challenging due to the higher dimensionality and computational demands for 3D skull models. Here, we present a practical deep-learning approach to generate implant geometry from defective 3D skull models created from CT scans. Our proposed 3D reconstruction system comprises two neural networks that produce high-quality implant models suitable for clinical use while reducing training time. The first network repairs low-resolution defective models, while the second network enhances the volumetric resolution of the repaired model. We have tested our method in simulations and real-life surgical practices, producing implants that fit naturally and precisely match defect boundaries, particularly for skull defects above the Frankfort horizontal plane.

C1-C2 subluxation in enthesitis-related arthritis: two case reports and literature review of ten cases.

BACKGROUND: C1-C2 subluxation is a rare complication of enthesitis-related arthritis (ERA). If left untreated, it may lead to functional impairment or cervical spinal cord compression. This study aims to highlight key points regarding the management of C1-C2 subluxation in ERA. CASE PRESENTATION: We present two cases of C1-C2 subluxation: an 8-year-old boy with ERA and 16-year-old boy with ERA with bilateral sacroiliitis. Ten cases of ERA in the literature were reviewed. The diagnosis of C1-C2 subluxation is mostly based on radiographs and cervical spine computed tomography. All patients were treated with non-steroidal anti-inflammatory drugs. Six ERA patients were treated surgically for cervical fusion. Most ERA patients with sacroiliitis had cervical collar protection. Neurologic abnormalities after treatment were not reported. Despite the use of cervical collar, cervical fusion and persisting ankylosis were found in two ERA patients with sacroiliitis without surgical treatment. CONCLUSIONS: Cervical spine protection and ruling out spinal cord compression should be prioritized, in addition to controlling the underlying inflammation in ERA. Cervical halter traction may be applied after severe cervical inflammation is excluded. To reduce the risk of complications, early recognition and appropriate treatments of C1-C2 subluxation in ERA are essential.

Robot-Assisted Radiofrequency Ablation Combined with Thermodynamic Simulation for Epilepsy Reoperations.

Repeat craniotomies to treat recurrent seizures may be difficult, and minimally invasive radiofrequency ablation is an alternative therapy. On the basis of this procedure, we aimed to develop a more reliable methodology which is helpful for institutions where real-time image monitoring or electrophysiologic guidance during ablation are not available. We used simulation combined with a robot-assisted radiofrequency ablation (S-RARFA) protocol to plan and execute brain epileptic tissue lesioning. Trajectories of electrodes were planned on the robot system, and time-dependent thermodynamics was simulated with radiofrequency parameters. Thermal gradient and margin were displayed on a computer to calculate ablation volume with a mathematic equation. Actual volume was measured on images after the ablation. This small series included one pediatric and two adult patients. The remnant hippocampus, corpus callosum, and irritative zone around arteriovenous malformation nidus were all treated with S-RARFA. The mean error percentage of the volume ablated between preoperative simulation and postoperative measurement was 2.4 ± 0.7%. No complications or newly developed neurologic deficits presented postoperatively, and the patients had little postoperative pain and short hospital stays. In this pilot study, we preliminarily verified the feasibility and safety of this novel protocol. As an alternative to traditional surgeries or real-time monitoring, S-RARFA served as successful seizure reoperation with high accuracy, minimal collateral damage, and good seizure control.

Tracheal reconstruction with pedicled tandem grafts engineered by a radial stretch bioreactor.

The engineering of tracheal substitutes is pivotal in improving tracheal reconstruction. In this study, we aimed to investigate the effects of biomechanical stimulation on tissue engineering tracheal cartilage by mimicking the trachea motion through a novel radial stretching bioreactor, which enables to dynamically change the diameter of the hollow cylindrical implants. Applying our bioreactor, we demonstrated that chondrocytes seeded on the surface of Poly (ε-caprolactone) scaffold respond to mechanical stimulation by improvement of infiltration into implants and upregulation of cartilage-specific genes. Further, the mechanical stimulation enhanced the accumulation of cartilage neo-tissues and cartilage-specific extracellular macromolecules in the muscle flap-remodeled implants and reconstructed trachea. Nevertheless, the invasion of fibrous tissues in the reconstructed trachea was suppressed upon mechanical loading.

Three-dimensional deep learning to automatically generate cranial implant geometry.

We present a 3D deep learning framework that can generate a complete cranial model using a defective one. The Boolean subtraction between these two models generates the geometry of the implant required for surgical reconstruction. There is little or no need for post-processing to eliminate noise in the implant model generated by the proposed approach. The framework can be used to meet the repair needs of cranial imperfections caused by trauma, congenital defects, plastic surgery, or tumor resection. Traditional implant design methods for skull reconstruction rely on the mirror operation. However, these approaches have great limitations when the defect crosses the plane of symmetry or the patient's skull is asymmetrical. The proposed deep learning framework is based on an enhanced three-dimensional autoencoder. Each training sample for the framework is a pair consisting of a cranial model converted from CT images and a corresponding model with simulated defects on it. Our approach can learn the spatial distribution of the upper part of normal cranial bones and use flawed cranial data to predict its complete geometry. Empirical research on simulated defects and actual clinical applications shows that our framework can meet most of the requirements of cranioplasty.

Predictive Value of Swab Cultures for Cryopreserved Flaps During Delayed Cranioplasties.

OBJECTIVE: To assess the predictive value of swab cultures of cryopreserved skull flaps during cranioplasties for surgical site infections (SSIs). METHODS: A retrospective review was conducted of consecutive patients who underwent delayed cranioplasties with cryopreserved autografts between 2009 and 2017. The results of cultures obtained from swabs and infected surgical sites were assessed. The accuracy, sensitivity, and specificity of swab cultures for SSIs were evaluated. RESULTS: The study included 422 patients categorized into two groups, swab and nonswab, depending on whether swab cultures were implemented during cranioplasties. The overall infection rate was 7.58%. No difference was seen in infection rates between groups. There were 18 false-positive and no true-positive swab culture results. All bacteria between swab cultures and SSI cultures were discordant. Meanwhile, there were 19 false-negative swab cultures. The results showed high specificity but low sensitivity for swab cultures to predict SSI occurrence and the pathogens. CONCLUSIONS: Owing to low accuracy and sensitivity, swab cultures of cryopreserved autografts should not be routinely performed during delayed cranioplasties.

Anterior sacral meningocele repair assisted by intraoperative intrathecal fluorescence and 3D printing model: illustrative case.

BACKGROUND: Marfan syndrome is rarely accompanied by anterior sacral meningocele (ASM) resulting from erosion of the sacrum by dural ectasia. ASM may induce symptoms due to severe mass effects. ASM may also mimic ovarian cysts, and the risk of cerebrospinal fluid (CSF) leakage is high if spontaneous rupture of the cyst occurs. In this study, the authors presented a rare case of ASM with iatrogenic CSF leakage in a 34-year-old woman with suspected Marfan syndrome. OBSERVATIONS: The patient initially presented with a giant ASM that was first misdiagnosed as an ovarian cyst. Previously, it had been partially resected, which was followed by iatrogenic CSF leakage. Symptoms of intracranial hypotension, including postural headache and dizziness, developed within 1 month. Brain magnetic resonance imaging (MRI) showed pituitary enlargement, bilateral subdural effusion, and tonsillar herniation. Preoperative computed tomography myelography provided three-dimensional (3D) examination of the deformed sacrum and CSF leakage site. Transabdominal approaches led to primary repair, and repair of the meningocele was achieved by intraoperative fluorescein fluorescence and 3D printed model-guided polymethyl methacrylate bone cement reconstruction. No CSF leakage or recurrent ASM was found at the 1.5-year follow-up visit. LESSONS: Intraoperative intrathecal fluorescence and 3D-printed models are useful for ASM repair. Preoperative MRI is helpful for differentiating ASM from other causes of a huge pelvic mass, including ovarian cyst.

Clinical and endocrinological manifestations of childhood-onset craniopharyngioma before surgical removal: A report from one medical center in Taiwan.

BACKGROUND: Craniopharyngiomas are benign tumors of embryologic origin located in the sellar region. Patients have both neurological and endocrinological symptoms. Symptoms may be subtle in the early clinical course, which leads to delayed diagnosis. This study evaluated the clinical and endocrinological manifestations of childhood-onset craniopharyngioma. METHODS: We retrospectively reviewed medical records of 45 children diagnosed as having craniopharyngioma between 1995 and 2019. We collected data on clinical symptoms and signs, height, weight, biochemical and hormone data, images, operation records, and pathology reports. A three-graded classification system was applied to define the degree of hypothalamic damage (HD). We analyzed clinical and endocrinological manifestations among patients with and without obesity, with short and normal stature, and with differing degrees of HD. RESULTS: Clinical endocrinologic manifestations included adrenocortical insufficiency (42%), central hypothyroidism (37%), short stature (31%), obesity (20%), weight < third percentile (19%), and polyuria or polydipsia (11%). The distribution of height and body mass index (BMI) revealed that a relatively large proportion of patients had short stature and obesity compared to the general population. Patients with grade 2 HD were significantly taller (height median SDS -0.07 vs. -2.05, P = 0.032), and had higher BMI (BMI median standard deviation scores [SDS] 1.14 vs. -0.54, P = 0.039) and shorter time to diagnosis (0.27 vs. 8.29 months, P = 0.007) than were those in the grade 0-1 HD. Delayed diagnosis was associated with short stature (6/7 vs. 4/26, P = 0.001) and no initial neurological symptoms (4/7 vs. 2/28, P = 0.009). CONCLUSION: Growth patterns may change variously depend on the tumor location and the severity of hypothalamic damage. Therefore, monitoring possible neurological symptoms and evaluating the growth patterns of patients during regular outpatient clinical visits are paramount.

Neurological and endocrinological manifestations of 49 children with intracranial pure germinoma at initial diagnosis in Taiwan.

BACKGROUND: Intracranial pure germinoma is a rare extragonadal neoplasm. Affected patients may have motor impairment, visual disturbance, neurological signs, and endocrine disorder, depending on the size and location of the tumor. This study investigated and analyzed patients' demographic data and neuroimaging, clinical, laboratory, and endocrinological findings. METHODS: We performed a retrospective chart review of 49 children diagnosed with pure germinoma in Taiwan from 1990 to 2018. The initial clinical presentation, tumor markers (beta-hCG, alpha fetoprotein, and carcinoembryonic antigen), pituitary function, and brain images were reviewed and analyzed. RESULTS: This study included 49 patients (37 boys and 12 girls). Their ages ranged from 7.5 to 17.9 years, and the mean age at diagnosis was 13.6 years. Initial symptoms included visual disturbance (n = 23, 47.9%), motor impairment (n = 20, 40.8%), polyuria (n = 20, 40.8%), headache (n = 17, 34.7%), dizziness or vertigo (n = 14, 28.6%), nausea/vomiting (n = 13, 26.5%), and short stature (n = 8, 18.2%). Laboratory data indicated growth hormone deficiency or low IGF-1 levels (n = 18, 85.7%), adrenal insufficiency (n = 21, 77.8%), central diabetes insipidus (n = 27, 55.1%), central hypothyroidism (n = 15, 48.4%), and hypogonadotropic hypogonadism (n = 4, 44.4%). CONCLUSION: Intracranial pure germinomas may initially manifest as neurological symptoms or endocrinological findings at diagnosis. As endocrinologic presentation is related to delayed diagnosis, clinicians should be aware of patients with such complaints. Laboratory data should be surveyed carefully, and neuroimaging must be considered if the result is abnormal.

Patient-Specific Three-Dimensional Printing Guide for Single-Stage Skull Bone Tumor Surgery: Novel Software Workflow with Manufacturing of Prefabricated Jigs for Bone Resection and Reconstruction.

OBJECTIVE: To describe a novel system workflow to design and manufacture patient-specific three-dimensional (3D) printing jigs for single-stage skull bone tumor excision and reconstruction and to present surgical outcomes of 14 patients. METHODS: A specific computer-aided design/computer-aided manufacturing software and hardware system was set up, including a virtual surgical planning subsystem and a 3D printing-associated manufacturing subsystem. Computed tomography data of the patient's skull were used for 3D rendering of the skull and tumor. The output of patient-specific designing included a 3D printing guide for tumor resection and a 3D printing model of the bone defect after tumor excision. A polymethyl methacrylate implant was fabricated preoperatively and used for repair. RESULTS: The specific 3D printing guide was used to design intraoperative jigs and implants for 14 patients (age range, 1-72 years) with skull bone tumors. In all cases, the cutting jig allowed precise excision of tumor and bone, and implants were exact fits for the defects created. All operative results were successful, without intraoperative or postoperative complications. Postoperative computed tomography scans were obtained for analysis. Postoperative 3D measurement of the skull symmetry index (cranial vault asymmetry index) showed significant improvement of head contour after surgery. CONCLUSIONS: The computer-aided design/computer-aided manufacturing system described allows definitive preoperative planning and fabrication for treatment of skull bone tumors. Apparent benefits of the method include more accurate determination of surgical margins and better oncological outcomes.

Bicoronal Incision and Frontal-Basal Approach for Removal of Sinonasal Fibrous Dysplasia Complicated by Orbital Subperiosteal Abscess.

BACKGROUND: Fibrous dysplasia (FD) is a benign, slowly progressive disease resulting from the replacement of normal bone by fibro-osseous tissue. The incidence of craniofacial involvement of FD is as high as 23%. Sinonasal involvement of FD may lead to obstruction of the natural sinus ostium, resulting in acute sinusitis. We present a rare case of sinonasal FD complicated by subperiosteal abscess that was removed by bicoronal incision and frontal-basal approach in the second surgery. CASE DESCRIPTION: A 16-year-old male patient presented with painful swelling on his left eye that had persisted for 2 days. Transnasal endoscopic drainage of the left orbital subperiosteal abscess was performed and progressive improvement of the swelling of the left eye was noted. After the acute phase, transcranial removal of the sinonasal bony lesion and mesh reconstruction of the left orbital wall were performed. There has been no progression of FD to date, with 24 months of follow-up. CONCLUSIONS: After the acute phase, radical excision with reconstruction or debulking surgery after skeletal maturation may prevent recurrence. Although malignant transformation is rare, long-term follow-up is necessary for FD.

HoloLens-Based AR System with a Robust Point Set Registration Algorithm.

By the standard of today's image-guided surgery (IGS) technology, in order to check and verify the progress of the surgery, the surgeons still require divert their attention from the patients occasionally to check against the display. In this paper, a mixed-reality system for medical use is proposed that combines an Intel RealSense sensor with Microsoft's Hololens head-mounted display system, for superimposing medical data onto the physical surface of a patient, so the surgeons do not need to divert their attention from their patients. The main idea of our proposed system is to display the 3D medical images of the patients on the actual patients themselves by placing the medical images and the patients in the same coordinate space. However, the virtual medical data may contain noises and outliers, so the transformation mapping function must be able to handle these problems. The transform function in our system is performed by the use of our proposed Denoised-Resampled-Weighted-and-Perturbed-Iterative Closest Points (DRWP-ICP) algorithm, which performs denoising and removal of outliers before aligning the pre-operative medical image data points to the patient's physical surface position before displaying the result using the Microsoft HoloLens display system. The experimental results shows that our proposed mixed-reality system using DRWP-ICP is capable of performing accurate and robust mapping despite the presence of noise and outliers.

Objective and quantifiable measuring mechanism for assessing flap pliability: Our experience with 92 patients.

BACKGROUND: Pliability describes a flaps' ability to bend under spatial limitations, yet a quantifiable measurement for this flexibility does not exist. METHODS: Between January 2015 and January 2017, we applied a novel measuring mechanism to two free flaps for head and neck reconstruction. We allocated a flap pliability score (FPS) to these flaps and observed correlations to common variables. RESULTS: Forty profunda artery perforator (PAP) and 52 anterolateral thigh (ALT) flaps were allotted a score depending on how pliable they performed on our test. Proximal PAP and distal ALT were more pliable than their respective opposite ends. Other interesting conclusions regarding these flaps were also made. CONCLUSIONS: With our technique, pliability of the proximal and distal ends of PAP and ALT flaps was ascertained. Herein, we describe an innovative measuring mechanism via which we can allocate a FPS to any flap and thus obtain information regarding how suitable they are for a given recipient site.

Adjuvant Radiation Therapy Compared with Observation Alone for Postoperative Residual Nonfunctional Pituitary Adenomas.

OBJECTIVE: The management of residual nonfunctional pituitary tumors after surgical resection remains controversial. In this study, we compared the prognosis of postoperative radiation therapy and observation only in patients with residual nonfunctional pituitary adenoma and reviewed the long-term complications after radiation therapy. METHODS: We retrospectively analyzed 90 patients who underwent surgery for nonfunctional pituitary adenomas from January 2008 to April 2012. Residual tumors were classified by size, location, and pathologic staining. Tumor progression was defined as volume progression ≥15% with or without clinical symptoms. Postoperative radiation therapy was performed <1 year after the last surgery. We compared the progression and 3-year and 5-year progression-free survival between the observation group and postoperative radiation therapy group. Postradiation complications including hypopituitarism, diabetes insipidus, deterioration in visual field or acuity, cranial nerve palsy, and hydrocephalus were also analyzed. RESULTS: More of the patients who received postoperative radiation therapy had a tumor progression-free survival of ≥3 years than did those who did not receive postoperative radiation therapy. Postoperative radiation therapy was significantly beneficial for the patients with a tumor size ≥3 cm or with tumors in the cavernous sinus. The most frequent complication after radiation therapy was hypopituitarism and a few cases had third cranial nerve palsy; however, there were no significant relationships with radiation therapy. CONCLUSIONS: In this study, immediate radiation therapy after tumor resection was an effective and relatively safe treatment for residual or progressive nonfunctional pituitary adenomas. Moreover, the long-term complications of radiation therapy were mild.

Long-Term Complications of Cranioplasty Using Stored Autologous Bone Graft, Three-Dimensional Polymethyl Methacrylate, or Titanium Mesh After Decompressive Craniectomy: A Single-Center Experience After 596 Procedures.

OBJECTIVE: Cranioplasty is a technically simple procedure intended to repair defects of the skull to provide protection after craniectomy, improve functional outcomes, and restore cosmesis. Several materials have been used for the restoration of skull defects, including autologous bone grafts (AGs), polymethyl methacrylate (PMMA) flaps, and titanium mesh (T-mesh). However, the long-term results of cranioplasty after use of these materials are controversial. METHODS: Medical records of 596 patients who underwent cranioplasty at our medical center between 2009 and 2015 with at least 2.5 years of follow-up were retrospectively reviewed. Patients were classified into 3 groups according to the materials used: AG, three-dimensional PMMA, and T-mesh. Demographic and clinical characteristics and postoperative complications were analyzed. RESULTS: Cranioplasty with AG had the highest bone flap depression rate (4.9%; P = 0.02) and was associated with a 26% long-term bone flap resorption. Younger age was a risk factor for bone flap resorption. T-mesh had a higher risk of postoperative skin erosion and bone exposure (17%; P = 0.004). Patients with diabetes, previous craniotomy, or hydrocephalus showed a higher risk of postoperative skin erosion. PMMA was associated with the highest rate of postoperative infection (14.4% <3 months, 28.1% >3 months; P < 0.05), and previous craniotomy may increase the infection risk after cranioplasty with PMMA. CONCLUSIONS: Complications after cranioplasty are high, and the various types of cranioplasty materials used are associated with different complications. Surgeons need to be aware of these potential complications and should choose the appropriate material for each individual patient.

De Novo Formation of Pial Arteriovenous Fistulas: Systematic Review of Acquired Lesions and Their Clinical Differences Compared with Primary Lesions.

OBJECTIVE: Acquired pial arteriovenous fistula (pAVF) is an extremely rare intracranial vascular malformation, with few case reports in the English literature. This study presents a thorough review and analysis of all acquired pAVF cases from the literature in addition to an illustrated case. METHODS: We report a case with de novo development of intracranial pAVF after craniotomy. A medical literature database search between 1975 and 2018, including the Medline, Ovid, and PubMed databases, was performed to identify all reports with possible acquired lesions. Differences between these acquired lesions and previously reported primary lesions were evaluated. RESULTS: A total of 8 patients with de novo formation of acquired pAVF were included in this series. Most of these pAVFs were fed and drained via a similar arteriovenous pattern, from distal/cortical branches of the middle cerebral artery (6/8, 75%) to the superficial middle cerebral vein (6/8, 75%). Compared with a previously reported primary pAVF series, acquired pAVF tended to be asymptomatic (P < 0.0001) and found essentially in adults (P = 0.0061). Fewer venous varices (P = 0.0049) and associated intracranial mass effect (P = 0.0189) were found in the cases of acquired pAVF. All 4 reported acquired pAVFs that were treated microsurgically resulted in complete angiographic obliteration (4/4, 100%). The overall outcome was good or stable even with observation only (7/8, 87.5%). CONCLUSIONS: Acquired pAVF is highly correlated with sentinel neurosurgical procedures or venous occlusion events. These lesions should be regarded as a different disease entity from primary pAVF because of the relatively low-flow shunting and benign clinical course.