[Clinical anatomy of the free latissimus dorsi myocutaneous flap and its application in the restoration of giant defects of the head and neck].

PURPOSE: To investigate the feasibility and effect of free latissimus dorsi myocutaneous flap in the reconstruction of giant head and neck defects. METHODS: Free latissimus dorsi myocutaneous flap on the cadaver was simulated dissected, and measured by Image-Pro Plus 6.0 to assess the feasibility of repairing giant head and neck defects. Between May 2011 and September 2022, seven patients with giant head and neck defects of different causes repaired with the latissimus dorsi myocutaneous flap were retrospectively analyzed. RESULTS: The diameter of the initiating thoracodorsal artery was (4.03±0.56) mm, and the mean lengths of the arteriolar and venous pedicles of the latissimus dorsi myocutaneous flaps obtained from human specimens were (85.5±10.5) mm and (104±4.2) mm, respectively. Among 7 patients, 5 cases had scalp defects, the remaining 2 cases had neck defects. There were no substantial postoperative problems in the donor site, and all seven latissimus dorsi myocutaneous flaps were successfully transplanted. CONCLUSIONS: For the treatment of considerable head and neck deformities, the latissimus dorsi myocutaneous flap is an optimal muscle flap due to its abundance of tissue, enough length of vascular pedicles, and sufficient venous drainage.

Simulated augmented reality-based calibration of optical see-through head mound display for surgical navigation.

PURPOSE: Calibration of an optical see-through head-mounted display is critical for augmented reality-based surgical navigation. While conventional methods have advanced, calibration errors remain significant. Moreover, prior research has focused primarily on calibration accuracy and procedure, neglecting the impact on the overall surgical navigation system. Consequently, these enhancements do not necessarily translate to accurate augmented reality in the optical see-through head mount due to systemic errors, including those in calibration. METHOD: This study introduces a simulated augmented reality-based calibration to address these issues. By replicating the augmented reality that appeared in the optical see-through head mount, the method achieves calibration that compensates for augmented reality errors, thereby reducing them. The process involves two distinct calibration approaches, followed by adjusting the transformation matrix to minimize displacement in the simulated augmented reality. RESULTS: The efficacy of this method was assessed through two accuracy evaluations: registration accuracy and augmented reality accuracy. Experimental results showed an average translational error of 2.14 mm and rotational error of 1.06° across axes in both approaches. Additionally, augmented reality accuracy, measured by the overlay regions' ratio, increased to approximately 95%. These findings confirm the enhancement in both calibration and augmented reality accuracy with the proposed method. CONCLUSION: The study presents a calibration method using simulated augmented reality, which minimizes augmented reality errors. This approach, requiring minimal manual intervention, offers a more robust and precise calibration technique for augmented reality applications in surgical navigation.

Head model dataset for mixed reality navigation in neurosurgical interventions for intracranial lesions.

Mixed reality navigation (MRN) technology is emerging as an increasingly significant and interesting topic in neurosurgery. MRN enables neurosurgeons to "see through" the head with an interactive, hybrid visualization environment that merges virtual- and physical-world elements. Offering immersive, intuitive, and reliable guidance for preoperative and intraoperative intervention of intracranial lesions, MRN showcases its potential as an economically efficient and user-friendly alternative to standard neuronavigation systems. However, the clinical research and development of MRN systems present challenges: recruiting a sufficient number of patients within a limited timeframe is difficult, and acquiring low-cost, commercially available, medically significant head phantoms is equally challenging. To accelerate the development of novel MRN systems and surmount these obstacles, the study presents a dataset designed for MRN system development and testing in neurosurgery. It includes CT and MRI data from 19 patients with intracranial lesions and derived 3D models of anatomical structures and validation references. The models are available in Wavefront object (OBJ) and Stereolithography (STL) formats, supporting the creation and assessment of neurosurgical MRN applications.

Comparative analysis of GoPro and digital cameras in head and neck flap harvesting surgery video documentation: an innovative and efficient method for surgical education.

BACKGROUND: An urgent need exists for innovative surgical video recording techniques in head and neck reconstructive surgeries, particularly in low- and middle-income countries where a surge in surgical procedures necessitates more skilled surgeons. This demand, significantly intensified by the COVID-19 pandemic, highlights the critical role of surgical videos in medical education. We aimed to identify a straightforward, high-quality approach to recording surgical videos at a low economic cost in the operating room, thereby contributing to enhanced patient care. METHODS: The recording was comprised of six head and neck flap harvesting surgeries using GoPro or two types of digital cameras. Data were extracted from the recorded videos and their subsequent editing process. Some of the participants were subsequently interviewed. RESULTS: Both cameras, set at 4 K resolution and 30 frames per second (fps), produced satisfactory results. The GoPro, worn on the surgeon's head, moves in sync with the surgeon, offering a unique first-person perspective of the operation without needing an additional assistant. Though cost-effective and efficient, it lacks a zoom feature essential for close-up views. In contrast, while requiring occasional repositioning, the digital camera captures finer anatomical details due to its superior image quality and zoom capabilities. CONCLUSION: Merging these two systems could significantly advance the field of surgical video recording. This innovation holds promise for enhancing technical communication and bolstering video-based medical education, potentially addressing the global shortage of specialized surgeons.

A computational modelling tool for prediction of head reshaping following endoscopic strip craniectomy and helmet therapy for the treatment of scaphocephaly.

BACKGROUND: Endoscopic strip craniectomy followed by helmet therapy (ESCH) is a minimally invasive approach for correcting sagittal craniosynostosis. The treatment involves a patient-specific helmet designed to facilitate lateral growth while constraining sagittal expansion. In this study, finite element modelling was used to predict post-treatment head reshaping, improving our comprehension of the necessary helmet therapy duration. METHOD: Six patients (aged 11 weeks to 9 months) who underwent ESCH at Connecticut Children's Hospital were enrolled in this study. Day-1 post-operative 3D scans were used to create skin, skull, and intracranial volume models. Patient-specific helmet models, incorporating areas for growth, were designed based on post-operative imaging. Brain growth was simulated through thermal expansion, and treatments were modelled according to post-operative Imaging available. Mechanical testing and finite element modelling were combined to determine patient-specific mechanical properties from bone samples collected from surgery. Validation compared simulated end-of-treatment skin surfaces with optical scans in terms of shape matching and cranial index estimation. RESULTS: Comparison between the simulated post-treatment head shape and optical scans showed that on average 97.3 ± 2.1 % of surface data points were within a distance range of -3 to 3 mm. The cranial index was also accurately predicted (r = 0.91). CONCLUSIONS: In conclusion, finite element models effectively predicted the ESCH cranial remodeling outcomes up to 8 months postoperatively. This computational tool offers valuable insights to guide and refine helmet treatment duration. This study also incorporated patient-specific material properties, enhancing the accuracy of the modeling approach.

Outside Europe.

This chapter illustrates that cranial surgery was not limited to Europe. There was however no contribution to improving knowledge outside Europe until medical science departed for the Arab world.

Head growth in patients with myelomeningocele treated with prenatal and postnatal surgery.

OBJECTIVE: The need for permanent CSF diversion is lower in patients who have undergone prenatal surgery for myelomeningocele (MMC) than in those who have undergone postnatal closure. Differences in brain development and head growth between treatment groups are not known, particularly for those who do not require surgical treatment for hydrocephalus. The objective of this study was to determine differences in head growth and to generate MMC-specific head circumference (HC) growth curves for patients who underwent either prenatal or postnatal surgery. METHODS: The authors retrospectively identified patients from St. Louis Children's Hospital who were treated for MMC between 2016 and 2021. HC data were obtained from birth until the most recent follow-up or hydrocephalus treatment. Nonlinear least-squares regression analysis was performed to fit the data into four models: two-term power, Gompertz, West ontogenetic, and Weibull. Subsequently, the curves were assessed for their utility in predicting hydrocephalus treatment. RESULTS: Sixty-one patients (29 females [47.5%], 25 [41%] underwent prenatal surgery, mean gestational age at birth 36.6 weeks) were included in the study. The Weibull model best fit the HC data (prenatal adjusted R2 = 0.95, postnatal adjusted R2 = 0.95), while the Gompertz model had the worst fit (prenatal adjusted R2 = 0.56, postnatal adjusted R2 = 0.39) across both cohorts. Prenatal MMC repair patients had significantly larger HC measurements than their postnatal repair counterparts. The 50th percentile of the Weibull curve was determined as a useful threshold for hydrocephalus treatment: children with HC measurements that crossed and remained above this threshold were significantly more likely to have hydrocephalus treatment regardless of time of MMC repair (prenatal relative risk [RR] 10.0 [95% CI 1.424-70.220], sensitivity 85.7% [95% CI 0.499-0.984], and specificity 82.4% [95% CI 0.600-0.948]; postnatal RR 4.750 [95% CI 1.341-16.822], sensitivity 90.5% [95% CI 0.728-0.980], and specificity 75.0% [95% CI 0.471-0.924]). The HC growth curves of the MMC patients treated prenatally were significantly larger than the WHO HC curves (p < 0.001). CONCLUSIONS: The Weibull model was identified as the HC growth curve with the best fit for MMC patients and serves as a useful predictor of hydrocephalus treatment. For MMC patients with hydrocephalus, prenatal repair patients fit the model well but postnatal repair patients did not, potentially indicating different mechanisms of hydrocephalus development. Those treated prenatally had significantly larger HC measurements compared with both the general population and those treated postnatally. Further study is needed to understand the long-term cognitive outcomes and optimal management of clinically asymptomatic patients with large HC measurements who were treated prenatally for MMC.

Flap loss in head and neck reconstruction: Is there a singular cause for failure?

Despite the high success rates reported in head and neck reconstruction, free flap failures continue to persist. Understanding the factors associated with flap loss and improving overall success are paramount. This study aimed to comprehensively assess the factors influencing flap revision and free tissue transfer survival in head and neck reconstruction. The study included 70 patients with defects in the lower two-thirds of the head and neck region and underwent reconstruction using free flaps. Patient age, gender, smoking status, comorbidities and data on the location and aetiology of the defect, the specific type of flap employed, the recipient artery and vein chosen, instances of revision and the overall success of the flap were collected. The investigation aimed to establish correlations between these variables as well as flap success and revision rates. No statistically significant differences were observed in arterial and venous anastomosis revision rates, or flap survival, in relation to variables such as age, gender, flap type, smoking status, comorbidities, recipient artery or vein and the number of vein anastomoses. The malignant tumour group exhibited a lower requirement for arterial revision and a higher flap survival rate compared to the benign tumour group. This study underscores the comparable safety profiles of perforator-based and conventional flaps in head and neck reconstruction. Furthermore, it reveals that patient characteristics are not contraindications for free tissue transfer. Additionally, the quantity of the veins and choice of recipient vessels are flexible and do not significantly impact flap success. The higher rates of flap success in patients with malignant aetiology requires further investigation.

Thickness and design features of clinical cranial implants-what should automated methods strive to replicate?

PURPOSE: New deep learning and statistical shape modelling approaches aim to automate the design process for patient-specific cranial implants, as highlighted by the MICCAI AutoImplant Challenges. To ensure applicability, it is important to determine if the training data used in developing these algorithms represent the geometry of implants designed for clinical use. METHODS: Calavera Surgical Design provided a dataset of 206 post-craniectomy skull geometries and their clinically used implants. The MUG500+ dataset includes 29 post-craniectomy skull geometries and implants designed for automating design. For both implant and skull shapes, the inner and outer cortical surfaces were segmented, and the thickness between them was measured. For the implants, a 'rim' was defined that transitions from the repaired defect to the surrounding skull. For unilateral defect cases, skull implants were mirrored to the contra-lateral side and thickness differences were quantified. RESULTS: The average thickness of the clinically used implants was 6.0 ± 0.5 mm, which approximates the thickness on the contra-lateral side of the skull (relative difference of -0.3 ± 1.4 mm). The average thickness of the MUG500+ implants was 2.9 ± 1.0 mm, significantly thinner than the intact skull thickness (relative difference of 2.9 ± 1.2 mm). Rim transitions in the clinical implants (average width of 8.3 ± 3.4 mm) were used to cap and create a smooth boundary with the skull. CONCLUSIONS: For implant modelers or manufacturers, this shape analysis quantified differences of cranial implants (thickness, rim width, surface area, and volume) to help guide future automated design algorithms. After skull completion, a thicker implant can be more versatile for cases involving muscle hollowing or thin skulls, and wider rims can smooth over the defect margins to provide more stability. For clinicians, the differing measurements and implant designs can help inform the options available for their patient specific treatment.

[Repaired four cases of hypopharyngeal combined neck skin defects using a folded supraclavicular flap].

Objective:To evaluate the outcomes following the use of folded supraclavicular flap repaired hypopharyngeal combined neck skin defects. Methods:Folded supraclavicular flap were designed to repaired four cases of hypopharyngeal combined neck skin defects patients. Evaluate their repair effect （3 men,1 woman; mean age:66 years）. Hypopharyngeal fistula from 3.2 cm×1.8 cm to 4.5 cm×3.8 cm,skin defects in the neck from 3.8 cm×2.2 cm to 5.1 cm×4.5 cm. The folded supraclavicular flap from 8 cm×5 cm to 13 cm×9 cm. Results:All flaps survived, head and neck appearance was satisfactory, and no patient experienced a major complication. All patients resumed an oral diet function. No fistula recurrence or stricture developed after 6-19 months of follow-up. Conclusion:The folded supraclavicular flap is a safe and effective flap Repaired for hypopharyngeal combined neck skin defects.

Evaluating Head and Neck Reconstruction Outcomes Proves Difficult-Seeking Improvement in Reporting.

This Viewpoint advocates for the improvement of the quality of head and neck reconstruction studies through accurate depictions of the defect and reconstruction performed.

Use of supermicrosurgery in craniofacial and head and neck soft tissue reconstruction: a systematic review of the literature and meta-analysis.

Supermicrosurgery is an evolving approach in the reconstruction of head and neck (HN) and craniofacial (CF) defects. This systematic review aims to evaluate the use of supermicrosurgery for arterial or combined arterial and venous anastomoses in the reconstruction of HN and CF soft tissue defects, and the associated success, total complication, and reoperation rates. A literature search was conducted on PubMed, Dynamed, DARE, EMBASE, Cochrane, and British Medical Journal (BMJ) electronic databases (PROSPERO ID: CRD42023476825). Nine studies fulfilled the inclusion criteria with 35 patients who underwent soft tissue reconstructive procedures using supermicrosurgery. Twenty-one flaps were performed on 20 patients (57.1%) with the remaining 15 patients (42.9%) undergoing supermicrosurgical replantation. The most common pathology requiring reconstruction was HN trauma (n = 16, 45.7%) followed by malignancy (n = 15, 42.9%). The pooled success rate for supermicrosurgery was 98% (95% CI 90 to 100, p = 1.00; I2 = 0%). The cumulative complication rate across all the studies was 46% (95% CI 13 to 80, p < 0.01; I2 = 0%), and the pooled rate of reoperation was 1% (95% CI 0 to 8, p = 0.23; I2 = 24%). The use of supermicrosurgery for HN and CF soft tissue reconstruction has an overall success rate of 98%, which is commensurate with traditional microsurgery for HN reconstruction. Complication and reoperation rates are comparable to previous literature. This study confirms the feasibility of supermicrosurgery as a safe and reliable reconstructive option for HN and CF defects.

Is hardware colonization associated with latent hardware complications and removal in maxillomandibular free flap reconstruction?

BACKGROUND: The relationship between hardware colonization, latent hardware complications, and hardware removal remains unclear following osteocutaneous free flap reconstruction of the jaws. METHODS: Retrospective cohort study of all patients undergoing free flap reconstruction of the maxilla or mandible from 2016 to 2021. RESULTS: A total of 240 subjects were included. Hardware colonization was associated with latent hardware complication in bivariate (p ≤ 0.001) and multivariate analysis (p ≤ 0.001). Time to latent hardware complication was 6.87 months earlier in colonized subjects (p ≤ 0.001). Of the 35 subjects undergoing hardware removal, 25 initiated but failed conservative therapy, and resolution of symptoms was achieved in 24 subjects after one operative intervention and 33 subjects after repeat intervention if indicated. CONCLUSIONS: Hardware colonization increases the risk and onset of latent hardware complication. Prompt hardware removal may improve outcomes by leading to faster resolution of symptoms without the burden and cost of conservative therapies.

Greater Saphenous Vein Graft Harvest from Anterolateral Thigh Free Flap Incision: A Novel Technique.

The greater saphenous vein can be harvested from the standard incision for an anterolateral free flap and used as a vein graft in complex head and neck reconstruction. Laryngoscope, 134:648-650, 2024.

Turbocharging as a strategy to boost extended perforator flap vascularity in head and neck reconstruction-A report of two cases.

Perforator flap has been applied as the most common flap for soft tissue defect reconstruction. Here, we presented two cases using turbocharging procedure of perforator to perforator as a salvage strategy. The first case was a 54-year-old male with recurrent squamous cell carcinoma (SCC) in the left buccal area and mouth floor. A 6 × 22 cm posteromedial thigh (PMT) flap was designed for reconstruction. The two eccentric perforators of the PMT flap could not conjoin together during dissection nearby the main pedicle of profunda femoral artery (PFA) resulting in inadequate perfusion. Side branched stump before clipped the branch of distal perforator was preserved, then the proximal perforator was divided and end-to-end anastomosis of side branch of distal perforator was done successfully. The second case was a 52-year-old male underwent wide composite excision of right tongue SCC. After excision, anterolateral thigh (ALT) flap around 7 × 15 cm was harvested from left thigh and two perforators were included which one tiny perforator supplied by the descending branch (DB) and the other major perforator originated from oblique branch (OB) of lateral circumflex femoral artery (LCFA). However, the OB main perforator injury showed inadequate perfusion of flap. We trimmed the injury zone of OB perforator, and shift to re-anastomosis of OB perforators to side branch of DB of LCFA directly. The flap demonstrated excellent perfusion immediately after the operation, and it exhibited complete survival 2 weeks postoperatively. These results indicated that the turbocharging procedure, from perforator to perforator, could serve as a strategy for salvaging perfusion-compromised flaps, especially in cases of eccentric perforators or perforator injury resulting in inadequate perfusion.

Facial Masculinization Surgery: An Analysis of Interest Trends Using Search Term Analysis.

INTRODUCTION: Facial masculinization surgery (FMS) is increasingly popular among cisgender and transgender men. The benefits of FMS are focused on facial identity and have been proven to decrease gender dysphoria in this population. Previous research showed increasing interest in gender affirmation surgery and facial feminization surgery, but the prevalence of FMS has not been explored. It is difficult to find these data based on surgical records alone because institutions do not have standardized methods of reporting and lack publications in the field. Our study aimed to analyze public interest in FMS by using worldwide Google Trends to quantify these trends. METHODS: A worldwide Google Trends search was completed from January 1, 2008, to December 31, 2022, for terms focused on FMS. Then, search terms were analyzed for nonfacial masculinization procedures and were aggregated. Lastly, a PubMed search was conducted for the terms "transgender" and "facial masculinization" from January 1, 2008, to December 31 st , 2022, to compare publication rates. RESULTS: Our data showed an increasing interest in FMS through Google search trends since the year 2008. A similar trend was demonstrated for non-FMS gender-affirming terms. PubMed analysis showed "transgender" medicine publishing rates were approximately 39.65 times greater than "facial masculinization" publishing rates, although "facial masculinization" medicine did produce a positive trend over the study period of approximately 4 publications per year. The medical literature on transgender surgeries rapidly outpaces publications specifically focusing on FMS. CONCLUSION: Our study showed increasing interest in gender affirmation surgery over time, particularly FMS. These increasing trends should encourage greater scientific exploration of FMS and research to properly quantify and assess surgical outcomes in this special population. Additional educational interventions for both the general public and medical providers, to increase awareness of unique challenges that impact this community and highlight changes in health care coverage over time, should be created to keep pace with increasing patient demand and address the physical, systemic, and psychosocial issues faced by people who identify as transgender.

Management of Persistent Syringomyelia in Patients Operated for Chiari Malformation Type 1.

BACKGROUND: The treatment of persistent syringomyelia associated with Chiari malformation type 1 (CM1) is unclear. This study aims to evaluate the clinical and radiologic outcomes of syringo-subarachnoid shunt (SSS) as a treatment for persistent syringomyelia following posterior fossa decompression (PFD) for CM1. METHODS: Forty-nine cases treated for CM1 associated syringomyelia at a single center were analyzed, 17 of them undergoing reoperation due to persistent syrinx formation. The patients' demographic data, neurologic presentations, and radiologic results were analyzed, including cerebellar herniation, posterior fossa volume, the level at which the syrinx started and finished, the size and diameter of the syrinx. RESULTS: Seventeen patients underwent SSS placement, with 1 minor surgical complication (a cerebrospinal fluid leak) occurring and requiring revision. No morbidity or mortality was observed. Among these 17 reoperated patients, partial or complete resorption of the syrinx was observed in all cases. The results suggest that if the syrinx diameter is >10 mm at its thickest point, extends for more than 10 vertebrae, and starts from the upper cervical region and extends to the upper thoracic region, the syrinx may not regress after the first surgery and potentially predicting the need for a second operation before PFD. CONCLUSIONS: SSS placement for persistent syrinx following PFD for CM1 is a safe and effective surgical treatment method. These criteria may also help predict the need for a second surgery and the overall disease outcome for both the surgeon and patient.

Minimally Invasive Approach to Access Vessels for Microvascular Anastomosis in Head and Neck Reconstruction.

OBJECTIVES: To describe our technique, review indications, and evaluate the outcomes of the minimal access approach for recipient vessel identification in microvascular tissue transfer. METHODS: Retrospective chart review of all patients who underwent microvascular reconstruction using the minimal access technique between 2015 and 2021. RESULTS: We report 236 cases, comprising 214 patients with a mean age of 60.2 years (3-88). The most common primary defect sites were the mandible (22.6%), cranium (14%), maxilla (13.2%), skull base (12.8%), and nose/nasal cavity (10.6%). Indications for free flap reconstruction included head and neck cancer extirpation (32.2%), osteoradionecrosis (29.7%), acquired deformity (14.0%), chronic wound (11.9%) and oral motor dysfunction (7.2%). Free flap donor sites used were the anterolateral thigh (84.3%), fibula (7.2%), and radial forearm (6.4%). Vessels utilized include superficial temporal (49.8%), facial (38.3%), angular (11.1%), and transverse cervical (0.4%). The overall complication rate was 14% (n = 33), with surgical complications at the recipient site accounting for 67.6% (n = 25). Flap failure occurred in 3.4% of procedures. Prior head and neck surgery and free flaps were associated with an increased risk of major recipient site complications (n = 20, p = 0.0257 and n = 14, p = 0.0117, respectively). CONCLUSION: Minimal access techniques allow consistent recipient vessel identification for microvascular-free tissue transfer. These approaches may be utilized in reconstructing a broad range of head and neck defects, are low morbidity, and contribute to an overall shorter length of stay. LEVEL OF EVIDENCE: 2 Laryngoscope, 134:2177-2181, 2024.