Reaction of human walking to transient block of vision: analysis in the context of indirect, referent control of motor actions.

Human locomotion may result from monotonic shifts in the referent position, R, of the body in the environment. R is also the spatial threshold at which muscles can be quiescent but are activated depending on the deflection of the current body configuration Q from R. Shifts in R are presumably accomplished with the participation of proprioceptive and visual feedback and responsible for transferring stable body balance (equilibrium) from one place in the environment to another, resulting in rhythmic activity of multiple muscles by a central pattern generator (CPG). We tested predictions of this two-level control scheme. In particular, in response to a transient block of vision during locomotion, the system can temporarily slow shifts in R. As a result, the phase of rhythmical movements of all four limbs will be changed for some time, even though the rhythm and other characteristics of locomotion will be fully restored after perturbation, a phenomenon called long-lasting phase resetting. Another prediction of the control scheme is that the activity of multiple muscles of each leg can be minimized reciprocally at specific phases of the gait cycle both in the presence and absence of vision. Speed of locomotion is related to the rate of shifts in the referent body position in the environment. Results confirmed that human locomotion is likely guided by feedforward shifts in the referent body location, with subsequent changes in the activity of multiple muscles by the CPG. Neural structures responsible for shifts in the referent body configuration causing locomotion are suggested.

Lower extremity outcome measures: considerations for clinical trials in spinal cord injury.

STUDY DESIGN: This is a focused review article. OBJECTIVES: To identify important concepts in lower extremity (LE) assessment with a focus on locomotor outcomes and provide guidance on how existing outcome measurement tools may be best used to assess experimental therapies in spinal cord injury (SCI). The emphasis lies on LE outcomes in individuals with complete and incomplete SCI in Phase II-III trials. METHODS: This review includes a summary of topics discussed during a workshop focusing on LE function in SCI, conceptual discussion of corresponding outcome measures and additional focused literature review. RESULTS: There are a number of sensitive, accurate, and responsive outcome tools measuring both quantitative and qualitative aspects of LE function. However, in trials with individuals with very acute injuries, a baseline assessment of the primary (or secondary) LE outcome measure is often not feasible. CONCLUSION: There is no single outcome measure to assess all individuals with SCI that can be used to monitor changes in LE function regardless of severity and level of injury. Surrogate markers have to be used to assess LE function in individuals with severe SCI. However, it is generally agreed that a direct measurement of the performance for an appropriate functional activity supersedes any surrogate marker. LE assessments have to be refined so they can be used across all time points after SCI, regardless of the level or severity of spinal injury. SPONSORS: Craig H. Neilsen Foundation, Spinal Cord Outcomes Partnership Endeavor.

Fully-integrated framework for the segmentation and registration of the spinal cord white and gray matter.

The spinal cord white and gray matter can be affected by various pathologies such as multiple sclerosis, amyotrophic lateral sclerosis or trauma. Being able to precisely segment the white and gray matter could help with MR image analysis and hence be useful in further understanding these pathologies, and helping with diagnosis/prognosis and drug development. Up to date, white/gray matter segmentation has mostly been done manually, which is time consuming, induces a bias related to the rater and prevents large-scale multi-center studies. Recently, few methods have been proposed to automatically segment the spinal cord white and gray matter. However, no single method exists that combines the following criteria: (i) fully automatic, (ii) works on various MRI contrasts, (iii) robust towards pathology and (iv) freely available and open source. In this study we propose a multi-atlas based method for the segmentation of the spinal cord white and gray matter that addresses the previous limitations. Moreover, to study the spinal cord morphology, atlas-based approaches are increasingly used. These approaches rely on the registration of a spinal cord template to an MR image, however the registration usually doesn't take into account the spinal cord internal structure and thus lacks accuracy. In this study, we propose a new template registration framework that integrates the white and gray matter segmentation to account for the specific gray matter shape of each individual subject. Validation of segmentation was performed in 24 healthy subjects using T2*-weighted images, in 8 healthy subjects using diffusion weighted images (exhibiting inverted white-to-gray matter contrast compared to T2*-weighted), and in 5 patients with spinal cord injury. The template registration was validated in 24 subjects using T2*-weighted data. Results of automatic segmentation on T2*-weighted images was in close correspondence with the manual segmentation (Dice coefficient in the white/gray matter of 0.91/0.71 respectively). Similarly, good results were obtained in data with inverted contrast (diffusion-weighted image) and in patients. When compared to the classical template registration framework, the proposed framework that accounts for gray matter shape significantly improved the quality of the registration (comparing Dice coefficient in gray matter: p=9.5×10-6). While further validation is needed to show the benefits of the new registration framework in large cohorts and in a variety of patients, this study provides a fully-integrated tool for quantitative assessment of white/gray matter morphometry and template-based analysis. All the proposed methods are implemented in the Spinal Cord Toolbox (SCT), an open-source software for processing spinal cord multi-parametric MRI data.

Relationships between lower body strength and the energy cost of treadmill walking in a cohort of healthy older adults: a cross-sectional analysis.

PURPOSE: Gait speed is associated with survival in older adults and it was suggested that an elevated energy cost of walking (Cw) is an important determinant of gait speed reduction. Thus far, little is known about the factors that contribute to a lower Cw but it was shown that lower body strength training could reduce the Cw. Therefore, the objective of this study was to investigate the relationship between lower body strength and the Cw in a cohort of healthy older adults. METHODS: A total of 48 participants were included in this study (70.7 ± 5.4 years). After a geriatric and a neuropsychological assessment, participants underwent a fitness testing protocol which included a maximal oxygen uptake test, assessment of the Cw at 4 km h-1 on a treadmill, an isokinetic maximal strength test for the ankle, knee and hip joints and a body composition assessment. Relationships between strength variables and the Cw were assessed with partial correlations and linear regression analyses. RESULTS: Hip extensors and hip flexors peak torque was significantly correlated with the Cw (r = -0.36 and -0.32, respectively; p < 0.05). A tendency towards significance was identified for the ankle plantar flexors (r = -0.25, p = 0.09). Hip extensors peak torque was the only significant neuromuscular parameter included in the linear regression analysis (p < 0.05). CONCLUSION: These results show that hip extensors are an important muscle group with regards to the Cw measured on a treadmill in this cohort of healthy older adults.

Patient Satisfaction with In-Home Telerehabilitation After Total Knee Arthroplasty: Results from a Randomized Controlled Trial.

Background and Introduction: Telerehabilitation after total knee arthroplasty (TKA) is supported by strong evidence on the effectiveness of such intervention and from a cost-benefit point of view. Satisfaction of patients toward in-home telerehabilitation after TKA has not yet been examined thoroughly in large-scale clinical trials. This study aims to compare satisfaction level of patients following in-home telerehabilitation (TELE) after TKA to one of the patients following a usual face-to-face home visit (STD) rehabilitation. Secondarily, to determine if any clinical or personal variables were associated to the level of satisfaction. MATERIALS AND METHODS: This study was embedded in a multicenter randomized controlled trial with 205 patients randomized into two groups. Rehabilitation intervention was the same for both groups; only approach for service delivery differed (telerehabilitation or home visits). Participants were assessed at baseline (before TKA), at hospital discharge, and at 2 and 4 months postdischarge (E4) using functional outcomes. Patient satisfaction was measured using the validated Health Care Satisfaction Questionnaire (HCSQ) at E4. RESULTS: Characteristics of all participants were similar at baseline. Satisfaction level of both groups did not differ and was very high (over 85%). It was neither correlated to personal characteristics nor to improvements of functional level from preoperative to E4. Satisfaction was rather found associated to walking and stair-climbing performances. CONCLUSIONS: These results, in conjunction with evidences of clinical effectiveness and cost benefits demonstrated in the same sample of patients, strongly support the use of telerehabilitation to improve access to rehabilitation services and efficiency of service delivery after TKA.

Do Performance-Based Wheelchair Propulsion Tests Detect Changes Among Manual Wheelchair Users With Spinal Cord Injury During Inpatient Rehabilitation in Quebec?

OBJECTIVE: To quantify and compare the responsiveness and concurrent validity of 3 performance-based manual wheelchair propulsion tests among manual wheelchair users with subacute spinal cord injury (SCI) undergoing inpatient rehabilitation. DESIGN: Quasi-experimental repeated-measures design. SETTING: Publicly funded comprehensive inpatient SCI rehabilitation program. PARTICIPANTS: Consenting adult manual wheelchair users with a subacute SCI admitted and discharged from inpatient rehabilitation (N=14). INTERVENTION: Participants performed 20-m propulsion at both self-selected natural and maximal speeds, the slalom, and the 6-minute propulsion tests at rehabilitation admission and discharge. MAIN OUTCOME MEASURES: Time required to complete the performance-based wheelchair propulsion tests. Standardized response means (SRMs) were computed for each performance test and Pearson correlation coefficients (r) were calculated to explore the associations between performance tests. RESULTS: The slalom (SRM=1.24), 20-m propulsion at maximum speed (SRM=.99), and 6-minute propulsion tests (SRM=.84) were the most responsive. The slalom and 20-m propulsion at maximum speed were strongly correlated at both admission (r=.93) and discharge (r=.92). CONCLUSIONS: The slalom and 6-minute propulsion tests best document wheelchair propulsion performance change over the course of inpatient rehabilitation. Adding the 20-m propulsion test performed at maximal speed provides a complementary description of performance change.

Anisotropic Multishell Analytical Modeling of an Intervertebral Disk Subjected to Axial Compression.

Studies on intervertebral disk (IVD) response to various loads and postures are essential to understand disk's mechanical functions and to suggest preventive and corrective actions in the workplace. The experimental and finite-element (FE) approaches are well-suited for these studies, but validating their findings is difficult, partly due to the lack of alternative methods. Analytical modeling could allow methodological triangulation and help validation of FE models. This paper presents an analytical method based on thin-shell, beam-on-elastic-foundation and composite materials theories to evaluate the stresses in the anulus fibrosus (AF) of an axisymmetric disk composed of multiple thin lamellae. Large deformations of the soft tissues are accounted for using an iterative method and the anisotropic material properties are derived from a published biaxial experiment. The results are compared to those obtained by FE modeling. The results demonstrate the capability of the analytical model to evaluate the stresses at any location of the simplified AF. It also demonstrates that anisotropy reduces stresses in the lamellae. This novel model is a preliminary step in developing valuable analytical models of IVDs, and represents a distinctive groundwork that is able to sustain future refinements. This paper suggests important features that may be included to improve model realism.

Conditions of Use, Reliability, and Quality of Audio/Video-Mediated Communications During In-Home Rehabilitation Teletreatment for Postknee Arthroplasty.

BACKGROUND: Audio/video-mediated communication between patients and clinicians using videoconferencing over telecommunication networks is a key component of providing teletreatments in rehabilitation. OBJECTIVE: The objectives of this study were to (1) document the conditions of use, performance, and reliability of videoconferencing-based communication in the context of in-home teletreatment (TELE) following total knee arthroplasty (TKA) and (2) assess from the perspective of the providers, the quality attributes of the technology used and its impact on clinical objectives. MATERIALS AND METHODS: Descriptive embedded study in a randomized controlled trial using a sample of 97 post-TKA patients, who received a total of 1,431 TELE sessions. Technical support use, service delivery reliability, performance, and use of network connection were assessed using self-report data from a costing grid and automated logs captured from videoconferencing systems. Physical therapists assessed the quality and impact of video-mediated communications after each TELE session on seven attributes. RESULTS: Installation of a new Internet connection was required in 75% of the participants and average technician's time to install test and uninstall technology (including travel time) was 308.4 min. The reliability of service delivery was 96.5% of planned sessions with 21% of TELE session requiring a reconnection during the session. Remote technical support was solicited in 43% of the sessions (interventions were less than 3-min duration). Perceived technological impacts on video-mediated communications were minimal with quality of the overall technical environment evaluated as good or acceptable in 96% of the sessions and clinical objectives reached almost completely or completely in 99% of the sessions. CONCLUSIONS: In-home rehabilitation teletreatments can be delivered reliably but requires access to technical support for the initial setup and maintenance. Optimization of the processes of reliably connecting patients to the Internet, getting the telerehabilitation platform in the patient's home, installing, configuring, and testing will be needed to generalize this approach of service delivery.

180° turn while walking: characterization and comparisons between subjects with and without stroke.

[Purpose] Limitations in performing the 180°-turning increase the risk of falls and disabilities in stroke patients. The aim of this study was to characterize and compare the 180°-turning between people with and without stroke, considering the direction towards which they turned. [Subjects and Methods] Fourteen subjects with stroke and 14 matched healthy controls performed the 180°-turning twice while walking: towards the self-selected, and the opposite directions. The turning performances were recorded using three video cameras. The videos were randomly analyzed by a single examiner, who characterized the turning, while considering the time required to complete the task, the number of steps, balance, and turning type. Friedman Tests and ANOVA (2 × 2) were used to compare the groups and turning direction factors (turning towards the self-selected versus opposite sides, and towards the paretic/non-dominant versus non-paretic/dominant sides). [Results] No interaction between the groups and turning directions, and no significant differences between the turning directions were found. However, significant differences were found between the groups for all variables used to characterize the turning performance, except for the type of turning. [Conclusion] Stroke subjects demonstrated poor performance on the 180°-turning, regardless of the turning direction. Duration, number of steps, and balance loss indicated difficulties in turn performance.

Inter- and Intra-Rater Reliability of the Visual Vertical in Subacute Stroke.

BACKGROUND AND PURPOSE: Visual vertical (VV) has been used increasingly as a routine clinical assessment to identify alteration of verticality perception as a possible cause of postural disorders after stroke. This study aims to determine whether the reliability of VV is sufficient to support a wide clinical use in neurorehabilitation for monitoring of patients with stroke. METHODS: Twenty patients with subacute stroke in neurorehabilitation unit were tested after a first and unique hemispheric stroke. To evaluate the inter-rater reliability, VV was assessed the same day by 2 examiners whose degrees of expertise differed. The second examiner repeated the test the next day to investigate intrarater reliability. VV orientation (mean, primary criterion) and uncertainty (SD, secondary criterion) were calculated for 10 trials. Their reliability was quantified by the intraclass correlation coefficient, Bland-Altman plots, and the minimal detectable change. The concordance between 2 examiners was quantified by Cohen's κ coefficients (κ). RESULTS: About VV orientation, inter- and intrarater reliability were excellent (intraclass correlation coefficient, 0.979 and 0.982). The Bland-Altman plots and the minimal detectable change revealed a difference inferior to 2° between 2 tests. The concordance between 2 assessments for the diagnosis of abnormal VV orientation was absolute for the same examiner (κ=1; P<0.05) and excellent between 2 examiners (κ=0.92; P<0.05). As for VV uncertainty the intrarater reliability was satisfactory (intraclass correlation coefficient, 0.836) but the inter-rater reliability was poor (intraclass correlation coefficient, 0.211). CONCLUSIONS: The orientation of the VV is a highly reliable criterion, which may be used both in research and in routine clinical practice.

Cost analysis of in-home telerehabilitation for post-knee arthroplasty.

BACKGROUND: Rehabilitation provided through home visits is part of the continuum of care after discharge from hospital following total knee arthroplasty (TKA). As demands for rehabilitation at home are growing and becoming more difficult to meet, in-home telerehabilitation has been proposed as an alternate service delivery method. However, there is a need for robust data concerning both the effectiveness and the cost of dispensing in-home telerehabilitation. OBJECTIVE: The objective of this study was to document, analyze, and compare real costs of two service delivery methods: in-home telerehabilitation and conventional home visits. METHODS: The economic analysis was conducted as part of a multicenter randomized controlled trial (RCT) on telerehabilitation for TKA, and involved data from 197 patients, post-TKA. Twice a week for 8 weeks, participants received supervised physiotherapy via two delivery methods, depending on their study group allocation: in-home telerehabilitation (TELE) and home-visit rehabilitation (VISIT). Patients were recruited from eight hospitals in the province of Quebec, Canada. The TELE group intervention was delivered by videoconferencing over high-speed Internet. The VISIT group received the same intervention at home. Costs related to the delivery of the two services (TELE and VISIT) were calculated. Student's t tests were used to compare costs per treatment between the two groups. To take distance into account, the two treatment groups were compared within distance strata using two-way analyses of variance (ANOVAs). RESULTS: The mean cost of a single session was Can $93.08 for the VISIT group (SD $35.70) and $80.99 for the TELE group (SD $26.60). When comparing both groups, real total cost analysis showed a cost differential in favor of the TELE group (TELE minus VISIT: -$263, 95% CI -$382 to -$143). However, when the patient's home was located less than 30 km round-trip from the health care center, the difference in costs between TELE and VISIT treatments was not significant (P=.25, .26, and .11 for the <10, 10-19, and 20-29 km strata, respectively). The cost of TELE treatments was lower than VISIT treatments when the distance was 30 km or more (30-49 km: $81<$103, P=.002; ≥50 km: $90<$152, P<.001). CONCLUSIONS: To our knowledge, this is the first study of the actual costs of in-home telerehabilitation covering all subcosts of telerehabilitation and distance between the health care center and the patient's home. The cost for a single session of in-home telerehabilitation compared to conventional home-visit rehabilitation was lower or about the same, depending on the distance between the patient's home and health care center. Under the controlled conditions of an RCT, a favorable cost differential was observed when the patient was more than 30 km from the provider. Stakeholders and program planners can use these data to guide decisions regarding introducing telerehabilitation as a new service in their clinic. TRIAL REGISTRATION: International Standard Registered Clinical Study Number (ISRCTN): 66285945; http://www.isrctn.com/ISRCTN66285945 (Archived by WebCite at http://www.webcitation.org/6WlT2nuX4).

Changes in activation timing of knee and ankle extensors during gait are related to changes in heteronymous spinal pathways after stroke.

BACKGROUND: Extensor synergy is often observed in the paretic leg of stroke patients. Extensor synergy consists of an abnormal stereotyped co-activation of the leg extensors as patients attempt to move. As a component of this synergy, the simultaneous activation of knee and ankle extensors in the paretic leg during stance often affects gait pattern after stroke. The mechanisms involved in extensor synergy are still unclear. The first objective of this study is to compare the co-activation of knee and ankle extensors during the stance phase of gait between stroke and healthy individuals. The second objective is to explore whether this co-activation is related to changes in heteronymous spinal modulations between quadriceps and soleus muscles on the paretic side in post-stroke individuals. METHODS: Thirteen stroke patients and ten healthy individuals participated in gait and heteronymous spinal modulation evaluations. Co-activation was measured using peak EMG activation intervals (PAI) and co-activation amplitude indexes (CAI) between knee and ankle extensors during the stance phase of gait in both groups. The evaluation of heteronymous spinal modulations was performed on the paretic leg in stroke participants and on one leg in healthy participants. This evaluation involved assessing the early facilitation and later inhibition of soleus voluntary EMG induced by femoral nerve stimulation. RESULTS: All PAI were lower and most CAI were higher on the paretic side of stroke participants compared with the co-activation indexes among control participants. CAI and PAI were moderately correlated with increased heteronymous facilitation of soleus on the paretic side in stroke individuals. CONCLUSIONS: Increased co-activation of knee and ankle extensors during gait is related to changes in intersegmental facilitative pathways linking quadriceps to soleus on the paretic side in stroke individuals. Malfunction of intersegmental pathways could contribute to abnormal timing of leg extensors during the stance phase of gait in hemiparetic individuals.

Center-of-pressure total trajectory length is a complementary measure to maximum excursion to better differentiate multidirectional standing limits of stability between individuals with incomplete spinal cord injury and able-bodied individuals.

BACKGROUND: Sensorimotor impairments secondary to a spinal cord injury affect standing postural balance. While quasi-static postural balance impairments have been documented, little information is known about dynamic postural balance in this population. The aim of this study was to quantify and characterize dynamic postural balance while standing among individuals with a spinal cord injury using the comfortable multidirectional limits of stability test and to explore its association with the quasi-static standing postural balance test. METHODS: Sixteen individuals with an incomplete spinal cord injury and sixteen able-bodied individuals participated in this study. For the comfortable multidirectional limits of stability test, participants were instructed to lean as far as possible in 8 directions, separated by 45° while standing with each foot on a forceplate and real-time COP visual feedback provided. Measures computed using the center of pressure (COP), such as the absolute maximal distance reached (COPmax) and the total length travelled by the COP to reach the maximal distance (COPlength), were used to characterize performance in each direction. Quasi-static standing postural balance with eyes open was evaluated using time-domain measures of the COP. The difference between the groups and the association between the dynamic and quasi-static test were analyzed. RESULTS: The COPlength of individuals with SCI was significantly greater (p ≤ 0.001) than that of able-bodied individuals in all tested directions except in the anterior and posterior directions (p ≤ 0.039), indicating an increased COP trajectory while progressing towards their maximal distance. The COPmax in the anterior direction was significantly smaller for individuals with SCI. Little association was found between the comfortable multidirectional limits of stability test and the quasi-static postural balance test (r ≥ -0.658). CONCLUSION: Standing dynamic postural balance performance in individuals with an incomplete spinal cord injury can be differentiated from that of able-bodied individuals with the comfortable limits of stability test. Performance among individuals with an incomplete spinal cord injury is characterized by lack of precision when reaching. The comfortable limits of stability test provides supplementary information and could serve as an adjunct to the quasi-static test when evaluating postural balance in an incomplete spinal cord injury population.

Modifications in ankle dorsiflexor activation by applying a torque perturbation during walking in persons post-stroke: a case series.

BACKGROUND: Results obtained in a previous study (Gait Posture 34:358-363, 2011) have shown that, in non-disabled participants, a specific increase in ankle dorsiflexor (Tibialis anterior [TA]) activation can be induced by walking with a torque perturbation that plantarflexes the ankle during the swing phase. After perturbation removal, the increased TA activation persisted temporarily and was associated with a more dorsiflexed ankle during swing. The objective of the present case-series study was to verify if these results can be reproduced in persons post-stroke. METHODS: Six participants who sustained a stroke walked on a treadmill before, during and after exposure to a torque perturbation applied at the ankle by a robotized ankle-foot orthosis. Spatiotemporal gait parameters, ankle and knee kinematics, and the electromyographic activity of TA and Soleus were recorded. Mean amplitude of the TA burst located around toe off and peak ankle dorsiflexion angle during swing were compared across the 3 walking periods for each participant. RESULTS: At the end of the walking period with the perturbation, TA mean amplitude was significantly increased in 4 of the 6 participants. Among these 4 participants, modifications in TA activation persisted after perturbation removal in 3 of them, and led to a statistically significant increase in peak dorsiflexion during swing. CLINICAL IMPLICATIONS: This approach may be helpful to evaluate the residual adaptive capacity in the ankle dorsiflexors after a stroke and guide decision-making for the selection of optimal rehabilitation interventions. Future work will investigate the clinical impact of a multiple-session gait training based on this approach in persons presenting a reduced ankle dorsiflexion during the swing phase of walking.

Perception threshold of locomotor symmetry while walking on a split-belt treadmill in healthy elderly individuals.

Some hemiparetic patients walk asymmetrically. To better understand the mechanisms of this deficiency, the perception of locomotor symmetry was investigated in healthy elderly individuals. 16 participants (6 women, 10 men; M age = 70.9 yr., SD = 4.1) walked on a split-belt treadmill either at a self-selected or imposed gait speed. The speed of the two belts was initially similar (or different) and then gradually differed (or matched), so participants had to detect the point of perceived asymmetry (or symmetry). The results revealed that thresholds occurred when the belt speed ratios were .88 and .85. Initial gait speed did not affect the threshold. The parameter that correlated the most with belt speed asymmetry was stance time of the parameters measured. Future studies will investigate whether stroke affects gait symmetry judgments.

A comprehensive STPA-PSO framework for quantifying smart glasses risks in manufacturing.

The integration of cutting-edge technologies, such as wearables, in complex systems is crucial for enhancing collaboration between humans and machines in the era of Industry 5.0. However, this increased interaction also introduces new challenges and risks, including the potential for human errors. A thorough analysis of the literature reveals an absence of studies that have quantified these risks, underscoring the utmost importance of this research. To address the above gap, the present study introduces the STPA-PSO methodology, which aims to quantify the risks associated with the use of smart glasses in complex systems, with a specific focus on human error risks. The proposed methodology leverages the Systems-Theoretic Process Analysis (STPA) approach to proactively identify hazards, while harnessing the power of the Particle Swarm Optimization (PSO) algorithm to accurately calculate and optimize risks, including those related to human errors. To validate the effectiveness of the methodology, a case study involving the assembly of a refrigerator was conducted, encompassing various critical aspects, such as the Industrial, Financial, and Occupational Health and Safety (OHS) aspects. The results provide evidence of the efficacy of the STPA-PSO approach in assessing, quantifying, and managing risks during the design stage. By proposing a robust and comprehensive risk quantification framework, this study makes a significant contribution to the advancement of system safety analysis in complex environments, providing invaluable insights for the seamless integration of wearables and ensuring safer interactions between humans and machines.

Direct tumoral puncture embolization of onyx before endoscopic endonasal resection of a massive juvenile angiofibroma for a patient with Von Willebrand disease - A case report and review of literature.

INTRODUCTION: Standard treatment of a juvenile angiofibroma (JNA) is surgical resection, usually with an endoscopic endonasal surgery and a preoperative embolization. However, standard intra-arterial embolization may fail to completely devascularize tumors. A novel technique of direct intranasal intratumoral onyx embolization has been described. The aim of this study is to demonstrate the safety and the usefulness of this embolization technique on a pediatric case of JNA and to compare our results to previously reported cases. PRESENTATION OF CASE: A twelve-year-old patient suffering from Von Willebrand disease presented with a voluminous JNA with intracranial extension. Internal carotid artery (ICA) branches partially vascularized the tumor. The patient had two previous incomplete surgical resections, which were preceded by a standard embolization, due to massive perioperative bleeding. DISCUSSION: A direct intratumoral embolization of onyx safely allowed complete tumoral devascularization. Tumoral resection was then completed by an endonasal endoscopic approach. Surgery time was decreased (4,5 h versus 5,5 and 6,5 h) and blood loss were minimized (300 ml versus 1 l and 1,3 l). No complication occurred. Twelve articles previously reported this embolization technique. We present the first reported case of onyx embolization being used for a pediatric patient with a coagulation disorder and a voluminous tumor. CONCLUSION: A direct intratumoral onyx embolization allowed complete resection of a massive JNA, for a patient with Von Willebrand disease. Our data suggest that this technique is safe and may be instrumental for a JNA's resection, even if little vascularization comes from ICA branches.

HPV-Related Multiphenotypic Sinonasal Carcinoma: A Clinicoradiological Series of 3 Cases With Full Endoscopic Surgical Outcome.

Context: Human papillomavirus (HPV)-related multiphenotypic sinonasal carcinoma (HMSC), formerly known as HPV-related carcinoma with adenoid cystic like features, is a rare tumor subtype with unusual correlation between radiological, histopathological, and surgical findings. The shared histological characteristics with other sinonasal tumors make the diagnosis challenging. Optimal surgical and oncological treatments for this rare condition remains to be clearly defined. Methods: The objective of the study was to describe the unique characteristics and endoscopic surgical treatment of this rare tumor. In this retrospective case series, all patients with an HMSC diagnosis treated in our tertiary center were selected. Results: Three HMSC cases were identified, including 2 male and 1 female patients. All cases originated from the posterior nasal cavity. One case presented with a tumor of 8.9 cm × 6.4 cm × 8.7 cm, which is the largest tumor volume described to date. All patients received exclusively endoscopic surgical treatment, followed by adjuvant radiation therapy. No patient showed clinical or radiological sign of disease recurrence, or regional or distant metastasis, with a follow-up ranging from 9 months to 4 years. In 2 cases, initial diagnoses incorrectly suggested adenoid cystic or basaloid squamous cell carcinoma. HPV-DNA testing confirmed the presence of HPV in all cases, with identification of strains 16 and 18. Conclusion and Relevance: HMSC represents a newly identified diagnosis that constitutes a significant challenge for both clinicians and pathologists. It is crucial to acknowledge its indolent clinical course and the apparent contradiction between aggressive radiological features and the noninvasive nature of surgical findings. Skull base surgeons should be aware that, despite these complexities, endoscopic treatment is achievable in the majority of cases. This understanding is essential for the effective management of HMSC.

Development and Validation of a Novel Human-Fixed Cadaveric Model Reproducing Cerebrospinal Fluid Circulation for Simulation of Endoscopic Endonasal Skull Base Surgery.

BACKGROUND AND OBJECTIVES: Endoscopic endonasal surgery is a well-established surgical approach to the skull base. Surgeons need a reusable long-lasting tool to acquire the skills needed for skull base reconstruction. The aim of this study was to elaborate and validate a human formalin-fixed cadaveric model that reproduces a realistic cerebrospinal fluid (CSF) circulation and that adequately renders a CSF leak. METHODS: An external ventricular drain that connects with a peristaltic pump is placed in the subarachnoid space, which allows a water circulation that reproduces CSF circulation. Intracranial pressure is measured in real time. Endoscopic endonasal skull base approaches are performed, to create different skull base openings and CSF leaks. Participants were tasked with reconstruction of the defects using a standardized multilayered approach, with the goal of obtaining a watertight closure under normal intracranial pressure ranges. Compiled data included time of reconstruction, years of experience of participants, and success/failure to achieve a watertight reconstruction. A Likert questionnaire was also used. RESULTS: The cadaveric model reproduced CSF circulation in 4 types of dural defects: sellar, suprasellar, transcribriform, and transclival. Intracranial pressures were similar to physiological conditions and were reproducible. Each model was tested multiple times, over several months. Success rates concurred with training levels (r = .8282 and P = .0017). A strong inverse correlation was also found between years of experience and time of reconstruction (r = .4977 and P < .0001). Participants agreed that the model was realistic (median Likert score of 4), and they strongly agreed that it allowed for the improvement of their surgical skills (median Likert score of 5). CONCLUSION: This novel human-fixed cadaveric model for CSF circulation is efficient and adequately reproduces surgical conditions for skull base approaches. The model is unique, easy to reproduce, and reusable. It can be used as a tool for teaching and for research purposes.