Superior Extension Research Articles

Different types of combined endoscopic and transcranial approaches for complex giant pituitary adenomas: how I do it

BackgroundSurgery for giant pituitary adenomas (GPAs) poses significant challenges, particularly when the tumor cannot be fully addressed using either the endoscopic endonasal approach (EEA) or the microscopic transcranial approach (MTCA) alone.MethodWe utilized two combined approaches for complex GPAs: 1) expanded endoscopic endonasal approach (EEEA) combined with microscopic pterional approach (MPA), and 2) EEEA combined with endoscopic transventricular approach (ETVA).ConclusionThe combined approach is an effective surgical technique for complex GPAs. The EEEA-MPA approach is suitable for GPAs with superior and lateral extension, while the EEEA-ETVA approach is beneficial for tumors with lateral ventricular invasion.

Expanding the reach of the trans-middle cerebellar peduncle approach: pontine cavernous malformations, tissue transgression beyond the safe entry zone, and the invisible triangle.

In the authors' microsurgical experience, the trans-middle cerebellar peduncle (MCP) approach to the lateral and central pons has been the most common approach to brainstem cavernous malformations (BSCMs). This approach through a well-tolerated safe entry zone (SEZ) allows a wide vertical or posterior trajectory, reaching pontine lesions extending into the midbrain, medulla, and pontine tegmentum. Better understanding of the relationships among lesion location, surgical trajectory, and long-term clinical outcomes could determine areas of safe passage. A single-surgeon cohort study of all primary trans-MCP BSCM resections was conducted from July 1, 2017, to June 30, 2021. Preoperative and postoperative MR images were independently reviewed by 3 investigators blinded to the intervention, using a standardized rubric to define BSCM regions of interest (ROIs) involved with a lesion or microsurgical tract. Statistical testing, including the chi-square test with the Bonferroni correction, logistic regression, and structural equation modeling, was performed to analyze relationships between ROIs and clinical outcomes. Thirty-one patients underwent primary trans-MCP BSCM resection during the study period. The median age was 50 years (IQR 24-49 years); 19 (61%) patients were female, and 12 (39%) were male. Seven (23%) patients had familial cavernous malformation syndromes. The median follow-up was 9 months (range 6-37 months). At the last follow-up, composite neurological outcomes were favorable: 22 (71%) patients had 0 (n = 12, 39%) or 1 (n = 10, 32%) major persistent deficit, 5 patients (16%) had 2 deficits, 2 (7%) had 3 deficits, and 1 patient each (3%) had 4 or 6 deficits. Unfavorable composite outcomes were significantly associated with lesions (OR 7.14, p = 0.04) or surgical tracts (OR 12.18, p < 0.001) extending from the superior cerebellar peduncle (SCP) into the contralateral medial midbrain. The ipsilateral dorsal pons was the most frequently implicated ROI involving a surgical tract and the development of new postoperative deficits. This region involved the rhomboid pontine territory and transgression of the pontine tegmentum (OR 7.53, p < 0.001). Structural equation modeling supported medial midbrain and pontine tegmentum transgression as the primary drivers of morbidity. Trans-MCP resection is a safe and effective treatment for BSCMs, including lesions with marked superior or inferior ipsilateral extension. Two trajectories are associated with increased neurological risk: first, a superomedial trajectory to lesions extending into the midbrain that transgresses the SCP, its decussation, or both; and second, a posteromedial trajectory to lesions extending into the pontine tegmentum. The corticospinal tract, SCP, and pontine tegmentum form an invisible triangle within the pontine white matter tolerant of transgression. When the surgeon works within this triangle, most deep pontine BSCMs, including large lesions, those with contralateral or posterior extension, and others extending into the midbrain and medulla, can be resected safely with the trans-MCP approach.

"Open-window" craniectomy for the removal of frontal sinus mucosa to prevent a delayed mucocele: illustrative case.

Frontal craniotomies for a medial subfrontal approach necessitate crossing the frontal sinus. Large superior extensions of the frontal sinus into frontal bone can result in mucosal retention in a free craniotomy bone flap, leading to a delayed mucocele with significant associated morbidity. The authors describe an "open-window" craniectomy technique that permits mucosal removal under direct vision and maintains the inner table on the bone flap's inferior side, helping to seal off the sinus opening with a pericranial flap. An illustrative case involving a medial right frontal craniotomy for a third ventricle mass in a patient with a large superior extension of the frontal sinus into frontal bone is presented. After creating a free frontal bone flap, the inner table was drilled out to the margins of the frontal sinus cavity and any remaining mucosa was cleared. A portion of the inner table above the bone flap's inferior margin was left in place, resembling an open window when viewed from the inner table side. The remaining anterior and posterior wall of the flap inferiorly provided a matched surface for the opening into the remaining frontal sinus, which was covered by pericranium. Long-term follow-up indicated no major complications or delayed mucocele. The open-window craniectomy technique can be considered for frontal sinus violations in patients with large superior frontal bone extension.

LONG-TERM FOLLOW-UP ON A RARE CASE OF PERIOPERATIVE POSTERIOR ISCHEMIC OPTIC NEUROPATHY: FINDING HOPE IN THE DARKNESS

Abstract&#x0D; Introduction : Perioperative posterior ischemic optic neuropathy (PION) following maxillectomy is a rare and devastating condition that leads to permanent vision loss in most reported cases. This case report offers a different perspective through long-term follow-up, providing valuable insights into the prognosis and potential treatments for PION.&#x0D; Case Illustration : Following a left maxillectomy for ameloblastoma, a 28-year-old female experienced sudden vision loss in her left eye. The visual acuity was 5/60, and an altitudinal inferior visual field defect with a superior extension was present. Ishihara's color vision examination revealed 15/38. The patient was diagnosed with perioperative PION and treated with neurotropic and folic acid. After 16 months, optic atrophy was observed. However, there are complete recovery in visual acuity to 5/5 and Ishihara score to 38/38, along with a significant improvement in the visual field defect.&#x0D; Discussion : The current management of perioperative PION is focused on prevention, because once vision loss occurs, it is usually severe and irreversible. In our case, the patient exhibited a favorable outcome after a long follow-up period, suggesting that there is still potential for improvement in PION patients. The finding is consistent with previous study, which reported that a small percentage of patients may still experience improved vision during follow-up. The role of neurotropics in improving patient outcomes is further supported by in vitro studies that demonstrate early neurotropic treatment significantly prevents loss of retinal ganglion cells in PION.&#x0D; Conclusion : Visual improvement is still possible in perioperative PION and early neurotropic administration may be considered in therapy

NEO212, temozolomide conjugated to NEO100, exerts superior therapeutic activity over temozolomide in preclinical chemoradiation models of glioblastoma.

The chemotherapeutic standard of care for patients with glioblastoma (GB) is radiation therapy (RT) combined with temozolomide (TMZ). However, during the twenty years since its introduction, this so-called Stupp protocol has revealed major drawbacks, because nearly half of all GBs harbor intrinsic treatment resistance mechanisms. Prime among these are the increased expression of the DNA repair protein O6-guanine-DNA methyltransferase (MGMT) and cellular deficiency in DNA mismatch repair (MMR). Patients with such tumors receive very little, if any, benefit from TMZ. We are developing a novel molecule, NEO212 (TMZ conjugated to NEO100), that harbors the potential to overcome these limitations. We used mouse models that were orthotopically implanted with GB cell lines or primary, radioresistant human GB stem cells, representing different treatment resistance mechanisms. Animals received NEO212 (or TMZ for comparison) without or with RT. Overall survival was recorded, and histology studies quantified DNA damage, apoptosis, microvessel density, and impact on bone marrow. In all tumor models, replacing TMZ with NEO212 in a schedule designed to mimic the Stupp protocol achieved a strikingly superior extension of survival, especially in TMZ-resistant and RT-resistant models. While NEO212 displayed pronounced radiation-sensitizing, DNA-damaging, pro-apoptotic, and anti-angiogenic effects in tumor tissue, it did not cause bone marrow toxicity. NEO212 is a candidate drug to potentially replace TMZ within the standard Stupp protocol. It has the potential to become the first chemotherapeutic agent to significantly extend overall survival in TMZ-resistant patients when combined with radiation.

Factors affecting the use of magnetic resonance imaging in a Southern European region: a qualitative study

ObjectivesThe use of Magnetic Resonance Imaging (MRI) has increased significantly in recent years. Superior diagnostic capability and extension of criteria for the performance of MRI may explain this increase, but there are also non-clinical factors that influence doctors’ decisions. We aim to describe the views of doctors in the Basque Country (Spain) regarding factors affecting MRI orders. MethodsWe conducted a qualitative study using semi-structured interviews with doctors based on intentional sampling to cover a diverse range of interviewees according to personal and professional characteristics (sex, workplace, post of responsibility). We analyzed transcript content using an inductive approach. ResultsFactors identified by doctors were classified into three themes: 1) superior diagnostic capability of the MRI compared to other imaging modalities has favoured MRI use and inclusion in Clinical Practice Guidelines; 2) patient demands, owing to lower trust and acceptance of doctors’ judgment than to technology-based medicine, leads to patient-doctor relationships that result unnecessary MRI test; 3) structural or contextual aspects of the health system, such as excessive rotation of doctors or a lack of time to carry out a thorough patient examination, which disempower doctors and favour overuse. ConclusionsDoctors identified non-clinical factors that affect MRI use and that lead to unintended consequences both for the healthcare system and for patients. We recommend an organizational approach to give doctors enough resources to overcome non-clinical factors that lead to excessive MRI orders in order to optimize its use.

Feed-forward cascaded stochastic resonance and its application in ship radiated line signature extraction

Extracting ship-radiated line signatures from intense background noise presents a significant challenge in remote passive sonar detection and identification. While stochastic resonance (SR) has shown promise for enhancing signal-to-noise ratio (SNR), cascaded stochastic resonance (CSR) offers a superior extension by gradually transitioning energy from high to low frequencies, resulting in smoother waveforms and more evident signatures. However, CSR relies heavily on the first level and lacks robustness, especially at slightly lower SNR. To overcome these limitations, we propose a feed-forward cascaded stochastic resonance (FCSR) method that leverages complete target signal information in each level and superimposes it with the output from the last level, leading to gradual improvements in SNR with high robustness. The superposition weights are designed as a function of the number of cascaded levels with an increasing trend to optimize the output of the entire cascaded system. Furthermore, a phase alignment strategy was developed to improve the superposition process. Through theoretical analysis, we demonstrate the effectiveness of the proposed FCSR method. Further simulation analyses demonstrates that FCSR outperforms CSR, with a remarkable 18 dB improvement in filtering performance under low SNR conditions, an average anti-noise ability enhancement of over 10 dB, and a robustness improvement exceeding 30% at −30 dB. We also validate the practicality and effectiveness of our proposed method through application verification, exhibiting excellent enhancement performance. This study illuminates the importance of reutilizing complete target signal information and emphasizes the potential of cascaded systems to extract signatures from heavy background noise.

Reassessment of the electrical connection between the pulmonary veins and the left atrium: A study to determine the different contributions of myocardial fibers along the standard ablation circumference.

Circumferential ablation around the ipsilateral pulmonary veins (PVs) is the standard strategy for atrial fibrillation ablation. The present study seeks to assess which regions of the standard ablation circumference are the main contributors to the venoatrial electrical connection. A total of 41 patients were included under a specific atrial fibrillation ablation protocol in which the anterior and posterior segments of the standard circumference, between the equatorial line of the superior and the inferior ipsilateral PVs, were ablated first. If PV isolation was not achieved, ablation was extended superiorly or inferiorly, on the basis of the earliest atrial activation recorded during pacing from inside the PV. Complete PV isolation and the length of the areas not requiring ablation (ANRA) at the time of electrical isolation were evaluated. Ablation of the anterior and posterior segments of the standard circumference led to the isolation of 77% left-PV pairs and 51% right-PV pairs (p = 0,015). A superior extension was required in 23% left-PV pairs and in 46% right-PV pairs, while an inferior extension was required only in 10% left-PV pairs and in 11% right-PV pairs. PV isolation was achieved before completing the standard ablation circumference in 97% left-PV pairs and in 94% right-PV pairs, with a median ANRA of 36.9 (IQR: 30.9-42.1) mm in the left PVs [16.0 (IQR: 12.0-19.0) mm superior and 18.8 (IQR: 16.1-24.9) mm inferior, p < 0.01] and 36.9 (IQR: 30.2-41.0) mm in the right PVs [15.1 (IQR: 10.7-19.1) mm superior and 20.6 (IQR: 16.9-23.3) mm inferior, p < 0.01]. The myocardial fibers along the anterior and posterior regions of the standard ablation circumference are the main contributors to the electrical connection between the pulmonary veins and the left atrium. Ablation of these regions results in PV isolation in the majority of patients.

Electrical connection between the left atrium and the pulmonary veins: a study to understand the contribution of myocardial fibers along the standard ablation circumference

Abstract Funding Acknowledgements Type of funding sources: None. Background Pulmonary vein (PV) isolation with circumferential ablation around ipsilateral PVs is the standard strategy for atrial fibrillation ablation. The electrical connection between the left atrium (LA) and the pulmonary veins (PV) is determined by the heterogeneous arrangement of myocardial fibers along the PV-LA junction. Purpose We sought to assess which regions of the standard ablation circumference are the main contributors to the venoatrial electrical connection. Methods Forty-one patients underwent a specific atrial fibrillation ablation protocol in which the anterior and posterior segments of the standard circumference were ablated first. If PV isolation was not achieved, ablation was extended superiorly or inferiorly, based on the earliest atrial activation recorded during pacing from the PV. Complete PV isolation and the length of the areas non-requiring ablation (ANRA) at the time of electrical isolation were evaluated. Results Ablation of the anterior and posterior segments of the standard circumference led to isolation of 77% left-PV pairs and 51% right-PV pairs (p=0,015). A superior extension was required in 23% left-PV pairs and in 46% right-PV pairs, while an inferior extension was required only in 10% left-PV pairs and in 11% right-PV pairs. PV isolation was achieved before completing the standard ablation circumference in 97% left-PV pairs and in 94% right-PV pairs, with an ANRA of 35.8±9.0mm in left PVs (16.1±5.2 mm superior and 19.7±5.6 mm inferior, p&amp;lt;0,01), and 35.5±9.5 mm in right PVs (15.2±5.7 mm superior and 20.9±5.3mm inferior, p&amp;lt;0,01). Conclusion The myocardial fibers along the anterior and posterior regions of the standard ablation circumference are the main contributors to the electrical connection between the LA and the PVs. Ablation of these regions results in PV isolation in the majority of patients.

PO-05-146 AN UNUSUAL ATRIOVENTRICULAR REENTRY TACHYCARDIA: SUCCESSFUL ABLATION OF NOVEL SLOW PATHWAY AT SUPERIOR SEPTAL PERIMITRAL LEFT ATRIUM

Atrioventricular nodal reentrant tachycardia (AVNRT) is a common supraventricular tachycardia (SVT), treated with catheter ablation of slow pathway. The right and left inferior slow pathway (SP) extensions of the AV node are widely recognized, but other SPs are very rare. We present a case of atypical AVNRT that was successfully ablated at the superior septal perimitral left atrium. N/A A 75-year-old man with history of coronary artery disease status post coronary artery bypass grafting and recurrent episodes of symptomatic SVT despite diltiazem and metoprolol presented for catheter ablation. Mid RP SVT (cycle length, CL 350 ms) with concentric atrial activation was inducible with atrial and ventricular extrastimulation. Synchronized premature ventricular complexes and ventricular entrainment excluded AV reentry. Very late coupled premature atrial complex from coronary sinus (CS) delivered synchronous to septal A activation delayed next A and reset SVT indicating AVNRT and excluding ectopic junctional (JT) or atrial tachycardia (AT). Further, AH interval during SVT was much longer than AH with atrial pacing at same CL excluding AT. We concluded mechanism to be atypical AVNRT. On activation mapping of right atrium, earliest A was recorded in the fast pathway region, earlier than locations of right and left slow pathways in the triangle of Koch and CS respectively. Radiofrequency ablation lesions anatomically targeting both slow pathways were delivered at base of triangle of Koch and inside CS without affecting SVT. High density activation maps of both right and left atria were created during SVT using Orion basket catheter and Rhythmia (Boston Scientific) mapping system. Earliest A was recorded in the superior septal perimitral left atrium, superior to the location of His bundle electrogram, and anatomically adjacent to aortic sinuses of Valsalva (not mapped). We concluded this to be an unusual left superior extension of the AV node. Radiofrequency ablation lesion using IntellaNav MiFi catheter at this site promptly terminated SVT. Consolidation lesions were delivered and anchored to the mitral annulus. The tachycardia was no longer inducible on programmed electrical stimulation despite isoproterenol. The patient has remained symptom free for 6 months since ablation. With activation mapping we identified the retrograde slow pathway participating in an unusual atypical AVNRT at superior septal perimitral left atrium.

Modeling COVID-19 Real Data Set by a New Extension of Haq Distribution

Modeling real-life pandemics is very important; this study focuses on introducing a new superior flexible extension of the asymmetric Haq distribution known as the power Haq distribution (PHD). The most fundamental mathematical properties are derived. We determine its parameters using ten estimation methods. The asymptotic behavior of its estimators is investigated through simulation, and a comparison is done to find out the most efficient method for estimating the parameters of the distribution under consideration. We use a sample for the COVID-19 data set to evaluate the proposed model’s performance and usefulness in fitting the data set in comparison to other well-known models.

Comparison Between the Supracerebellar Infratentorial and Precuneal Interhemispheric, Transtentorial Approaches to the Cerebellomesencephalic Fissure: An Anatomoradiological Study and Illustrative Cases.

The dorsal brainstem and cerebellomesencephalic fissure are challenging surgical targets. To afford a preferentially craniocaudal trajectory to this region, the precuneal interhemispheric transtentorial approach (PCIT) has been proposed. To didactically describe and compare exposures and anatomic indications of the supracerebellar infratentorial approach (SCIT) and PCIT to the cerebellomesencephalic fissure. Nine formalin-fixed, latex-injected cadaveric head specimens were used to perform a midline SCIT and bilateral PCITs and measure the distance of each approach. Twenty-four formalin-fixed specimens were used to measure the distance from the most posterior cortical bridging vein entering the superior sagittal sinus to the calcarine sulcus and the torcula. Fifty-one magnetic resonance images were reviewed to calculate the angle of each approach. Three illustrative surgical cases were described. Mean distances from the brain or cerebellar surface to the operative target of the PCIT and SCIT were 7.1 cm (range: 5-7.7 cm) and 5.5 cm (range: 3.8-6.2 cm), respectively. The SCIT provided direct access to structures of the quadrigeminal cistern bilaterally. The PCIT provided access from the ipsilateral inferior colliculus to the ipsilateral infratrochlear zone. The PCIT's benefit was the direct access it provided to the cerebellomesencephalic fissure because of its superior to inferior trajectory. The PCIT is indicated for unilateral lesions of the cerebellomesencephalic fissure and dorsal brainstem that harbor a craniocaudal long axis and do not have a superior extension beyond the superior colliculi. The SCIT is beneficial for lesions that extend bilaterally, have an anteroposterior long axis, or involve the Galenic complex.

Low radius of curvature growth-friendly rib-based implants increase the risk of developing clinically significant proximal junctional kyphosis.

Clinically significant proximal junctional kyphosis (PJK) occurs in 20% of children with scoliosis treated with posterior distraction-based growth-friendly surgery. In an effort to identify modifiable risk factors, it has been theorized biomechanically that low radius of curvature (ROC) implants (i.e., more curved rods) may increase post-operative thoracic kyphosis, and thus may pose a higher risk of developing PJK. We sought to test the hypothesis that early onset scoliosis (EOS) patients treated with low ROC distraction-based implants will have a greater risk of developing clinically significant PJK as compared to those treated with high ROC (straighter) implants. We conducted a retrospective review of prospectively collected data obtained from a multi-centre EOS database on children treated with rib-based distraction with a minimum 2-year follow-up. Variables of interest included: implant ROC at index (220mm or 500mm), participant age, pre-operative scoliosis, pre-operative kyphosis, and scoliosis etiology. PJK was defined as clinically significant if revision surgery with a superior extension of the upper instrumented vertebrae was performed. In 148 participants with scoliosis, there was a higher risk of clinically significant PJK with low ROC (more curved) rods (OR: 2.6 (95% CI 1.09-5.99), χ2 (1, n = 148) = 4.8, p = 0.03). Participants had a mean pre-operative age of 5.3years (4.6y 220mm vs 6.2y 500mm, p = 0.002). A logistic regression model was created with age as a confounding variable, but it was determined to be not significant (p = 0.6). Scoliosis etiologies included 52 neuromuscular, 52 congenital, 27 idiopathic, 17 syndromic with no significant differences in PJK risk between etiologies (p = 0.07). Overall, participants had pre-op scoliosis of 69° (67° 220mm vs 72° 500mm, p = 0.2), and kyphosis of 48° (45° 220mm vs 51° 500mm, p = 0.1). The change in thoracic kyphosis pre-operatively to final follow-up (mean 4.0 ± 0.2years) was higher in participants treated with 220mm implants compared to 500mm implants (220mm: 7.5 ± 2.6° vs 500mm: - 4.0 ± 3.0°, p = 0.004). Use of low ROC (more curved) posterior distraction implants is associated with a significantly greater increase in thoracic kyphosis which likely led to a higher risk of developing clinically significant PJK in participants with EOS. Level III - retrospective comparative study.

Preparation of nanocellulose by a biological method from hemp stalk in contrast to the chemical method and its application on the electrospun composite film.

In this study, CNFs were provided by an efficient, unmodified, and clean biological method with enzymes and a small amount of alkali, compared to the CNCs with the chemical method involving a strong acid. To provide an accurate targeted selection for future applications, we made the following comparison by analyzing the differences in the preparation method, performance, and application performance of the two nanocelluloses. The result of this study indicated that CNFs and CNCs exhibited a crystallinity index of 58.2 and 83.5%, respectively. CNFs had a mean length (L) of 192.3 nm and a diameter (D) of 1.9 nm, and the average L and D of CNCs reached 123.6 nm and 3.7 nm, respectively. The solution viscosity of CNFs and CNCs reached 7.46 Pa s and 1.91 Pa s, respectively. CNFs and CNCs exhibited zeta potential values of -88.26 mV and -26.40 mV, respectively. The electrospun composite film of PLA-CNFs and PLA-CNCs achieved water contact angles of 138.7 and 34.5°, and the water-oil contact angle reached 24.7 and 30.5°, respectively. The breaking strength of PLA-CNFs and PLA-CNCs reached 96.07 cN and 163.23 cN, and the break elongation followed an order of PLA-CNCs (32.16%) < PLA-CNFs (34.70%). In brief, CNFs can make the composite membrane hydrophobic and with superior extension, and CNCs can make the composite membrane hydrophilic and enhance its strength. Both the composite films conformed to the non-toxic standard, and the PLA-CNFs film more significantly contributed to the cell growth, which is expected to serve as a medical material.

Surgical morbidity of the extradural anterior petrosal approach: the Lariboisière experience.

Concerns about the approach-related morbidity of the extradural anterior petrosal approach (EAPA) have been raised, especially regarding temporal lobe and venous injuries, hearing impairment, facial nerve palsy, cerebrospinal fluid fistula, and seizures. There is lack in the literature of studies with detailed analysis of surgical complications. The authors have presented a large series of patients who were treated with EAPA, focusing on complications and their avoidance. The authors carried out a retrospective review of patients who underwent EAPA at their institution between 2012 and 2021. They collected preoperative clinical characteristics, operative reports, operative videos, findings on neuroimaging, histological diagnosis, postoperative course, and clinical status at last follow-up. For pathologies without petrous bone invasion, the amount of petrous apex drilling was calculated and classified as low (< 70% of the volume) or high (≥ 70%). Complications were dichotomized as approach related and resection related. This study included 49 patients: 26 with meningiomas, 10 brainstem cavernomas, 4 chondrosarcomas, 4 chordomas, 2 schwannomas, 1 epidermoid cyst, 1 cholesterol granuloma, and 1 osteoblastoma. The most common approach-related complications were temporal lobe injury (6.1% of patients), seizures (6.1%), pseudomeningocele (6.1%), hearing impairment (4.1%), and dry eye (4.1%). Approach-related complications occurred most commonly in patients with a meningioma (p = 0.02) and Meckel's cave invasion (p = 0.02). Gross-total or near-total resection was correlated with a higher rate of tumor resection-related complications (p = 0.02) but not approach-related complications (p = 0.76). Inferior, lateral, and superior tumoral extension were not correlated with a higher rate of tumor resection-related complications. No correlation was found between high amount of petrous bone drilling and approach- or resection-related complications. EAPA is a challenging approach that deals with critical neurovascular structures and demands specific skills to be safely performed. Contrary to general belief, its approach-related morbidity seems to be acceptable at dedicated skull base centers. Morbidity can be lowered with careful examination of the preoperative neuroradiological workup, appropriate patient selection, and attention to technical details.

Femoral Head Vascularity After Arthroscopic Femoral Osteochondroplasty: An In Vivo Dynamic Contrast-Enhanced MRI Study.

A serious concern with surgical procedures around the hip joint is iatrogenic injury of the arterial supply to the femoral head (FH) and consequent development of FH osteonecrosis. Cam-type morphology can extend to the posterosuperior area. Understanding the limit of the posterior superior extension of the femoral osteochondroplasty is paramount to avoid underresection and residual impingement while maintaining FH vascularity. The aim of this study was to quantify the impact of arthroscopic femoral osteochondroplasty on the FH vascular supply. It was hypothesized that keeping the superior extension of the resection zone anterior to the 12-o'clock position would maintain FH vascularity. Case series; Level of evidence, 4. Ten adult patients undergoing arthroscopic femoroacetabular impingement (FAI) surgery were included in the study. Computed tomography (CT) scans were obtained before and after arthroscopic osteochondroplasty to define the extension of resection margins. To quantify FH vascularity, postoperative dynamic contrast-enhanced magnetic resonance imaging (DCE-MRI) was obtained at 2 time points: immediately after surgery and at the 3-month follow-up. Custom MRI analysis software was used to quantify perfusion. CT scan analysis demonstrated that the superior resection margin was maintained anterior to the 12-o'clock position in half of the patients. The remining 5 patients had a mean posterior extension of 11.4° ± 7.5°. The immediate postoperative DCE-MRI revealed diminished venous outflow in the operative side but no difference in overall FH perfusion. At the 3-month follow-up DCE-MRI, there was no perfusion difference between the operative and nonoperative FHs. This study provides previously unreported quantitative MRI data on in vivo perfusion of the FH after the commonly performed arthroscopic femoral osteochondroplasty for the treatment of cam-type FAI. Maintaining resection margins anterior to the 12-o'clock position, or even 10° posteriorly, was not observed to impair perfusion to the FH.

Increased superior translation following multiple simulated anterior dislocations of the shoulder.

Recurrent shoulder dislocations can result in kinematic changes of the glenohumeral joint. The number of prior shoulder dislocations may contribute to increased severity of capsulolabral lesions. The kinematics of the glenohumeral joint following multiple dislocations remain poorly understood. The purpose of this study was to assess the kinematics of the glenohumeral joint during anterior dislocations of the shoulder, and more specifically, altered translational motion following multiple dislocations. The kinematics of the glenohumeral joint were hypothesized to change and correlate with the number of dislocations. Eight fresh-frozen cadaveric shoulders were dissected free of all soft tissues except the glenohumeral capsule. Each joint was mounted in a robotic testing system. At 60 degrees of glenohumeral abduction, an internal and external rotational torque (1.1 Nm) were applied to the humerus, and the resulting joint kinematics were recorded. Anterior forces were applied to the humerus to anteriorly dislocate the shoulder and the resulting kinematics were recorded during each dislocation. Following each dislocation, the same rotational torque was applied to the humerus, and the resulting joint kinematics were also recorded. A repeated-measures analysis of variance (ANOVA) was used to compare the kinematics following each dislocation. During the 7th, 8th, 9th, and 10th dislocations, the humerus significantly translated superiorly compared with the shoulder during the 1st dislocation (p < 0.05). Following the 3rd, 4th, 5th, and 10th dislocations, the humeral head significantly translated superiorly compared with the shoulder following the 1st dislocation in the position of 60 degrees of abduction in response to external rotation torque (p < 0.05). Multiple anterior shoulder dislocations lead to abnormal translational kinematics and result in increased superior translation of the humerus. This may contribute to pathologic superior extension of capsulolabral injuries. Superior translation of the humerus with overhead motion in the setting of recurrent instability may also place the shoulder at risk for extension of the capsulolabral injuries.

S3633 Metastatic Gastric Adenocarcinoma in 23-Year-Old Female

Introduction: Gastric cancer is the fourth most common malignancy in the USA. Since there are no screening recommendations in place, most gastric cancers are detected at a later stage in the USA. The average age of occurrence of gastric cancer is >40 years. Some of the most common risk factors include Helicobacter pylori infection, atrophic gastritis, ethnicity, and dietary factors. Case Description/Methods: A 23-year-old female with a past medical history of attention deficit hyperactivity disorder presented with complaints of worsening cough and exertional dyspnea for 2 months. The patient also reported experiencing poor appetite, occasional nausea, vomiting, and unintentional weight loss of 10 pounds in 2 months with low back pain. The patient does not smoke cigarettes and drinks alcohol socially. No significant family history. Physical examination was unremarkable. Labs were normal except for mildly elevated ALP. Chest x-ray showed bilateral infiltrates. CT chest showed a miliary pattern of the lung parenchyma with multifocal patchy infiltrates and mediastinal and hilar lymphadenopathy. CT abdomen and pelvis (Figure) showed a calcified mass at the lesser curvature measuring up to 36.4 mm, with mixed attenuation lesion in the left hepatic lobe along with portal, celiac, and retroperitoneal lymphadenopathy; metastatic lesion within the L2 vertebral body with mild superior endplate compression and soft tissue extension to epidural space along with left portal venous thrombosis. Upper GI endoscopy (Figure) showed a large, infiltrative, ulcerated, noncircumferential mass on the lower curvature of the gastric body. Biopsy of the gastric mass revealed infiltrative adenocarcinoma, poorly differentiated with mucous and signet-ring features. Tumor cells were negative for E-cadherin expression and HER-2 immunohistochemical staining and positive for PD-L1 and MYC amplification. The plan was to perform palliative chemotherapy because of the advanced nature of the disease. Discussion: Significant progress has been made in understanding gastric adenocarcinomas, but the pathways leading to the development of gastric cancer are still unclear. As gastric cancer exhibits heterogeneity and molecular expressions, it makes it more difficult to understand. Improvements in micro-array-based gene expression profiling can help us to better delineate the tumor behavior and help us with treatment.Figure 1.: a. CT abdomen - partially calcified gastric mass; b. EGD - A large infiltrative and ulcerated, noncircumferential mass on the lesser curvature of the gastric body; c. & d. Histopathology - H&E stain (20 x): gastric mucosa infiltrated by carcinoma cells with a signet-ring morphology.

Anatomic distribution of local recurrence of nasopharyngeal carcinoma in the Era of IMRT: Suggestion of modification of clinical target volume delineation.

e18060 Background: Target volume delineation in nasopharyngeal carcinoma (NPC) remains a challenge because of the narrow therapeutic margin. There are no-well established guidelines for clinical target volume (CTV) delineation with long-term follow-up. Current consensus continues to rely heavily on bony structure and experience from conventional two and three- dimensional radiation. The aim of our study, is to clarify different anatomic distribution of local recurrence of NPC based on various T stages and spread patterns, provide a high-risk map of local recurrence of NPC, and thus provide suggestion for modification of CTV delineation based on T stages and spread patterns. Methods: We retrospectively enrolled 869 patients with newly diagnosed nonmetastatic NPC treated with definitive IMRT in our institution. With a median follow-up of 54.4 months, 72 patients developed local failure. All the cases of local failure were reviewed and those of local residual disease were excluded. After that, 52 cases with tracaeble primary radiotherapy plans and MR imaging of local recurrence were included in this study. Gross tumor volume of local recurrence (GTVr) and normal structures were delineated in each recurrent patient on primary CT of radiotherapy. The overlap of normal structures with GTVr were analyzed, as well as the stepwise patterns of tumor spread in NPC, based on different T stages and relapsed risk (≥5%, ≥10%, ≥20%, etc). Results: The anatomic distributions of local recurrence of various primary T stages were compared between early and late stages of NPC. Of note, these structures were significantly highly involved in T3/4 cases, compared with T1/2 cases, including lateral pterygoid muscle, inferior orbital fissure，posterior ethmoid sinus，cavernous sinus as well as hypoglossal canal. As for tumor spread patterns of local relapse, most cases relapsed in the nasopharynx and retropharyngeal lymph node (38.5%), followed by anterior-lateral tumor extension (via nasal cavity-pterygoid process-pterygopalatine fossa, 17.31%), posterior tumor extension (via prevertebral muscle-clivus, 13.46%), anterior-superior extension (via nasal cavity-ethmoid sinus-sphenoidal sinus,13.46%), superior extension(via foramen lacerum-cavernous sinus, 11.54%), etc. Finally, we depicted a map of high-risk area based on different T stages and relapsed risk (≥5%, ≥10%, ≥20%). Conclusions: Comprehensive analysis of local recurrence distributions and tumor spread patterns in real-world IMRT provides important reference for modification of CTV delineation for primary NPC. Certain structures such as cavernous sinus and lateral pterygoid muscle are not routinely recommended in the delineation of high-risk CTV for T1-2 disease. Future individualized delineations should be based on relapsed risk and tumor spread patterns.

A superior extension for the Lomax distribution with application to Covid-19 infections real data

We present a new continuous lifetime model with four parameters by combining the Lomax and the Weibull distributions. The extended odd Weibull Lomax (EOWL) distribution is what we’ll call it. This new distribution possesses several desirable properties thanks to the simple linear representation of its hazard rate function, moments, and moment -generating function, with stress-strength reliability that are provided in a simple closed forms. The parameters of the EOWL model are estimated using classical methods such as the maximum likelihood (MLE) and the maximum product of spacing (MPS) and estimated also but using a non-classical method such as Bayesian analytical approaches. Bayesian estimation is performed using the Monte Carlo Markov Chain method. Monte Carlo simulation are used to assess the effectiveness of the estimation methods throughout the Metropolis Hasting (MH) algorithm. To illustrate the suggested distribution’s effectiveness and suitability for simulating real-world pandemics, we used three existing COVID-19 data sets from the United Kingdom, the United States of America, and Italy which are studied to serve as illustrative examples. We graphed the P-P plots and TTT plots for the proposed distribution proving its superiority in a graphical manner for modelling the three data sets in the paper.