Surgical Implantation of Brain Computer Interfaces

This article discusses the function and capabilities of brain computer interfaces as a novel approach to rehabilitation for a variety of neurological disorders.

Robotic-Assisted Navigation for Stereotactic Neurosurgery: A Cadaveric Investigation of Accuracy, Time, and Radiation

BACKGROUND AND OBJECTIVES

Despite frequent use, stereotactic head frames require manual coordinate calculations and manual frame settings that are associated with human error. This study examines freestanding robot-assisted navigation (RAN) as a means to reduce the drawbacks of traditional cranial stereotaxy and improve targeting accuracy.

METHODS

Seven cadaveric human torsos with heads were tested with 8 anatomic coordinates selected for lead placement mirrored in each hemisphere. Right and left hemispheres of the brain were randomly assigned to either the traditional stereotactic arc-based (ARC) group or the RAN group. Both target accuracy and trajectory accuracy were measured. Procedural time and the radiation required for registration were also measured.

RESULTS

The accuracy of the RAN group was significantly greater than that of the ARC group in both target (1.2 ± 0.5 mm vs 1.7 ± 1.2 mm, P = .005) and trajectory (0.9 ± 0.6 mm vs 1.3 ± 0.9 mm, P = .004) measurements. Total procedural time was also significantly faster for the RAN group than for the ARC group (44.6 ± 7.7 minutes vs 86.0 ± 12.5 minutes, P < .001). The RAN group had significantly reduced time per electrode placement (2.9 ± 0.9 minutes vs 5.8 ± 2.0 minutes, P < .001) and significantly reduced radiation during registration (1.9 ± 1.1 mGy vs 76.2 ± 5.0 mGy, P < .001) compared with the ARC group.

CONCLUSION

In this cadaveric study, cranial leads were placed faster and with greater accuracy using RAN than those placed with conventional stereotactic arc-based technique. RAN also required significantly less radiation to register the specimen's coordinate system to the planned trajectories. Clinical testing should be performed to further investigate RAN for stereotactic cranial surgery.

ATM deficiency confers specific therapeutic vulnerabilities in bladder cancer

Ataxia-telangiectasia mutated (ATM) plays a central role in the cellular response to DNA damage and ATM alterations are common in several tumor types including bladder cancer. However, the specific impact of ATM alterations on therapy response in bladder cancer is uncertain. Here, we combine preclinical modeling and clinical analyses to comprehensively define the impact of ATM alterations on bladder cancer. We show that ATM loss is sufficient to increase sensitivity to DNA-damaging agents including cisplatin and radiation. Furthermore, ATM loss drives sensitivity to DNA repair-targeted agents including poly(ADP-ribose) polymerase (PARP) and Ataxia telangiectasia and Rad3 related (ATR) inhibitors. ATM loss alters the immune microenvironment and improves anti-PD1 response in preclinical bladder models but is not associated with improved anti-PD1/PD-L1 response in clinical cohorts. Last, we show that ATM expression by immunohistochemistry is strongly correlated with response to chemoradiotherapy. Together, these data define a potential role for ATM as a predictive biomarker in bladder cancer.

Static compression and fatigue behavior of heat-treated selective laser melted titanium alloy (Ti6Al4V) gyroid cylinders

Porous additively-manufactured structures could have a niche in orthopaedic implants, due to their potential to reduce stiffness (stress-shielding), improve bony ingrowth, and potential to house reservoirs of drug-eluting non-structural biomaterials. Computer aided design and finite element (FE) modelling plays an important role in the design of porous structured biomedical implants; however it is important to validate both their static and fatigue behaviours using experimental testing. This study compared the mechanical behaviors of titanium cylindrical gyroid structures of varying porosities using physical testing of additively manufactured prototypes and FE models. There was agreement in the measured and predicted relationships between porosity and apparent modulus of elasticity. As porosity increased (and wall thickness decreased), the structures failed at a lower number of cycles when loaded at the same percentage of their yield strengths. Calibration of the fatigue strength coefficient from a previously published value of 1586.5 MPa-1225 MPa greatly improved the fatigue life prediction accuracy for all the gyroid structures. Nevertheless, differences of up to 54% in the predicted versus experimental fatigue lives remained, which could be attributed to difficulties with how the precise time and location of failure is defined in the simulations, and/or minor differences in nominal and actual porosities. Although further calibration and validation should be explored, this study demonstrates that static and fatigue FE-modelling techniques could be used to aid in the design of porous prosthetics.

A click-based electrocorticographic brain-computer interface enables long-term high-performance switch-scan spelling

Background

Brain-computer interfaces (BCIs) can restore communication in movement- and/or speech-impaired individuals by enabling neural control of computer typing applications. Single command "click" decoders provide a basic yet highly functional capability.

Methods

We sought to test the performance and long-term stability of click-decoding using a chronically implanted high density electrocorticographic (ECoG) BCI with coverage of the sensorimotor cortex in a human clinical trial participant (ClinicalTrials.gov, NCT03567213) with amyotrophic lateral sclerosis (ALS). We trained the participant's click decoder using a small amount of training data (< 44 minutes across four days) collected up to 21 days prior to BCI use, and then tested it over a period of 90 days without any retraining or updating.

Results

Using this click decoder to navigate a switch-scanning spelling interface, the study participant was able to maintain a median spelling rate of 10.2 characters per min. Though a transient reduction in signal power modulation interrupted testing with this fixed model, a new click decoder achieved comparable performance despite being trained with even less data (< 15 min, within one day).

Conclusion

These results demonstrate that a click decoder can be trained with a small ECoG dataset while retaining robust performance for extended periods, providing functional text-based communication to BCI users.

Analysis of global Napier grass (Cenchrus purpureus) collections reveals high genetic diversity among genotypes with some redundancy between collections

Genetic diversity amongst genotypes of several Napier grass collections was analyzed and compared with the diversity in a set of open pollinated progeny plants. A total of 114,881 SNP and 46,293 SilicoDArT genome-wide markers were generated on 574 Napier grass genotypes. Of these, 86% of the SNP and 66% of the SilicoDArT markers were mapped onto the fourteen chromosomes of the Napier grass genome. For genetic diversity analysis, a subset of highly polymorphic and informative SNP markers was filtered using genomic position information, a maximum of 10% missing values, a minimum minor allele frequency of 5%, and a maximum linkage-disequilibrium value of 0.5. Extensive genetic variation, with an average Nei's genetic distance value of 0.23, was identified in the material. The genotypes clustered into three major and eleven sub-clusters with high levels of genetic variation contained both within (54%) and between (46%) clusters. However, we found that there was low to moderate genetic differentiation among the collections and that some overlap and redundancy occurred between collections. The progeny plants were genetically diverse and divergent from the germplasm collections, with an average FST value of 0.08. We also reported QTL regions associated with forage biomass yield based on field phenotype data measured on a subset of the Napier grass collections. The findings of this study offer useful information for Napier grass breeding strategies, enhancement of genetic diversity, and provide a guide for the management and conservation of the collections.

Bisoprolol versus celiprolol on dynamic hyperinflation, cardiopulmonary exercise and domiciliary safety in COPD: a single-centre, randomised, crossover study

BACKGROUND

Chronic obstructive pulmonary disease (COPD) is frequently associated with cardiovascular disease. The utility of beta-blockers for treating patients with COPD may be beneficial, but their safety remains uncertain, including worsening of dynamic hyperinflation (DH) during exercise. We hypothesised that among cardioselective beta-blockers celiprolol, due to its partial beta-2 agonist activity, may be safer than bisoprolol on exercise DH.

METHODS

We measured isotime inspiratory capacity (IC) during cycle endurance testing in eleven moderate-severe COPD subjects, alongside other non-invasive cardiopulmonary exercise, bioreactance cardiac output, pulmonary function, biomarkers and daily domiciliary measures. Participants received titrated doses of either bisoprolol (maximim 5 mg) or celiprolol (maximum 400 mg) in randomised crossover fashion, each over 4 weeks.

RESULTS

Clinically relevant DH occurred between resting and exercise isotime IC but showed no significant difference with either beta-blocker compared with post-run-in pooled baseline or between treatments. There were no other significant differences observed for remaining exercise ventilatory; non-invasive cardiac output; resting pulmonary function; beta-2 receptor and cardiac biomarkers; domiciliary pulmonary function, oxygen saturation and symptom outcomes, either between treatments or compared with baseline. No significant adverse effects occurred.

CONCLUSIONS

Significant DH in moderate-severe COPD subjects was no different between bisoprolol or celiprolol or versus baseline. A broad spectrum of other non-invasive cardiopulmonary and domiciliary safety outcomes was equally reassuring. Bronchoprotection with a concomitant long-acting muscarinic antagonist might be an important safety measure in this context.

TRIAL REGISTRATION NUMBER

NCT02380053.

Control of working memory maintenance by theta-gamma phase amplitude coupling of human hippocampal neurons

Retaining information in working memory (WM) is a demanding process that relies on cognitive control to protect memoranda-specific persistent activity from interference. How cognitive control regulates WM storage, however, remains unknown. We hypothesized that interactions of frontal control and hippocampal persistent activity are coordinated by theta-gamma phase amplitude coupling (TG-PAC). We recorded single neurons in the human medial temporal and frontal lobe while patients maintained multiple items in WM. In the hippocampus, TG-PAC was indicative of WM load and quality. We identified cells that selectively spiked during nonlinear interactions of theta phase and gamma amplitude. These PAC neurons were more strongly coordinated with frontal theta activity when cognitive control demand was high, and they introduced information-enhancing and behaviorally relevant noise correlations with persistently active neurons in the hippocampus. We show that TG-PAC integrates cognitive control and WM storage to improve the fidelity of WM representations and facilitate behavior.

Evaluation of a Treatment-Dose Enoxaparin Protocol for Patients With Obesity

BACKGROUND

Treatment-dose enoxaparin is not well studied in obese patients. Guidelines suggest that obese patients receiving enoxaparin therapy for acute venous thromboembolism (VTE) should receive a standard initial dose, 1 mg/kg, based on actual body weight. It is possible that this dosing strategy in obese patients may be overestimated, leading to a higher bleeding risk compared to non-obese patients.

OBJECTIVE

To gather data regarding enoxaparin treatment dosing and anti-Xa level monitoring in patients who are obese to guide dose adjustments.

METHODS

A single-center, retrospective chart review that included patients who were ordered treatment-dose enoxaparin and had a BMI ≥ 40 kg/m², which resulted in an automatic pharmacy consult.The primary endpoint of this study was incidence of bleeding.

RESULTS

The analysis included 102 patients. Most patients (92.1%) had a BMI of ≥ 40-60 kg/m² while 7.8% of patients had a BMI of > 60 kg/m². The average initial and final doses were 1.0 ± 0.1 mg/kg and 0.9 ± 0.2 mg/kg, respectively. The incidence of bleeding was 4.9%. The average dose for those that bled was 0.7 ± 0.1 mg/kg. On average, patients who bled had higher BMIs than patients who did not bleed (51.6 kg/m² vs. 48.0 kg/m²). Of the 71 patients with an initial anti-Xa level, 42 of the levels were considered supratherapeutic (59.2%).

CONCLUSION

A 1 mg/kg starting dose of enoxaparin may be too high for patients who are obese as many patients required an adjustment to their dose after initial anti-Xa levels.

The relationship between left ventricular dilation and right ventricular diastolic function in children with a patent ductus arteriosus

The impact of a dilated left ventricular (LV) on right ventricular (RV) diastolic function has not been investigated. We hypothesized that in patients with a patent ductus arteriosus (PDA), LV dilation causes elevation of the RV end-diastolic pressure (RVEDP) through ventricular-ventricular interaction. We identified patients' ages 6 months to 18 years who underwent transcatheter PDA closure at our center from 2010 to 2019. One hundred and thirteen patients were included with a median age of 3 years (0.5-18). The median LV end-diastolic dimension (LVEDD) Z-score was 1.6 (-1.4-6.3). RVEDP was positively associated with RV systolic pressure (0.38, P < 0.01), ratio of pulmonary artery/aortic systolic pressure (0.4, P < 0.01), and pulmonary capillary wedge pressure (0.71, P < 0.01). RVEDP was not associated with LVEDD Z-score (0.03, P = 0.74). In children with a PDA, RVEDP was not associated with LV dilation, but was positively associated with RV systolic pressure.

Mavacamten induces a clinical, hemodynamic, and biomarker response beyond the primary endpoint in EXPLORER-HCM: results from a post hoc machine learning analysis

Introduction

Mavacamten, a first-in-class selective inhibitor of cardiac myosin, was demonstrated in EXPLORER-HCM (NCT03470545) to be superior to placebo in achieving a primary endpoint of either (1) a ≥1.5 mL/kg/min increase in peak oxygen consumption (pVO2) and at least one New York Heart Association (NYHA) class reduction, or (2) a ≥3.0 mL/kg/min pVO2 increase without NYHA class worsening, in adults with obstructive hypertrophic cardiomyopathy (oHCM). However, the observed benefits of mavacamten were broader than the primary endpoint, suggesting a complex effect of the drug beyond improvements in these two parameters.

Purpose

A post hoc investigation of mavacamten clinical effects beyond the primary endpoint of EXPLORER-HCM.

Methods

EXPLORER data at week 30 were analyzed to evaluate improvements from baseline in primary (specified above), secondary (e.g. postexercise left ventricular outflow tract gradient and Kansas City Cardiomyopathy Questionnaire-Clinical Summary Score) and exploratory endpoints (e.g. circulating NT-ProBNP and cardiac Troponin I). Responses were classified as improved or not improved based on published thresholds, clinical standards and analyses of the EXPLORER data. Patients were grouped according to their improvement status using unsupervised hierarchical clustering.

Results

The cluster analysis resulted in four main groups with the following trends (Table); Group 1 = patients who met the primary endpoint and showed improvement in secondary/exploratory endpoints; Group 2 = patients with improvement in secondary/exploratory endpoints who did not meet the primary endpoint; Group 3 = patients who met the primary endpoint without substantial secondary/exploratory endpoint responses; Group 4 = patients without appreciable improvement in any endpoint. A substantially larger proportion of patients in Group 1 received mavacamten compared with placebo (88% vs. 12%, respectively). A similar trend was observed in Group 2 patients who exhibited improvements in secondary/exploratory endpoints (85% mavacamten vs. 15% placebo). Group 3 consisted predominantly of placebo-treated patients who met the primary endpoint but had negligible responses to secondary/exploratory endpoints (5% mavacamten vs. 95% placebo). Group 4 consisted predominantly of placebo-treated patients without appreciable clinically relevant responses from this analysis (10% mavacamten vs. 90% placebo).

Conclusions

Mavacamten was associated with clinical improvements beyond the primary endpoint of EXPLORER-HCM and was predominantly accompanied by amelioration of other measures associated with oHCM pathophysiology. In contrast, most placebo-treated patients who met the primary endpoint did not exhibit improvement in the underlying pathophysiology. These findings suggest a potential underestimation of mavacamten clinical impact based on the primary endpoint and prompt a deeper examination of mavacamten efficacy in patients with oHCM based on other clinically relevant endpoints.

Funding Acknowledgement

Type of funding sources: Private company. Main funding source(s): MyoKardia, Inc., a wholly owned subsidiary of Bristol Myers Squibb

A Rare Case of an Isolated Left Adrenal Haematoma in Blunt Force Trauma

Isolated left adrenal gland injuries following blunt abdominal trauma are extremely rare, accounting for only 1.5-4% of all adrenal trauma cases. Most traumatic injuries are right-sided and associated with other concurrent organ injuries. While acute, unilateral adrenal injuries can be asymptomatic, it is important to recognise the potentially life-threatening complications from haemorrhage and/or adrenal insufficiency. Due to its rarity, there are currently no established guidelines for management, monitoring, or follow-up of adrenal gland trauma. We present a case report of a rare, isolated, post-traumatic left adrenal gland haemorrhage. A 39-year-old man presented with mild abdominal pain following a mountain bike accident. Initial assessment revealed tenderness in the left upper quadrant with normal vital signs and biochemistry, but computer tomography (CT) imaging demonstrated an enlarged left adrenal gland with regional fat stranding and free fluid consistent with an acute adrenal haematoma. He was admitted to the ward for observation and discharged on day three of admission. At a six-week follow-up, he reported a complete resolution in symptoms. Follow-up CT of the adrenals at five months post-injury demonstrated complete resolution of the isolated adrenal haematoma. Post-traumatic isolated left adrenal gland injuries are rare in the reported literature, and this case highlights the lack of current guidelines for management and monitoring in cases of isolated adrenal haemorrhage. The current consensus appears to be appropriate with conservative management and follow-up with serial abdominal CT until the resolution of haemorrhage and/or symptoms.

A Service Evaluation of Dental Assessments Prior to Treatment for Head and Neck Cancer in NHS Grampian

To minimise the risk of Osteoradionecrosis (ORN) following radiotherapy, dental assessments are carried out by Restorative Consultants to determine teeth of poor prognosis requiring extraction before the commencement of radiotherapy for oncological treatment. Social deprivation is a high-risk factor for poor oral health and head and neck cancer (HANC), consequently highlighting the importance of the prehabilitation pathway, including dental assessment.

AIM

To retrospectively assess the demographics of the HAN oncology patient cohort, treatment modality, prehabilitation pathway and timeframe within NHS Grampian and highlight the role of the Restorative Dental Consultant.

MATERIALS AND METHODS

Retrospective assessment of 120 HANC patients' clinical records from May 2018 to December 2019. The patients were selected as a continuous cohort from Restorative Consultant dental assessment clinics.

RESULTS

Radiotherapy was the most common treatment modality, with 91% of patients receiving treatment; the mean time between completing dental extractions and commencing radiotherapy for oncological treatment was 17.98 days.

CONCLUSION

The HANC prehabilitation pathway should be conducted in a timeframe that allows patients to have sufficient time for healing between extractions and oncological treatment commencing to reduce ORN risk. The study also demonstrates an increased incidence of HANC in areas of higher social deprivation.

0835 Substance Abuse, An Important Factor in the Evaluation of Hypersomnia Disorders

Introduction

A detailed history is essential in the diagnostic workup of hypersomnia, but can be limited by withheld information. A common piece of information hidden during a detailed history is the presence of substance abuse/use. AASM guidelines dictate an MSLT study must be conducted in patients free from certain psychoactive medications. The guidelines mention these therapies be stopped at least 2 weeks prior to the planned study date and recommend utilizing an urinary drug screen to evaluate patients who undergo the study. From review of the available literature, substance abuse has significant effects upon sleep architecture and the development of hypersomnia. Certain substances such as stimulants may normalize a disorder of hypersomnolence and the opposite holds true for sedatives and depressants.

Report of Cases: Mr. RB, a 52-year-old Veteran with a medical history inclusive of hypertension, DM2, cocaine abuse and hypersomnia. Initial workup demonstrated presence of OSA (AHI 16.4, O2 nadir 87%). After diagnosing and treating OSA, Mr. RB returned to clinic with complaints of persistent hypersomnia. Mr. RB was then evaluated by MSLT study for further assessment. Patient reported absence of cocaine use at time of clinic visit and prior to study. The results of the MSLT demonstrate MSL of 0.5 minutes and 3/4 SOREMs. Unfortunately, UDS verified Mr. RB had recently used cocaine (581 ng/mL). Mr. RB was then followed up in clinic due to persistent symptoms, with new reports of cataplexy, hypnopompic hallucination and sleep paralysis. Mr. RB also reported abstaining from cocaine use. A repeat MSLT was performed with MSL of 1.2 minutes and 3/5 SOREMS. Unfortunately, Mr. RB was again found to have recently used cocaine (441 ng/mL) on UDS. Mr. RB was then lost to follow-up.

Conclusion

This case demonstrates the importance of obtaining a truthful history during the evaluation of a sleep disorder. This case also demonstrates the utility of verifying the history obtained with laboratory testing. During this case, the physicians working with Mr. RB demonstrated detailed note documentation regarding reports of cocaine abstinence which was later disproven during the drug screening during the sleep study and follow up clinic appointment.

Support (If Any)

1. Angarita, G. A., Emadi, N., Hodges, S., & Morgan, P. T. (2016). Sleep abnormalities associated with alcohol, cannabis, cocaine, and opiate use: A comprehensive review. Addiction Science & Clinical Practice, 11(1). https://doi.org/10.1186/s13722-016-0056-72. Anniss, A. M., Young, A., & O'Driscoll, D. M. (2016). Importance of urinary drug screening in the multiple sleep latency test and maintenance of wakefulness test. Journal of Clinical Sleep Medicine, 12(12), 1633–1640. https://doi.org/10.5664/jcsm.63483. Dzodzomenyo, S., Stolfi, A., Splaingard, D., Earley, E., Onadeko, O., & Splaingard, M. (2015). Urine toxicology screen in multiple sleep latency test: The correlation of positive tetrahydrocannabinol, drug negative patients, and narcolepsy. Journal of Clinical Sleep Medicine, 11(02), 93–99. https://doi.org/10.5664/jcsm.44484. Krahn, L. E., Arand, D. L., Avidan, A. Y., Davila, D. G., DeBassio, W. A., Ruoff, C. M., & Harrod, C. G. (2021). Recommended protocols for the multiple sleep latency test and maintenance of wakefulness test in adults: Guidance from the American Academy of Sleep Medicine. Journal of Clinical Sleep Medicine, 17(12), 2489–2498. https://doi.org/10.5664/jcsm.96205.Roehrs, T. A., & Roth, T. (2015). Sleep disturbance in substance use disorders. Psychiatric Clinics of North America, 38(4), 793–803. https://doi.org/10.1016/j.psc.2015.07.0086. emasinghe Bandaralage, S., Sriram, B., Rafla, M., Sharma, N., & McWhae, S. (2021). P130 an audit of urinary drug screening use in multiple sleep latency and maintenance of wakefulness testing in an australian tertiary centre. SLEEP Advances, 2(Supplement_1). https://doi.org/10.1093/sleepadvances/zpab014.171

0832 Nocturnal Tachypnea with Non-Invasive Ventilation; A case report

Introduction

We present a case of nocturnal tachypnea secondary to suspected auto-triggering in a patient on Bilevel device. Auto-triggering is a patient-ventilator asynchrony in which a ventilator breath is triggered in the absence of inspiratory muscle activity. This phenomenon was mostly described in postcardiac surgery and in brain dead patients on mechanical ventilation. Detecting this asynchrony is important as it can lead to patient discomfort, poor compliance and hypocarbia that can lead to apneic events.

Report of Cases: An 82-year-old male with history of chronic atrial fibrillation, coronary artery disease (s/p bypass surgery) and Ischemic cardiomyopathy (EF 25-30%). He had moderate obstructive sleep apnea with central apnea. He was started on AutoPAP then was upgraded to BPAP (IPAP 16/EPAP 9 cmH2O). His wife reported episodes of nocturnal tachypnea and increased daytime somnolence. This was confirmed by the compliance reports from his BPAP device, and a portable sleep study obtained while using the BPAP (respiratory rate &gt; 40 breaths/minute).

Conclusion

Vignaux et al estimated the incidence of auto-triggering with NIV to be 13%. This phenomenon can be caused by a major circuit leak or secondary to cardiogenic oscillations. Effect of cardiogenic oscillation on the pulmonary air flow was described by West and Hugh-Jones in 1961. Our patient had dilated cardiomyopathy with hyperdynamic circulation which we believe was the major cause of his auto-triggering asynchrony. Changes in intracardiac volume and cardiac movements during systole resulted in intrapulmonary flow oscillations exceeding the set flow-trigger threshold leading to the tachypnea. In our patient, the events resolved after cardiac resynchronization procedure that improved the overall cardiac function and adjusting the trigger sensitivity.

Support (If Any)

[1]Kondili E, Prinianakis G, Georgopoulos D.; Patient ventilator interaction, Br J Anaesth. 2003; 91: 106-119 [2] Richard Arbour; Cardiogenic Oscillation and Ventilator Autotriggering in Brain-Dead Patients: A Case Series. Am J Crit Care 1 September 2009; 18 (5): 496–488. doi: https://doi.org/10.4037/ajcc2009690 [3] Imanaka, Hideaki MD; Nishimura, Masaji MD; Takeuchi, Muneyuki MD; Kimball, William R. MD, PhD; Yahagi, Naoki MD; Kumon, Keiji MD Auto-triggering caused by cardiogenic oscillation during flow-triggered mechanical ventilation, Critical Care Medicine: February 2000 - Volume 28 - Issue 2 - p 402-407 [4]Vignaux L, Vargas F, Roeseler J, Tassaux D, Thille AW, Kossowsky MP, et al. Patient-ventilator asynchrony during non-invasive ventilation for acute respiratory failure: a multicenter study. Intensive Care Med 2009;35(5):840–846

Neural fragility as an EEG marker of the seizure onset zone

Over 15 million patients with epilepsy worldwide do not respond to drugs. Successful surgical treatment requires complete removal or disconnection of the seizure onset zone (SOZ), brain region(s) where seizures originate. Unfortunately, surgical success rates vary between 30 and 70% because no clinically validated biological marker of the SOZ exists. We develop and retrospectively validate a new electroencephalogram (EEG) marker-neural fragility-in a retrospective analysis of 91 patients by using neural fragility of the annotated SOZ as a metric to predict surgical outcomes. Fragility predicts 43 out of 47 surgical failures, with an overall prediction accuracy of 76% compared with the accuracy of clinicians at 48% (successful outcomes). In failed outcomes, we identify fragile regions that were untreated. When compared to 20 EEG features proposed as SOZ markers, fragility outperformed in predictive power and interpretability, which suggests neural fragility as an EEG biomarker of the SOZ.

Serum antibody response against periodontal bacteria and coronary heart disease: Systematic review and meta-analysis

AIM

The present systematic review and meta-analysis assessed the strength of a reported association between elevated serum anti-periodontal bacterial antibody responses and coronary heart disease (CHD).

MATERIALS AND METHODS

Twenty original studies were identified after systematically searching five databases. The majority (n = 11) compared serum anti-Porphyromonas gingivalis (Pg) and/or anti-Aggregatibacter actinomycetemcomitans (Aa) IgG antibody responses between CHD patients and control participants. The strength of the association between serum anti-Pg antibodies and CHD (n = 10) and serum anti-Aa antibodies and CHD (n = 6) was investigated using a meta-analysis approach separately.

RESULTS

Most studies (61%) reported that the serum IgG antibody responses were elevated in CHD patients than in controls. The meta-analyses showed a significant association between elevated serum IgG antibody responses (anti-Pg and anti-Aa) and CHD, with pooled odds ratios of 1.23 [95% confidence interval (CI): 1.09-1.38, p = .001] and 1.25 (95% CI: 1.04-1.47, p = .0004), respectively.

CONCLUSIONS

A modest increase of CHD events in individuals with higher serum anti-Pg and anti-Aa IgG antibody responses may support their use as potential biomarkers to detect and monitor at-risk populations. However, the observed inconsistencies with the design and interpretation of immunoassays warrant standardization of the immunoassays assessing antibody responses against periodontal bacteria.

Proposed Quality Performance Indicators (QPI's) for axillary lymphadenectomy in metastatic cutaneous melanoma

INTRODUCTION

Axillary lymph node clearance (ALNC) continues to play a central role in the management of melanoma. However, what defines an adequate lymphadenectomy remains unclear. We aimed to propose Quality Performance Indicators (QPIs) for ALNC and to determine if the number of lymph nodes (LNs) removed impacts survival.

METHODS

We reviewed patients who underwent ALNC for melanoma at the Waitemata District Health Board and Melanoma Unit between February 2005 and October 2019, performed by two surgeons with standardized technique and surveillance.

RESULTS

105 patients with stage III melanoma were included, of which 73 had clinically evident disease and 32 had clinically occult disease. The mean total number of LNs excised was 29 (SD 10.90, range 10-76). On multivariate analysis, lymph node ratio (HR 4.48, 95% CI 1.55-12.93, p = 0.006), extracapsular spread (HR 2.53, 95% CI 1.06-6.05, p = 0.036) and distant recurrence (HR 11.24, 95% CI 3.79-33.31, p < 0.001) were significant predictors of mortality. The number of LNs removed did not predict survival outcomes, while the lymph node ratio did significantly predict survival outcomes. The regional recurrence rate was 3.8%.

DISCUSSION

We propose that QPIs for ALNC in melanoma include a 90th percentile LN yield of greater than 15, a mean LN yield of 20, a regional recurrence rate of less than 10%, and an overall complication rate of less than 50%.

CONCLUSION

The establishment of QPIs can help ensure that surgical oncology patients receive the highest quality of care.

Apparent diffusion coefficient is associated with seizure outcome after magnetic resonance-guided laser interstitial thermal therapy for mesial temporal lobe epilepsy

BACKGROUND

Magnetic resonance-guided laser interstitial thermal therapy (MRgLiTT) is becoming a first-line surgical therapy for mesial temporal lobe epilepsy (mTLE) due to good seizure control and low complication risk. However, seizure outcomes after MRgLiTT remain highly variable and there is a need to improve patient selection and post-operative prognostication. In this retrospective study, we investigated whether the pre-operative MRI-derived apparent diffusion coefficient (ADC), used as a marker of tissue pathology in the mesial temporal structures could help predict seizure outcome.

METHODS

Thirty-five patients who underwent MRgLiTT at our institution between 2014 and 2019 were included in the study. Demographic and clinical data were retrospectively collected. Seizure outcome was defined as good (ILAE Class I-II) and poor (ILAE Class III-VI). Volumetrics were performed on pre-ablation hippocampus and amygdala. Ablation volumes, and the proportion of ablated hippocampus and amygdala calculated via their respective mean voxel-wise ADC intensities were quantified from pre-operative and intra-operative post-ablation MRIs and statistically compared between the two outcome cohorts. Univarate and multivariate regression analysis was performed to identify demographic, clinical, and radiographic predictors of seizure outcome.

RESULTS

Mean age at LiTT was 36 years and 14 (40 %) were female. Mean follow-up duration was 1.90 ± 0.17 years. Twenty-seven (77 %) patients had mesial temporal sclerosis. There was no significant difference in the ablation volumes and proportion of ablated volume of hippocampus and amygdala between the two outcome groups. Patients with good seizure outcome had significantly higher normalized ADC intensities in the ablated mesial temporal structures compared to those with poor outcome (0.01 ± 0.08 vs.-0.29 ± 0.06; p = 0.015).

CONCLUSIONS

mTLE patients with higher ADC intensities in the ablated regions of the hippocampus and the amygdala are more likely to have good seizure outcome following MRgLiTT. Our results suggest that pre-operative ADC analysis may improve both patient selection and epileptogenic zone targeting during MRgLiTT. Further investigation with large, prospective cohorts is needed to validate the clinical utility of ADC in improving seizure outcome following MRgLiTT.

442 Feasibility of a Sleep Technologist Driven Intervention Protocol to Address CPAP Adherence in Hospitalized Patients

Introduction

Obstructive sleep apnea (OSA) is associated with development of high blood pressure, diabetes, pulmonary hypertension, heart attack, stroke, atrial fibrillation, motor vehicle accidents, and death. These comorbidities may result in hospital admissions. Much of the therapy has been directed towards outpatient treatment with CPAP. Unfortunately, patient adherence to CPAP therapy is not optimal. We conducted a feasibility study to determine if a sleep technologist driven intervention protocol could address CPAP adherence in hospitalized patients.

Methods

Tampa General Hospital Sleep Center developed a quality improvement protocol that would address inadequate CPAP adherence. The components include: 1. Education on the cause and need for treatment of OSA based on comorbidities, 2. Choosing a patient preferred mask, 3. Mask desensitization while awake. These criteria were used to test the feasibility of implementing this protocol in hospitalized patients: 1. Completion of the protocol within 48 hours of receiving a consult, 2. Implementation of various components of the protocol, 3. Obtaining outcome measures to evaluate efficacy. Outcome measures include patient willingness to retry CPAP (on a scale from 0–10) and CPAP smartcard download. Additional outcome data included: patient reasoning for CPAP noncompliance and self-administered questionnaires (ESS, ISI, GAD-7, PHQ-9, SF-26).

Results

During November 2020, 31 inpatient consults were placed to the TGH Sleep Center. Within 48 hours of consult, the technologists implemented the protocol in 19 patients – 17 received mask fittings, 3 received education, and 3 had CPAP setting adjustments. 9 patients indicated their willingness to retry CPAP with an average rating of 9.1. 7 compliance downloads were obtained the following morning and usage ranged from 0:52 to 11:07 hours. 12 consults were not completed due to not meeting inclusion criteria (5), patient refusal (4), or other reasons (3).

Conclusion

This study demonstrates feasibility of a sleep technologist driven intervention protocol to address CPAP adherence in hospitalized patients. However, there were inconsistencies in protocol execution and obtaining outcome measures. We speculate that protocol improvement will require: 1. More consistent patient education, 2. Better correction of patient specific adherence issues, 3. Obtaining all smartcard downloads, 4. Compiling outcome measures using a convenient digital interface.

Support (if any):

788 Is Dysphagia a Marker for Obstructive Sleep Apnea (OSA) in Traumatic Brain Injury (TBI) Patients: A VA TBI Model System Study

Introduction

Recent work has highlighted prevalent obstructive not central sleep apnea following traumatic brain injury (TBI). Treatment of comorbid OSA may facilitate neurologic recovery but widespread screening is limited. Mixed support exists for the presence of dysphagia as a biomarker of OSA in the general population and stroke patients. Dysphagia is common following TBI; however, no study has examined the relation between OSA and dysphagia in this cohort. Leveraging data from a recent six-center clinical trial of OSA and TBI during inpatient rehabilitation, this secondary analysis examined the association between OSA severity indices and proxy measures of dysphagia.

Methods

Level 1 polysomnography (PSG) was used to assess OSA (AHI ≥ 5 and ≥ 15) during inpatient rehabilitation for the overall sample (N=248; 203 male; 60.6% severe injury) evaluated at a median of 120.6 days post-TBI and subset ≤ 60 days post-injury. Dysphagia was approximated as the presence of a PEG tube and/or a modified texture diet (MTD) on the day of PSG. Chi square and Fisher’s Exact tests were utilized for group comparisons.

Results

As previously reported, OSA in this cohort was prevalent (68.2% (n=169) at AHI ≥ 5 and 33.5% (n=83) AHI ≥ 15) with predominantly obstructive events. 27.4% (n=68) met criteria for dysphagia combining proxy measures (34 peg; 49 MTD). No significant difference was found for presence of dysphagia across OSA severity cutoffs (AHI ≥ 5 & 15; p=0.1029 & 0.5959). When examining OSA across the individual proxy measures, persons without a peg tube were significantly more likely to have OSA at AHI ≥ 5 (62.5% vs 5.65%; p=0.0003) and AHI ≥ 15 (31.05% vs 2.42%; p=0.0353). When examining participants less than 60 days post-TBI, the group differences remained.

Conclusion

The incidence of dysphagia in TBI patients, as indexed by a modified diet or presence of a feeding tube, was not elevated in those with OSA. Sample bias (for undergoing Level 1 PSG and improvement facilitating inpatient rehabilitation admission) may have contributed to findings. Finally, future work with more sensitive indices of dysphagia is needed to accurately evaluate this association.

Support (if any)

PCORI (CER-1511–33005), NIIDLRR (90DPTB0004)

Earlier diagnosis of lung cancer in a randomised trial of an autoantibody blood test followed by imaging

The EarlyCDT-Lung test is a high-specificity blood-based autoantibody biomarker that could contribute to predicting lung cancer risk. We report on the results of a phase IV biomarker evaluation of whether using the EarlyCDT-Lung test and any subsequent computed tomography (CT) scanning to identify those at high risk of lung cancer reduces the incidence of patients with stage III/IV/unspecified lung cancer at diagnosis compared with the standard clinical practice at the time the study began.The Early Diagnosis of Lung Cancer Scotland (ECLS) trial was a randomised controlled trial of 12 208 participants at risk of developing lung cancer in Scotland in the UK. The intervention arm received the EarlyCDT-Lung test and, if test-positive, low-dose CT scanning 6-monthly for up to 2 years. EarlyCDT-Lung test-negative and control arm participants received standard clinical care. Outcomes were assessed at 2 years post-randomisation using validated data on cancer occurrence, cancer staging, mortality and comorbidities.At 2 years, 127 lung cancers were detected in the study population (1.0%). In the intervention arm, 33 out of 56 (58.9%) lung cancers were diagnosed at stage III/IV compared with 52 out of 71 (73.2%) in the control arm. The hazard ratio for stage III/IV presentation was 0.64 (95% CI 0.41-0.99). There were nonsignificant differences in lung cancer and all-cause mortality after 2 years.ECLS compared EarlyCDT-Lung plus CT screening to standard clinical care (symptomatic presentation) and was not designed to assess the incremental contribution of the EarlyCDT-Lung test. The observation of a stage shift towards earlier-stage lung cancer diagnosis merits further investigations to evaluate whether the EarlyCDT-Lung test adds anything to the emerging standard of low-dose CT.

Coherent Structures Modulate Atmospheric Surface Layer Flux-Gradient Relationships

Since its inception in the 1940s, Monin-Obukhov similarity theory (MOST), which relates turbulent fluxes to mean vertical gradients in the lower atmosphere, has become ubiquitous for predicting surface fluxes of quantities transported by the flow in numerical weather, climate, and hydrological forecasting models. Despite its widespread use, MOST does not account for the effects of large coherent structures in the flow, which modulate the amplitude of turbulent fluctuations, and are responsible for a large fraction of the total transport. Herein, we demonstrate that the incorporation of the large-scale streamwise velocity u_{l}(x,t)=G_{δ}⋆u(x,t), where G_{δ} is a low-pass filtering kernel, into dimensional analysis leads to an additional dimensionless parameter α(x,t), which captures the modulating influence of these structures on flux-gradient relationships. Atmospheric observations and large-eddy simulations are used to demonstrate that observed deviations from MOST can indeed be explained by this new parameter; coherent structures induce an alternating loading and unloading of the mean velocity gradient near the surface.

First-In-Human Experience With Integration of Wireless Intracranial Pressure Monitoring Device Within a Customized Cranial Implant

BACKGROUND

Decompressive craniectomy is a lifesaving treatment for intractable intracranial hypertension. For patients who survive, a second surgery for cranial reconstruction (cranioplasty) is required. The effect of cranioplasty on intracranial pressure (ICP) is unknown.

OBJECTIVE

To integrate the recently Food and Drug Administration-approved, fully implantable, noninvasive ICP sensor within a customized cranial implant (CCI) for postoperative monitoring in patients at high risk for intracranial hypertension.

METHODS

A 16-yr-old female presented for cranioplasty 4-mo after decompressive hemicraniectomy for craniocerebral gunshot wound. Given the persistent transcranial herniation with concomitant subdural hygroma, there was concern for intracranial hypertension following cranioplasty. Thus, cranial reconstruction was performed utilizing a CCI with an integrated wireless ICP sensor, and noninvasive postoperative monitoring was performed.

RESULTS

Intermittent ICP measurements were obtained twice daily using a wireless, handheld monitor. The ICP ranged from 2 to 10 mmHg in the supine position and from -5 to 4 mmHg in the sitting position. Interestingly, an average of 7 mmHg difference was consistently noted between the sitting and supine measurements.

CONCLUSION

This first-in-human experience demonstrates several notable findings, including (1) newfound safety and efficacy of integrating a wireless ICP sensor within a CCI for perioperative neuromonitoring; (2) proven restoration of normal ICP postcranioplasty despite severe preoperative transcranial herniation; and (3) proven restoration of postural ICP adaptations following cranioplasty. To the best of our knowledge, this is the first case demonstrating these intriguing findings with the potential to fundamentally alter the paradigm of cranial reconstruction.

Recurrence analysis of slow-fast systems

Many complex systems exhibit periodic oscillations comprising slow-fast timescales. In such slow-fast systems, the slow and fast timescales compete to determine the dynamics. In this study, we perform a recurrence analysis on simulated signals from paradigmatic model systems as well as signals obtained from experiments, each of which exhibit slow-fast oscillations. We find that slow-fast systems exhibit characteristic patterns along the diagonal lines in the corresponding recurrence plot (RP). We discern that the hairpin trajectories in the phase space lead to the formation of line segments perpendicular to the diagonal line in the RP for a periodic signal. Next, we compute the recurrence networks (RNs) of these slow-fast systems and uncover that they contain additional features such as clustering and protrusions on top of the closed-ring structure. We show that slow-fast systems and single timescale systems can be distinguished by computing the distance between consecutive state points on the phase space trajectory and the degree of the nodes in the RNs. Such a recurrence analysis substantially strengthens our understanding of slow-fast systems, which do not have any accepted functional forms.

0806 Prescription Correlates of Nightmare Disorder Among Veterans

Introduction

In the James A. Haley Veterans Administration (JAHVA) Vista database, the ICD-9 code 307.47 for Nightmare disorder (ND) is infrequently used and appears independently of codes for PTSD. We wanted to determine if certain drugs that may affect sleep are associated with ND.

Methods

All patients with ND visiting JAHVA between 2007 and 2011 were selected along with control patients who visited JAHVA on one of 20 random days, one day each quarter year. Controls were assigned an index date reflecting their selection quarter. Associations with prescriptions for opioids, antidepressants (SSRI’s, SSNI’s, Tricyclics), antihistamines and benzodiazepine/Z-drugs were initially investigated. Two analyses were performed: risk factor analysis- patients with ND diagnosis dates (cases) or index dates (controls) prior to 2008 were excluded and only prescription dates that preceded the ND diagnosis or index date were considered; treatment analysis- cases and controls with a ND diagnosis date or index date after 2010 were excluded and only prescription dates that were subsequent to the ND diagnosis or index date respectively were considered. Logistic regression adjusting for age, gender, race and Hispanic ethnicity was used to determine the association between drug groups and ND.

Results

In risk factor analysis (667 cases, 14,739 controls), opioids and antihistamines were significantly less prevalent among would-be ND patients than controls (OR=0.627 and 0.610 respectively); no drug group was predictive of ND. In contrast, all drug groups were significantly associated with ND in treatment analysis (803 cases, 15,530 controls). The strongest associations were seen with benzodiazepine (OR=3.026; 95% CI: 2.472, 3.703) and SSRI (OR=2.789; 95% CI=2.316, 3.358) prescriptions.

Conclusion

Our data suggest that some JAHVA providers may be treating ND with medication, most notably with benzodiazepines/Z-drugs and antidepressants. The role of anti-histamine and opioid prescriptions needs further elucidation. The ramifications of these treatment decisions should be explored.

Support

This material is the result of work supported with resources and the use of facilities at the James A. Haley Veterans’ Hospital.

Complete Posterior Vitreous Detachment Reduces the Need for Treatment of Diabetic Macular Edema

BACKGROUND AND OBJECTIVE

To evaluate the vitreomacular interface and its relation to treatment burden for diabetic macular edema (DME) in patients without overt vitreomacular traction (VMT).

PATIENTS AND METHODS

A retrospective cohort study of 494 eyes from 274 patients who had macular spectral-domain optical coherence tomography (SD-OCT) and did not have proliferative diabetic retinopathy, DME, or VMT at the initial visit. Posterior vitreous detachment (PVD) was categorized at the initial visit into five stages (0-4) using SD-OCT parameters alone.

RESULTS

Two of 34 eyes (6.9%) presenting with a complete PVD required DME treatment during follow-up, whereas 144 of 460 eyes (31.3%) without a complete PVD at baseline required treatment (P = .001, Chi-squared). After adjusting for age, ethnicity, gender, and HbA1c, complete PVD at baseline was associated with a significant reduction in risk of DME therapy (hazard ratio: 0.18; 95% confidence interval, 0.05-0.73; P = .02).

CONCLUSION

Complete PVD is independently associated with a reduced need for DME treatment. [Ophthalmic Surg Lasers Imaging Retina. 2019;50:e266-e273.].

Dynamical systems approach to study thermoacoustic transitions in a liquid rocket combustor

Liquid rockets are prone to large amplitude oscillations, commonly referred to as thermoacoustic instability. This phenomenon causes unavoidable developmental setbacks and poses a stern challenge to accomplish the mission objectives. Thermoacoustic instability arises due to the nonlinear interaction between the acoustic and the reactive flow subsystems in the combustion chamber. In this paper, we adopt tools from dynamical systems and complex systems theory to understand the dynamical transitions from a state of stable operation to thermoacoustic instability in a self-excited model multielement liquid rocket combustor based on an oxidizer rich staged combustion cycle. We observe that this transition to thermoacoustic instability occurs through a sequence of bursts of large amplitude periodic oscillations. Furthermore, we show that the acoustic pressure oscillations in the combustor pertain to different dynamical states. In contrast to a simple limit cycle oscillation, we show that the system dynamics switches between period-3 and period-4 oscillations during the state of thermoacoustic instability. We show several measures based on recurrence quantification analysis and multifractal theory, which can diagnose the dynamical transitions occurring in the system. We find that these measures are more robust than the existing measures in distinguishing the dynamical state of a rocket engine. Furthermore, these measures can be used to validate models and computational fluid dynamics simulations, aiming to characterize the performance and stability of rockets.

Pragmatic evaluation of inhaled corticosteroid particle size formulations on asthma control

BACKGROUND

Extra-fine particle formulations of inhaled corticosteroid (ICS) are associated with improved lung delivery.

OBJECTIVES

A pragmatic study to assess patient-reported outcomes after switching from fine to extra-fine particle ICS in persistent asthma.

METHODS

Twenty-four patients (mean age 48 year, FEV₁ 84%, ACQ 1.67) received 4 weeks run-in with a constant dose of fine particle ICS (mean dose 710 µg), followed by switching to an equivalent dose of extra-fine particle hydrofluoroalkane beclomethasone dipropionate (mean dose 355µg). Asthma control questionnaire (ACQ), the primary outcome and mini asthma quality of life questionnaire (mAQLQ) were measured pre- and post-run-in (baseline) and after 4 weeks and 8 weeks of switching.

RESULTS

Comparing pre- vs post-run-in, there were no differences for ACQ: 1.67 vs 1.65 or AQLQ: 5.08 vs 5.34. There were mean (95%CI) improvements (P < 0.001) from baseline after 8 weeks for ACQ: -0.53 (-0.83, -0.23) and AQLQ: 0.69 (0.35, 1.04), which exceeded the minimal clinically important difference (MCID) of 0.5 for both. There were also differences (P < 0.05) in domiciliary symptoms and reliever use. There were no significant changes at 8 weeks in lung function, FeNO or blood eosinophils.

CONCLUSIONS

Pragmatic switching from fine to extra-fine particle ICS at half the dose was associated with clinically relevant improvements in asthma control and quality of life, but not lung function or type 2 biomarkers.

CT-guided percutaneous cryoablation of an osteoid osteoma of the rib☆

An osteoid osteoma is a benign bone tumor that arises from osteoblastic dysfunction and usually presents as nonspecific, nocturnal pain located in the diaphysis of long bones, with <1% occurring in the ribs. It is most commonly treated with nonsteroidal anti-inflammatory drugs or merely observed; when these treatments do no prove efficacious, either open surgery or interventional ablation are pursued. Herein, we report a rare case of an osteoid osteoma located in the rib of a 19-year-old male that was histologically diagnosed through computed tomography (CT)-guided biopsy. Using CT guidance, the tumor was ablated by creating an artificial pneumothorax in order to induce a margin of space safe enough for cryoablation. It is important to be aware of the possibility that an osteoid osteoma may be present in the ribs, as the differential diagnosis includes costochondritis, pneumonia, osteoblastoma, enchondroma, osteosarcoma, cyst, and Brodie abscess. In addition, we have shown that CT-guided cryoablation can be an effective and less invasive treatment when compared to open en bloc resection, highlighting the role of interventional radiology in bone tumor ablation.