Pre-operative carbohydrate drink in pediatric spine fusion: randomized control trial.

PURPOSE: As rapid discharge protocols for pediatric spine fusion shorten stays, gastrointestinal (GI) complications are uncovered and cause delays in discharge. A pre-operative carbohydrate (CHO) drink has been shown to improve perioperative GI symptoms and functional return but has not been examined in pediatric spine patients. We aimed to determine if a preoperative CHO drink is safe in pediatric spine fusion patients, and if it improves their comfort scores and return of bowel function. METHODS: We prospectively randomized ASA-1 and -2 pediatric spine fusion patients to either a pre-anesthesia carbohydrate drink 2 h prior to surgery or to a control group (standard 8 h NPO), blinded to surgical team. We documented time to return to flatus, bowel movement, GI symptoms, and comfort scores for 72 h post-operatively or until discharge. RESULTS: 62 patients were randomized. There was no significant differences between the groups' pre-operative characteristics, surgical details, nor post-operative morphine dose equivalents, except for EBL (405 cc control, 340 cc CHO drink, p = 0.044). There were no perioperative complications related to ingestion of the CHO drink. CHO group had a positive trend for earlier return of flatus (21% vs. 3% return at 12 h), and comfort scores for anxiety and abdominal pain, but no statistically significant differences. There was no difference in length of stay or time to first bowel movement. CONCLUSION: There were no complications related to ingestion of a CHO drink 2 h prior to pediatric spinal fusion surgery. Further studies are needed to develop a study blinded to the participants with larger sample size. Level of evidence I.

The Clinical Significance of the Lowest Instrumented Vertebra in Adolescent Idiopathic Scoliosis.

Selecting the lowest instrumented vertebra (LIV) in fusion for adolescent idiopathic scoliosis is potentially the most nuanced decision a surgeon has to make. This article reviews the literature on the range-of-motion loss related to the LIV, ability to return to sports based on LIV, correlation between LIV and disk degeneration, and short-term and long-term clinical outcomes related to LIV.

Intraoperative Neuromonitoring for Spines at Risk During Nonspine Surgery: A 9-Year Review.

BACKGROUND: Patients with certain spinal anomalies are at risk for rare but devastating spinal cord injuries under anesthesia. We created a Spine at Risk (SAR) program to evaluate and recommend precautions for such patients, including intraoperative neuromonitoring (IONM) use for the highest-risk patients. We aimed to review all monitored nonspine procedures to determine rate of potential spinal cord injuries avoided in those who would otherwise have been unmonitored. METHODS: We performed a retrospective review of our institutional SAR program from 2011 to 2019 to analyze the number of nonspine anesthetized procedures that were done under IONM, the characteristics of those that had an IONM alert; and the clinical outcomes. RESULTS: Of the 3,453 patients flagged for SAR review, 1121 (33%) received a precaution recommendation, and 359 (10% of all flagged) were given IONM recommendations. Of those, 57 patients (16% of recommendations, 2% of all flagged) had a total of 102 nonspine anesthetized procedures done under IONM. Seven patients had a total of 10 cases with IONM alerts. Two cases were aborted when improved signals could not be obtained after working through a checklist; one of these patients woke with transient neurological deficits. Signals improved to baseline in 7 cases by working through a signal loss checklist. One case was aborted preoperatively when monitorable baseline signals could not be obtained. CONCLUSIONS: In the highest-risk spinal anomaly patients, we monitored an average of 11.7 nonspine cases per year, with a 10% rate of IONM alerts, and no permanent neurological deficits. Although the majority of patients remain safe during procedures, in the most critical patients IONM allowed the team to identify and react to alerts that may have otherwise led to permanent neurological injury. This is the largest series of spinal cord-monitored nonspine pediatric cases. It is important for pediatric orthopedic surgeons to evaluate at-risk patients and recommend IONM where appropriate, to protect both patients and our procedural colleagues. LEVEL OF EVIDENCE: Case series, level IV.

A curated data resource to support safe carbon dioxide transport-route planning.

Supporting the national target of net-zero greenhouse gas emissions in the United States by 2050, the Bipartisan Infrastructure Law (BIL) authorized investments into carbon capture and storage (CCS), highlighting the need for the safe and sustainable transport of carbon dioxide (CO2). Curated to support CO2 pipeline route planning optimization and assess existing energy transport corridors, the CCS Pipeline Route Planning Database is a compilation of 47 publicly available, authoritative geospatial data resources, spanning the contiguous U.S., and some including Alaska and Hawaii. Key considerations were identified following comprehensive literature review, which included state legislation, known pipeline stressors, and energy, environmental, and social justice (EJSJ) considerations. Data layers were sorted into relevant categories (i.e., natural hazards, boundaries) and assigned preliminary weights representing potential social, environmental, and economic costs associated with routing pipelines. Version one of the CCS Pipeline Route Planning Database, made available on the Energy Data eXchange® (EDX), contains categorized vector features representing protected areas, public and energy infrastructure, EJSJ factors, potential risks, federal and state regulations and legislation, and natural features, along with associated metadata. This paper provides details on individual layers, methods used to identify data needs, acquire, and process the disparate data, as well as planned enhancements to future versions of this database.

Spectral Fusion of Heartbeat and Accelerometer Data for Estimation of Breathing Rate in Wearable Patches.

Despite developments in wearable devices for detecting various bio-signals, continuous measurement of breathing rate (BR) remains a challenge. This work presents an early proof of concept that employs a wearable patch to estimate BR. We propose combining techniques for calculating BR from electrocardiogram (ECG) and accelerometer (ACC) signals, while applying decision rules based on signal-to-noise (SNR) to fuse the estimates for improved accuracy.

Can we automate spine fusion surgical site infection data capture?

PURPOSE: Spine fusion surgical site infection (SSI) rate is reported to national quality databases and used as a benchmark for orthopedic departments and hospital systems. However, accurate data require resource-heavy administrative review and even this has shown to vary. We aimed to create a passive electronic medical record (EMR) algorithm to automatically capture spine fusion SSI and compared its accuracy against the administrative chart review and self-reported morbidity and mortality (M&M) rates. METHODS: We retrospectively reviewed a single institution's spine fusion records for 7 years for all 90-day post-operative SSIs. We used Centers for Disease Control and Prevention (CDC) SSI definition coupled with intention to treat as an infection by orthopedics/infectious disease service as the gold standard. We compared our gold standard to administrative hand-checked SSI data, anonymously reported departmental M&M, and a passive EMR algorithm (ICD-9 or -10 post-operative SSI diagnosis code entered, or all four of: positive culture, antibiotic prescription between 3-90 days post-op, re-operation/re-admission, and a qualifying diagnosis). RESULTS: Nine hundred and fourteen spine fusions were included, with a 2.8% SSI rate (0.9% superficial and 2.0% deep). Passive EMR algorithm was the most sensitive at 89% (vs 76% administrative review, 73% M&M); all were highly specific at 99-100%. M&M was 100% positively predictive, administrative review 95%, and EMR 79%. CONCLUSION: Our passive EMR algorithm was more sensitive to pediatric spine fusion 90-day SSI than self-reported M&M and hand-checked administrative chart review. Although EMR may over-report, it can be used by others to narrow the initial sample for review, reduce resource burden involved with administrative spine SSI review, and provide a quality check for M&M self-reporting. LEVEL OF EVIDENCE: III.

Heterochrony and parallel evolution of echinoderm, hemichordate and cephalochordate internal bars.

Deuterostomes comprise three phyla with radically different body plans. Phylogenetic bracketing of the living deuterostome clades suggests the latest common ancestor of echinoderms, hemichordates and chordates was a bilaterally symmetrical worm with pharyngeal openings, with these characters lost in echinoderms. Early fossil echinoderms with pharyngeal openings have been described, but their interpretation is highly controversial. Here, we critically evaluate the evidence for pharyngeal structures (gill bars) in the extinct stylophoran echinoderms Lagynocystis pyramidalis and Jaekelocarpus oklahomensis using virtual models based on high-resolution X-ray tomography scans of three-dimensionally preserved fossil specimens. Multivariate analyses of the size, spacing and arrangement of the internal bars in these fossils indicate they are substantially more similar to gill bars in modern enteropneust hemichordates and cephalochordates than to other internal bar-like structures in fossil blastozoan echinoderms. The close similarity between the internal bars of the stylophorans L. pyramidalis and J. oklahomensis and the gill bars of extant chordates and hemichordates is strong evidence for their homology. Differences between these internal bars and bar-like elements of the respiratory systems in blastozoans suggest these structures might have arisen through parallel evolution across deuterostomes, perhaps underpinned by a common developmental genetic mechanism.

Interfacet distance at L4 is increased in spines with high-pelvic incidence.

Pelvic incidence (PI) is an angular measurement linked to spinal pathologies. There is an increasing distance between facet joints moving caudally down the sagittal plane of the spine. We defined pedicle divergence (PD) as the ratio of interfacet distance (IFD) between adjacent levels. This study aimed to evaluate the relationship between PI and PD. Two hundred and thirty specimens were obtained from the Hamann-Todd Osteological Collection. Specimens were catalogued for age, sex, race, PI, PD, and lumbar facet angle. Multivariate linear regression analysis was performed to determine the relationship between variables. IRB approval was not required. Average age at death was 57.0 years ±6.2 years. There were 211 (92%) male specimens and 176 (77%) were white. Average PI was 47.1 ± 10.5°. For PD between L3/L4, there was a relationship with PI (ß = -0.18, p = 0.008). For PD between L4/L5, there was an opposite relationship with PI (ß = 0.21, p = 0.003). Regression analyses of the interfacet to body ratio at each level found an association with PI only at L4 (p = 0.008). This study demonstrated that PI has a significant association with IFD in the lower lumbar spine. Increasing PI was associated with increased PD between L3/L4 and decreased PD between L4/L5. These results further support the close relationship between pelvic morphology and the lower lumbar spine, and suggest that L4 may have an important role in compensating for aberrant PI.

A delayed diagnosis of high-grade spondylolisthesis.

ABSTRACT: Spondylolysis, or pars defect, occurs in nearly half of children with back pain. Despite the marked prevalence, diagnosis of spondylolysis with spondylolisthesis often is delayed or missed secondary to referred pain and uncharacteristic presentation. This article describes an 8-year-old patient with 15 months of right heel pain who was initially treated by her primary care provider for presumed Sever disease before being referred to orthopedics. After orthopedic consultation, she was diagnosed with a high-grade spondylolisthesis with L5 nerve root compression. Although spondylolysis is an infrequent diagnosis, particularly in a patient this young, missing the diagnosis can significantly reduce a patient's quality of life.

The pediatric "Spine at Risk" program: 9-year review of a novel safety screening tool.

PURPOSE: We implemented an EMR-based "Spine at Risk" (SAR) alert program in 2011 to identify pediatric patients at risk for intraoperative spinal cord injury (SCI) and prompt an evaluation for peri-operative recommendations prior to anesthetic. SAR alerts were activated upon documentation of a qualifying ICD-9/10 diagnosis or manually entered by providers. We aimed to determine the frequency of recommended precautions for those auto-flagged by diagnosis versus by provider, the frequency of precautions, and whether the program prevented SCIs during non-spinal surgery. METHODS: We performed a retrospective chart review of patients from 2011 to 19 with an SAR alert. We recorded how the chart was flagged, recommended precautions, and reviewed data for SCIs at our institution during non-spinal operations. RESULTS: Of the 3453 patients with an SAR alert over the 9-year study period, 1963 were auto-flagged by diagnosis and 1490 by manual entry. Only 38.7% and 24.3% of the patients in these respective groups were assigned precaution recommendations, making the auto-flag 62.8% better than providers at identifying patients needing precautions. Cervical spine positioning precautions were needed most frequently (86.7% of diagnosis-flagged; 30.0% of provider-flagged), followed by intraoperative neuromonitoring (IONM) (25.2%; 6.1%), thoracolumbar positioning restrictions (16.1%; 7.9%), and fiberoptic intubation (13.9%; 5.7%). There were no SCIs in non-spinal procedures during the study. CONCLUSION: EMR-based alerts requiring evaluation by a Neurosurgeon or Orthopaedic surgeon prior to anesthesia can prevent SCIs during non-spinal procedures. The majority of identified patients are not found to be at risk, and will not require special precautions. LEVEL OF EVIDENCE: III.

Autonomic dysfunction in epilepsy mouse models with implications for SUDEP research.

Epilepsy has a high prevalence and can severely impair quality of life and increase the risk of premature death. Sudden unexpected death in epilepsy (SUDEP) is the leading cause of death in drug-resistant epilepsy and most often results from respiratory and cardiac impairments due to brainstem dysfunction. Epileptic activity can spread widely, influencing neuronal activity in regions outside the epileptic network. The brainstem controls cardiorespiratory activity and arousal and reciprocally connects to cortical, diencephalic, and spinal cord areas. Epileptic activity can propagate trans-synaptically or via spreading depression (SD) to alter brainstem functions and cause cardiorespiratory dysfunction. The mechanisms by which seizures propagate to or otherwise impair brainstem function and trigger the cascading effects that cause SUDEP are poorly understood. We review insights from mouse models combined with new techniques to understand the pathophysiology of epilepsy and SUDEP. These techniques include in vivo, ex vivo, invasive and non-invasive methods in anesthetized and awake mice. Optogenetics combined with electrophysiological and optical manipulation and recording methods offer unique opportunities to study neuronal mechanisms under normal conditions, during and after non-fatal seizures, and in SUDEP. These combined approaches can advance our understanding of brainstem pathophysiology associated with seizures and SUDEP and may suggest strategies to prevent SUDEP.

Repeat Pediatric Trisomy 21 Radiographic Exam: Does Atlantoaxial Instability Develop Over Time?

BACKGROUND: Atlantoaxial instability (AAI) is common in pediatric patients with Trisomy 21 and can lead to spinal cord injury during sports, trauma, or anesthetized neck manipulation. Children with Trisomy 21 therefore commonly undergo radiographic cervical spine screening, but recommendations on age and timing vary. The purpose of this study was to determine if instability develops over time. METHODS: We performed a retrospective review for all pediatric Trisomy 21 patients receiving at least 2 cervical spine radiographic series between 2008 and 2020 at our institution. Atlantodens interval (ADI) and space available for the cord at C1 (SAC) were measured; bony abnormalities such as os odontoidium, and age and time between radiographs were noted. AAI was determined by ADI ≥6 mm or SAC ≤14 mm based on our groups' prior study. Those who developed instability were compared with those who did not. RESULTS: A total of 437 cervical spine radiographic series from 192 patients were evaluated, with 160 included. Mean age at first radiograph was 7.4±4.4 years, average ADI was 3.1 mm (±1.2), and SAC was 18.1 mm (±2.6). The average time between first and last radiographs was 4.3 years (±1.8), with average final ADI 3.2 mm (±1.4) and SAC 18.9 mm (±2.9). Seven patients (4%) had instability: 4 were unstable on their initial studies and 3 (1.6%) on subsequent imaging. Os odontoideum was found in 5 (71%) unstable spines and 3 (2%) stable spines (P<0.0001); only 1 patient that became unstable on subsequent radiograph did not have an os. There was no specific age cut-off or surveillance time period after which one could be determined no longer at risk. CONCLUSIONS: Trisomy 21 patients have a 4.4% overall rate of AAI in our series with a 1.6% rate of progression to instability over ∼4 years. Given this nearly 1 in 23 risk of instability, we recommend initial surveillance radiograph for all children over 3 years with Trisomy 21; repeat asymptomatic surveillance should continue in those with os odontoideum given their high instability risk. LEVEL OF EVIDENCE: Level II-diagnostic study.

An actionable anti-racism plan for geoscience organizations.

Geoscience organizations shape the discipline. They influence attitudes and expectations, set standards, and provide benefits to their members. Today, racism and discrimination limit the participation of, and promote hostility towards, members of minoritized groups within these critical geoscience spaces. This is particularly harmful for Black, Indigenous, and other people of color in geoscience and is further exacerbated along other axes of marginalization, including disability status and gender identity. Here we present a twenty-point anti-racism plan that organizations can implement to build an inclusive, equitable and accessible geoscience community. Enacting it will combat racism, discrimination, and the harassment of all members.

The body image disturbance questionnaire-scoliosis better correlates to quality of life measurements than the spinal assessment questionnaire in pediatric idiopathic scoliosis.

PURPOSE: Idiopathic scoliosis (IS) patients can have body dissatisfaction which can affect their perception of health. Two body image measures, the Spinal Appearance Questionnaire (SAQ) and the Body Image Disturbance Questionnaire-Scoliosis (BIDQ-S), have been used in pediatric IS with variable correlation to the SRS-22r and radiographs, but have not been compared to each other. As patient reported outcomes (PROs) continue to be highlighted in large database studies and national hospital ranking system scoring, we should narrow use to the best and most efficient. We aim to determine which of two better correlates to pediatric IS patients' radiographs and quality of life (QoL) scores. METHODS: Consecutive IS patients aged 10-19 years old without surgery prospectively completed BIDQ-S, SAQ, SRS-22r, and PedsQL self-reported outcome measures. BIDQ-S and SAQ were compared in correlation to the two QoL surveys, as well as to radiographic major curve, shoulder asymmetry, lateral upright ribcage offset at apex, and coronal/sagittal balance. Spearman's r was used for correlations. RESULTS: 104 surveys with mean age 14.4 years and mean major curve 42° (14°-74°) were included. BIDQ-S and SAQ scores strongly correlated to each other (r = 0.76), but BIDQ-S had a stronger correlation to total SRS-22r (- 0.75 vs - 0.61 SAQ), PedsQL total (- 0.76 vs - 0.55) and better or no difference in each SRS-22r and PedsQL domain. Both poorly correlated to radiographs (main curve: r = 0.32 BIDQ-S, 0.31 SAQ). CONCLUSION: The BIDQ-S correlates better to SRS-22r and PedsQL for pediatric IS patients than the SAQ. Neither correlate well to radiographs. LEVEL OF EVIDENCE: III.

Classifying vertebral artery anatomy abnormality in children with skeletal dysplasia.

PURPOSE: Skeletal dysplasia (SKD) have predictably abnormal occipitocervical skeletal anatomy, but a similar understanding of their vertebral artery anatomy is not known. Knowledge and classification of vertebral artery anatomy in SKD patients is important for safe surgical planning. We aimed to determine if predictably abnormal vertebral artery anatomy exists in pediatric SKD. METHODS: We performed a retrospective review of CTAs of the neck for pediatric patients at a single institution from 2006 to 2018. CTAs in SKD and controls were reviewed independently in blinded fashion by two radiologists who classified dominance, vessel curvature at C2, direction at C3, and presence of fenestration and intersegmental artery. RESULTS: 14 skeletal dysplasia patients were compared to 32 controls. The path of the vertebral artery at C2 foramen was no different between the cohorts or by side, right (p = 0.43) or left (p = 0.13), nor for medial or lateral exiting direction from C3 foramen on right (p = 0.82) or left (p = 0.60). Dominance was most commonly neutral in both groups (71% in SKD and 63% in controls). There were no fenestrated nor first intersegmental arteries in our cohort. CONCLUSION: No systematic differences were detected between SKD and control patients with respect to vertebral artery anatomy. Nonetheless, surgically relevant variability was observed in both groups. Paying particular attention to the direction of exit at C3 and curvature at C2 with respect to the foramen and vessel dominance are important and easily classifiable abnormalities that both surgeons and radiologists can use to communicate and employ in pre-operative planning. LEVEL OF EVIDENCE: III.

Lean into Clinical Pharmacy: An Experience in Implementing Key Performance Indicators and Gemba Walks into Clinical Pharmacy Services.

Purpose: The Lean methodology was applied to clinical metrics by a critical care pharmacy team. The experiences associated with the development and implementation of clinical metrics and their impact on daily workflow are described. Summary: The Lean methodology has been introduced into the healthcare system as a means of process improvement, which can eliminate waste through appropriate medication utilization. At OhioHealth Riverside Methodist Hospital, the department of pharmacy was tasked with the development of clinical metrics after a health system wide Gemba walk was initiated. The pharmacy department's critical care team developed a strategy identifying and evaluating clinical metrics pertaining to their everyday workflow. Each clinical metric was evaluated in accordance with a pre-defined goal. Metrics requiring heavy documentation and those in which the pharmacist does not have autonomous authority to manage were often challenging to implement and were less successful. Throughout this process, the lessons learned focused on generating ideas that were easily documented, evidence-based, and department specific. The critical care team discovered that the outcome of the most successful metrics highlighted clinical pharmacist value and data generated could be used to support funding for additional resources. Conclusion: The critical care pharmacy team developed a streamlined process to implement clinical metrics as means of identifying areas for improvement using the Lean methodology.

Results of Conservative and Surgical Management in Children with Idiopathic and Nonidiopathic Os Odontoideum.

OBJECTIVE: The outcomes of conservative and operative treatment of os odontoideum in children remain unclear. Our objective was to study the outcomes of conservative and surgical treatment of idiopathic os odontoideum in children and compare these outcomes in age- and treatment-matched nonidiopathic children with os odontoideum. METHODS: A retrospective multicenter review identified 102 children with os odontoideum, of whom 44 were idiopathic with minimum 2-year follow-up. Ten patients were treated conservatively, and 34 underwent spinal arthrodesis. Both groups were matched with nonidiopathic patients by age and type of treatment. Cervical arthrodesis was recommended for patients with increased atlantoaxial distance or reduced space available for the cord in flexion-extension radiographs. RESULTS: All 20 children undergoing conservative treatment remained asymptomatic during follow-up, but 1 nonidiopathic patient developed cervical instability. The idiopathic group had significantly less severe radiographic cervical instability and less neurologic complications than the nonidiopathic group (P < 0.05 for all comparisons). Thirty-three (97%) patients in the idiopathic group and 32 (94%) patients in the nonidiopathic group (94%) had spinal fusion at final follow-up (P = 0.55). The risk of complications (15% vs. 41%; odds ratio 0.234, 95% confidence interval 0.072-0.757, P = 0.015) and nonunion (6% vs. 24%; odds ratio 0.203, 95% confidence interval 0.040-0.99, P = 0.040) were significantly lower in the idiopathic than in the nonidiopathic group. Idiopathic children undergoing rigid fixation achieved spinal fusion. CONCLUSIONS: Idiopathic patients with stable atlantoaxial joint at presentation remained asymptomatic and intact during conservative treatment. Idiopathic children with os odontoideum undergoing spinal arthrodesis had significantly fewer complications and nonunion than nonidiopathic children. LEVEL OF EVIDENCE: III.

NSQIP versus institutional morbidity and mortality conference: complementary complication reporting in pediatric spine fusion.

PURPOSE: Other fields of medicine have demonstrated underreported surgical complication rates by institutional M&M compared to NSQIP. However, a study comparing surgical complication rates in the pediatric spine population, using an identical set of patients rather than nationally extrapolated, has not been performed. METHODS: A single institution's ASC-NSQIP Pediatric spine fusion cases and its departmental team-reported M&M database for the same were reviewed for January 1, 2012 to December 31, 2018. Differences in surgical complication reporting between the two databases for the identical patient cohort were recorded. RESULTS: NSQIP identified 50 pediatric spine fusion patients with complications out of 386 NSQIP-algorithm-sampled cases (13%). Of these complications, 23 were not reported in the M&M conference database (6% of NSQIP-sampled cases, 2.5% of all M&M cases). The most common under-reported complication categories include pneumonia (100% under-reported), clostridium difficile (100%), urinary tract infection (83%), and superficial wound disruption (67%). During the same 7 years, M&M covered 924 spine fusions and identified 162 complications. Of these 162 patients, 22 were included in the NSQIP sampling and were not reported as complications (6% of NSQIP sampled patients). CONCLUSION: Recognizing complication rates is central to implement strategies for delivering better quality care. NSQIP data may serve as an important quality check for pediatric spine institutional M&M data, but both may not include all complications even within its sampled patients. In general, NSQIP's protocols identified more medical complications, while M&M has a surgical focus, benefits from the limitless follow-up, and involves timely departmental awareness of complications.

Delayed Postoperative Spinal Cord Ischemia After Posterior Spinal Fusion in a Pediatric Patient with Syrinx and Decompressed Chiari: A Case Report.

CASE: We present a case of delayed postoperative neurologic deficits 1 day after posterior spinal fusion in a pediatric patient with syrinx and previous Chiari decompression, which reversed with urgent rod removal. CONCLUSION: There is limited literature on delayed cord injury occurring after surgery in a patient with scoliosis of neuromuscular origin. Patients with syrinx and a history of Chiari decompression may have spinal cords more sensitive to injury including delayed ischemia after deformity treatment and should be paid extra perioperative attention including considering prolonged mean arterial pressure goals or more conservative deformity correction.

Dynamic Impairment of Olfactory Behavior and Signaling Mediated by an Olfactory Corticofugal System.

Processing of olfactory information is modulated by centrifugal projections from cortical areas, yet their behavioral relevance and underlying neural mechanisms remain unclear in most cases. The anterior olfactory nucleus (AON) is part of the olfactory cortex, and its extensive connections to multiple upstream and downstream brain centers place it in a prime position to modulate early sensory information in the olfactory system. Here, we show that optogenetic activation of AON neurons in awake male and female mice was not perceived as an odorant equivalent cue. However, AON activation during odorant presentation reliably suppressed behavioral odor responses. This AON-mediated effect was fast and constant across odors and concentrations. Likewise, activation of glutamatergic AON projections to the olfactory bulb (OB) transiently inhibited the excitability of mitral/tufted cells (MTCs) that relay olfactory input to the cortex. Single-unit MTC recordings revealed that optogenetic activation of glutamatergic AON terminals in the OB transiently decreased sensory-evoked MTC spiking, regardless of the strength or polarity of the sensory response. The reduction in MTC firing during optogenetic stimulation was confirmed in recordings in awake mice. These findings suggest that glutamatergic AON projections to the OB impede early olfactory signaling by inhibiting OB output neurons, thereby dynamically gating sensory throughput to the cortex.SIGNIFICANCE STATEMENT The anterior olfactory nucleus (AON) as an olfactory information processing area sends extensive projections to multiple brain centers, but the behavioral consequences of its activation have been scarcely investigated. Using behavioral tests in combination with optogenetic manipulation, we show that, in contrast to what has been suggested previously, the AON does not seem to form odor percepts but instead suppresses behavioral odor responses across odorants and concentrations. Furthermore, this study shows that AON activation inhibits olfactory bulb output neurons in both anesthetized as well as awake mice, pointing to a potential mechanism by which the olfactory cortex can actively and dynamically gate sensory throughput to higher brain centers.