Determining Differences in Perioperative Functional Mobility Patterns in Lumbar Decompression Versus Fusion Patients Using Smartphone Activity Data.

BACKGROUND AND OBJECTIVES: Smartphone activity data recorded through high-fidelity accelerometry can provide accurate postoperative assessments of patient mobility. The "big data" available through smartphones allows for advanced analyses, yielding insight into patient well-being. This study compared rate of change in functional activity data between lumbar fusion (LF) and lumbar decompression (LD) patients to determine preoperative and postoperative course differences. METHODS: Twenty-three LF and 18 LD patients were retrospectively included. Activity data (steps per day) recorded in Apple Health, encompassing over 70 000 perioperative data points, was classified into 6 temporal epochs representing distinct functional states, including acute preoperative decline, immediate postoperative recovery, and postoperative decline. The daily rate of change of each patient's step counts was calculated for each perioperative epoch. RESULTS: Patients undergoing LF demonstrated steeper preoperative declines than LD patients based on the first derivative of step count data (P = .045). In the surgical recovery phase, LF patients had slower recoveries (P = .041), and LF patients experienced steeper postoperative secondary declines than LD patients did (P = .010). The rate of change of steps per day demonstrated varying perioperative trajectories that were not explained by differences in age, comorbidities, or levels operated. CONCLUSION: Patients undergoing LF and LD have distinct perioperative activity profiles characterized by the rate of change in the patient daily steps. Daily steps and their rate of change is thus a valuable metric in phenotyping patients and understanding their postsurgical outcomes. Prospective studies are needed to expand upon these data and establish causal links between preoperative patient mobility, patient characteristics, and postoperative functional outcomes.

Effects of Augmented Reality on Thoracolumbar Pedicle Screw Instrumentation Across Different Levels of Surgical Experience.

OBJECTIVE: Augmented reality (AR) is an emerging technology that may accelerate skill acquisition and improve accuracy of thoracolumbar pedicle screw placements. We aimed to quantify the relative assistance of AR compared with freehand (FH) pedicle screw accuracy across different surgical experience levels. METHODS: A spine fellowship-trained and board-certified attending neurosurgeon, postgraduate year 4 neurosurgery resident, and second-year medical student placed 32 FH and 32 AR-assisted thoracolumbar pedicle screws in 3 cadavers. A cableless, voice-activated AR system was paired with a headset. Accuracy was assessed using χ2 analysis and the Gertzbein-Robbins scale. Angular error, distance error, and time per pedicle screw were collected and compared. RESULTS: The attending neurosurgeon had 91.6% (11/12) clinically acceptable (Gertzbein-Robbins scale A or B) insertion in both FH and AR groups; the resident neurosurgeon had 100% (9/9) FH and AR in both cases; the medical student had 72.3% (8/11) FH accuracy and 81.8% (9/11) AR accuracy. The medical student displayed significantly lower ideal (Gertzbein-Robbins scale A) FH accuracy compared with the resident neurosurgeon (P = 0.017) and attending neurosurgeon (P = 0.005), but no difference when using AR. FH screw placement was faster by both the attending neurosurgeon (median 46 seconds vs. 94.5 seconds, P = 0.0047) and the neurosurgery resident neurosurgeon (median 144 seconds vs. 140 seconds, P = 0.05). Total clinically acceptable AR and FH accuracy was 90.6% (29/32) and 87.5% (28/32), respectively (P = 0.69). CONCLUSIONS: AR screw placement allowed an inexperienced medical student to double their accuracy in 1 training session. With subsequent iterations, this promising technology could serve as an important tool for surgical training.

Demographic and Socioeconomic Trends in Cervical Fusion Utilization from 2004 Through 2021 and the COVID-19 Pandemic.

BACKGROUND: Cervical fusion rates increased in the U.S. exponentially 1990-2014, but trends leading up to/during the COVID-19 pandemic have not been fully evaluated by patient socioeconomic status (SES). Here, we provide the most recent, comprehensive characterization of demographic and SES trends in cervical fusions, including during the pandemic. METHODS: We collected the following variables on adults undergoing cervical fusions, 1/1/2004-3/31/2021, in Optum's Clinformatics Data Mart: age, Charlson Comorbidity Index, provider's practicing state, gender, race, education, and net worth. We performed multivariate linear and logistic regression to evaluate associations of cervical fusion rates with SES variables. RESULTS: Cervical fusion rates increased 2004-2016, then decreased 2016-2020. Proportions of Asian, Black, and Hispanic patients undergoing cervical fusions increased (OR = 1.001,1.001,1.004, P < 0.01), with a corresponding decrease in White patients (OR = 0.996, P < 0.001) over time. There were increases in cervical fusions in higher education groups (OR = 1.006, 1.002, P < 0.001) and lowest net worth group (OR = 1.012, P < 0.001). During the pandemic, proportions of White (OR = 1.015, P < 0.01) and wealthier patients (OR ≥ 1.015, P < 0.01) undergoing cervical fusions increased. CONCLUSIONS: We present the first documented decrease in annual cervical surgery rates in the U.S. Our data reveal a bimodal distribution for cervical fusion patients, with racial-minority, lower-net-worth, and highly-educated patients receiving increasing proportions of surgical interventions. White and wealthier patients were more likely to undergo cervical fusions during the COVID-19 pandemic, which has been reported in other areas of medicine but not yet in spine surgery. There is still considerable work needed to improve equitable access to spine care for the entire U.S.

Large Language Model-Based Neurosurgical Evaluation Matrix: A Novel Scoring Criteria to Assess the Efficacy of ChatGPT as an Educational Tool for Neurosurgery Board Preparation.

INTRODUCTION: Technological advancements are reshaping medical education, with digital tools becoming essential in all levels of training. Amidst this transformation, the study explores the potential of ChatGPT, an artificial intelligence model by OpenAI, in enhancing neurosurgical board education. The focus extends beyond technology adoption to its effective utilization, with ChatGPT's proficiency evaluated against practice questions from the Primary Neurosurgery Written Board Exam. METHODS: Using the Congress of Neurologic Surgeons (CNS) Self-Assessment Neurosurgery (SANS) Exam Board Review Prep questions, we conducted 3 rounds of analysis with ChatGPT. We developed a novel ChatGPT Neurosurgical Evaluation Matrix (CNEM) to assess the output quality, accuracy, concordance, and clarity of ChatGPT's answers. RESULTS: ChatGPT achieved spot-on accuracy for 66.7% of prompted questions, 59.4% of unprompted questions, and 63.9% of unprompted questions with a leading phrase. Stratified by topic, accuracy ranged from 50.0% (Vascular) to 78.8% (Neuropathology). In comparison to SANS explanations, ChatGPT output was considered better in 19.1% of questions, equal in 51.6%, and worse in 29.3%. Concordance analysis showed that 95.5% of unprompted ChatGPT outputs and 97.4% of unprompted outputs with a leading phrase were aligned. CONCLUSIONS: Our study evaluated the performance of ChatGPT in neurosurgical board education by assessing its accuracy, clarity, and concordance. The findings highlight the potential and challenges of integrating AI technologies like ChatGPT into medical and neurosurgical board education. Further research is needed to refine these tools and optimize their performance for enhanced medical education and patient care.

Defining the minimal clinically important difference in smartphone-based mobility after spine surgery: correlation of survey questionnaire to mobility data.

OBJECTIVE: Patient-reported outcome measures (PROMs) are the gold standard for assessing postoperative outcomes in spine surgery. However, PROMs are also limited by the inherent subjectivity of self-reported qualitative data. Recent literature has highlighted the utility of patient mobility data streamed from smartphone accelerometers as an objective measure of functional outcomes and complement to traditional PROMs. Still, for activity-based data to supplement existing PROMs, they must be validated against current metrics. In this study, the authors assessed the relationships and concordance between longitudinal smartphone-based mobility data and PROMs. METHODS: Patients receiving laminectomy (n = 21) or fusion (n = 10) between 2017 and 2022 were retrospectively included. Activity data (steps-per-day count) recorded in the Apple Health mobile application over a 2-year perioperative window were extracted and subsequently normalized to allow for intersubject comparison. PROMS, including the visual analog scale (VAS), Patient Reported Outcome Measurement Information System Pain Interference (PROMIS-PI), Oswestry Disability Index (ODI), and EQ-5D, collected at the preoperative and 6-week postoperative visits were retrospectively extracted from the electronic medical record. Correlations between PROMs and patient mobility were assessed and compared between patients who did and those who did not achieve the established minimal clinically important difference (MCID) for each measure. RESULTS: A total of 31 patients receiving laminectomy (n = 21) or fusion (n = 10) were included. Change between preoperative and 6-week postoperative VAS and PROMIS-PI scores demonstrated moderate (r = -0.46) and strong (r = -0.74) inverse correlations, respectively, with changes in normalized steps-per-day count. In cohorts of patients who achieved PROMIS-PI MCID postoperatively, indicating subjective improvement in pain, there was a 0.784 standard deviation increase in normalized steps per day, representing a 56.5% improvement (p = 0.027). Patients who did achieve the MCID of improvement in either PROMIS-PI or VAS after surgery were more likely to experience an earlier sustained improvement in physical activity commensurate to or greater than their preoperative baseline (p = 2.98 × 10-18) than non-MCID patients. CONCLUSIONS: This study demonstrates a strong correlation between changes in mobility data extracted from patient smartphones and changes in PROMs following spine surgery. Further elucidating this relationship will allow for more robust supplementation of existing spine outcome measure tools with analyzed objective activity data.

Endoscopic fenestration of an enlarging giant occipital arachnoid cyst.

This case demonstrates an endoscopic fenestration of an enlarging giant occipital arachnoid cyst. The patient is a 42-year-old woman presenting with headache, progressive vision loss, and nausea and vomiting. MRI demonstrates a large, nonenhancing cystic lesion in the right occipital lobe measuring up to 8.3 cm, consistent with an arachnoid cyst. This surgical video illustrates the technique for an endoscopic fenestration into the native ventricular system utilizing stereotactic MRI-guided stealth navigation. Postoperatively, the patient had full recovery with improvement of headaches and vision and was discharged on postoperative day 1 without complications. The video can be found here: https://stream.cadmore.media/r10.3171/2023.1.FOCVID22129.

Characterizing and Improving Nomenclature for Reporting Lumbar Interbody Fusion Techniques.

OBJECTIVE: Lumbar interbody fusion (LIF) techniques have seen impressive innovation in recent years, leading to an expansion of the LIF lexicon. This study systematically analyzes LIF nomenclature in contemporary literature and proposes a standardized classification system for reporting LIF terminology. METHODS: A search query was conducted through the PubMed database using "lumbar fusion OR lumbar interbody fusion." A total of 1455 articles were identified, and 605 references to LIF were recorded. Following a systematic review of the terminology, we developed a LIF reporting guidelines that capture the existing LIF nomenclature while avoiding redundant or ambiguous terminology. RESULTS: The most referenced anatomical approaches were transforaminal (43.0%), followed by posterior (25.0%), lateral (19.7%), and anterior (10.9%). Overall, there were 72 unique ways to describe LIF. Unique prefixes were recorded by approach (posterior: 26; lateral: 13; anterior: 3). Forty unique prefixes/suffixes overlapped in their usage. "MI" (14.4%), "MIS" (38.1%), and "MISS" (0.6%) all referenced a minimally invasive approach. "O" (12.5%), "CO" (1.3%), and "TO" (1.3%) all described open techniques. "Endo" (0.6%), "Endoscopic-assisted" (1.3%), and "PE" (1.9%) all referenced endoscopic-assisted procedures. CONCLUSIONS: The current LIF nomenclature contains many unique LIF terms that were found to be inconsistently defined, redundant, or ambiguous. We propose the standardization of a 4-part naming system which highlights the crucial parts of LIF: (1) intraoperative repositioning, (2) patient position, (3) anatomical approach, and (4) orientation of the surgical corridor to the psoas muscles.

A Prospective Cohort Study of Radiation Exposure to a Spine Surgeon's Exposed Body Parts During Utilization of Intraoperative Radiation-based Imaging.

STUDY DESIGN: Prospective cohort study. SUMMARY OF BACKGROUND DATA: C-arm fluoroscopy and O-arm navigation are vital tools in modern spine surgeries, but their repeated usage can endanger spine surgeons. Although a surgeon's chest and abdomen are protected by lead aprons, the eyes and extremities generally receive less protection. OBJECTIVE: In this study, we compare differences in intraoperative radiation exposure across the protected and unprotected regions of a surgeon's body. METHODS: Sixty-five consecutive spine surgeries were performed by a single spine-focused neurosurgeon over 9 months. Radiation exposure to the primary surgeon was measured through dosimeters worn over the lead apron, under the lead apron, on surgical loupes, and as a ring on the dominant hand. Differences were assessed with rigorous statistical testing and radiation exposure per surgical case was extrapolated. RESULTS: During the study, the measured radiation exposure over the apron, 176 mrem, was significantly greater than that under the apron, 8 mrem (P = 0.0020), demonstrating a shielding protective effect. The surgeon's dominant hand was exposed to 329 mrem whereas the eyes were exposed to 152.5 mrem of radiation. Compared with the surgeon's protected abdominal area, the hands (P = 0.0002) and eyes (P = 0.0002) received significantly greater exposure. Calculated exposure per case was 2.8 mrem for the eyes and 5.1 mrem for the hands. It was determined that a spine-focused neurosurgeon operating 400 cases annually will incur a radiation exposure of 60,750 mrem to the hands and 33,900 mrem to the eyes over a 30-year career. CONCLUSIONS: Our study found that spine surgeons encounter significantly more radiation exposure to the eyes and the extremities compared with protected body regions. Lifetime exposure exceeds the annual limits set by the International Commission on Radiologic Protection for the extremities (50,000 mrem/y) and the eyes (15,000 mrem/y), calling for increased awareness about the dangerous levels of radiation exposure that a spine surgeon incurs over one's career.

Virtual and Augmented Reality in Spine Surgery: A Systematic Review.

BACKGROUND: Augmented reality (AR) and virtual reality (VR) implementation in spinal surgery has expanded rapidly over the past decade. This systematic review summarizes the use of AR/VR technology in surgical education, preoperative planning, and intraoperative guidance. METHODS: A search query for AR/VR technology in spine surgery was conducted through PubMed, Embase, and Scopus. After exclusions, 48 studies were included. Included studies were then grouped into relevant subsections. Categorization into subsections yielded 12 surgical training studies, 5 preoperative planning, 24 intraoperative usage, and 10 radiation exposure. RESULTS: VR-assisted training significantly reduced penetration rates or increased accuracy rates compared to lecture-based groups in 5 studies. Preoperative VR planning significantly influenced surgical recommendations and reduced radiation exposure, operating time, and estimated blood loss. For 3 patient studies, AR-assisted pedicle screw placement accuracy ranged from 95.77% to 100% using the Gertzbein grading scale. Head-mounted display was the most common interface used intraoperatively followed by AR microscope and projector. AR/VR also had applications in tumor resection, vertebroplasty, bone biopsy, and rod bending. Four studies reported significantly reduced radiation exposure in AR group compared to fluoroscopy group. CONCLUSIONS: AR/VR technologies have the potential to usher in a paradigm shift in spine surgery. However, the current evidence indicates there is still a need for 1) defined quality and technical requirements for AR/VR devices, 2) more intraoperative studies that explore usage outside of pedicle screw placement, and 3) technological advancements to overcome registration errors via the development of an automatic registration method.

Standardizing Lumbar Interbody Fusion Nomenclature.

STUDY DESIGN: This article is a research methodology study. OBJECTIVE: We summarize current ambiguities and inaccuracies regarding lumbar interbody fusion nomenclature and propose a standardized reporting method to improve the clarity of future research and communication among spine surgeons and researchers. SUMMARY OF BACKGROUND DATA: Lumbar interbody fusion techniques have seen an impressive degree of refinement over recent years. This innovation has ushered in a plethora of naming conventions for these new surgical approaches. Many of the current trends in naming lumbar fusion techniques are, however, redundant and contradictory, creating unnecessary confusion in the field. METHODS: Following an extensive literature review, we developed a 4-part naming convention that highlights the crucial features of lumbar fusion surgical procedures. RESULTS: Current literature regarding lumbar fusions is rife with inconsistent usage and privatization of terminology that can inadvertently result in ambiguous operative vocabulary, potentially compromising the accuracy of future research. We propose a 4-part naming system that highlights crucial features of lumbar interbody fusions, including (1) intra-operative repositioning, (2) patient position, (3) surgical technique, and (4) orientation of the surgical corridor to the psoas muscle. CONCLUSIONS: This study raises awareness of current inconsistencies in naming conventions and proposes a standardized system for improving the clarity of lumber interbody fusion terminology for the broader spine community. LEVEL OF EVIDENCE: Level V.

Combined L5-S1 Anterior Lumbar Interbody Fusion and Multilevel Lateral Lumbar Interbody Fusion in a Single-Stage Lateral Decubitus Position Using Fluoroscopy-Based Instrument Tracking System.

Anterior lumbar interbody fusion (ALIF), traditionally performed supine, allows for significant restoration of lumbar lordosis, disc height, and foraminal height in degenerative spine diseases; however, an iatrogenic injury to the viscera and the great vessels can have devastating consequences. Although lateral lumbar interbody fusion (LLIF) is an acceptable and minimally invasive alternative at the L5-S1 level, this approach is suboptimal because of a narrow surgical corridor limited by the iliac crest, common iliac artery and vein, and psoas. Furthermore, combining supine L5-S1 ALIF and lateral decubitus (LD) LLIF requires time-consuming patient repositioning.1,2 To maximize the advantages of both procedures in patients with disease spanning the lumbosacral junction, ALIF and LLIF can be performed in a single stage with the patient remaining in an LD position throughout. To improve the efficiency of this single-position procedure, a fluoroscopy-based instrument tracking system (TrackX Technology Inc., Hillsborough, North Carolina, USA) was used to navigate surgical tools during the procedure. We show this technique in a 43-year-old patient with medically intractable back and leg pain secondary to multi-level degenerative lumbar spondylosis. The patient consented to this procedure; all participants consented to publication of their images. This tracking system allowed for accurate and precise virtual projections of surgical instruments, thereby facilitating the identification of midline and proper trajectories to perform discectomy and implant placement, reducing the amount of intraoperative fluoroscopy use, and eliminating intraoperative computed tomography. To our knowledge, this is the first operative video showing a fluoroscopy-based instrument tracking system used in a combined single-position LD-ALIF and LD-LLIF.

"July Effect" in Spinal Fusions: A Coarsened Exact-Matched Analysis.

BACKGROUND: Few neurosurgical studies examine the July Effect within elective spinal procedures, and none uses an exact-matched protocol to rigorously account for confounders. OBJECTIVE: To evaluate the July Effect in single-level spinal fusions, after coarsened exact matching of the patient cohort on key patient characteristics (including race and comorbid status) known to independently affect neurosurgical outcomes. METHODS: Two thousand three hundred thirty-eight adult patients who underwent single-level, posterior-only lumbar fusion at a single, multicenter university hospital system were retrospectively enrolled. Primary outcomes included readmissions, emergency department visits, reoperation, surgical complications, and mortality within 30 days of surgery. Logistic regression was used to analyze month as an ordinal variable. Subsequently, outcomes were compared between patients with surgery at the beginning vs end of the academic year (ie, July vs April-June), before and after coarsened exact matching on key characteristics. After exact matching, 99 exactly matched pairs of patients (total n = 198) were included for analysis. RESULTS: Among all patients, operative month was not associated with adverse postoperative events within 30 days of the index operation. Furthermore, patients with surgeries in July had no significant difference in adverse outcomes. Similarly, between exact-matched cohorts, patients in July were observed to have noninferior adverse postoperative events. CONCLUSION: There was no evidence suggestive of a July Effect after single-level, posterior approach spinal fusions in our cohort. These findings align with the previous literature to imply that teaching hospitals provide adequate patient care throughout the academic year, regardless of how long individual resident physician assistants have been in their particular role.

The Influence of Radiologist Practice Setting on Identification of Vascular Compression from Magnetic Resonance Imaging in Trigeminal Neuralgia.

OBJECTIVE: Preoperative magnetic resonance imaging (MRI) studies are routinely ordered for trigeminal neuralgia (TN), though with contested reliability in contemporary literature. A potential reason for this disagreement is inconsistency in MRI reading methodologies. Here, we compare the rate of reported neurovascular compression on preoperative MRI by radiologists employed in community or private practice settings and academic neuroradiologists. METHODS: A retrospective review was conducted on patients who underwent endoscopic microvascular decompression for TN with intraoperatively visualized neurovascular compression and primary read by a non-academic or community radiologist. Patient imaging was then re-read by a board-certified neuroradiologist practicing in an academic setting, who was blinded to the initial read and the side of TN symptoms. RESULTS: Non-academic radiologists reported vascular compression in 26.0% (20/77) of all patients, and mention was rarely made of the non-pathological side (sensitivity = 26.0%). On academic neuroradiologist re-reads, vascular compression was noted in 87.0% (67/77) of patients on the pathological side and in 57.1% (44/77) on the non-pathological side (sensitivity = 87.0%, specificity = 42.9%). Isotropic/near isotropic 3-dimensional steady state or heavily T2-weighted sequences were read with 92.3% sensitivity and 36.9% specificity, compared to 58.3% sensitivity and 66.7% specificity using routine T2 weighted sequences. CONCLUSIONS: The frequency of vascular compression reported by non-academic radiologists is much lower than what is reported by academic neuroradiologists reading the same MRI scans. These results highlight the effect of practice setting on the predictive power of neuroimaging. Future studies are indicated to further investigate these relationships, as well as to trial newer imaging modalities.

Methods and Impact for Using Federated Learning to Collaborate on Clinical Research.

BACKGROUND: The development of accurate machine learning algorithms requires sufficient quantities of diverse data. This poses a challenge in health care because of the sensitive and siloed nature of biomedical information. Decentralized algorithms through federated learning (FL) avoid data aggregation by instead distributing algorithms to the data before centrally updating one global model. OBJECTIVE: To establish a multicenter collaboration and assess the feasibility of using FL to train machine learning models for intracranial hemorrhage (ICH) detection without sharing data between sites. METHODS: Five neurosurgery departments across the United States collaborated to establish a federated network and train a convolutional neural network to detect ICH on computed tomography scans. The global FL model was benchmarked against a standard, centrally trained model using a held-out data set and was compared against locally trained models using site data. RESULTS: A federated network of practicing neurosurgeon scientists was successfully initiated to train a model for predicting ICH. The FL model achieved an area under the ROC curve of 0.9487 (95% CI 0.9471-0.9503) when predicting all subtypes of ICH compared with a benchmark (non-FL) area under the ROC curve of 0.9753 (95% CI 0.9742-0.9764), although performance varied by subtype. The FL model consistently achieved top three performance when validated on any site's data, suggesting improved generalizability. A qualitative survey described the experience of participants in the federated network. CONCLUSION: This study demonstrates the feasibility of implementing a federated network for multi-institutional collaboration among clinicians and using FL to conduct machine learning research, thereby opening a new paradigm for neurosurgical collaboration.

Simultaneous Anterior Posterior Approach for Single-Position Lateral Lumbar Interbody Fusion with Robotic Assistance: Technical Guidelines and Early Outcomes.

BACKGROUND: Lumbar lateral interbody fusion (LLIF) is traditionally performed in 2 stages: placing the interbody cage in the lateral decubitus position, then placing the percutaneous pedicle screw in the prone position. Performing interbody fusion and posterior fixation simultaneously could improve operative efficiency and clinical outcomes associated with longer operative times. We describe the operative steps and report clinical and radiographic outcomes associated with a simultaneous anterior and posterior approach (SAPA) for LLIF. METHODS: Patients who underwent SAPA LLIF performed by a single surgeon over 1 year were retrospectively reviewed. Demographic, clinical, and radiographic data were analyzed, an operative guideline was created, and a learning curve was constructed using operative times. RESULTS: SAPA LLIF was performed in 11 patients. Three patients experienced transient postoperative femoral nerve plexopathy with symptoms of ipsilateral hip flexion weakness and/or anterior thigh numbness; there were no other complications in the cohort. Radiographically, patients achieved significant increases in disc height (8.3 mm vs. 13.5 mm, P = 0.002) and foraminal height (20.2 mm vs. 25.3 mm, P = 0.0001). Patients showed significant improvements in Oswestry Disability Index (52 vs. 27.8, P = 0.002) and Patient-Reported Outcome Measurement Information System Physical Function (32.6 vs. 39, P = 0.048) and Pain Interference (64.9 vs. 59.6, P = 0.001) at 3 months. A downward trend in operative time was observed for 1-level SAPA LLIF. CONCLUSIONS: SAPA LLIF is a safe approach for LLIF that results in favorable clinical outcomes. This technique can potentially improve operative efficiency further along the course of a surgeon's learning curve.

Intraoperative Hypotension Is Not Correlated With Acute Kidney Injury During Spinal Fusion Surgery.

BACKGROUND: Intraoperative hypotension (IOH) has been found to be associated with organ damage, including cardiac injury and acute kidney injury (AKI). However, to our knowledge, this relationship has not been studied in a neurosurgery-specific patient population. In this report, we review our institutional experience to understand the magnitude of association between IOH in spinal fusion operations and incidence of postoperative AKI. METHODS: This retrospective cohort study included 910 patients who underwent posterior spinal fusion procedures performed in the prone position. Intraoperative variables collected and analyzed include minute-by-minute mean arterial pressure (MAP) from an arterial catheter, intermittent blood pressure cuff readings, volume of administered intravenous fluids, urine output, and all relevant vitals and administered medications. The electronic medical record was queried for additional patient data. IOH was defined as MAP <65 mm Hg for greater than 10 minutes. The primary endpoints of the study were presence and staging of AKI ( [Kidney Disease: Improving Global Outcomes] consensus classification), postoperative ileus, and postoperative troponin leak. RESULTS: Using a partial correlation analysis, no association was found between IOH metrics (IOH occurrence, IOH duration >10 minutes, and total IOH time) and any outcome metrics, including AKI, except for vasopressor usage and estimated blood loss. Patient age at surgery was not associated with any outcome variables. The lack of association between IOH and AKI contrasts with existing literature; this could be due to underlying differences in our patient population or could highlight a more complex relationship between IOH and AKI than previously understood. CONCLUSION: Occurrence and duration of IOH were not associated with AKI, postoperative ileus, troponin leak, length of stay, or any other major outcome variables in spinal fusion patients. CLINICAL RELEVANCE: These findings depart from previous literature showing a correlation between IOH and AKI and provide level 3 evidence clinically relevant to spinal surgery. Further research is needed to better understand the exact nature of this relationship.