Chen, Selby

Background: Pulse pressure variation (PPV) is widely used to guide fluid responsiveness in mechanically ventilated patients, but its accuracy in the prone position remains uncertain. Prone positioning alters respiratory mechanics and venous return, potentially diminishing the respiratory variation in stroke volume that PPV is designed to detect. We conducted a systematic review and meta-analysis to evaluate the diagnostic accuracy of PPV for predicting fluid responsiveness during prone spine surgery. Methods: We searched MEDLINE, Embase, Scopus, and Cochrane through July 2025 for prospective studies evaluating PPV in adults undergoing prone spine surgery. Two reviewers independently screened studies, extracted data, assessed risk of bias using QUADAS-2, and pooled diagnostic performance using a bivariate random-effects model. The protocol was registered with PROSPERO (CRD420251106134). Results: Of 599 records, 34 underwent full-text review, and 10 studies (433 patients) were included. PPV thresholds ranged from 7% to 15%. Most studies were at low risk of bias except for the index test because thresholds were determined post hoc. For predicting fluid responsiveness, PPV had a pooled sensitivity of 68% (95% CI: 61%-75%) and specificity of 76% (95% CI: 65%-84%), with a summary area under the receiver operating characteristic curve of 0.72 (95% CI: 0.64-0.80). Conclusions: PPV showed only moderate diagnostic performance for predicting fluid responsiveness during prone spine surgery. Its performance may have been influenced by threshold variability, heterogeneous reference standards, fluid-challenge protocols, ventilation strategies, and positioning systems. PPV should therefore be interpreted alongside complementary dynamic assessments rather than in isolation, particularly during lung-protective ventilation.

OBJECTIVE Hundreds of thousands of Americans undergo decompression for lumbar spinal stenosis annually. The mild (minimally invasive lumbar decompression) procedure was developed as a potentially less invasive alternative to open decompression; however, much of the evidence has been gathered from industry-sponsored studies. The present study sought to compare real-world clinical outcomes between the mild procedure and open decompression for lumbar spinal stenosis. METHODS All patients who underwent the mild procedure at a single-institution, multisite, tertiary care center from 2005 to October 2024 were included. One-to-one propensity score matching was used to identify patients who underwent open decompression at the same institution, with age, sex, smoking, and comorbidities as covariates. Primary outcomes were change in pain on the numeric rating scale (NRS), surgical reoperation, and perioperative complications. For pain, the minimal clinically important difference (MCID) was defined as a 30% improvement in NRS score. RESULTS A total of 175 patients who underwent the mild procedure (mean age 76.3 ± 8.7 years; 44.6% female) were matched to 175 patients treated with open decompression (mean age 75.4 ± 8.7 years; 44.0% female). Among patients with at least 60 days of follow-up, those treated with open decompression were more likely to achieve the MCID for pain (43.1% vs 22.2%, p < 0.001). Patients treated with mild were more likely to require reoperation (46.2% vs 29.3%, p = 0.008). Those who underwent the mild procedure experienced lower rates of durotomies (0% vs 2.9%, p = 0.024) but had higher rates of neurological deficits (6.3% vs 0.6%, p = 0.003). CONCLUSIONS For patients with symptomatic lumbar stenosis, those who underwent open decompression were more likely to achieve pain improvement and less likely to require reoperation compared with those who underwent the mild procedure.

OBJECTIVE Surgical site infection (SSI) is a leading cause of morbidity following posterior spine surgery. The optimal choice of skin closure technique depending on patient- and procedure-specific characteristics remains to be elucidated. METHODS The Neurosurgery Enterprise Registry (NER) at Mayo Clinic was queried for patients who underwent posterior spine surgery from 2017 to 2023. Propensity matching was performed to match patients on the basis of the development of SSI and baseline characteristics, including age, sex, race, and comorbidities. Perioperative outcomes were analyzed using data from the NER and medical records. RESULTS A total of 18,842 cases of posterior spine surgery were identified in the NER, and SSI was observed in 154 cases (0.8%). Of these patients, 308 patients were included in the 1:1 propensity score–matched cohort analysis, with 154 patients included in each group. Sutures were used in 224 patients (72.7%) and staples in 84 patients (27.3%) (p < 0.01). Female patients comprised 45.1% of the sutures group and 46.4% of the staples group (p = 0.8). The mean ± SD age was 59.8 ± 15.4 years in the sutures group and 60.8 ± 11.9 years in the staples group (p = 0.6). Fusion was performed in 27.2% of patients in the sutures group and 44% in the staples group (p < 0.01). Multilevel fusion comprised 68.9% of fusion cases in the sutures group and 67.6% in the staples group (p = 0.8). Comorbidities, such as diabetes (p = 0.6), hypertension (p = 0.1), and the use of disease-modifying antirheumatic drugs (DMARDs) (p = 0.5) and immunosuppressants (p = 0.2), did not differ between groups. Univariate analysis performed in the propensity score–matched cohort showed that SSI was observed in 53.6% of patients in the sutures group and 40.5% in the staples group (p = 0.04). No significant differences were noted regarding 30-day (p = 0.3), 90-day (p = 0.2), and 1-year (p = 0.3) readmissions and 30-day (p = 0.7), 90-day (p = 0.8), and 1-year (p = 0.8) reoperations. On multivariable logistic regression, SSI was not significantly associated with the choice of skin closure technique (p = 0.3). CONCLUSIONS After adjustment for spinal fusion, number of fused levels, the use of immunosuppressants, and other risk factors, SSI development was not significantly associated with the use of sutures versus staples following posterior spine surgery in our institution. Additionally, no significant differences were observed regarding baseline characteristics and other perioperative outcomes. The authors’ analysis shows that skin closure technique did not significantly affect SSI rates and other outcomes in these patients.

OBJECTIVE The implementation of robotics and spinal anesthesia (SA) in spine surgery is rapidly expanding, offering significant benefits for an increasingly complex and aging patient population with degenerative spinal disease. Here, the authors present the largest cohort to date evaluating the combined use of these two techniques in minimally invasive (MIS) transforaminal lumbar interbody fusion (TLIF). METHODS The authors retrospectively analyzed surgical outcomes of a series of patients who underwent robot-assisted (RA)–MIS TLIF under SA and general anesthesia (GA) at their institution from 2018 to 2024. Primary outcomes included operative times and postoperative pain intensity. Secondary outcomes included estimated blood loss, intraoperative complications, postoperative functional status, length of stay (LOS), and discharge status. To address potential confounders, a 1:1 propensity score–matching and regression analysis was implemented. Statistical analyses were conducted using Python. RESULTS A total of 209 patients underwent RA-MIS TLIF, with 31 (14.83%) receiving SA and 178 (85.17%) GA. After propensity score matching, the SA cohort demonstrated significantly shorter median total operating room (OR) time, total procedure time, time from entering the OR to skin incision, and time from closure to leaving the OR (all p < 0.01). Additionally, postoperative pain scores were significantly lower (p < 0.01), and LOS was significantly shorter (p < 0.01) in the SA cohort. Regression analysis, adjusting for potential confounders, further supported these findings. CONCLUSIONS RA-MIS TLIF fusion under SA is a safe and effective approach that significantly reduces operative time, postoperative pain, and hospital LOS in patients undergoing surgery for degenerative lumbar spine disease.

Study design: Cohort study. Objective: This study aimed to evaluate influence of facet cysts on outcomes in patients undergoing lumbar decompression, and the influence of spinal fusion in patients undergoing decompression for facet cysts. Summary of Background Data: The impact of facet cysts on outcomes following lumbar spine surgery for degenerative spine disease remains unclear. Methods: Our multicenter institutional Neurosurgery Enterprise Registry was queried for patients who underwent lumbar decompression for degenerative spine conditions. Patients were divided into 2 cohorts: those with lumbar spine facet cysts and those without. Retrospective propensity-score matching was performed using 13 baseline variables to adjust for potential confounding factors, including age, sex, race, body mass index, and comorbidities. Secondary analysis comparing outcomes in patients with facet cysts cases undergoing decompression only versus those undergoing decompression and fusion was conducted. Results: A total of 6768 patients were reviewed, of which 188 (2.8%) had facet cysts, which underwent lumbar decompression during 2019–2023. After 3:1 matching, patients with facet cysts were compared with 564 patients without it. We found no significant differences in LOS, nonroutine discharge, postoperative complications, readmissions, and reoperations. In addition, in cases with facet cysts, decompression reported no increased risk for discharge opioids, readmissions, and reoperations, whereas fusion (in a separate cohort of 127 patients with facet cysts) was associated with an increased risk for nonroutine discharge (3.7% vs. 10.2%, P=0.021), complications (2.1% vs. 7.1%, P=0.042), and longer LOS (0.89±1.69 vs. 3.74±2.03 d, P<0.001) and operative time (138.78±62.99 vs. 273.07±111.51 min, P <0.001). Conclusions: The presence of facet cysts does not significantly affect outcomes of lumbar decompression for degenerative spine disease. Decompression alone for facet cysts can have better outcomes than decompression and fusion. The need for fusion should be weighted with its higher risks of complications, longer hospital stays, and nonroutine discharges.

Study Design Systematic Review. Objective To assess the current literature regarding the accuracy of different imaging modalities and criteria used to assess lumbar fusion, and their correlation with surgical direct observation as the current Gold Standard. Methods Following PRISMA guidelines, we conducted a comprehensive search of PubMed, Embase, Google Scholar, and Cochrane Library, studies were included if they focused on patients with a prior history of lumbar interbody fusion and at least 1 year of radiographic follow-up. The review assessed the sensitivity, specificity, and accuracy of different imaging techniques, and their correlation with surgical findings. Results Thirteen studies (1989-2019) were reviewed, including 715 patients, common imaging modalities included plain radiographs (53.8%), Computed Tomography (CT) (69.2%), and dynamic radiographs (30.7%). CT appeared as the most utilized modality post-2006. There was substantial variability in diagnostic accuracy, with CT showing high variability in sensitivity and specificity. Descriptive criteria for fusion were widely used, but interobserver agreement was generally low. Conclusion The review highlights a lack of standardized criteria for assessing lumbar fusion. Despite advancements in imaging techniques, the variability in diagnostic parameters suggests a need for consensus and multicentric studies to stablish reliable, universal criteria for evaluating fusion success.

Background Spinal subdural empyema rarely involves the spinal cord and may result in devastating neurological deficits. These lesions typically require prompt diagnosis, surgical evacuation, and antibiotic therapy. Here, we present the clinical course, imaging, and narrated operative video of a thoracic spinal subdural empyema initially diagnosed as an intramedullary neoplasm. Case Description A 73-year-old female presented with a 6-month history of worsening thoracic myelopathy; over the last few weeks, she rapidly developed paraplegia. She was initially diagnosed with an enlarging thoracic intramedullary mass. A spinal biopsy was performed for the presumptive diagnosis of primary intramedullary central nervous system lymphoma. However, at surgery, the thoracic lesion proved to be a chronic subdural empyema (i.e., surrounded by arachnoid granulations and soft-purulent tissue). Interestingly, the operative specimen failed to grow any specific organism. Conclusion Spinal subdural empyema should be one of the differential diagnoses considered for patients presenting with intradural spinal cord lesions.

Study Design: Retrospective cohort analysis. Objective: To determine whether the C2 exposure technique was a predictor of change in cervical alignment and patient-reported outcomes measures (PROMs) after posterior cervical decompression and fusion (PCDF) for degenerative indications. Background: In PCDF handling of the C2 posterior paraspinal musculature during the operative approach varies by surgeon technique. To date, no studies have investigated whether maintenance of the upper cervical semispinalis cervicis attachments as compared with complete reflection of upper cervical paraspinal musculature from the posterior bony elements is associated with superior radiographic and clinical outcomes after PCDF. Patients and Methods: All adult patients who underwent C2–T2 PCDF for myelopathy or myeloradiculopathy at multi-institutional academic centers between 2013 and 2020 were retrospectively identified. Patients were dichotomized by the C2 exposure technique into semispinalis preservation or midline muscular reflection groups. Preoperative and short and long-term postoperative radiographic outcomes (upper cervical alignment, global alignment, and fusion status) and PROMs (Visual Analog Scale–Neck, Neck Disability Index, and Short Form-12) were collected. Univariate analysis compared patient factors, radiographic measures, and PROMs across C2 exposure groups. Results: A total of 129 patients met the inclusion/exclusion criteria (73 muscle preservation and 56 muscle reflection). Patients in the muscular preservation group were on average younger (P = 0.005) and more likely to have bone morphogenic protein (P < 0.001) and C2 pars screws (P = 0.006) used during surgery. Preoperative to postoperative changes in C2 slope, C2 tilt, C2–C3 segmental lordosis, C2–C3 listhesis, C0–C2 Cobb angle, proximal junctional kyphosis, ADI, C1 lamina-occiput distance, C2 sagittal vertical axis, C2–C7 lordosis, and PROMs at all follow-up intervals did not vary significantly by C2 exposure technique. Likewise, there were no significant differences in fusion status, C2–C3 pseudoarthrosis, C2 screw loosening, and complication and revision rates between C2 exposure groups. Conclusions: Preservation of C2 semispinalis attachments versus muscular reflection did not significantly impact cervical alignment, clinical outcomes, or proximal junction complications in long-segment PCDF. Level of Evidence: Level III.

BACKGROUND AND OBJECTIVES: Cervical disk arthroplasty (CDA) offers the advantage of motion preservation in the treatment of focal cervical pathology. At present, implant sizing is performed using subjective tactile feedback and imaging of trial cages. This study aims to construct interpretable machine learning (IML) models to accurately predict postoperative range of motion (ROM) and identify the optimal implant sizes that maximize ROM in patients undergoing CDA. METHODS: Adult patients who underwent CDA for single-level disease from 2012 to 2020 were identified. Patient demographics, comorbidities, and outcomes were collected, including symptoms, examination findings, subsidence, and reoperation. Affected disk height, healthy rostral disk height, and implant height were collected at sequential time points. Linear regression and IML models, including bagged regression tree, bagged multivariate adaptive regression spline, and k-nearest neighbors, were used to predict ROM change. Model performance was assessed by calculating the root mean square error (RMSE) between predicted and actual changes in ROM in the validation cohort. Variable importance was assessed using RMSE loss. Area under the curve analyses were performed to identify the ideal implant size cutoffs in predicting improved ROM. RESULTS: Forty-seven patients were included. The average RMSE between predicted and actual ROM was 7.6° (range: 5.8-10.1) in the k-nearest neighbors model, 7.8° (range: 6.5-10.0) in the bagged regression tree model, 7.8° (range: 6.2-10.0) in the bagged multivariate adaptive regression spline model, and 15.8° (range: 14.3-17.5°) in a linear regression model. In the highest-performing IML model, graft size was the most important predictor with RMSE loss of 6.2, followed by age (RMSE loss = 5.9) and preoperative caudal disk height (RMSE loss = 5.8). Implant size at 110% of the normal adjacent disk height was the optimal cutoff associated with improved ROM. CONCLUSION: IML models can reliably predict change in ROM after CDA within an average of 7.6 degrees of error. Implants sized comparably with the healthy adjacent disk may maximize ROM.

BACKGROUND AND OBJECTIVES: Degenerative spine disease is a leading cause of disability, with increasing prevalence in the older patients. While age has been identified as an independent predictor of outcomes, its predictive value is limited for similar older patients. Here, we aimed to determine the most predictive frailty score of adverse events in patients aged 80 and older undergoing instrumented lumbar fusion. METHODS: We proceeded with a multisite (3 tertiary academic centers) retrospective review including patients undergoing instrumented fusion aged 80 and older from January 2010 to present. A composite end point encompassing 30-day return to operating room, readmission, and mortality was created. We estimated the area under the receiver operating characteristic curve for frailty scores (Modified Frailty Index-5 [MFI-5], Modified Frailty Index-11 [MFI-11], and Charlson Comorbidity Index [CCI]) in relation to that composite score. In addition, we estimated the association between each score and the composite end point by means of logistic regression. RESULTS: A total of 153 patients with an average age of 85 years at the time of surgery were included. We observed a 30-day readmission rate of 11.1%, reoperation of 3.9%, and mortality of 0.6%. The overall rate of the composite end point at 30 days was 25 (15.1%). The AUC for MFI-5 was 0.597 (0.501-0.693), for MFI-11 was 0.620 (0.518-0.723), and for CCI was 0.564 (0.453-0.675). The association between the scores and composite end point did not reach statistical significance for MFI-5 (odds ratio [OR] = 1.45 [0.98-2.15], P = .061) and CCI (OR = 1.13 [0.97-1.31], P = .113) but was statistically significant for MFI-11 (OR = 1.46 [1.07-2.00], P = .018). CONCLUSION: This is the largest study comparing frailty index scores in octogenarians undergoing instrumented lumbar fusion. Our findings suggest that while MFI-11 score correlated with adverse events, the predictive ability of existing scores remains limited, highlighting the need for better approaches to identify select patients at age extremes.