The Association Between Task Complexity and Cortical Language Mapping Accuracy.

BACKGROUND AND OBJECTIVES: Direct cortical stimulation (DCS) mapping enables the identification of functional language regions within and around gliomas before tumor resection. Intraoperative mapping is required because glioma-infiltrated cortex engages in synchronous activity during task performance in a manner similar to normal-appearing cortex but has decreased ability to encode information for complex tasks. It is unknown whether task complexity influenced DCS mapping results. We aim to understand correlations between audiovisual picture naming (PN) task complexity and DCS error rate. We also asked what functional and oncological factors might be associated with higher rates of erroneous responses. METHODS: We retrospectively reviewed intraoperative PN and word reading (WR) task performance during awake DCS language mapping for resection of dominant hemisphere World Health Organization grade 2 to 4 gliomas. The complexity of word tested in PN/WR tasks, patient characteristics, and tumor characteristics were compared between correct and incorrect trials. RESULTS: Between 2017 and 2021, 74 patients met inclusion criteria. At median 18.6 months of follow-up, 73.0% were alive and 52.7% remained recurrence-free. A total of 2643 PN and 978 WR trials were analyzed. A greater number of syllables in PN was associated with a higher DCS error rate (P = .001). Multivariate logistic regression found that each additional syllable in PN tasks independently increased odds of error by 2.40 (P < .001). Older age was also an independent correlate of higher error rate (P < .043). World Health Organization grade did not correlate with error rate (P = .866). More severe language impairment before surgery correlated with worse performance on more complex intraoperative tasks (P < .001). A higher error rate on PN testing did not correlate with lower extent of glioma resection (P = .949). CONCLUSION: Word complexity, quantified by the number of syllables, is associated with higher error rates for intraoperative PN tasks but does not affect extent of resection.

Use of minimally invasive ultrasound transducer during tubular microdiscectomy.

Minimally invasive ultrasound during tubular microdiscectomy is novel. The authors report the technique during surgery for L5-S1 herniated disc. Ultrasound provided real-time visualization of the pathology and neural elements. After discectomy and tactile assessment, ultrasound showed decompression of the thecal sac and traversing nerve root. The patient tolerated the procedure well, with resolution of preoperative pain and strength improvement. Postoperative MRI revealed a residual asymptomatic disc fragment that was retrospectively identified on ultrasonography. Minimally invasive ultrasound could become a useful supplement to direct visual and tactile assessment during tubular microdiscectomy, but further experience with surgical anatomy on ultrasound is required. The video can be found here: https://stream.cadmore.media/r10.3171/2024.1.FOCVID23206.

Performance of the IMPACT and CRASH prognostic models for traumatic brain injury in a contemporary multicenter cohort: a TRACK-TBI study.

OBJECTIVE: The International Mission on Prognosis and Analysis of Clinical Trials in Traumatic Brain Injury (IMPACT) and Corticosteroid Randomization After Significant Head Injury (CRASH) prognostic models for mortality and outcome after traumatic brain injury (TBI) were developed using data from 1984 to 2004. This study examined IMPACT and CRASH model performances in a contemporary cohort of US patients. METHODS: The prospective 18-center Transforming Research and Clinical Knowledge in Traumatic Brain Injury (TRACK-TBI) study (enrollment years 2014-2018) enrolled subjects aged ≥ 17 years who presented to level I trauma centers and received head CT within 24 hours of TBI. Data were extracted from the subjects who met the model criteria (for IMPACT, Glasgow Coma Scale [GCS] score 3-12 with 6-month Glasgow Outcome Scale-Extended [GOSE] data [n = 441]; for CRASH, GCS score 3-14 with 2-week mortality data and 6-month GOSE data [n = 831]). Analyses were conducted in the overall cohort and stratified on the basis of TBI severity (severe/moderate/mild TBI defined as GCS score 3-8/9-12/13-14), age (17-64 years or ≥ 65 years), and the 5 top enrolling sites. Unfavorable outcome was defined as GOSE score 1-4. Original IMPACT and CRASH model coefficients were applied, and model performances were assessed by calibration (intercept [< 0 indicated overprediction; > 0 indicated underprediction] and slope) and discrimination (c-statistic). RESULTS: Overall, the IMPACT models overpredicted mortality (intercept -0.79 [95% CI -1.05 to -0.53], slope 1.37 [1.05-1.69]) and acceptably predicted unfavorable outcome (intercept 0.07 [-0.14 to 0.29], slope 1.19 [0.96-1.42]), with good discrimination (c-statistics 0.84 and 0.83, respectively). The CRASH models overpredicted mortality (intercept -1.06 [-1.36 to -0.75], slope 0.96 [0.79-1.14]) and unfavorable outcome (intercept -0.60 [-0.78 to -0.41], slope 1.20 [1.03-1.37]), with good discrimination (c-statistics 0.92 and 0.88, respectively). IMPACT overpredicted mortality and acceptably predicted unfavorable outcome in the severe and moderate TBI subgroups, with good discrimination (c-statistic ≥ 0.81). CRASH overpredicted mortality in the severe and moderate TBI subgroups and acceptably predicted mortality in the mild TBI subgroup, with good discrimination (c-statistic ≥ 0.86); unfavorable outcome was overpredicted in the severe and mild TBI subgroups with adequate discrimination (c-statistic ≥ 0.78), whereas calibration was nonlinear in the moderate TBI subgroup. In subjects ≥ 65 years of age, the models performed variably (IMPACT-mortality, intercept 0.28, slope 0.68, and c-statistic 0.68; CRASH-unfavorable outcome, intercept -0.97, slope 1.32, and c-statistic 0.88; nonlinear calibration for IMPACT-unfavorable outcome and CRASH-mortality). Model performance differences were observed across the top enrolling sites for mortality and unfavorable outcome. CONCLUSIONS: The IMPACT and CRASH models adequately discriminated mortality and unfavorable outcome. Observed overestimations of mortality and unfavorable outcome underscore the need to update prognostic models to incorporate contemporary changes in TBI management and case-mix. Investigations to elucidate the relationships between increased survival, outcome, treatment intensity, and site-specific practices will be relevant to improve models in specific TBI subpopulations (e.g., older adults), which may benefit from the inclusion of blood-based biomarkers, neuroimaging features, and treatment data.

Resection of a Recurrent Lumbar Chordoma With Intradural Extension and Complex Dural Repair: 2-Dimensional Operative Video.

Chordomas are derived from embryonic notochord remnants and comprise 1%-4% of all bone tumors.1 Nearly all chordomas arise in the axial skeleton, with 50% in the sacrococcygeal region, 35% in the skull base and 15% within mobile spine vertebrae.1,2 Regional recurrence after en bloc surgery is common and 30%-40% of patients develop metastatic disease.3-6 In this operative video, we present a 41-year old man who previously underwent en bloc lateral L1 corpectomy and received high-dose hybrid photon and proton radiation therapy for treatment of his L1 chordoma. On surveillance imaging, 2 years post op MRI revealed recurrence of the chordoma, now extending to the L2-3 epidural space. Further radiation alone was considered but was not performed due to lack of separation between the tumor and neural elements, thus increasing the risk of radiation-induced neurological injury. Combination revision surgical resection with subsequent boost radiation therapy was pursued instead. The technical nuances to achieve complex ventral and dorsal dural repair after removal of a transdural lumbar chordoma are shown in detail. Postoperatively, the patient had no new neurological deficits. At 13 months postoperatively, he reports no new pain, can ambulate without assistance, and completed 33 treatments of radiation therapy with proton beam. The patient consented to the procedure and to the publication of his image.

Trans-Sternal Multilevel Corpectomy for Cervicothoracic Renal Cell Metastasis: 2-Dimensional Operative Video.

The operative management of pathological fractures at the cervicothoracic junction is a surgical challenge. Here, we present the case of a 48-year-old male patient presenting with 2 months of progressive left upper extremity weakness as well as back and bilateral arm pain (Karnofsky Performance Status 60%) who was found to have pathological fractures from C7, T1, and T2 due to metastatic renal cell carcinoma. Renal cell carcinoma is known to metastasize to bone and cause cord compression.1 Given the extensive metastasis with this highly vascular tumor, endovascular embolization was performed preoperatively to minimize intraoperative blood loss.2 Surgical management consisted of a two-stage procedure. Posterior spinal fusion from C2-T7 with C7-T2 decompression was performed during stage 1. Stage 2 consisted of a trans-sternal approach for C7, T1, and T2 corpectomy for cord decompression and placement of a cage and plate for anterior column support.3 Although prior surgeons have suggested to access upper thoracic pathology through an interaortocaval window, in this case we demonstrate a trans-sternal approach to C6-T3 that starts superior to the innominate vein and aortic arch and angles inferiorly dorsal to these vascular structures.4 When planning for a manubriotomy/trans-sternal approach, access to T1/T2 remains the most decisive factor and is most successful with a sternotomy.5 At 12-month follow-up, the patient demonstrated improvement in his left upper extremity strength and overall functional status (3/5 strength in hand grip and interossei with 5/5 in all remaining motor groups; Karnofsky Performance Status 80%). The patient consented to participate in the surgery and surgical video.

Real-Time Intraoperative Ultrasound Using a Minimally Invasive Transducer During Anterior Cervical Spine Surgery.

BACKGROUND AND OBJECTIVES: Intraoperative ultrasound (IOUS) during anterior cervical surgery is hindered by large transducer size and small operative corridor. We hypothesized that a linear (minimally invasive) transducer designed for transsphenoidal surgery can visualize the spinal cord, nerve roots, and surrounding structures during anterior cervical approaches, facilitating intraoperative assessment of central and foraminal decompression. METHODS: IOUS was used to evaluate 26 levels in 17 patients (15 anterior cervical discectomy and fusion, 1 corpectomy, 1 arthroplasty) with a linear probe (7 × 6-mm end-fire transducer, 150-mm length, 12-15 MHz). After pin-based distraction, discectomy, and posterior longitudinal ligament resection, IOUS assessed adequacy of cord decompression and, following proximal foraminotomy or uncinectomy, nerve root decompression. If indicated, additional decompression was completed. Criteria for adequate central and foraminal decompression were visualization of subarachnoid space around the cord and cerebrospinal fluid pulsatility along the root sleeve/absence of nerve root compression distal to the root sleeve, respectively. RESULTS: IOUS successfully visualized the cord, nerve roots, and surrounding structures in all 26 levels and influenced management in 11 levels (42.3%). IOUS indicated persistent cord and nerve root compression in 2 and 7 levels, respectively. Planned uncinectomy was aborted in 2 levels after IOUS demonstrated adequate nerve root decompression with intervertebral distraction/proximal foraminotomy alone. IOUS identified persistent nerve root compression after initial proximal foraminotomy in 4 levels and uncinectomy in 2 levels. An unplanned uncinectomy was performed in 1 level after IOUS showed persistent nerve root compression after multiple iterations of proximal foraminotomy. At follow-up (mean 3.1 months), the mean improvement in Numeric Rating Scale neck and arm pain, Neck Disability Index, and modified Japanese Orthopedic Association was 4.0%, 3.2%, 3.7%, and 0.7%, respectively. CONCLUSION: The neural elements and their relationships to surrounding bone/soft tissue can be visualized using a minimally invasive IOUS transducer during anterior cervical surgery without having to remove pin-based distraction. This allows surgeons to intraoperatively verify the extent of central and foraminal decompression.

Systematic review and meta-analysis of topical tranexamic acid in spine surgery.

OBJECTIVE: Tranexamic acid (TXA) is an antifibrinolytic drug associated with reduced blood loss in a range of surgical specialties, including neurosurgery, orthopedic surgery, and cardiac surgery. Concerns about venous thromboembolism and seizures from intravenous (IV) TXA have led to increased use of topical TXA. Given the relative scarcity of the literature on topical TXA compared with that on IV TXA within neurosurgery, the authors aimed to conduct a systematic review and meta-analysis on the safety, efficacy, and optimal administration of topical TXA in a wide range of spinal procedures and pathologies. METHODS: The PRISMA guidelines, Cochrane risk of bias tool, and Newcastle-Ottawa Scale were used to extract randomized controlled trials and high-quality case-control and cross-sectional/cohort studies (adult studies only) from PubMed, Web of Science, Cochrane Library, and Embase published between 2016 and 2023. Studies were analyzed by two independent reviewers for variables including dosage, TXA administration route, type of spine procedure, blood loss, adverse events including thromboembolism and infection, postoperative hemoglobin level, and hospitalization length. Pooled analysis comparing intraoperative and postoperative blood loss, postoperative hemoglobin levels, and hospitalization length of stay on the basis of route of TXA administration was conducted. RESULTS: Four cohort studies, 1 cross-sectional study, 1 case-control study, and 12 randomized controlled trials, together involving 2045 patients, were included. The most common route of topical TXA administration was via TXA in saline solution. Other routes of topical TXA included retrograde injection and TXA-soaked Gelfoam. In pooled analysis, topical TXA significantly reduced visible blood loss (standardized mean difference [SMD] -0.22, 95% CI -0.45 to -0.00001), postoperative blood loss (SMD -1.63, 95% CI -2.03 to -1.22), and length of hospital stay (SMD -1.02, 95% CI -1.42 to -0.61), as well as higher postoperative hemoglobin (SMD 0.59, 95% CI 0.34-0.83), compared with non-TXA controls. No significant differences in outcomes were found between topical and IV TXA or between combined (topical and IV) and IV TXA. Thromboembolism and infection rates did not significantly differ between any TXA administration group and non-TXA controls. CONCLUSIONS: In pooled analyses, topical TXA was associated with decreased perioperative blood loss in a wide range of scenarios, including cervical spine surgery and thoracolumbar trauma, as well as in patients with a thromboembolic history.

Surgical resection of lumbar intradural metastatic renal cell carcinoma.

A 60-year-old male with renal cell carcinoma (RCC) presented with back pain, weakness, and bowel and bladder urgency. MRI demonstrated a cauda equina tumor at L2. Following L1-3 laminectomies, intraoperative ultrasound localized the tumor. After dural opening, a vascular tumor was adherent to the cauda equina. Intraoperative nerve stimulation helped to identify the nerve rootlets. Tumor was removed in a piecemeal fashion. Tumor dissection caused periodic spasms in L1-3 distributions. A neuromonitoring checklist was used to recover motor evoked potential signals with elevated mean arterial pressures. Hemostasis was challenging with the vascular tumor. Intraoperative ultrasound confirmed tumor debulking. Pathology confirmed metastatic RCC.

Three-level ACDF versus 3-level laminectomy and fusion: are there differences in outcomes? An analysis of the Quality Outcomes Database cervical spondylotic myelopathy cohort.

OBJECTIVE: The authors sought to compare 3-level anterior with posterior fusion surgical procedures for the treatment of multilevel cervical spondylotic myelopathy (CSM). METHODS: The authors analyzed prospective data from the 14 highest enrolling sites of the Quality Outcomes Database CSM module. They compared 3-level anterior cervical discectomy and fusion (ACDF) and posterior cervical laminectomy and fusion (PCF) surgical procedures, excluding surgical procedures crossing the cervicothoracic junction. Rates of reaching the minimal clinically important difference (MCID) in patient-reported outcomes (PROs) were compared at 24 months postoperatively. Multivariable analyses adjusted for potential confounders elucidated in univariable analysis. RESULTS: Overall, 199 patients met the inclusion criteria: 123 ACDF (61.8%) and 76 PCF (38.2%) patients. The 24-month follow-up rates were similar (ACDF 90.2% vs PCF 92.1%, p = 0.67). Preoperatively, ACDF patients were younger (60.8 ± 10.2 vs 65.0 ± 10.3 years, p < 0.01), and greater proportions were privately insured (56.1% vs 36.8%, p = 0.02), actively employed (39.8% vs 22.8%, p = 0.04), and independently ambulatory (14.6% vs 31.6%, p < 0.01). Otherwise, the cohorts had equivalent baseline modified Japanese Orthopaedic Association (mJOA), Neck Disability Index (NDI), numeric rating scale (NRS)-arm pain, NRS-neck pain, and EQ-5D scores (p > 0.05). ACDF patients had reduced hospitalization length (1.6 vs 3.9 days, p < 0.01) and a greater proportion had nonroutine discharge (7.3% vs 22.8%, p < 0.01), but they had a higher rate of postoperative dysphagia (13.5% vs 3.5%, p = 0.049). Compared with baseline values, both groups demonstrated improvements in all outcomes at 24 months (p < 0.05). In multivariable analyses, after controlling for age, insurance payor, employment status, ambulation status, and other potential clinically relevant confounders, ACDF was associated with a greater proportion of patients with maximum satisfaction on the North American Spine Society Patient Satisfaction Index (NASS) (NASS score of 1) at 24 months (69.4% vs 53.7%, OR 2.44, 95% CI 1.17-5.09, adjusted p = 0.02). Otherwise, the cohorts shared similar 24-month outcomes in terms of reaching the MCID for mJOA, NDI, NRS-arm pain, NRS-neck pain, and EQ-5D score (adjusted p > 0.05). There were no differences in the 3-month readmission (ACDF 4.1% vs PCF 3.9%, p = 0.97) and 24-month reoperation (ACDF 13.5% vs PCF 18.6%, p = 0.36) rates. CONCLUSIONS: In a cohort limited to 3-level fusion surgical procedures, ACDF was associated with reduced blood loss, shorter hospitalization length, and higher routine home discharge rates; however, PCF resulted in lower rates of postoperative dysphagia. The procedures yielded comparably significant improvements in functional status (mJOA score), neck and arm pain, neck pain-related disability, and quality of life at 3, 12, and 24 months. ACDF patients had significantly higher odds of maximum satisfaction (NASS score 1). Given comparable outcomes, patients should be counseled on each approach's complication profile to aid in surgical decision-making.

Technical Nuances of Cervical Laminoplasty: Supplemental Manuscript to Operative Video.

STUDY DESIGN: Operative video and supplemental manuscript. OBJECTIVE: The technical nuances of open-door laminoplasty are described. Potential complications of open-door laminoplasty and strategies for their minimization are discussed. SUMMARY OF BACKGROUND DATA: Cervical laminoplasty may be indicated in patients with cervical myelopathy due to cervical stenosis in the setting of spondylosis, ossification of the posterior longitudinal ligament, congenital stenosis, and traumatic central cord syndrome. METHODS: A video illustrates the nuances of the surgical technique for cervical laminoplasty. RESULTS: Myelopathic patients with preserved lordotic sagittal profile, central stenosis involving several levels, and minimal to no axial neck pain are ideal candidates for laminoplasty. CONCLUSIONS: Cervical laminoplasty provides more stability compared with laminectomy alone and a better range of motion compared with laminectomy with posterior spinal fusion. Understanding the nuances of laminoplasty may help surgeons to avoid complications.

The COVID-19 Pandemic as an Opportunity for Operational Innovation at 2 Student-Run Free Clinics.

The onset of the COVID-19 pandemic and subsequent county shelter-in-place order forced the Cardinal Free Clinics (CFCs), Stanford University's 2 student-run free clinics, to close in March 2020. As student-run free clinics adhering to university-guided COVID policies, we have not been able to see patients in person since March of 2020. However, the closure of our in-person operations provided our student management team with an opportunity to innovate. In consultation with Stanford's Telehealth team and educators, we rapidly developed a telehealth clinic model for our patients. We adapted available telehealth guidelines to meet our patient care needs and educational objectives, which manifested in 3 key innovations: reconfigured clinic operations, an evidence-based social needs screen to more effectively assess and address social needs alongside medical needs, and a new telehealth training module for student volunteers. After 6 months of piloting our telehealth services, we believe that these changes have made our services and operations more robust and provided benefit to both our patients and volunteers. Despite an uncertain and evolving public health landscape, we are confident that these developments will strengthen the future operations of the CFCs.

Cellular Control of Viscosity Counters Changes in Temperature and Energy Availability.

Cellular functioning requires the orchestration of thousands of molecular interactions in time and space. Yet most molecules in a cell move by diffusion, which is sensitive to external factors like temperature. How cells sustain complex, diffusion-based systems across wide temperature ranges is unknown. Here, we uncover a mechanism by which budding yeast modulate viscosity in response to temperature and energy availability. This "viscoadaptation" uses regulated synthesis of glycogen and trehalose to vary the viscosity of the cytosol. Viscoadaptation functions as a stress response and a homeostatic mechanism, allowing cells to maintain invariant diffusion across a 20°C temperature range. Perturbations to viscoadaptation affect solubility and phase separation, suggesting that viscoadaptation may have implications for multiple biophysical processes in the cell. Conditions that lower ATP trigger viscoadaptation, linking energy availability to rate regulation of diffusion-controlled processes. Viscoadaptation reveals viscosity to be a tunable property for regulating diffusion-controlled processes in a changing environment.