Faculty Bibliography

STUDY DESIGN/METHODS:Retrospective analysis of a multicenter series of deformity patients undergoing thoracolumbar instrumentation to the pelvis. OBJECTIVE:Introduce the C2 coronal angle (C2C) as a novel metric, assess its association with quality-of-life and neck-specific outcomes, and compare the strength of this association with the traditional linear C7-CSVL offset. SUMMARY OF BACKGROUND DATA/BACKGROUND:While assessment of the sagittal plane incorporates vertebropelvic angles for surgical planning, angular coronal measurements have not been evaluated as predictors of patient-reported outcomes following adult spinal deformity (ASD) surgery. METHODS:Demographics, comorbidities, and radiographic parameters were collected preoperatively and at 2-year follow-up. Coronal angles were measured between CSVL and the center of the C2 body (C2C). Primary endpoints were patient‑reported outcomes at two years (SRS‑22, SF‑36, NDI) and whether patients achieved the minimal clinically important difference (MCID). Univariable and multivariable regression models examined the relationship between C2C and PROMs. An ROC analysis with Youden's Index identified optimal C2C thresholds for predicting NDI >20. RESULTS:Among 328 patients (mean age 64.0 years, 12.6 levels fused), postoperative absolute C2C was independently associated with PROMs. Each 1° increase in C2C was associated with decreased 2-yr SRS-Total (P=0.014) and activity (P=0.024), pain (P=0.033), and mental health (P=0.029) subdomains. Each 1° increase reduced odds of achieving NDI MCID by 34% (OR=0.66, P=0.022). ROC identified an optimal C2C threshold of 3.5°. Patients exceeding this had nearly twice the odds of neck disability (OR=1.90, P=0.049) and significantly lower SF-36 Physical Component (P=0.004) and Physical Functioning (P=0.011) scores. C2C was more strongly associated with SRS-Total than C7-CSVL (AIC=657 vs. 660; adj. R²=0.058 vs.0.048). CONCLUSIONS:Achieving postoperative C2C ≤3.5° is independently associated with reduced neck disability and optimized quality of life after ASD surgery. C2C was more strongly associated with SRS-Total than C7-CSVL and could be considered as a complementary measure of coronal alignment.

OBJECTIVE:To evaluate the impact of prolonged unaided duration of deafness (DoD) on speech perception outcomes following cochlear implantation in adults. METHODS:A retrospective review was performed of adult cochlear implant recipients at a single high-volume center between 2012 and 2023. Patients with ≥ 5 years of documented unaided deafness meeting cochlear implant (CI) criteria were stratified into three groups (5-9, 10-19, and ≥ 20 years DoD). The primary outcome was CNC word recognition scores at 3 and 12 months post-operatively. RESULTS:Forty-one patients met inclusion criteria. At 3 months, patients with ≥ 20 years DoD demonstrated lower CNC word recognition scores compared with shorter duration groups. No significant differences were observed between groups at 12 months. Patients without measurable pre-operative hearing thresholds were more likely to be device non-users or fail to achieve open-set speech perception. CONCLUSION/CONCLUSIONS:Patients demonstrated meaningful speech perception outcomes across a range of deafness durations, though longer DoD was associated with slower early improvement. Absence of measurable pre-operative hearing thresholds may identify a subgroup at higher risk for limited functional benefit and should be considered during pre-operative counseling.

Sensory processing is fundamentally shaped by stimulation history. For example, in visual cortex, neural responses are reduced for repeated or sustained stimuli (adaptation). These phenomena are well characterized and effectively modeled by divisive normalization. We asked whether these same computational principles govern somatosensory processing. We used fMRI (6 participants, all female) and intracranial electroencephalography (iEEG, 2 participants, both male) to measure responses to time-varying vibrotactile stimuli in human somatosensory cortex. Stimuli consisted of single- and paired-pulses with durations and interstimulus intervals ranging from 0.05 to 1.2 s. We extracted BOLD time courses to capture neural response amplitudes, and high-frequency iEEG broadband envelopes to capture fast neural dynamics. In both experiments, we observed pronounced sub-additive temporal summation. Responses to longer or repeated stimuli were consistently lower than predicted by linear integration. Computational modeling revealed that divisive normalization models outperformed linear models in cross-validated accuracy across both datasets. These results demonstrate that somatosensory temporal dynamics closely mirror those in the visual system. Our findings suggest that the nervous system employs similar computational principles across modalities to encode sensory information across time.Significance statement How the brain integrates sensory information over time is a fundamental question in neuroscience. While nonlinear temporal integration is well documented in visual cortex, it has not been extensively mapped in the human somatosensory system. By combining fMRI with intracranial EEG in humans, we demonstrate that somatosensory responses to tactile stimulation exhibit subadditive temporal summation. This nonlinearity is accurately captured by a divisive normalization model, matching observations in the visual system. Our results suggest that normalization is a canonical computation shared across different modalities to manage temporal dynamics, providing a unified framework for understanding how the brain encodes dynamic sensory stimuli.

INTRODUCTION/BACKGROUND:Nonacute subdural hematomas (nSDH) are common yet serious extra-axial hemorrhages that result in significant morbidity and mortality. Middle meningeal artery (MMA) embolization (MMAE) is a recent endovascular treatment that involves occlusion of the MMA, inducing hemostasis in and around the hematoma. While many aspects of MMAE have been explored, there is currently limited data on the optimal extent of embolization. OBJECTIVE:To determine whether single or multiple pedicle embolization of the MMA is superior in inducing hemostasis in nSDH. METHODS:We compared single versus multi pedicle embolization by a retrospective multicenter analysis of nSDH patients who underwent MMAE between 2019 and 2024 at participating centers in the MESH (MMA Embolization for Subdural Hematoma) Registry. 679 patients who received a liquid embolic agent with branch-level embolization data were included. RESULTS:While multi-pedicle embolization hastened nSDH thinning at 1 month (5.7 vs. 3.3 mm reduction; difference 2.4 mm, 95% CI 1.0-3.8; P = .002), by 3 months thickness reduction had converged between groups (8.2 vs. 8.4 mm; P = .91). Among 679 patients (456 multi-pedicle, 223 single-pedicle), favorable functional outcome (mRS 0-2) was more frequent with multi-pedicle embolization (53.5% vs. 43.0%; adjusted OR 1.81, 95% CI 1.26-2.60; P = .001), whereas recurrence, rescue surgery, and treatment failure did not differ. CONCLUSION/CONCLUSIONS:Future, multi-center randomized prospective trials are warranted to address confounding variables that limit this observational study. Follow-up beyond 3 months was limited, so durability is unknown.

INTRODUCTION/BACKGROUND:Predicting post-operative changes in thoracic kyphosis (TK) remains challenging in adult spinal deformity (ASD) surgery. This study aimed to quantify both iatrogenic and reciprocal changes in TK following lumbar correction and assess their maintenance at 2-year follow-up. METHODS:A retrospective analysis was performed on 356 ASD patients treated with posterior instrumentation from T9-11 to the pelvis, with a minimum 2-year follow-up. TK values were compared with normative data. Multivariate analysis identified thoracolumbar parameters associated with reciprocal thoracic changes and proximal failure. RESULTS:=0.40). Between 6 weeks and 2 years, 9.3% experienced TK decompensation >15°, and 9.6% required proximal extension for junctional issues-defined collectively as "thoracic failures" (17.4%). Independent predictors of failure included advanced age (OR 3.6), more proximal lumbar correction (OR 1.9), and pronounced early mid-thoracic kyphosis (OR 2.3). CONCLUSION/CONCLUSIONS:In ASD surgery with Upper Instrumented Vertebra (UIV) between T9 and T11, changes in TK were largely proportional to lumbar correction, leading to normalization in most cases. However, age, the location of lumbar correction, and early post-operative thoracic shape independently predicted thoracic failure, highlighting the need for tailored alignment strategies.

Recent research has used large language models (LLMs) to study the neural basis of naturalistic language processing in the human brain. LLMs have rapidly grown in complexity, leading to improved language processing capabilities. Here, we utilized several families of transformer-based LLMs to investigate the relationship between model size and their ability to capture linguistic information in the human brain. Crucially, a subset of LLMs were trained on a fixed training set, enabling us to dissociate model size from architecture and training set size. We used electrocorticography (ECoG) to measure neural activity in epilepsy patients while they listened to a 30 min naturalistic audio story. We fit electrode-wise encoding models using contextual embeddings extracted from each hidden layer of the LLMs to predict word-level neural signals. In line with prior work, we found that larger LLMs better capture the structure of natural language and better predict neural activity. We also found a logarithmic relationship where the encoding performance peaks in relatively earlier layers as model size increases. We also observed variations in the best-performing layer across different brain regions, corresponding to an organized language processing hierarchy.

BackgroundThe use of carbon fiber-reinforced polyetheretherketone (CFR-PEEK) instrumentation in spinal surgery has emerged as an alternative to traditional titanium-based implants in recent years. This study aims to evaluate the use and performance of carbon fiber instrumentation in patients with primary spinal tumors focusing on adverse event (AE) risk, overall survival and oncologic outcomes.MethodsData were collected from the AO Spine Primary Tumor Research and Outcomes Network (PTRON), a multicenter international registry. The primary endpoint was the incidence of AEs, while secondary endpoints included the risk of developing at least one AE, overall survival, local tumor control, and disease progression.ResultsA total of 359 patients enrolled in the PTRON registry met the inclusion criteria and were included in the study. Among them, 84 receiving carbon fiber implants (23%), 243 titanium implants (68%), and 32 a combination of both (9%). Median follow-up times were 1.9 years (IQR: 0.4-3.0), 1.3 years (IQR: 0.5-2.4) and 1.1 years (IQR: 0.5-1.7), in the carbon fiber, titanium and combination groups, respectively. The estimated risk of having at least one postoperative AE, including construct failures with and without loss of correction, wound infection (deep or superficial), non-union and wound dehiscence, was statistically comparable between patients receiving carbon fiber, titanium or a combination of both carbon fiber and titanium implants (P > 0.05). Kaplan-Meier survival analyses and multivariable Cox proportional hazards models showed no significant differences in overall survival, recurrence-free survival, or progression-free survival between the implant groups.ConclusionCarbon fiber spinal implants demonstrate a comparable safety and oncologic profile to traditional titanium implants while allowing for improved tumor surveillance and easier radiation delivery.

Current predictive models for pregnancy and infant outcomes often focus on limited endpoints and rely on costly tests or imaging. Here we developed the Mother-Child AI Agent (MoChiAgent), an LLM-based clinical assistant that orchestrates multiple tools to integrate sequential electronic health record (EHR) data, including routine laboratory tests, for forecasting maternal and infant diseases. MoChiAgent's core predictive engine, MoChiFormer, was developed and internally evaluated using 4,401,599 longitudinal clinical visits and externally validated using independent maternal and infant cohorts consisting of 263,452 and 23,192 visits, respectively. MoChiFormer reconstructs missing laboratory values, reduces batch effects and learns EHR representations that support gestational, fetal and infant age estimation, health-trajectory modelling and stratification of current and future disease risk. Subsequently, a Knowledge Search Tool utilizes these forecasts to retrieve evidence-based intervention and treatment recommendations from curated medical literature and authoritative guidelines. For maternal health, MoChiFormer accurately identified key gestational conditions, achieving AUROCs of 0.89 for placental abruption, 0.89 for premature rupture of membranes, and 0.91 for preterm labour. Analysis of paired mother-infant data further revealed transgenerational risk associations, with infants born to mothers in specific clusters showing substantially elevated risks of neonatal jaundice (HR = 2.81, 95% CI 2.60-3.03) and haematological diseases (HR = 2.83, 95% CI 2.62-3.05). Integrating maternal gestational EHRs with infant records improved prediction of infant conditions, including chromosomal abnormalities and respiratory disorders. These findings suggest that MoChiAgent can provide clinically relevant, actionable decision-support information to enhance risk-stratified care for mothers and infants.

Grief is an under-recognized yet pervasive experience in neurosurgery, arising not only from the death of patients and loved ones but also from losses related to professional identity, health, and personal relationships. Despite its relevance, grief is often conflated with burnout or overlooked entirely within surgical culture. When personal adversity strikes, such as loss, illness, or major life upheaval, the intensity of neurosurgical practice can amplify these challenges, influencing professional identity, performance, and overall resilience. As the field continues to evolve and diversify, it is increasingly important to foster open dialogue about vulnerability, personal hardship, and life beyond the operating room. This perspective examines how neurosurgeons experience and process loss, distinguishing grief from burnout and resilience, and highlighting the need for institutional and cultural change.

OBJECTIVE:To evaluate cochlear implant (CI) speech perception and usage outcomes in patients after prolonged unilateral deafness. METHODS:Retrospective cohort study at five tertiary academic centers of adult patients with prolonged (> 10 years) unilateral severe to profound hearing loss who underwent cochlear implantation. Main outcome measures included post-operative word recognition scores (WRSs) and average daily usage of CI. RESULTS:A total of 68 patients were analyzed with a median duration of unilateral deafness of 17 years (IQR, 12-35 years). The mean individual average daily CI usage was 8.4 h (SD, 4.5 h) at ≤ 1 year after implantation and 7.1 h (SD, 5.0 h) at > 1 year. The majority of patients (54.5%, 30 patients) had an absolute increase in WRS of ≥ 20% after implantation and 32.7% (18 patients) had an absolute increase of ≥ 50%. Univariate analysis comparing pre- and post-operative speech recognition in patients who completed the same test revealed a clinically and statistically significant improvement, with a mean change of 28.4% (SD 31.6%; p < 0.001) at their latest audiogram. In the analysis excluding those without post-operative data, duration of deafness was not predictive of post-CI WRS on multivariable analysis. CONCLUSIONS:Most patients with prolonged unilateral auditory deprivation in our study benefited from a CI. Although the duration of auditory deprivation was found to be inconsistently associated with poorer CI speech perception performance, our findings support individualized CI candidacy assessment and suggest that prolonged deafness alone should not be used as an absolute exclusion criterion for cochlear implantation.