Stimulating native seizures with neural resonance: a new approach to localize the seizure onset zone.

Successful outcomes in epilepsy surgery rely on the accurate localization of the seizure onset zone. Localizing the seizure onset zone is often a costly and time-consuming process wherein a patient undergoes intracranial EEG monitoring, and a team of clinicians wait for seizures to occur. Clinicians then analyse the intracranial EEG before each seizure onset to identify the seizure onset zone and localization accuracy increases when more seizures are captured. In this study, we develop a new approach to guide clinicians to actively elicit seizures with electrical stimulation. We propose that a brain region belongs to the seizure onset zone if a periodic stimulation at a particular frequency produces large amplitude oscillations in the intracranial EEG network that propagate seizure activity. Such responses occur when there is 'resonance' in the intracranial EEG network, and the resonant frequency can be detected by observing a sharp peak in the magnitude versus frequency response curve, called a Bode plot. To test our hypothesis, we analysed single-pulse electrical stimulation response data in 32 epilepsy patients undergoing intracranial EEG monitoring. For each patient and each stimulated brain region, we constructed a Bode plot by estimating a transfer function model from the intracranial EEG 'impulse' or single-pulse electrical stimulation response. The Bode plots were then analysed for evidence of resonance. First, we showed that when Bode plot features were used as a marker of the seizure onset zone, it distinguished successful from failed surgical outcomes with an area under the curve of 0.83, an accuracy that surpassed current methods of analysis with cortico-cortical evoked potential amplitude and cortico-cortical spectral responses. Then, we retrospectively showed that three out of five native seizures accidentally triggered in four patients during routine periodic stimulation at a given frequency corresponded to a resonant peak in the Bode plot. Last, we prospectively stimulated peak resonant frequencies gleaned from the Bode plots to elicit seizures in six patients, and this resulted in an induction of three seizures and three auras in these patients. These findings suggest neural resonance as a new biomarker of the seizure onset zone that can guide clinicians in eliciting native seizures to more quickly and accurately localize the seizure onset zone.

Graph theoretical analysis of evoked potentials shows network influence of epileptogenic mesial temporal region.

It is now widely accepted that seizures arise from the coordinated activity of epileptic networks, and as a result, traditional methods of analyzing seizures have been augmented by techniques like single-pulse electrical stimulation (SPES) that estimate effective connectivity in brain networks. We used SPES and graph analytics in 18 patients undergoing intracranial EEG monitoring to investigate effective connectivity between recording sites within and outside mesial temporal structures. We compared evoked potential amplitude, network density, and centrality measures inside and outside the mesial temporal region (MTR) across three patient groups: focal epileptogenic MTR, multifocal epileptogenic MTR, and non-epileptogenic MTR. Effective connectivity within the MTR had significantly greater magnitude (evoked potential amplitude) and network density, regardless of epileptogenicity. However, effective connectivity between MTR and surrounding non-epileptogenic regions was of greater magnitude and density in patients with focal epileptogenic MTR compared to patients with multifocal epileptogenic MTR and those with non-epileptogenic MTR. Moreover, electrodes within focal epileptogenic MTR had significantly greater outward network centrality compared to electrodes outside non-epileptogenic regions and to multifocal and non-epileptogenic MTR. Our results indicate that the MTR is a robustly connected subnetwork that can exert an overall elevated propagative influence over other brain regions when it is epileptogenic. Understanding the underlying effective connectivity and roles of epileptogenic regions within the larger network may provide insights that eventually lead to improved surgical outcomes.

Predictors of Infectious Complications after Targeted Prophylaxis for Prostate Needle Biopsy.

PURPOSE: The incidence of infectious complications after transrectal ultrasound guided prostate needle biopsy is rising. We sought to identify the incidence and predictors of infection in a large cohort of men undergoing biopsy who receive targeted prophylaxis. MATERIALS AND METHODS: We retrospectively reviewed the records of 5,214 consecutive patients who underwent transrectal ultrasound guided prostate needle biopsy from January 2013 to December 2014 at UroPartners, a large urology group comprising 28 clinics in metropolitan Chicago. At 1 microbiology laboratory all swabs were processed, the presence of fluoroquinolone resistant gram-negative rods was identified and sensitivity tests were performed. Prophylaxis for biopsy was guided by rectal swab culture. Characteristics of patients with and without infectious complications were compared using the Kruskal-Wallis and chi-square tests. Multivariable logistic regression was done to determine predictors of infectious complications. Analyses were performed with R, version 2.14.2 (https://www.r-project.org/). RESULTS: Of the 5,214 biopsies performed 56 infectious (1.1%) and 24 sepsis complications (0.46%) were found. On univariable analysis nonCaucasian race and fluoroquinolone resistant microbes were predictors of infection (p <0.05). On multivariable analysis fluoroquinolone resistant rectal vault flora (OR 9.98, 95% CI 3.79-26.3) and the number of biopsy cores taken (OR 1.28 per core, 95% CI 1.04-1.54) were independent predictors of infection. CONCLUSIONS: Despite targeted prophylaxis patients with fluoroquinolone resistant rectal vault flora have higher odds of infectious complications following transrectal ultrasound guided prostate needle biopsy. In these patients one should consider using other biopsy approaches or techniques to minimize risk.

Preoperative factors associated with failure in unstented primary ureteroscopy for nephrolithiasis.

INTRODUCTION: Primary ureteroscopy for nephrolithiasis is often completed without prior ureteral stenting. However, failure can occur due to inability to access the stone, requiring ureteral stenting for passive dilation and a second procedure. This typically results in increased morbidity due to a prolonged period of ureteral stenting and subsequent stent related symptoms. Patient counseling preoperatively is important to discuss the risk of failure. MATERIALS AND METHODS: We reviewed all primary ureteroscopies for nephrolithiasis performed by four urologists at our institution from November 2007 to November 2016. Univariate analysis was performed to compare groups with Chi squared analysis, Fisher's exact test, Student's t-tests and Mann-Whitney U test as appropriate. Binomial logistic regression was then performed analyzing the statistically significant univariate factors. RESULTS: Failure rate for accessing the unstented ureter was 6.04% (30/497). Thirty ureteroscopies were identified who failed without prior ureteral stenting. A total of 422 ureteroscopies were identified with successful initial attempt with records complete for analysis. Failures were more likely to have a proximal ureteral stone (46.6% versus 23.9%). This remained significant on logistic regression. There was no difference in stone size, number of stones, age, sex, history of stones, prior abdominal or retroperitoneal surgery. Failure of primary ureteroscopy in women was associated with proximal stones (50.0% versus 20.9%) and women with a prior hysterectomy and/or oophorectomy (67.0% versus 32.0%). Both remained significant on logistic regression. Men did not have any significant factors. CONCLUSION: The vast majority of ureteroscopy is performed without prior ureteral stenting. Proximal ureteral stones appear to be the only factor associated with failure in primary ureteroscopy. Additionally, one may consider counseling women with prior hysterectomy and/or oophorectomy that they may be at increased risk of requiring a second procedure.

Inguinal hernia containing a kidney with a duplicated system: an exceptionally rare case.

An inguinal hernia is a commonly encountered surgical case, with multiple unusual contents being reported. We present an exceptionally rare case of an inguinal hernia. Computed tomography imaging of the 62-year-old male patient showed a large left inguinal hernia extending into the left scrotum that contained a duplicated left kidney. There was an associated large left hydrocele and incidental non-obstructive nephrolithiasis. Left nephropexy, left orchiectomy, and repair of the incarcerated left inguinal hernia with mesh placement via a preperitoneal (retroperitoneal) approach were performed. The patient was discharged to home on post-operative day 5 and the post-operative course was uneventful. We discuss a possible mechanism for this rare event.

Characteristics, trends, and management of Penile cancer in the United States: A population-based study.

BACKGROUND: Penile cancer (PeCa) is a rare disease. HPV infection, smoking, phimosis, and lichen sclerosus represent well-known associated risk factors. OBJECTIVES: Primary aim of our study is to evaluate the incidence and risk factors of PeCa and to outline the adopted diagnostic and therapeutic approaches. Secondary aim is to investigate risk factors associated with aggressive disease and to identify the complications arising from its surgical treatment. MATERIALS AND METHODS: We conducted a retrospective analysis using the PearlDiver™ Mariner database, from January 1, 2011, to December 31, 2021, identifying all patients diagnosed with PeCa and PeIN, evaluating comorbidities, risk factors, and social and economic conditions. We evaluated the imaging modalities employed for staging as well as the treatment strategies. Finally, we evaluated the most frequent complications associated with inguinal lymphadenectomy (ILND). RESULTS: During the study period, 17,494 patients were diagnosed with PeCa and 5,965 with penile intraepithelial neoplasia (PeIN). US was the most frequently utilized imaging modality, followed by PET and PET/CT. Use of CT and MRI was around 5%. Surgical treatment was the predominant strategy, utilized in 31.3% of PeCa and 22.9% of PeIN. Wide Local Excision/Glansectomy emerged as the most common surgical procedures. MLR analysis identified smoking as a risk factor for metastatic PeCa (OR; 95% CI = 1.49; 1.379-1.609), HPV infections were associated with a 35% decrease in risk (OR; 95% CI = 0.65; 0.562-0.744) (all P < 0.001). Lichen sclerosus and phimosis were associated with a doubled risk of demolitive surgery. Approximately 40% of patients experienced complications associated with ILND. CONCLUSION: Despite advances in PeCa management, there's no significant move toward more conservative treatments. Surgical treatments are still marked by high rates of complications, potentially affect the sexual and psychosocial health of patients. These issues may foster a tendency toward avoidance behaviors, contributing to a delayed clinical presentation and treatment.

Incidence and Management of Radiation Cystitis After Pelvic Radiotherapy for Prostate Cancer: Analysis From a National Database.

OBJECTIVE: To determine the incidence of radiation cystitis on prostate cancer (PCa) patients undergoing pelvic radiotherapy (RT), evaluating the most used management strategies, and identifying potential risk factors associated with the development of this condition. METHODS: A retrospective analysis was conducted using the PearlDiver Mariner database, containing patient records compiled between 2011 and 2022. International Classification of Diseases (ICD) and Current Procedural Terminology (CPT) codes were employed to identify population and outcomes. We evaluated patients who underwent RT for PCa and subsequently developed radiation cystitis. Primary objective was to determine the overall incidence of radiation cystitis. Furthermore, we investigated its associated risk factors and management. RESULTS: A total of 274,865 PCa patients underwent RT during the study period. Of these, 48,713 (17.7%) experienced hematuria following RT, while 7721 (2.8%) were diagnosed with radiation cystitis. After the diagnosis, 2307 patients (29.9%) received diagnostic or therapeutic endoscopic interventions. Only 59 patients (0.76%) underwent endovascular embolization, while 151 patients (1.95%) required cystectomy. Hyperbaric oxygen therapy, administered to 1287 patients (16.67%), was the only treatment that displayed a significant upward trend. Multivariate logistic regression identified obesity (OR 1.29; 95% CI 1.23-1.35), smoking (OR 1.27; 95% CI 1.22-1.33), and diabetes (OR 1.32; 95% CI 1.26-1.39), as significant risk factors for radiation cystitis (all P-values <.001). CONCLUSION: Radiation cystitis represents a rare complication after pelvic RT with significant clinical impact. Its incidence has remained stable throughout the study period. The identified risk factors corroborate the pathophysiology of radiation cystitis. Hyperbaric oxygen therapy was the only treatment to show an upward trend during the study period.

Implementation of single-port robotic urologic surgery: experience at a large academic center.

The Single-Port (SP) robotic system is increasingly being implemented in the United States, allowing for several minimally invasive urologic procedures to be performed. The present study aims to describe our single-center experience since the adoption of the SP platform. We retrospectively collected and analyzed consecutive SP cases performed at a major teaching hospital in the Midwest (Rush University Medical Center) from December 2020 to December 2023. Demographic variables were collected. Surgical and pathological outcomes were analyzed in the overall cohort and for each type of procedure. The study timeframe was divided into two periods to assess the evolution of SP technical features over time. In total, 160 procedures were performed, with robot-assisted radical prostatectomy (RARP) being the most common (49.4%). Overall, 54.4% of the procedures were extraperitoneal, with a significantly higher adoption of this approach in the second half of the study period (30% vs 74.3%, p < 0.001). A "plus one" assistant port was adopted in 38.1% of cases, with a shift towards a "pure" single-port surgery in the most recent procedures (21.1% vs 76.7%, p < 0.001). The median LOS was 33.5 h (30-48), with a rate of any grade and CD ≥ 3 postoperative complications of 9.4% and 2.5%, respectively, and a 30-day readmission rate of 1.9%. SP robotic surgery can be safely and effectively implemented for various urologic procedures. With increasing experience, the SP platform allows shifting away from transperitoneal procedures, potentially minimizing postoperative pain, and shortening hospital stay and postoperative recovery.

Single-port vs multi-port robot-assisted partial nephrectomy: A single center propensity score-matched analysis.

INTRODUCTION AND OBJECTIVES: The aim of the study is to compare key outcomes of Single-Port (SP) and Multi-Port (MP) robot-assisted partial nephrectomy (RAPN). METHODS: A retrospective analysis was conducted on our prospectively collected database of patients who underwent SP-RAPN or MP-RAPN at our institution from January 2021 to August 2023. To adjust for potential baseline pre-operative confounders, a 1:1 propensity-score matching analysis (PSMa) was performed. The primary endpoint was to compare perioperative outcomes between the two groups. The secondary endpoint was to compare the achievement of the "Trifecta" outcome (defined as negative surgical margins, absence of high-grade complications and change in eGFR values (ΔeGFR) < 10% at 6 months follow-up) in the matched cohort. RESULTS: After PSMa, 30 SP cases were matched 1:1 to 30 MP cases. In the matched cohort, there were no significant differences between SP and MP approaches in operative time, estimated blood loss, ischemia time, transfusions rate, intraoperative complications, postoperative complications, and positive surgical margin rates. Patients who underwent SP-RAPN had a shorter median length of stay [25 (IQR:24.0-34.5) vs 34 (IQR:30.2-48.0) hours, p < 0.003]. The Trifecta outcome was achieved in 16 (57%) of SP patients and 17 (63%) of MP patients (p = 0.8). CONCLUSIONS: SP-RAPN can be safely implemented in a Center with an established MP-RAPN program. Despite being early in the SP-RAPN experience, key surgical outcomes are not compromised. While offering comparable perioperative and short-term functional outcomes, SP-RAPN can translate into faster recovery and shorter LOS, paving the way for outpatient robotic surgery.

Characteristics of patients diagnosed with both melanoma and renal cell cancer.

BACKGROUND: Patients with renal cell carcinoma (RCC) and malignant melanoma (MM) have an increased risk of additional malignancies. We identified characteristics of MM and RCC associated with a patient developing both cancers. METHODS: A total of 147,656 cases of RCC and 225,548 of MM submitted to the Surveillance, Epidemiology, and End Results database between 1973 and 2008 were analyzed. Standardized incidence ratios (SIR) with 95 % confidence intervals (CI) were calculated for MM after RCC and vice versa. Clinical and pathological characteristics were compared between patients with RCC or MM only and with both cancers using multivariable proportional hazards and competing risks regression models. RESULTS: Overall 1,241 patients developed both cancers. The crude incidence rates of RCC in patients with a prior MM diagnosis and vice versa were 5.2 and 9.4 per 10,000 person-years, respectively. There was an excess of MM in RCC patients (SIR 1.45, CI 1.34-1.57) and of RCC in MM patients (SIR 1.34, CI 1.25-1.43). Median years from RCC to MM diagnosis was 4.3 (2.0-7.8) and from MM to RCC 4.7(2.3-9.9). Patients with a history of MM had more papillary RCC (10.2 vs. 4.8 %, p = 0.01) and were more likely to be female (25.9 vs. 20.5 %, p < 0.001). On multivariable analyses, ocular MM was independently associated with subsequent RCC (HR 1.76 CI 1.24-2.49), as were increasing age, and male sex. CONCLUSIONS: We confirmed a bidirectional association between RCC and MM. A history of MM was found to be associated with papillary RCC and advanced RCC. Ocular MM predicted an increased risk of RCC diagnosis. Further research is warranted into the mechanisms responsible for the association between RCC and MM.

Cortico-cortical evoked potentials in response to varying stimulation intensity improves seizure localization.

OBJECTIVE: As single pulse electrical stimulation (SPES) is increasingly utilized to help localize the seizure onset zone (SOZ), it is important to understand how stimulation intensity can affect the ability to use cortico-cortical evoked potentials (CCEPs) to delineate epileptogenic regions. METHODS: We studied 15 drug-resistant epilepsy patients undergoing intracranial EEG monitoring and SPES with titrations of stimulation intensity. The N1 amplitude and distribution of CCEPs elicited in the SOZ and non-seizure onset zone (nSOZ) were quantified at each intensity. The separability of the SOZ and nSOZ using N1 amplitudes was compared between models using responses to titrations, responses to one maximal intensity, or both. RESULTS: At 2 mA and above, the increase in N1 amplitude with current intensity was greater for responses within the SOZ, and SOZ response distribution was maximized by 4-6 mA. Models incorporating titrations achieved better separability of SOZ and nSOZ compared to those using one maximal intensity. CONCLUSIONS: We demonstrated that differences in CCEP amplitude over a range of current intensities can improve discriminability of SOZ regions. SIGNIFICANCE: This study provides insight into the underlying excitability of the SOZ and how differences in current-dependent amplitudes of CCEPs may be used to help localize epileptogenic sites.

Minimally Invasive Radical Nephroureterectomy: 5-Year Update of Techniques and Outcomes.

The gold standard treatment for non-metastatic upper tract urothelial cancer (UTUC) is represented by radical nephroureterectomy (RNU). The choice of surgical technique in performing UTUC surgery continues to depend on several factors, including the location and extent of the tumor, the patient's overall health, and very importantly, the surgeon's skill, experience, and preference. Although open and laparoscopic approaches are well-established treatments, evidence regarding robot-assisted radical nephroureterectomy (RANU) is growing. Aim of our study was to perform a critical review on the evidence of the last 5 years regarding surgical techniques and outcomes of minimally invasive RNU, mostly focusing on RANU. Reported oncological and function outcomes suggest that minimally invasive RNU is safe and effective, showing similar survival rates compared to the open approach.

A click-based electrocorticographic brain-computer interface enables long-term high-performance switch-scan spelling.

Background: Brain-computer interfaces (BCIs) can restore communication in movement- and/or speech-impaired individuals by enabling neural control of computer typing applications. Single command "click" decoders provide a basic yet highly functional capability. Methods: We sought to test the performance and long-term stability of click-decoding using a chronically implanted high density electrocorticographic (ECoG) BCI with coverage of the sensorimotor cortex in a human clinical trial participant (ClinicalTrials.gov, NCT03567213) with amyotrophic lateral sclerosis (ALS). We trained the participant's click decoder using a small amount of training data (< 44 minutes across four days) collected up to 21 days prior to BCI use, and then tested it over a period of 90 days without any retraining or updating. Results: Using this click decoder to navigate a switch-scanning spelling interface, the study participant was able to maintain a median spelling rate of 10.2 characters per min. Though a transient reduction in signal power modulation interrupted testing with this fixed model, a new click decoder achieved comparable performance despite being trained with even less data (< 15 min, within one day). Conclusion: These results demonstrate that a click decoder can be trained with a small ECoG dataset while retaining robust performance for extended periods, providing functional text-based communication to BCI users.

Stable Decoding from a Speech BCI Enables Control for an Individual with ALS without Recalibration for 3 Months.

Brain-computer interfaces (BCIs) can be used to control assistive devices by patients with neurological disorders like amyotrophic lateral sclerosis (ALS) that limit speech and movement. For assistive control, it is desirable for BCI systems to be accurate and reliable, preferably with minimal setup time. In this study, a participant with severe dysarthria due to ALS operates computer applications with six intuitive speech commands via a chronic electrocorticographic (ECoG) implant over the ventral sensorimotor cortex. Speech commands are accurately detected and decoded (median accuracy: 90.59%) throughout a 3-month study period without model retraining or recalibration. Use of the BCI does not require exogenous timing cues, enabling the participant to issue self-paced commands at will. These results demonstrate that a chronically implanted ECoG-based speech BCI can reliably control assistive devices over long time periods with only initial model training and calibration, supporting the feasibility of unassisted home use.

Urological manifestations of sarcoidosis.

PURPOSE: We describe the urological manifestations of sarcoidosis and how the disease may affect the management of multiple urological conditions. MATERIALS AND METHODS: We performed a PubMed® search using the query sarcoidosis and multiple urological terms. RESULTS: Sarcoidosis is a disease that has variable manifestations. There is often genitourinary involvement that is clinically silent. However, sarcoidosis may cause symptoms, such as nephrolithiasis, which are sometimes the first manifestation of the disease. Renal function may be affected, and appropriate recognition and treatment may avert progressive functional decline. The presence of sarcoidosis may also confound the diagnosis and staging of various urological malignancies, particularly renal and testicular carcinoma. CONCLUSIONS: Urologists should be aware of the urological manifestations of sarcoidosis to avoid misdiagnoses and the over staging of urological cancers, and to identify when it is an underlying cause of nephrolithiasis or obstructive uropathy.

Piriform Cortex Ablation Volume Is Associated With Seizure Outcome in Mesial Temporal Lobe Epilepsy.

BACKGROUND: Growing evidence suggests that piriform cortex resection during anterior temporal lobectomy is important for achieving good seizure outcome in mesial temporal lobe epilepsy (mTLE). However, the relationship between seizure outcome and piriform cortex ablation during MR-guided laser interstitial thermal therapy (MRgLITT) remains unclear. OBJECTIVE: To determine whether ablation of piriform cortex was associated with seizure outcome in patients with mTLE undergoing MRgLITT. METHODS: We performed preablation and postablation volumetric analyses of hippocampus, amygdala, piriform cortex, and ablation volumes in patients with mTLE who underwent MRgLITT at our institution from 2014 to 2019. RESULTS: Thirty nine patients with mTLE were analyzed. In univariate logistic regression, percent piriform cortex ablation was associated with International League Against Epilepsy (ILAE) class 1 at 6 months (odds ratio [OR] 1.051, 95% CI [1.001-1.117], P = .045), whereas ablation volume, percent amygdala ablation, and percent hippocampus ablation were not ( P > .05). At 1 year, ablation volume was associated with ILAE class 1 (OR 1.608, 95% CI [1.071-2.571], P = .021) while percent piriform cortex ablation became a trend (OR 1.050, 95% CI [0.994-1.109], P = .054), and both percent hippocampus ablation and percent amygdala ablation were not significantly associated with ILAE class 1 ( P > .05). In multivariable logistic regression, only percent piriform cortex ablation was a significant predictor of seizure freedom at 6 months (OR 1.085, 95% CI [1.012-1.193], P = .019) and at 1 year (OR 1.074, 95% CI [1.003-1.178], P = .041). CONCLUSION: Piriform cortex ablation volume is associated with seizure outcome in patients with mTLE undergoing MRgLITT. The piriform cortex should be considered a high yield ablation target to achieve good seizure outcome.

Effects of stimulation intensity on intracranial cortico-cortical evoked potentials: A titration study.

OBJECTIVE: The aim of the present study was to investigate the optimal stimulation parameters for eliciting cortico-cortical evoked potentials (CCEPs) for mapping functional and epileptogenic networks. METHODS: We studied 13 patients with refractory epilepsy undergoing intracranial EEG monitoring. We systematically titrated the intensity of single-pulse electrical stimulation at multiple sites to assess the effect of increasing current on salient features of CCEPs such as N1 potential magnitude, signal to noise ratio, waveform similarity, and spatial distribution of responses. Responses at each incremental stimulation setting were compared to each other and to a final set of responses at the maximum intensity used in each patient (3.5-10 mA, median 6 mA). RESULTS: We found that with a biphasic 0.15 ms/phase pulse at least 2-4 mA is needed to differentiate between non-responsive and responsive sites, and that stimulation currents of 6-7 mA are needed to maximize amplitude and spatial distribution of N1 responses and stabilize waveform morphology. CONCLUSIONS: We determined a minimum stimulation threshold necessary for eliciting CCEPs, as well as a point at which the current-dependent relationship of several response metrics all saturate. SIGNIFICANCE: This titration study provides practical, immediate guidance on optimal stimulation parameters to study specific features of CCEPs, which have been increasingly used to map both functional and epileptic brain networks in humans.

Spatial-Temporal Functional Mapping Combined With Cortico-Cortical Evoked Potentials in Predicting Cortical Stimulation Results.

Functional human brain mapping is commonly performed during invasive monitoring with intracranial electroencephalographic (iEEG) electrodes prior to resective surgery for drug- resistant epilepsy. The current gold standard, electrocortical stimulation mapping (ESM), is time -consuming, sometimes elicits pain, and often induces after discharges or seizures. Moreover, there is a risk of overestimating eloquent areas due to propagation of the effects of stimulation to a broader network of language cortex. Passive iEEG spatial-temporal functional mapping (STFM) has recently emerged as a potential alternative to ESM. However, investigators have observed less correspondence between STFM and ESM maps of language than between their maps of motor function. We hypothesized that incongruities between ESM and STFM of language function may arise due to propagation of the effects of ESM to cortical areas having strong effective connectivity with the site of stimulation. We evaluated five patients who underwent invasive monitoring for seizure localization, whose language areas were identified using ESM. All patients performed a battery of language tasks during passive iEEG recordings. To estimate the effective connectivity of stimulation sites with a broader network of task-activated cortical sites, we measured cortico-cortical evoked potentials (CCEPs) elicited across all recording sites by single-pulse electrical stimulation at sites where ESM was performed at other times. With the combination of high gamma power as well as CCEPs results, we trained a logistic regression model to predict ESM results at individual electrode pairs. The average accuracy of the classifier using both STFM and CCEPs results combined was 87.7%, significantly higher than the one using STFM alone (71.8%), indicating that the correspondence between STFM and ESM results is greater when effective connectivity between ESM stimulation sites and task-activated sites is taken into consideration. These findings, though based on a small number of subjects to date, provide preliminary support for the hypothesis that incongruities between ESM and STFM may arise in part from propagation of stimulation effects to a broader network of cortical language sites activated by language tasks, and suggest that more studies, with larger numbers of patients, are needed to understand the utility of both mapping techniques in clinical practice.

Association of intraoperative end-tidal carbon dioxide level with ablation volume during magnetic resonance-guided laser interstitial thermal therapy for mesial temporal lobe epilepsy.

OBJECTIVE: Maximal safe ablation of target structures during magnetic resonance-guided laser interstitial thermal therapy (MRgLiTT) is critical to achieving good seizure outcome in patients with mesial temporal lobe epilepsy (mTLE). The authors sought to determine whether intraoperative physiological variables are associated with ablation volume during MRgLiTT. METHODS: Patients with mTLE who underwent MRgLiTT at our institution from 2014 to 2019 were retrospectively analyzed. Ablation volume was determined with volumetric analysis of intraoperative postablation MR images. Physiological parameters (systolic blood pressure [SBP], diastolic blood pressure [DBP], mean arterial pressure [MAP], end-tidal carbon dioxide [ETCO2]) measured 40 minutes prior to ablation were analyzed. Univariate and multivariate regression analyses were performed to determine independent predictors of ablation volume. RESULTS: Forty-four patients met the inclusion criteria. The median (interquartile range) ablation volume was 4.27 (2.92-5.89) cm3, and median ablation energy was 7216 (6402-8784) J. The median MAP, SBP, DBP, and ETCO2 values measured during the 40-minute period leading up to ablation were 72.8 (66.2-81.5) mm Hg, 104.4 (96.4-114.4) mm Hg, 62.4 (54.1-69.8) mm Hg, and 34.1 (32.0-36.2) mm Hg, respectively. In univariate analysis, only total laser energy (r = 0.464, p = 0.003) and 40-minute average ETCO2 (r = -0.388, p = 0.012) were significantly associated with ablation volume. In multivariate analysis, only ETCO2 ≤ 33 mm Hg (p = 0.001) was significantly associated with ablation volume. CONCLUSIONS: Total ablation energy and ETCO2, but not blood pressure, may significantly affect ablation volume in mTLE patients undergoing MRgLiTT. Mild hypocapnia was associated with increased extent of ablation. Intraoperative monitoring and modulation of ETCO2 may help improve extent of ablation, prediction of ablation volume, and potentially seizure outcome.