Prediction of Naming Outcome With fMRI Language Lateralization in Left Temporal Epilepsy Surgery

Is an earlier onset of focal epilepsy associated with atypical language lateralization? A systematic review, meta-analysis and new data

Right and bilateral language representation is common in focal epilepsy, possibly reflecting the influence of epileptogenic lesions and/or seizure activity in the left hemisphere. Atypical language lateralization is assumed to be more likely in cases of early seizure onset, due to greater language plasticity in childhood. However, evidence for this association is mixed, with most research based on small samples and heterogenous cohorts. In this preregistered meta-analysis we examined the association between age at seizure onset and fMRI-derived language lateralization in individuals with focal epilepsy. The pooled effect size demonstrated a correlation between an earlier onset and rightward language lateralization in the total sample (r = 0.1, p = .005, k = 58, n = 1240), with no difference in the correlation between age at seizure onset and language lateralization between left and right hemisphere epilepsy samples (Q=62.03, p = .302). In exploratory analyses of the individual participant data (n = 1157), we demonstrated strong evidence that a logarithmic model fits the data better than a linear (BF=350) or categorical model with 6 years of age as a cut-off (BF=36). These findings indicate that there is a small but significant relationship between age at seizure onset and language lateralization. The relationship was consistent with theories of language plasticity proposing an exponential decline in plasticity over early childhood. However, given that this effect was subtle and only found in larger sample sizes, an early age at seizure onset would not serve as a good indicator of atypical language lateralization on the individual patient level.

Lesion and lesion network localization of dysnomia after epilepsy surgery

Temporal lobe epilepsy surgery is an effective treatment option for patients with drug-resistant epilepsy. However, neurosurgery poses a risk for cognitive deficits-up to one-third of patients have a decline in naming ability following temporal lobe surgery. In this study, we aimed to better understand the neural correlates associated with reduced naming performance after temporal lobe surgery, with the goal of informing surgical planning strategies to mitigate the risk of dysnomia. We retrospectively identified 85 patients who underwent temporal lobe resective surgery (49 left temporal lobe, 36 right temporal lobe) for whom naming ability was assessed before and >3 months post-surgery using the Boston Naming Test. We used multivariate lesion-symptom mapping to identify resection sites associated with naming decline, and we used lesion network mapping to evaluate the broader functional and structural connectivity profiles of resection sites associated with naming decline. We validated our findings in an independent cohort of 59 individuals with left temporal lobectomy, along with repeating all analyses after combining the cohorts. Lesion laterality and location were important predictors of post-surgical naming performance. Naming performance significantly improved after right temporal lobectomy (P = 0.015) while a decrement in performance was observed following left temporal lobectomy (P = 0.002). Declines in naming performance were associated with surgical resection of the left anterior middle temporal gyrus (Brodmann area 21, r = 0.41, P < 0.001), along with a previously implicated basal temporal language area. Resection sites linked to naming decline showed a functional connectivity profile featuring a left-lateralized network closely resembling the extended semantic\default mode network, and a structural connectivity profile featuring major temporo-frontal association white matter tracts coursing through the temporal stem. This extends prior work by implicating the left anterior middle temporal gyrus in naming decline and provides additional support for the role of the previously identified basal temporal language area in naming decline. Importantly, the structural and functional connectivity profiles of these regions suggest they are key nodes of a broader extended semantic network. Together these regional and network findings may help in surgical planning and discussions of prognosis.

Is an earlier onset of focal epilepsy associated with atypical language lateralization? A systematic review, meta-analysis and new data

Right and bilateral language representation is common in focal epilepsy, possibly reflecting the influence of epileptogenic lesions and/or seizure activity in the left hemisphere. Atypical language lateralization is assumed to be more likely in cases of early seizure onset, due to greater language plasticity in childhood. However, evidence for this association is mixed, with most research based on small samples and heterogenous cohorts. In this preregistered meta-analysis we examined the association between age at seizure onset and fMRI-derived language lateralization in individuals with focal epilepsy. The pooled effect size demonstrated a correlation between an earlier onset and rightward language lateralization in the total sample (r=0.1, p=.005, k=58, n=1240), with no difference in the correlation between left and right hemisphere epilepsy samples (Q=62.03, p=.302). In exploratory analyses of the individual participant data (n=1157), we demonstrated strong evidence that a logarithmic model fits the data better than a linear (BF=350) or categorical model with 6 years of age as a cut-off (BF=36). These findings indicate that there is a small but significant relationship between age at seizure onset and language lateralization. The relationship was consistent with theories of language plasticity proposing an exponential decline in plasticity over early childhood. However, given that this effect was subtle and only found in larger sample sizes, an early age at seizure onset would not serve as a good indicator of atypical language lateralization on the individual patient level.

Epilepsy and Neuropsychology

Neuropsychological evaluation is an essential component of clinical care for people with epilepsy and also has a specialized role in predicting cognitive outcome after epilepsy surgery. Neuropsychological research in the field of epilepsy has had a significant impact on our knowledge regarding memory and language systems, lateralization of cognitive functions, and the heterogeneity in cognitive phenotypes among people with epilepsy. Interventions that consider the impact of health disparities, cognition, psychological functioning, individual risk and resilience factors, and modifiable lifestyle factors, are critical for optimizing cognitive functioning, psychological health, and quality of life for people with epilepsy.

Chinese Verbal Fluency Deficiency in Temporal Lobe Epilepsy with and without Hippocampal Sclerosis: A Multiscale Study

To test a Chinese character version of the phonemic verbal fluency task in patients with temporal lobe epilepsy (TLE) and assess the verbal fluency deficiency pattern in TLE with and without hippocampal sclerosis, a cross-sectional study was conducted including 30 patients with TLE and hippocampal sclerosis (TLE-HS), 28 patients with TLE and without hippocampal sclerosis (TLE-NHS), and 29 demographically matched healthy controls (HC). Both sexes were enrolled. Participants finished a Chinese character verbal fluency (VFC) task during functional MRI. The activation/deactivation maps, functional connectivity, degree centrality, and community features of the left frontal and temporal regions were compared. A neural network classification model was applied to differentiate TLE-HS and TLE-NHS using functional statistics. The VFC scores were correlated with semantic fluency in HC while correlated with phonemic fluency in TLE-NHS. Activation and deactivation deficiency was observed in TLE-HS and TLE-NHS (p < 0.001, k ≥ 10). Functional connectivity, degree centrality, and community features of anterior inferior temporal gyri were impaired in TLE-HS and retained or even enhanced in TLE-NHS (p < 0.05, FDR-corrected). The functional connectivity was correlated with phonemic fluency (p < 0.05, FDR-corrected). The neural network classification reached an area under the curve of 0.90 in diagnosing hippocampal sclerosis. The VFC task is a Chinese phonemic verbal fluency task suitable for clinical application in TLE. During the VFC task, functional connectivity of phonemic circuits was impaired in TLE-HS and was enhanced in TLE-NHS, representing a compensative phonemic searching strategy applied by patients with TLE-NHS.

Naming fMRI-guided white matter language tract volumes influence naming decline after temporal lobe resection

OBJECTIVE

The aim of this study was to explore the relation of language functional MRI (fMRI)-guided tractography with postsurgical naming decline in people with temporal lobe epilepsy (TLE).

METHODS

Twenty patients with unilateral TLE (9 left) were studied with auditory and picture naming functional MRI tasks. Activation maxima in the left posterobasal temporal lobe were used as seed regions for whole-brain fibre tractography. Clinical naming performance was assessed preoperatively, 4 months, and 12 months following temporal lobe resection. Volumes of white matter language tracts in both hemispheres as well as tract volume laterality indices were explored as moderators of postoperative naming decline using Pearson correlations and multiple linear regression with other clinical variables.

RESULTS

Larger volumes of white matter language tracts derived from auditory and picture naming maxima in the hemisphere of subsequent surgery as well as stronger lateralization of picture naming tract volumes to the side of surgery correlated with greater language decline, which was independent of fMRI lateralization status. Multiple regression for picture naming tract volumes was associated with a significant decline of naming function with 100% sensitivity and 93% specificity at both short-term and long-term follow-up.

INTERPRETATION

Naming fMRI-guided white matter language tract volumes relate to postoperative naming decline after temporal lobe resection in people with TLE. This can assist stratification of surgical outcome and minimize risk of postoperative language deficits in TLE.

Clinical recommendations for conducting pediatric functional language and memory mapping during the phase I epilepsy presurgical workup

Objective: Pediatric epilepsy surgery effectively controls seizures but may risk cognitive, language, or memory decline. Historically, the intra-carotid anesthetic procedure (IAP or Wada Test) was pivotal for language and memory function. However, advancements in noninvasive mapping, notably functional magnetic resonance imaging (fMRI), have transformed clinical practice, reducing IAP's role in presurgical evaluations. Method: We conducted a critical narrative review on mapping technologies, including factors to consider for discordance. Results: Neuropsychological findings suggest that if pre-surgery function remains intact and the surgery targets the eloquent cortex, there is a high chance for decline. Memory and language decline are particularly pronounced post-left anterior temporal lobe resection (ATL), making presurgical cognitive assessment crucial for predicting postoperative outcomes. However, the risk of functional decline is not always clear - particularly with higher rates of atypical organization in pediatric epilepsy patients and discordant findings from cognitive mapping. We found little research to date on the use of IAP and other newer technologies for lateralization/localization in pediatric epilepsy. Based on this review, we introduce an IAP decision tree to systematically navigate discordance in IAP decisions for epilepsy presurgical workup. Conclusions: Future research should be aimed at pediatric populations to improve the precision of functional mapping, determine which methods predict post-surgical deficits and then create evidence-based practice guidelines to standardize mapping procedures. Explicit directives are needed for resolving conflicts between developing mapping procedures and established clinical measures. The proposed decision tree is the first step to standardize when to consider IAP or invasive mapping, in coordination with the multidisciplinary epilepsy surgical team.

Concordance of verbal memory and language fMRI lateralization in people with epilepsy

BACKGROUND AND PURPOSE

This work investigates verbal memory functional MRI (fMRI) versus language fMRI in terms of lateralization, and assesses the validity of performing word recognition during the functional scan.

METHODS

Thirty patients with a diagnosis of epilepsy underwent verbal memory, visuospatial memory, and language fMRI. We used word encoding, word recognition, image encoding, and image recognition memory tasks, and semantic description, reading comprehension, and listening comprehension language tasks. We used three common lateralization metrics: network spatial distribution, maximum statistical value, and laterality index (LI).

RESULTS

Lateralization of signal spatial distribution resulted in poor similarity between verbal memory and language fMRI tasks. Signal maximum lateralization showed significant (>.8) but not perfect (1) similarity. Word encoding LI showed significant correlation only with listening comprehension LI (p = .016). Word recognition LI was significantly correlated with expressive language semantic description LI (p = .024) and receptive language reading and listening comprehension LIs (p = .015 and p = .019, respectively). There was no correlation between LIs of the visuospatial tasks and LIs of the language tasks.

CONCLUSIONS

Our results support the association between language and verbal memory lateralization, optimally determined by LI quantification, and the introduction of quantitative means for language fMRI interpretation in clinical settings where verbal memory lateralization is imperative.

Comparing neuropsychological functioning in Turkish patients with right and left temporal lobe epilepsy

We compared neuropsychiatric evaluations in temporal lobe epilepsy according to the lateralized hemisphere. Forty-one (68.3%) left-sided temporal lobe epilepsy (LTLE) were compared to 19 right-sided temporal lobe epilepsy (RTLE) (31.7%) (p < 0.001). RTLE mean age was 37 (22-46) years, and LTLE mean age 38 was (30-42). RTLE disease duration was 10 (6-20) years, and LTLE was 22 (10-33) (p < 0.013). Gender (man/woman) for RTLE was 7/12, and for LTLE was 18/23. LTLE scored poorer on the Wechsler Memory Scale (WMS)-III's Mental Control Months-error, WMS-V's "Forward Number Range" and "Backward Number Range" than RTLE (p < 0.017, p < 0.023, p < 0.004). There were differences between hemispheres for "Number of Items Remembered with a Hint" and "Total number of Recalled Items" (WMS-IV) (p < 0.038, p < 0.045). LTLE had lower scores in the Verbal Fluency -K-A-S letters words and WAIS (Wechsler Adult Intelligence Scale) similarity than RTLE (p < 0.019, p < 0.024, p < 0.033, p < 0.026). Oktem and Boston-number of Self-Named Items Tests were poorer in LTLE than RTLE (p < 0.05, p < 0.043). Mental Control Months-error (WMS-III), "Total Number of Recalled Items", "Number of Items Remembered with Hint" (WMS-IV), forward and backward number range (WMS-V), Oktem, Verbal Fluency -K,-A,-S letters words, WAIS similarity, and Boston-number of Self-Named Items tests, can help identify lateralization, particularly in LTLE.

Current State of Functional MRI in the Presurgical Planning of Brain Tumors

Surgical resection of brain tumors is challenging because of the delicate balance between maximizing tumor removal and preserving vital brain functions. Functional MRI (fMRI) offers noninvasive preoperative mapping of widely distributed brain areas and is increasingly used in presurgical functional mapping. However, its impact on survival and functional outcomes is still not well-supported by evidence. Task-based fMRI (tb-fMRI) maps blood oxygen level-dependent (BOLD) signal changes during specific tasks, while resting-state fMRI (rs-fMRI) examines spontaneous brain activity. rs-fMRI may be useful for patients who cannot perform tasks, but its reliability is affected by tumor-induced changes, challenges in data processing, and noise. Validation studies comparing fMRI with direct cortical stimulation (DCS) show variable concordance, particularly for cognitive functions such as language; however, concordance for tb-fMRI is generally greater than that for rs-fMRI. Preoperative fMRI, in combination with MRI tractography and intraoperative DCS, may result in improved survival and extent of resection and reduced functional deficits. fMRI has the potential to guide surgical planning and help identify targets for intraoperative mapping, but there is currently limited prospective evidence of its impact on patient outcomes. This review describes the current state of fMRI for preoperative assessment in patients undergoing brain tumor resection. Keywords: MR-Functional Imaging, CNS, Brain/Brain Stem, Anatomy, Oncology, Functional MRI, Functional Anatomy, Task-based, Resting State, Surgical Planning, Brain Tumor © RSNA, 2023.

Patients' long-term perspectives on gains and losses after temporal lobe resection for epilepsy

OBJECTIVE

To investigate long-term (>10 years) experiences and overall satisfaction with temporal lobe resections (TLB) for epilepsy.

METHODS

Eligible participants were identified through the administrative epilepsy surgery registry at Oslo University Hospital. Data were collected through individual, semi-structured interviews with fifty participants. Interview records were analyzed using reflexive thematic analysis.

RESULTS

Participants' answers were divided into two main themes: "looking back on surgery" and"considering gains and losses from surgery". Most participants expressed satisfaction with having undergone surgery. Nevertheless, postsurgical problems had been encountered, and presurgical hopes had only partly been fulfilled. They described memory and naming problems with a major impact on daily life. Further, they had thoughts about effects on employment, independence, and feelings of loneliness, and expressed a need for more and better preoperative information.

CONCLUSIONS

Presurgical hopes go beyond seizure freedom and memory and naming problems are experienced lasting many years after surgery in the temporal lobe. Better preoperative information, particularly about unwanted cognitive effects, is of prime importance. By exploring patientś presurgical hopes, a common ground for expectations on surgery may be found along with strategies on how to cope with cognitive difficulties and possible negative life changes.

MEG language mapping using a novel automatic ECD algorithm in comparison with MNE, dSPM, and DICS beamformer

Introduction

The single equivalent current dipole (sECD) is the standard clinical procedure for presurgical language mapping in epilepsy using magnetoencephalography (MEG). However, the sECD approach has not been widely used in clinical assessments, mainly because it requires subjective judgements in selecting several critical parameters. To address this limitation, we developed an automatic sECD algorithm (AsECDa) for language mapping.

Methods

The localization accuracy of the AsECDa was evaluated using synthetic MEG data. Subsequently, the reliability and efficiency of AsECDa were compared to three other common source localization methods using MEG data recorded during two sessions of a receptive language task in 21 epilepsy patients. These methods include minimum norm estimation (MNE), dynamic statistical parametric mapping (dSPM), and dynamic imaging of coherent sources (DICS) beamformer.

Results

For the synthetic single dipole MEG data with a typical signal-to-noise ratio, the average localization error of AsECDa was less than 2 mm for simulated superficial and deep dipoles. For the patient data, AsECDa showed better test-retest reliability (TRR) of the language laterality index (LI) than MNE, dSPM, and DICS beamformer. Specifically, the LI calculated with AsECDa revealed excellent TRR between the two MEG sessions across all patients (Cor = 0.80), while the LI for MNE, dSPM, DICS-event-related desynchronization (ERD) in the alpha band, and DICS-ERD in the low beta band ranged lower (Cor = 0.71, 0.64, 0.54, and 0.48, respectively). Furthermore, AsECDa identified 38% of patients with atypical language lateralization (i.e., right lateralization or bilateral), compared to 73%, 68%, 55%, and 50% identified by DICS-ERD in the low beta band, DICS-ERD in the alpha band, MNE, and dSPM, respectively. Compared to other methods, AsECDa's results were more consistent with previous studies that reported atypical language lateralization in 20-30% of epilepsy patients.

Discussion

Our study suggests that AsECDa is a promising approach for presurgical language mapping, and its fully automated nature makes it easy to implement and reliable for clinical evaluations.

Magnetic Resonance Imaging of Primary Adult Brain Tumors: State of the Art and Future Perspectives

MRI is undoubtedly the cornerstone of brain tumor imaging, playing a key role in all phases of patient management, starting from diagnosis, through therapy planning, to treatment response and/or recurrence assessment. Currently, neuroimaging can describe morphologic and non-morphologic (functional, hemodynamic, metabolic, cellular, microstructural, and sometimes even genetic) characteristics of brain tumors, greatly contributing to diagnosis and follow-up. Knowing the technical aspects, strength and limits of each MR technique is crucial to correctly interpret MR brain studies and to address clinicians to the best treatment strategy. This article aimed to provide an overview of neuroimaging in the assessment of adult primary brain tumors. We started from the basilar role of conventional/morphological MR sequences, then analyzed, one by one, the non-morphological techniques, and finally highlighted future perspectives, such as radiomics and artificial intelligence.

Cognitive decline and quality of life after resective epilepsy surgery

OBJECTIVES

The objectives of this study were to examine the association between cognitive decline and quality of life (QoL) change in a large sample of individuals with drug-resistant epilepsy who underwent resective surgery and to examine whether the association between cognitive decline and QoL is differentially affected by seizure classification outcome (Engel Class 1 vs. 2-4) or side of surgery (left vs. right hemisphere).

MATERIALS AND METHODS

The sample comprised 224 adults (ages ≥ 18) with drug-resistant focal epilepsy treated with resective surgery who underwent comprehensive pre-operative and post-operative evaluations including neuropsychological testing and the Quality of Life in Epilepsy Inventory - 31 between 1991 and 2020. Linear mixed-effects models were fit to examine subject-specific trajectories and assess the effects of time (pre- to post-operative), cognitive decline (number of measures that meaningfully declined), and the interaction between time and cognitive decline on pre- to post-operative change in QoL.

RESULTS

Increases in QoL following resection were observed (B = -10.72 [SE = 1.22], p < .001; mean difference between time point 1 and time point 2 QoL rating = 8.11). There was also a main effect of cognitive decline on QoL (B = -.85 [SE = .27], p = .002). Follow-up analyses showed that the number of cognitive measures that declined was significantly associated with post-surgical QoL, (r = -.20 p = .003), but not pre-surgical QoL, (r = -.04 p = .594), and with pre-to post-surgery raw change in QoL score, (r = -.18 p = .009). A cognitive decline by time point interaction was observed, such that those who had greater cognitive decline had less improvement in overall QoL following resection (B = .72 [SE = .27], p = .009). Similar results were observed within the Engel Class 1 outcome subgroup. However, within the Engel Class 2-4 outcome subgroup, QoL improved following resection, but there was no main effect of cognitive decline or interaction between cognitive decline and time point on QoL change. There was no main effect of resection hemisphere on overall QoL, nor were there interactions with hemisphere by time, hemisphere by cognitive decline, or hemisphere by time by cognitive decline.

CONCLUSIONS

Quality of life improves following epilepsy surgery. Participants who had cognitive decline across a greater number of measures experienced less improvement in QoL post-operatively overall, but there was no clear pattern of domain-specific cognitive decline associated with change in QoL. Our results indicate that cognitive decline in a diffuse set of cognitive domains negatively influences post-operative QoL, particularly for those who experience good seizure outcomes (i.e., seizure freedom), regardless of the site or side of resection.

fMRI to Predict Naming Decline: Can We Improve the Grade From a C to an A?

Prediction of Naming Outcome With fMRI Language Lateralization in Left Temporal Epilepsy Surgery

Gross WL, Helfand AI, Swanson SJ, Conant LL, Humphries CJ, Raghavan M, Mueller WM, Busch RM, Allen L, Anderson CT, Carlson CE, Lowe MJ, Langfitt JT, Tivarus ME, Drane DL, Loring DW, Jacobs M, Morgan VL, Allendorfer JB, Szaflarski JP, Bonilha L, Bookheimer S, Grabowski T, Vannest J, Binder JR; FMRI in Anterior Temporal Epilepsy Surgery (FATES) Study. Neurology. 2022;98(23):e2337-e2346. doi:10.1212/WNL.0000000000200552. PMID: 35410903; PMCID: PMC9202528.

Background and Objectives:

Naming decline after left temporal lobe epilepsy (TLE) surgery is common and difficult to predict. Preoperative language fMRI may predict naming decline, but this application is still lacking evidence. We performed a large multicenter cohort study of the effectiveness of fMRI in predicting naming deficits after left TLE surgery.

Methods:

At 10 US epilepsy centers, 81 patients with left TLE were prospectively recruited and given the Boston Naming Test (BNT) before and ≈7 months after anterior temporal lobectomy. An fMRI language laterality index (LI) was measured with an auditory semantic decision-tone decision task contrast. Correlations and a multiple regression model were built with a priori chosen predictors.

Results:

Naming decline occurred in 56% of patients and correlated with fMRI LI (r = −0.41, p < 0.001), age at epilepsy onset (r = −0.30, p = 0.006), age at surgery (r = −0.23, p = 0.039), and years of education (r = 0.24, p = 0.032). Preoperative BNT score and duration of epilepsy were not correlated with naming decline. The regression model explained 31% of the variance, with fMRI contributing 14%, with a 96% sensitivity, and 44% specificity for predicting meaningful naming decline. Cross-validation resulted in an average prediction error of 6 points.

Discussion:

An fMRI-based regression model predicted naming outcome after left TLE surgery in a large, prospective multicenter sample, with fMRI as the strongest predictor. These results provide evidence supporting the use of preoperative language fMRI to predict language outcome in patients undergoing left TLE surgery.

Improved localization of language areas using single voxel signal analysis of unprocessed fMRI data

Activated brain regions can be visualized and localized with the use of fMRI (functional magnetic imaging). This is based on changes in the blood flow in activated regions, or more precisely on the hemodynamic response function (HRF) and the Blood-Oxygen-Level-Dependent (BOLD) effect. This study used a task-based fMRI examination with language paradigms in order to stimulate the language areas. The measured fMRI data are frequently altered by different preprocessing steps for the analysis and the display of activations. These changes can lead to discrepancies between the displayed and the truly measured location of the activations. Simple t-maps were created with unprocessed fMRI data, to provide a more realistic representation of the language areas. HRF-dependent single-voxel fMRI signal analysis was performed to improve the analyzability of these activation maps.