Preoperative Functional Magnetic Resonance Imaging Research Articles

Brain Arteriovenous Malformations Located in Language Area: Surgical Outcomes and Risk Factors for Postoperative Language Deficits

Case selection for surgical treatment of language-area brain arteriovenous malformations (L-BAVMs) remains difficult. This study aimed to determine the surgical outcomes and risk factors for postoperative language deficits (LDs) in patients with L-BAVMs. Patients with L-BAVMs who underwent microsurgical resection between September 2012 and June 2016 were reviewed. All patients had undergone preoperative functional magnetic resonance imaging and diffusion tensor imaging. Both functional and angioarchitectural factors were analyzed regarding the postoperative LD. Functional factors included the eloquence involved, the side of blood-oxygenation level-dependent signal activation and the white-matter fibers (anterior segment, long segment [LS], and posterior segment of arcuate fasciculus, and the inferior fronto-occipital fasciculus) involved. Sixty-nine patients with L-BAVMs were reviewed. Postoperative short- and long-term LD was found in 32 (46.4%) and 14 (20.3%) patients, respectively. Twelve of the 14 patients with Geschwind's territory L-BAVMs (85.7%) had short-term LD, compared with 10 (34.5%) in Wernicke's and 10 (38.5%) in Broca's area. LS involvement (P= 0.001) and larger nidus size (P= 0.017) were independent risk factors for the short-term LD. Meanwhile, nidus size (P= 0.007), preoperative LD (P= 0.008), and LS involvement (P= 0.028) were independent risk factors for long-term LD. L-BAVMs located in Geschwind's territory can cause a high incidence of LD. LS involvement and larger nidus size are risk factors for postoperative short- and long-term LD, and preoperative LD is a risk factor for postoperative, long-term LD.

Functional Connectivity in Frontoparietal Network: Indicator of Preoperative Cognitive Function and Cognitive Outcome Following Surgery in Patients with Glioma.

Patients with diffuse glioma are known to have impaired cognitive functions preoperatively. However, the mechanism of these cognitive deficits remains unclear. Resting-state functional connectivity in the frontoparietal network (FPN) is associated with cognitive performance in healthy subjects. For this reason, it was hypothesized that functional connectivity of the FPN would be related to cognitive functioning in patients with glioma. To assess this relationship, preoperative cognitive status was correlated to patient-specific connectivity within the FPN. Further, we assessed whether connectivity could predict neuropsychologic outcome following surgery. Sixteen patients with diffuse glioma underwent neuropsychologic assessment and preoperative functional magnetic resonance imaging using task (n-back) and resting-state scans. Thirteen patients had postoperative cognitive assessment. An index of patient-specific functional connectivity in the FPN was derived by averaging connectivity values between 2 prefrontal and 2 parietal cortex regions defined by activation during the n-back task. The relationship of these indices with cognitive performance was assessed. Higher average connectivity within the FPN is associated with lower composite cognitive scores. Higher connectivity of the parietal region of the tumor-affected hemisphere is associated specifically with lower fluid cognition. Lower connectivity of the parietal region of the nontumor hemisphere is associated with worse neuropsychologic outcome 1 month after surgery. Resting-state functional connectivity between key regions of the FPN is associated with cognitive performance in patients with glioma and is related to cognitive outcome following surgery.

Brain Arteriovenous Malformations Located in Premotor Cortex: Surgical Outcomes and Risk Factors for Postoperative Neurologic Deficits.

The premotor cortex (PMC) is known to have a dual role in movement and language processing. Nevertheless, surgical outcomes of brain arteriovenous malformations located in PMC (PMC-BAVMs) have not been well defined. The aim of this study was to determine surgical outcomes and risk factors for neurologic deficits (NDs) after surgery in patients with PMC-BAVMs. We retrospectively reviewed patients with PMC-BAVMs who underwent surgical resection of the nidus. All patients had undergone preoperative functional magnetic resonance imaging, diffusion tensor imaging, magnetic resonance imaging, three-dimensional time-of-flight magnetic resonance angiography, and digital subtraction angiography. Functional and angioarchitectural factors were analyzed with respect to postoperative NDs. Function-related fiber tracts, corticospinal tract, and dominant arcuate fasciculus were tracked. Lesion-to-fiber distance was measured. We identified 36 patients with PMC-BAVMs. Radical resection was achieved in all patients. Four patients (11.1%) presented with limb-kinetic apraxia and bradykinesia. Short-term NDs developed in 12 (33.3%) patients, among which 6 developed aphasias and 7 developed muscle weakness. A shorter lesion-to-eloquent fiber distance (P= 0.012) and larger nidus size (P= 0.048) were significantly associated with short-term NDs. Long-term NDs occurred in 5 patients. Larger nidus size was significantly associated (P= 0.015) with long-term NDs. Varying degrees of motor and language deficits can be induced immediately after resection of PMC-BAVMs. Permanent and long-term severe motor or language deficits are rare. Shorter lesion-to-eloquent fiber distance is a risk factor for short-term NDs. Larger nidus size is a risk factor for short-term and long-term NDs.

Lateralizing language function with pre-operative functional magnetic resonance imaging in early proficient bilingual patients

Research on bilinguals with brain lesions is complicated by high patient variability, making it difficult to find well-matched controls. We benefitted from a database of over 700 patients and conducted an analysis of pre-operative functional magnetic resonance imaging data to assess language dominance in 25 early, highly proficient Spanish-English bilinguals, and 25 carefully matched monolingual controls. Our results showed that early bilingualism is associated with greater bilateral hemispheric involvement, and monolingualism is associated with stronger left hemisphere lateralization (p=0.009). The bilinguals showed more pronounced right hemisphere activation (p=0.008). Although language dominance values were concordant in the bilingual group, there were a few (12%) atypical cases with different lateralization patterns in L1 and L2. Finally, we found distinct areas of activity in first and second language within the language network, in addition to regions of convergence. These data underscore the need to map all languages proficiently spoken by surgical candidates.

Surgical Resection of Insular Gliomas and Roles of Functional Magnetic Resonance Imaging and Diffusion Tensor Imaging Tractography—Single Surgeon Experience

In gliomas located in proximity to eloquent areas, near total resection and subsequent radiotherapy is often preferred to avoid postoperative neurologic complications. Preoperative functional magnetic resonance imaging (fMRI) and diffusion tensor imaging (DTI) tractography provide new insights into surgeries of insular gliomas. In this study we report our experience of surgical management of insular gliomas and the role of fMRI and DTI tractography in planning the resection. We retrospectively compared the clinical and outcome variables of 61 patients who underwent surgical resection of insular gliomas. The study population was divided into 2 groups according to the use of fMRI and DTI tractography in planning the resection. The average age of the study population was 44.1 ± 12.6 years with 21 (34.4%) of the patients women. Nearly two thirds of them (40, or 65.6%) had World Health Organization grade II tumors, and 16 patients (26.2%) had grade IV tumors. The most common tumor was glioblastoma, observed in 16 patients (26.2%). In 10 (16.4%) patients, fMRI and DTI tractography were used. The overall mortality in the study population was 15 (24.6%). None of the patients where fMRI and DTI were used for planning the surgery died (29.4% vs. 0.0%; P= 0.05), and all of them had normal functioning (70.5% vs. 100.0%; P= 0.05) at 3 months' follow-up. Surgical resection of insular gliomas remains a challenge to the neurosurgeon and demands good knowledge of anatomic landmarks. Use of fMRI and DTI tractography may help achieve a good outcome.

Sources of Variation Influencing Concordance between Functional MRI and Direct Cortical Stimulation in Brain Tumor Surgery.

Object: Preoperative functional magnetic resonance imaging (fMRI) remains a promising method to aid in the surgical management of patients diagnosed with brain tumors. For patients that are candidates for awake craniotomies, surgical decisions can potentially be improved by fMRI but this depends on the level of concordance between preoperative brain maps and the maps provided by the gold standard intraoperative method, direct cortical stimulation (DCS). There have been numerous studies of the concordance between fMRI and DCS using sensitivity and specificity measures, however the results are variable across studies and the key factors influencing variability are not well understood. Thus, the present work addresses the influence of technical factors on fMRI and DCS concordance.Methods: Motor and language mapping data were collected for a group of glioma patients (n = 14) who underwent both preoperative fMRI and intraoperative DCS in an awake craniotomy procedure for tumor removal. Normative fMRI data were also acquired in a healthy control group (n = 12). The fMRI and DCS mapping data were co-registered; true positive (TP), true negative (TN), false positive (FP), and false negative (FN) occurrences were tabulated over the exposed brain surface. Sensitivity and specificity were measured for the total group, and for the motor and language sub-groups. The influence of grid placement, fMRI statistical thresholding, and task standardization were assessed. Correlations between proportions of agreement and error were also carefully scrutinized to evaluate concordance in more detail.Results: Concordance was significantly better for motor vs. language mapping. There was an inverse relationship between TP and TN with increasing statistical threshold, and FP dominated the total error. Sensitivity and specificity were reduced when tasks were not standardized across fMRI and DCS.Conclusions: Although the agreement between fMRI and DCS is good, variability is introduced by technical factors that can diminish the quality of patient data. Neurosurgeons should evaluate the usefulness of fMRI data while considering that (a) discordance arises primarily from FP fMRI results; (b) there is an inherent trade-off between sensitivity and specificity with fMRI statistical threshold; and (c) best results are achieved using batteries of tasks that are standardized across both mapping methods.

PC3 - 190 Impact of Functional Magnetic Resonance Imaging on Clinical Decision Making and Outcomes in Patients with Low Grade Gliomas

This study aims to evaluate the impact of preoperative functional magnetic resonance imaging (fMRI) on low grade glioma (LGG) patients’ outcomes and surgical planning. Methods In this retrospective matched cohort study of a single surgeon’s patients, we are comparing two groups of LGG patients (WHO grade II) based on exposure to fMRI. Sixteen LGG patients who underwent fMRI were selected, and 32 control (non-fMRI exposed) patients are being selected through propensity score matching from a pool of 764 brain tumour patients. To assess the impact of fMRI data on clinicians’ decision making process, neurosurgeons within a single centre are completing questionnaires regarding treatment options for each LGG fMRI patient based on clinical data and structural imaging before and after fMRI. Results Within the group of 16 LGG patients who have undergone fMRI studies over a 12-year period, most patients presented with seizures (81 percent), and most lesions were left-sided (81 percent) and frontal (75 percent). Patients underwent either craniotomy (50 percent), stereotactic biopsy (25 percent) or nonsurgically management (25 percent). In surgical patients, between presurgical assessment and eight week post-surgical follow-up, mean modified Rankin scale improved from 1.80 (sd 0.79) to 1.50 (sd 0.97). In our cohort, 5-year mortality was 12.5 percent (mean follow-up duration 5.46 years). Conclusions Data analysis is ongoing with plans to compare relevant patient demographics and outcomes, and to analyse questionnaires to elucidate how surgeons incorporate fMRI data into their therapeutic approach.

PS2 - 196 Investigating the Spatial Agreement Between Pre-Operative Functional MRI and Intra-Operative Direct Cortical Stimulation

Pre-operative functional magnetic resonance imaging (fMRI) has emerged as valuable clinical tool to help surgically manage patients diagnosed with brain tumours. Surgical decision-making may be significantly improved through the provision of fMRI, however its clinical usage is contingent on the level of agreement with direct cortical stimulation (DCS). While previous studies have been undertaken to investigate the spatial agreement between fMRI and DCS, the influence that various factors may have on fMRI sensitivity and specificity is not fully clear. Thus, in a group of eight brain tumour patients who underwent pre-operative fMRI followed intra-operative DCS during an awake craniotomy procedure, we measured the agreement between the two brain mapping techniques looking at the influence of behavioural task, statistical threshold, and task standardization. Results: There were significant differences between motor and language mapping, where agreement was better for the former. Sensitivity and specificity shared an inverse relationship with increasing fMRI threshold, and were significantly reduced in the case where tasks were not standardized. Lastly, false positive occurrences were identified as the dominate source of error in comparison to false negative occurrences. Conclusion: Thus, the results from this work suggest that fMRI can predict intraoperative findings with good accuracy, however, sources of variability may significantly reduce the quality of fMRI data at the single-subject level. Neurosurgeons should carefully evaluate fMRI data with these considerations prior to its inclusion in the surgical-decision making process.

Direct Repair of Chronic Achilles Tendon Ruptures Using Scar Tissue Located Between the Tendon Stumps.

Several surgical procedures for chronically ruptured Achilles tendons have been reported. Resection of the interposed scar tissue located between the tendon stumps and reconstruction using normal autologous tissue have been well described. We developed a direct repair procedure that uses scar tissue, which obviates the need to use normal autologous tissue. Thirty consecutive patients with Achilles tendon ruptures with a delay in diagnosis of >4 weeks underwent removal of a section of scar and healing tissue with direct primary suture of the ends of the tendon without the use of allograft or autograft. Patients were followed for a mean time of 33 months. Preoperative and postoperative clinical outcomes were measured with the Achilles Tendon Total Rupture Score (ATRS) and the American Orthopaedic Foot & Ankle Society (AOFAS) ankle-hindfoot score. In addition, the patients underwent preoperative and postoperative functional measurements and magnetic resonance imaging. Lastly, we evaluated the histology of the interposed healing tissue. The mean AOFAS scores were 82.8 points preoperatively and 98.1 points postoperatively. The mean postoperative ATRS was 92.0 points. At the time of the latest follow-up, none of the patients had experienced tendon reruptures or difficulties in walking or climbing stairs, and all except 2 patients could perform a single-limb heel rise. All athletes had returned to their pre-injury level of sports participation. Preoperative T2-weighted magnetic resonance imaging showed that 22 Achilles tendons were thickened with diffuse intratendinous high-signal alterations, and 8 Achilles tendons were thinned. Postoperative T2-weighted magnetic resonance imaging findings included fusiform-shaped tendon thickening and homogeneous low-signal alterations of the tendons in all patients. Histologically, the interposed scar tissue consisted of dense collagen fibers. Shortening of the tissue between the 2 tendon ends that included healing scar and direct repair of healing tendon without allograft or autograft can be effective for treatment-delayed or neglected Achilles tendon rupture. Therapeutic Level IV. See Instructions for Authors for a complete description of levels of evidence.

Brain Tumors: The Influence of Tumor Type and Routine MR Imaging Characteristics at BOLD Functional MR Imaging in the Primary Motor Gyrus.

Purpose To evaluate the effects of histologic features and anatomic magnetic resonance (MR) imaging characteristics of brain tumors on the functional MR imaging signal in the primary motor cortex (PMC), as false-negative blood oxygen level-dependent (BOLD) functional MR imaging activation can limit the accurate localization of eloquent cortices. Materials and Methods Institutional review board approval was obtained, and informed consent was waived for this HIPAA-compliant retrospective study. It comprised 63 patients referred between 2006 and 2014 for preoperative functional MR imaging localization of the Rolandic cortex. The patients had glioblastoma multiforme (GBM) (n = 20), metastasis (n = 21), or meningioma (n = 22). The volumes of functional MR imaging activation were measured during performance of a bilateral hand motor task. Ratios of functional MR imaging activation were normalized to PMC volume. Statistical analysis was performed for the following: (a) differences between hemispheres within each histologic tumor type (paired Wilcoxon test), (b) differences across tumor types (Kruskal-Wallis and Fisher tests), (c) pairwise tests between tumor types (Mann-Whitney U test), (d) relationships between fast fluid-attenuated inversion recovery (FLAIR) data and enhancement volume with activation (Spearman rank correlation coefficient), and (e) differences in activation volumes by tumor location (Mann-Whitney U test). Results A significant interhemispheric difference was found between the activation volumes in GBMs (mean, 511.43 voxels ± 307.73 [standard deviation] and 330.78 voxels ± 278.95; P < .01) but not in metastases (504.68 voxels ± 220.98 and 460.22 voxels ± 276.83; P = .15) or meningiomas (424.07 voxels ± 247.58 and 415.18 voxels ± 222.36; P = .85). GBMs showed significantly lower activation ratios (median, 0.49; range, 0.04-1.15) than metastases (median, 0.79; range, 0.28-1.66; P = .043) and meningiomas (median, 0.91; range, 0.52-2.05; P < .01). There was a moderate correlation with the volumes of FLAIR abnormality in metastases (ρ = -0.50) and meningiomas (ρ = -0.55). Enhancement volume (ρ = -0.11) and tumor distance from the PMC (median, 0.73 and range, 0.04-2.05 for near and median, 0.82 and range, 0.39-1.66 for far; P = .14) did not influence activation. Conclusion BOLD functional MR imaging activation in the ipsilateral PMC is influenced by tumor type and is significantly reduced in GBMs. FLAIR abnormality correlates moderately with the activation ratios in metastases and meningiomas. © RSNA, 2016 Online supplemental material is available for this article.

P.105 Clinical impact of functional magnetic resonance imaging for pre-operative planning in patients with low grade gliomas

Background: This study aims to evaluate the impact of pre-operative functional magnetic resonance imaging (fMRI) on low grade glioma (LGG) patients’ outcomes. Methods: In this retrospective matched cohort study (N =48) of a single surgeon’s patients, we are comparing two groups of LGG patients (WHO grade II) based on exposure to fMRI. A 1:2 propensity score match from a pool of 764 brain tumour patients was performed. Results: Within the group of 16 LGG patients who have undergone fMRI studies over a 12-year period, mean age was 40 years, and most presented with seizures (81%). Most lesions were left-sided (81%), and the lobes most commonly involved were frontal (75%) and temporal (31%). Patients underwent either craniotomy (50%), stereotactic biopsy (25%) or nonsurgically management (25%). In surgical patients, between presurgical assessment and eight week post-surgical follow-up, mean modified Rankin scale improved from 1.80±0.79 to 1.50±0.97. In our cohort, 5-year mortality was 12.5% (patients followed for a mean duration of 5.46 years). Conclusions: Data analysis is ongoing with plans to compare relevant demographics and outcomes via 1:2 propensity score matching of LGG patients who underwent fMRI against a control cohort.

Language system organization in a quadrilingual with a brain tumor: Implications for understanding of the language network

In pre-neurosurgery language mapping it is critical to identify language-specific regions in multilingual speakers. We conducted pre-operative functional magnetic resonance imaging, and intraoperative language mapping in the unique case of a highly proficient quadrilingual with a left frontal brain tumor who acquired her second language at age 5, and her third and fourth languages at 15. We found a predominantly different organization in each language with only a few areas shared by all 4 languages. Contrary to existing evidence, impairment across languages was not related to age of acquisition, amount of exposure, or language similarity. This case suggests that the functional structure of the language system may be highly idiosyncratic in multilingual individuals and supports detailed study in this group to inform neurocognitive models of language.

Safe Resection of Gliomas of the Dominant Angular Gyrus Availing of Preoperative FMRI and Intraoperative DTI: Preliminary Series and Surgical Technique

Language dysfunction, visual deficit, numeracy impairment, and Gerstmann syndrome often occur in the cortical area; furthermore, the subcortical white matter is the inviolable limit of "functional neurosurgery." Preoperative functional magnetic resonance imaging (fMRI) and tractography are capable of providing the data required for safe "surgical planning" at both the cortical and subcortical levels. We report our experience regarding high-grade gliomas affecting the dominant angular gyrus (AG), supramarginal gyrus (SMG), intraparietal sulcus (IPS), and their respective subcortical areas using intraoperative MRI and diffusion tensor imaging (DTI). Retrospectively, we reviewed a consecutive series of 27 patients operated in a BrainSuite for high-grade intraparenchymal tumors of the left posterior temporoparietal junction. We included tumors involving the dominant AG, SMG, and/or IPS and the subcortical course of arcuate fasciculus (AF) and all the patients who underwent preoperative fMRI and DTI to localize the AF and the eloquent cortical areas. Just after craniotomy, new volumetric MRI and DTI verified and corrected possible brain shift. After the gross total resection was carried out, and before approaching the residual mass close to the white matter tract, an intraoperative MRI was again performed. We operated on 27 patients, 15 males and 12 females, whose diagnosis was always high-grade glioma. During the preoperative neurologic examination, 6 patients were asymptomatic; 3 presented a Gerstmann syndrome; 16 showed dysphasic disturbances, 6 of which were associated with visual field deficits; and 2 showed weakness of the right limb. Our results suggest that this approach is completely safe and effective as an alternative to awake surgery.

Novel Method to Identify the Precentral Gyrus and Its Detailed Functional Distribution in Real Brain Surfaces Using Reconstructed 3D Brain Surface Imaging

Objective: To study the use of reconstructed 3D brain surface imaging (RBSI) to identify the precentral gyrus and its detailed functional distribution in epileptic patients. Method: A total of 12 refractory epilepsy cases that need intracranial electrode implantation were studied. In these patients, pre-operative magnetic resonance imaging (MRI) and functional MRI (fMRI) were conducted, and a cranial computed tomography (CT) scan was performed after electrode implantation. The RBSI was accomplished using Brain Voyager software based on MRI data, and then the 3D brain surface was integrated with the subdural electrode CT scan. The precentral gyrus was found in the reconstructed brain surface imaging according to their anatomical shape, and then were identified in the surgical field by comparing the exposed gyrus in the RBSI with the help of intraoperative photographs. Results: Total 12 cases of precentral gyrus was found and marked in the RBSI. There were 101 electrodes covering the precentral gyrus and 73 (72%) of them had motor response to electrical stimulation. In the contrast, (the area which is 1 cm ahead of the precentral gyrus), the motor response rate was 13% (17/130) (p < 0.05). During fMRI, 100% of the precentral gyrus and 58% (7/12) of post central gyrus was activated during hand movement. Whereas, no activation of the areas ahead of precentral gyrus was seen showing a significant difference between precentral gyrus and gyrus ahead. Conclusion: Our results demonstrated that using RBSI technique, it is possible to identify the precentral gyrus with precision.

Impact of Preoperative Functional Magnetic Resonance Imaging during Awake Craniotomy Procedures for Intraoperative Guidance and Complication Avoidance

Background: We wanted to study the role of functional MRI (fMRI) in preventing neurological injury in awake craniotomy patients as this has not been previously studied. Objectives: To examine the role of fMRI as an intraoperative adjunct during awake craniotomy procedures. Methods: Preoperative fMRI was carried out routinely in 214 patients undergoing awake craniotomy with direct cortical stimulation (DCS). Results: In 40% of our cases (n = 85) fMRI was utilized for the intraoperative localization of the eloquent cortex. In the other 129 cases significant noise distortion, poor task performance and nonspecific BOLD activation precluded the surgeon from using the fMRI data. Compared with DCS, fMRI had a sensitivity and specificity, respectively, of 91 and 64% in Broca's area, 93 and 18% in Wernicke's area and 100 and 100% in motor areas. A new intraoperative neurological deficit during subcortical dissection was predictive of a worsened deficit following surgery (p < 0.001). The use of fMRI for intraoperative localization was, however, not significant in preventing worsened neurological deficits, both in the immediate postoperative period (p = 1.00) and at the 3-month follow-up (p = 0.42). Conclusions: The routine use of fMRI was not useful in identifying language sites as performed and, more importantly, practiced tasks failed to prevent neurological deficits following awake craniotomy procedures.

Dissociated Language Functions: A Matter of Atypical Language Lateralization or Cerebral Plasticity?

The left hemisphere is generally considered to harbor language functions. Atypical cortical language lateralization is mainly demonstrated in left-handed and ambidextrous individuals, whereas dissociated language functions have been reported in association with brain injuries as a part of the reorganization process. We present a thoughtful discussion on the underlying mechanisms of dissociated language functions through an illustrative case of dissociated expressive language. A 31-year-old left-handed woman presented with a recurrent left frontal glioma. Preoperative language functional magnetic resonance imaging (fMRI) panel revealed right-sided dominance for two different language tasks (verbal fluency and visual naming), and the word chain task demonstrated maximal activation in the left hemisphere at the posterior margin of the tumor. The patient was operated on awake to assess language functions intraoperatively. Preoperative fMRI findings were confirmed revealing a task-specific dissociation of expressive language functions. Surgical resection was taken to the functional boundaries. Postoperatively, no language dysfunction occurred. Dissociated language functions are prone to occur in long-standing lesions. Different patterns of dissociation may be encountered due to interindividual particularities and cerebral plasticity. The presented patient is unique by demonstrating new insight into expressive language dissociation, emphasizing the role of a preoperative language fMRI panel and the capability of intraoperative language mapping for identifying special language networks.

Subcortical Injury Is an Independent Predictor of Worsening Neurological Deficits Following Awake Craniotomy Procedures

Tailored craniotomies for awake procedures limit cortical exposure. Recently we demonstrated that the identification of eloquent areas increased the risk of postoperative deficits. However, it was not clear whether the observed neurological deficits were caused by proximity of functional cortex to the tumor [cortical injury] or subcortical injury. We hypothesize that subcortical injury during tumor resection is an important predictor of postoperative neurological deficits compared to cortical injury. A retrospective review of 214 patients undergoing awake craniotomy was carried out in whom preoperative functional magnetic resonance imaging (fMRI) and cortical mapping (CM) were performed. A radiologist blinded to the clinical data reviewed and graded the postoperative changes on diffusion-weighted MR-imaging (DWI). Of the 40 cases who developed new intraoperative neurological deficit, 36 (90%) occurred during subcortical dissection, 3 (7.5%) during both subcortical and cortical dissection, and 1 (2.5%) during cortical dissection. Neurological dysfunction acquired during subcortical dissection was an independent predictor of postoperative deficits both in the immediate postoperative period (P < .001) and at the 3-month follow-up (P < .001). Significant DWI restriction in the subcortical white matter was predictive of neurological deficits both immediately and at 3 months, P = .011 and P < .001, respectively. New or worsening deficits were seen in 38% of patients; however, at 3 months 13% had a mild persistent neurological deficit. Subcortical injury with significant DWI changes result in postoperative neurological decline despite our efforts to preserve cortical areas of function. This underscores the importance of preserving subcortical fiber tracts during awake craniotomy procedures.

Imaging language networks before and after anterior temporal lobe resection: Results of a longitudinal fMRI study

SummaryPurpose: Anterior temporal lobe resection (ATLR) controls seizures in up to 70% of patients with intractable temporal lobe epilepsy (TLE) but, in the language dominant hemisphere, may impair language function, particularly naming. Functional reorganization can occur within the ipsilateral and contralateral hemispheres. We investigated reorganization of language in left-hemisphere–dominant patients before and after ATLR; whether preoperative functional magnetic resonance imaging (fMRI) predicts postoperative naming decline; and efficiency of postoperative language networks.Methods: We studied 44 patients with TLE due to unilateral hippocampal sclerosis (24 left) on a 3T GE-MRI scanner. All subjects performed language fMRI and neuropsychological testing preoperatively and again 4 months after left or right ATLR.Key Findings: Postoperatively, individuals with left TLE had greater bilateral middle/inferior frontal fMRI activation and stronger functional connectivity from the left inferior/middle frontal gyri to the contralateral frontal lobe than preoperatively, and this was not observed in individuals with right TLE. Preoperatively, in left and right TLE, better naming correlated with greater preoperative left hippocampal and left frontal activation for verbal fluency (VF). In left TLE, stronger preoperative left middle frontal activation for VF was predictive of greater decline in naming after ATLR. Postoperatively, in left TLE with clinically significant naming decline, greater right middle frontal VF activation correlated with better postoperative naming. In patients without postoperative naming decline, better naming correlated with greater activation in the remaining left posterior hippocampus. In right TLE, naming ability correlated with left hippocampal and left and right frontal VF activation postoperatively.Significance: In left TLE, early postoperative reorganization to the contralateral frontal lobe suggests multiple systems support language function. Postoperatively, ipsilateral recruitment involving the posterior hippocampal remnant is important for maintaining language, and reorganization to the contralateral hemisphere is less effective. Preoperative left middle frontal activation for VF was predictive of naming decline in left TLE after ATLR.

Functional MRI connectivity as a predictor of the surgical outcome of epilepsy

In planning epilepsy surgery, it is important to be able to assess the likelihood of success of surgery for each patient so that the possible risk and benefit can be properly considered. In this study, functional connectivity was investigated as a means for predicting surgical outcome from the preoperative functional magnetic resonance imaging (fMRI) of epilepsy patients. Resting-state simultaneous electroencephalography (EEG)-fMRI data were collected from 18 patients with intractable epilepsy before surgery and from 14 healthy subjects. For each patient, EEG-spike correlated fMRI analysis was performed and an activation cluster that overlapped the most with the planned resection area for each patient was chosen as the seed for the functional connectivity analysis. After the functional connectivity maps were computed, laterality indices of functional connectivity were contrasted between patients who had seizures after surgeries (seizure-recurrence group) and those who did not have them for at least a year (seizure-free group). Patients in the seizure-recurrence group had less-lateralized functional connectivity than patients in the seizure-free group (t(16) = 2.3, after control subtracted and Fisher transformed, p < 0.05, two-tailed). This study suggests the potential for using preoperative fMRI connectivity analysis as a predictive outcome measure. If confirmed by further research, a high laterality will be an important addition to the other predictors of better surgical outcome such as febrile seizures, mesial temporal sclerosis, tumors, abnormal MRI, and EEG/MRI concordance.

Preoperative Functional Magnetic Resonance Imaging (fMRI) and Transcranial Magnetic Stimulation (TMS)

Preoperative Functional Magnetic Resonance Imaging (fMRI) and Transcranial Magnetic Stimulation (TMS)