Contralateral Temporal Lobe Research Articles

Is additional mesial temporal resection necessary for intractable epilepsy with cavernous malformations in the temporal neocortex?

PurposeCavernous malformation (CM) in the temporal neocortex causes intractable epilepsy. Whether to resect additional mesial temporal structures in addition to the lesionectomy is a still controversial issue. To clarify the need for the procedure, we retrospectively analyzed pre- and postoperative clinical data of patients with surgically removed CM. Subjects and methodsWe included data from 18 patients with CM in the temporal neocortex who presented with intractable epilepsy. Eleven patients of our early series were treated with extended resection, i.e., lesionectomy and the resection of additional mesial temporal structures. Seven patients underwent lesionectomy, i.e., removal of the CM and of hemosiderin-stained surrounding brain tissue. Pathological assessments of the resected hippocampus were performed. Chronic intracranial electroencephalography (EEG) recordings were obtained in 6 patients. We performed perioperative neuropsychological assessments in all patients. ResultsThe seizure outcome was recorded as Engel class I in 17 patients (94.4%); Ia = 12 (66.7%) Ib = 2 (11.1%), Ic = 1 (5.6%), Id = 2 (11.1%), and class IIb in one patient (5.6%). Adding resection of the mesial temporal structures to lesionectomy did not alter the seizure outcome. Pathology of hippocampus revealed limited neuronal loss in CA4. Ictal onsets in the ipsilateral lateral cortex were detected in all 6 patients who underwent intracranial EEG. In 4 patients each, we also detected ictal onsets from the ipsilateral mesial temporal structures and from the contralateral temporal lobe. Postoperatively, in the patients where their CM was located in the language-dominant hemisphere (n = 10), the full-scale intelligence quotient (IQ) and the performance IQ increased (p < 0.05), whereas the verbal memory (WMS-R) deteriorated in two of 5 patients. ConclusionExcellent seizure outcomes were obtained even the lesionectomy alone. To confirm appropriate surgical strategy for lateral temporal CM with intractable epilepsy, further studies in large sample size are needed.

Low-voltage fast seizures in humans begin with increased interneuron firing.

Intracellular recordings from cells in entorhinal cortex tissue slices show that low-voltage fast (LVF) onset seizures are generated by inhibitory events. Here, we determined whether increased firing of interneurons occurs at the onset of spontaneous mesial-temporal LVF seizures recorded in patients. The seizure onset zone (SOZ) was identified using visual inspection of the intracranial electroencephalogram. We used wavelet clustering and temporal autocorrelations to characterize changes in single-unit activity during the onset of LVF seizures recorded from microelectrodes in mesial-temporal structures. Action potentials generated by principal neurons and interneurons (ie, putative excitatory and inhibitory neurons) were distinguished using waveform morphology and K-means clustering. From a total of 200 implanted microelectrodes in 9 patients during 13 seizures, we isolated 202 single units; 140 (69.3%) of these units were located in the SOZ, and 40 (28.57%) of them were classified as inhibitory. The waveforms of both excitatory and inhibitory units remained stable during the LVF epoch (p > > 0.05). In the mesial-temporal SOZ, inhibitory interneurons increased their firing rate during LVF seizure onset (p < 0.01). Excitatory neuron firing rates peaked 10 seconds after the inhibitory neurons (p < 0.01). During LVF spread to the contralateral mesial temporal lobe, an increase in inhibitory neuron firing rate was also observed (p < 0.01). Our results suggest that seizure generation and spread during spontaneous mesial-temporal LVF onset events in humans may result from increased inhibitory neuron firing that spawns a subsequent increase in excitatory neuron firing and seizure evolution. Ann Neurol 2018;84:588-600.

F07. Using ultra-high field 7T MRI for evaluation of EEG findings in patients with temporal lobe epilepsy

Introduction Assessment of patients for temporal lobe epilepsy (TLE) surgery requires multimodality input, including anatomical MRI, neuropsychological evaluation, functional neuroimaging, scalp electroencephalography (EEG) and invasive EEG recordings to ensure optimal surgical planning. Often EEG demonstrates abnormal foci that are not detected on 1.5T MRI. Ultra high-field MRI at 7T provides much improved resolution of the brain. We investigated the utility of 7T MRI to detect potential anatomical abnormalities associated with functional abnormalities detected by scalp and/or invasive EEG recordings. Methods Ultra-high-field data were acquired on a 7T neuroimaging optimized MRI scanner for 13 patients with a history of drug resistant TLE during evaluation for epilepsy surgery. All patients had video-EEG telemetry recordings in our Epilepsy Monitoring Unit. Additionally, 9 patients underwent invasive EEG recordings including subdural and/or depth electrodes. Qualitative evaluation of 7T imaging for scan quality and presence of focal abnormalities detected on EEG was performed. The correlation of 7T MRI findings with EEG recordings of focal slowing or interictal epileptic spikes (IEDs), and seizures was performed. Results Assessment of 7T MRI demonstrated concordance with the clinically suspected TLE in 8 out of 13 cases. Among these, 3 exhibited supportive abnormal 7T MRI abnormalities not detected by the clinical 1.5T MRI. Eleven out of 13 cases had scalp and/or invasive electrode EEG findings with no anatomic correlates on 1.5T or 7T MRI. Findings included IEDs localizing to the contralateral temporal lobe in 6 patients, frontal lobes in 3 patients, and parieto-occipital lobes in 2 patients. Qualitative assessment of 7T images did not reveal any focal anatomical abnormalities to account for the EEG findings in these patients. Conclusion To our knowledge, this is the first study to investigate the utility of 7T MRI in combination with scalp and invasive. Qualitative ultra high-field 7T MRI findings show a moderate concordance with clinical data. However, 7T MRI did not reveal focal anatomical findings to account for all the abnormalities detected by the scalp EEG recordings in patients with temporal lobe epilepsy.

Acyclovir resistance in herpes simplex virus type I encephalitis: a case report

Acyclovir resistance is rarely seen in herpes simplex virus (HSV) type I encephalitis. Prevalence rates vary between 0.5 % in immunocompetent patients (Christophers et al. 1998; Fife et al. 1994) and 3.5–10 % in immunocompromised patients (Stranska et al. 2005). We report a 45-year-old, immunocompetent (negative HIV antigen/antibody testing), female patient, without previous illness who developed—after a febrile prodromal stage—aphasia and psychomotor slowing. Cerebral magnetic resonance imaging (cMRI) showed right temporal and insular T2-hyperintense lesions with spreading to the contralateral temporal lobe. Cerebrospinal fluid (CSF) analysis yielded lymphocytic pleocytosis and elevated protein level. Polymerase chain reaction testing for HSV type I showed a positive result in repeat lumbar puncture. HSV type I encephalitis was diagnosed and intravenous acyclovir treatment was initiated (750 mg t.i.d.). Acyclovir treatment was intensified to 1000 mg t.i.d., due to clinical deterioration, ongoing pleocytosis and progression on cMRI 5 days after initiation of antiviral therapy. In parallel, acyclovir resistance testing showed mutation of thymidine kinase gene at position A156V prompting foscarnet therapy (60 mg t.i.d.). Patient’s condition improved dramatically over 2 weeks. Acyclovir resistance is rare but should be considered in case of clinical worsening of patient’s condition. To our knowledge, this is the first report of acyclovir resistance in HSV type I encephalitis of an immunocompetent and previously healthy patient in Austria.

MRI-negative temporal lobe epilepsy: A network disorder of neocortical connectivity.

To define the functional network changes that characterize MRI-negative temporal lobe epilepsy (TLE) and TLE with hippocampal sclerosis (HS-TLE). We studied 36 patients with medically refractory unilateral TLE, having either a normal clinical MRI (n = 18) or unilateral hippocampal sclerosis (n = 18). Patients were compared to healthy controls of equivalent age and sex (n = 27). Functional connectivity in 10 minutes of task-free functional MRI was assessed using a voxel-resolution graph theoretic analysis, using the metrics of degree, clustering coefficient, eigenvector, and betweenness centrality. Significant clusters were further explored with a seed-based analysis. MRI-negative TLE showed decreased connectivity at the ipsilateral superior and middle temporal gyri compared to controls (decreased eigenvector centrality). No functional abnormality was detected within mesial temporal structures. In contrast, HS-TLE showed increased connectivity within the affected hippocampus and anterior thalamus (increased clustering coefficient) and decreased connectivity of the ventromesial prefrontal cortex (decreased betweenness centrality). Using the detected clusters as seed regions revealed decreased connectivity from the sclerotic hippocampus to both the contralateral temporal lobe and regions of the default mode network. MRI-negative TLE is associated with impaired interictal connectivity of the temporal neocortex, lateralized to the epileptic side. HS-TLE shows a different pattern, with functional segregation of the sclerotic hippocampus and impairment of its long-range connectivity. This suggests that MRI-negative TLE is not merely a subtle version of hippocampal sclerosis, but is rather a separate condition that involves distinct brain networks.

Non-coplanar trajectories to improve organ at risk sparing in volumetric modulated arc therapy for primary brain tumors

Background and purposeTo evaluate non-coplanar volumetric modulated arc radiotherapy (VMAT) trajectories for organ at risk (OAR) sparing in primary brain tumor radiotherapy. Materials and methodsFifteen patients were planned using coplanar VMAT and compared against non-coplanar VMAT plans for three trajectory optimization techniques. A geometric heuristic technique (GH) combined beam scoring and Dijkstra’s algorithm to minimize the importance-weighted sum of OAR volumes irradiated. Fluence optimization was used to perform a local search around coplanar and GH trajectories, producing fluence-based local search (FBLS) and FBLS+GH trajectories respectively. ResultsGH, FBLS, and FBLS+GH trajectories reduced doses to the contralateral globe, optic nerve, hippocampus, temporal lobe, and cochlea. However, FBLS increased dose to the ipsilateral lens, optic nerve and globe. Compared to GH, FBLS+GH increased dose to the ipsilateral temporal lobe and hippocampus, contralateral optics, and the brainstem and body. GH and FBLS+GH trajectories reduced bilateral hippocampi normal tissue complication probability (p=0.028 and p=0.043, respectively). All techniques reduced PTV conformity; GH and FBLS+GH trajectories reduced homogeneity but less so for FBLS+GH. ConclusionsThe geometric heuristic technique best spared OARs and reduced normal tissue complication probability, however incorporating fluence information into non-coplanar trajectory optimization maintained PTV homogeneity.

Graph Theoretical Analysis of Structural Neuroimaging in Temporal Lobe Epilepsy with and without Psychosis.

PurposePsychosis is one of the most important psychiatric comorbidities in temporal lobe epilepsy (TLE), and its pathophysiology still remains unsolved. We aimed to explore the connectivity differences of structural neuroimaging between TLE with and without psychosis using a graph theoretical analysis, which is an emerging mathematical method to investigate network connections in the brain as a small-world system.Materials and MethodsWe recruited 11 TLE patients with unilateral hippocampal sclerosis (HS) presenting psychosis or having a history of psychosis (TLE-P group). As controls, 15 TLE patients with unilateral HS without any history of psychotic episodes were also recruited (TLE-N group). For graph theoretical analysis, the normalized gray matter images of both groups were subjected to Graph Analysis Toolbox (GAT). As secondary analyses, each group was compared to 14 age- and gender-matched healthy subjects.ResultsThe hub node locations were found predominantly in the ipsilateral hemisphere in the TLE-N group, and mainly on the contralateral side in the TLE-P group. The TLE-P group showed significantly higher characteristic path length, transitivity, lower global efficiency, and resilience to random or targeted attack than those of the TLE-N group. The regional comparison in betweenness centrality revealed significantly decreased connectivity in the contralateral temporal lobe, ipsilateral middle frontal gyrus, and bilateral postcentral gyri in the TLE-P group. The healthy subjects showed well-balanced nodes/edges distributions, similar metrics to TLE-N group except for higher small-worldness/modularity/assortativity, and various differences of regional betweenness/clustering.ConclusionIn TLE with psychosis, graph theoretical analysis of structural imaging revealed disrupted connectivity in the contralateral hemisphere. The network metrics suggested that the existence of psychosis can bring vulnerability and decreased efficiency of the whole-brain network. The sharp differences in structural networks between morphologically homogeneous groups are remarkable and may contribute to a better understanding of psychosis in TLE.

Compensatory Mechanism for Face Perception Suggested by a SPECT Activation Study

Background The bilateral temporo-occipital lobes are the usual site of pathology in patients with prosopagnosia. However, the mechanisms leading to this disorder are not fully understood. We investigated the neural mechanism of compensation for prosopagnosia in a patient with focal right posterior temporal lobe encephalitis without prosopagnosia. Methods A single-photon emission computed tomography (SPECT) scan was performed using a brain-dedicated 32-phototube SPECT scanner and technetium-99m hexamethyl-propylene amine oxime to measure regional cerebral blood flow (rCBF). A SPECT activation study was performed in each of two conditions: the familial faces retrieval task and a control task. Results The SPECT activation study revealed a significant increase in rCBF in the contralateral temporal lobe (from 72 during control conditions to 99 mL/100 g/min during the activation paradigm). Conclusions This finding suggests that the region contralateral to the brain lesion compensates for the function of face perception. Our result may explain the reason why prosopagnosia rarely occurs with single, well-circumscribed lesions. The activation pattern seen in this study may be helpful for understanding the neural mechanism of compensation for prosopagnosia.

Language processing of auditory cortex revealed by functional magnetic resonance imaging in presbycusis patients

Conclusion: Contralateral temporal lobe activation decreases with aging, regardless of hearing status, with elderly individuals showing reduced right ear advantage. Background: Aging and hearing loss possibly lead to presbycusis speech discrimination decline. Objectives: To evaluate presbycusis patients’ auditory cortex activation under verbal stimulation. Method: Thirty-six patients were enrolled: 10 presbycusis patients (mean age = 64 years, range = 60–70), 10 in the healthy aged group (mean age = 66 years, range = 60–70), and 16 young healthy volunteers (mean age = 25 years, range = 23–28). These three groups underwent simultaneous 1 kHz and 90 dB single-syllable word stimuli and (blood-oxygen-level-dependent functional magnetic resonance imaging) BOLD fMRI examinations. Results: The main activation regions were superior temporal and middle temporal gyrus. For all aged subjects, the right region of interest (ROI) activation volume was decreased compared with the young group. With left ear stimulation, bilateral ROI activation intensity held. With right ear stimulation, the aged group’s activation intensity was higher. Using monaural stimulation in the young group, contralateral temporal lobe activation volume and intensity were higher vs ipsilateral, while they were lower in the aged and presbycusis groups. On left and right ear auditory tasks, the young group showed right ear advantage, while the aged and presbycusis groups showed reduced right ear advantage.

Connectome Reorganization Associated With Surgical Outcome in Temporal Lobe Epilepsy.

To identify the distinct pattern of anatomical network reorganization in surgically refractory mesial temporal lobe epilepsy (MTLE) patients using a longitudinal design. We collected longitudinal diffusion-weighted images of 19 MTLE patients before and after anterior temporal lobectomy. Patients were classified as seizure-free (SF) or nonseizure-free (NSF) at least 1 year after surgery. We constructed whole-brain anatomical networks derived from white matter tractography and evaluated network connectivity measures by graph theoretical analysis. The reorganization trajectories of network measures in SF and NSF patients were investigated by two-way mixed analysis of variance, with factors "group" (SF vs NSF) and "treatment" (presurgery vs postsurgery). Widespread brain structures showed opposite reorganization trajectories in FS and NSF groups (interaction effect). Most of them showed group difference before surgery and then converge after surgery, suggesting that surgery remodeled these structures into a similar status. Conversly, contralateral amygdala-planum-temporale and thalamic-parietal tracts showed higher connectivity strength in NSF than in SF patients after surgery, indicating maladaptive neuroplastic responses to surgery in NSF patients. Our findings suggest that surgical outcomes are associated not only with the preoperative pattern of anatomical connectivity, but also with connectome reconfiguration following surgery. The reorganization of contralateral temporal lobe and corticothalamic tracts may be particularly important for seizure control in MTLE.

The feeling of familiarity for music in patients with a unilateral temporal lobe lesion: A gating study

Previous research has indicated that the medial temporal lobe (MTL), and more specifically the perirhinal cortex, plays a role in the feeling of familiarity for non-musical stimuli. Here, we examined contribution of the MTL to the feeling of familiarity for music by testing patients with unilateral MTL lesions. We used a gating paradigm: segments of familiar and unfamiliar musical excerpts were played with increasing durations (250, 500, 1000, 2000, 4000ms and complete excerpts), and participants provided familiarity judgments for each segment. Based on the hypothesis that patients might need longer segments than healthy controls (HC) to identify excerpts as familiar, we examined the onset of the emergence of familiarity in HC, patients with a right MTL resection (RTR), and patients with a left MTL resection (LTR). In contrast to our hypothesis, we found that the feeling of familiarity was relatively spared in patients with a right or left MTL lesion, even for short excerpts. All participants were able to differentiate familiar from unfamiliar excerpts as early as 500ms, although the difference between familiar and unfamiliar judgements was greater in HC than in patients. These findings suggest that a unilateral MTL lesion does not impair the emergence of the feeling of familiarity. We also assessed whether the dynamics of the musical excerpt (linked to the type and amount of information contained in the excerpts) modulated the onset of the feeling of familiarity in the three groups. The difference between familiar and unfamiliar judgements was greater for high than for low-dynamic excerpts for HC and RTR patients, but not for LTR patients. This indicates that the LTR group did not benefit in the same way from dynamics. Overall, our results imply that the recognition of previously well-learned musical excerpts does not depend on the integrity of either right or the left MTL structures. Patients with a unilateral MTL resection may compensate for the effects of unilateral damage by using the intact contralateral temporal lobe. Moreover, we suggest that remote semantic memory for music might depend more strongly on neocortical structures rather than the MTL.

1-A-D-26. Pre-operative magnetoencephalographic spike localization in patients with surgically-cured epilepsy

This study investigated the characteristic localization of magnetoencephalographic (MEG) “green” spikes unrelated to epileptogenicity. Preoperative interictal MEG spike localization was compared with surgical resection areas in 17 patients, who achieved complete seizure freedom after withdrawal from antiepileptic medications. No MEG spikes were detected in two patients. In three patients, all MEG spike-areas were resected. Eleven patients had MEG spikes in both resection and other areas. Spike localization remote from resection-area was classified into three types: (1) antero-mesial temporal spikes ( n = 4); (2) contralateral temporal spikes ( n = 3); and (3) posterior temporo-parietal spikes ( n = 5). Both the antero-mesial and contralateral temporal spikes were found only in patients with mesial temporal lobe epilepsy (TLE). The posterior temporo-parietal spikes were found in patients with mesial TLE, as well as other epilepsies. Mesial temporal spikes generated from the hippocampus can propagate to the anterior temporal neocortex and contralateral temporal lobe. Since these temporal neocortical spikes did not reflect epileptogenicity, seizure freedom was achieved after amygdalohippocampectomy. Temporo-parietal spikes found in TLE and other epilepsies can be a “green” MEG spikes. MEG has high sensitivity to activity in the temporo-parietal area, to where spikes propagate easily.

Thalamotemporal alteration and postoperative seizures in temporal lobe epilepsy.

ObjectiveThere are competing explanations for persistent postoperative seizures after temporal lobe surgery. One is that 1 or more particular subtypes of mesial temporal lobe epilepsy (mTLE) exist that are particularly resistant to surgery. We sought to identify a common brain structural and connectivity alteration in patients with persistent postoperative seizures using preoperative quantitative magnetic resonance imaging and diffusion tensor imaging (DTI).MethodsWe performed a series of studies in 87 patients with mTLE (47 subsequently rendered seizure free, 40 who continued to experience postoperative seizures) and 80 healthy controls. We investigated the relationship between imaging variables and postoperative seizure outcome. All patients had unilateral temporal lobe seizure onset, had ipsilateral hippocampal sclerosis as the only brain lesion, and underwent amygdalohippocampectomy.ResultsQuantitative imaging factors found not to be significantly associated with persistent seizures were volumes of ipsilateral and contralateral mesial temporal lobe structures, generalized brain atrophy, and extent of resection. There were nonsignificant trends for larger amygdala and entorhinal resections to be associated with improved outcome. However, patients with persistent seizures had significant atrophy of bilateral dorsomedial and pulvinar thalamic regions, and significant alterations of DTI‐derived thalamotemporal probabilistic paths bilaterally relative to those patients rendered seizure free and controls, even when corrected for extent of mesial temporal lobe resection.InterpretationPatients with bihemispheric alterations of thalamotemporal structural networks may represent a subtype of mTLE that is resistant to temporal lobe surgery. Increasingly sensitive multimodal imaging techniques should endeavor to transform these group‐based findings to individualize prediction of patient outcomes. Ann Neurol 2015;77:760–774

Incidence of functional bi-temporal connections in the human brain in vivo and their relevance to epilepsy surgery

The incidence of functional connections between human temporal lobes and their latencies were investigated using intracranial EEG responses to electrical stimulation with 1 msec single pulses in 91 patients assessed for surgery for treatment of epilepsy. The areas studied were amygdala, hippocampus, parahippocampal gyrus, fusiform gyrus, inferior and mid temporal gyrus. Furthermore, we assessed whether the presence of such connections are related to seizure onset extent and postsurgical seizure control. Responses were seen in any region of the contralateral temporal lobe when stimulating temporal regions in 30 patients out of the 91 (32.96%). Bi-hippocampal or bi-amygdalar projections were seen in only 5% of temporal lobes (N = 60) and between both fusiform gyri in 7.1% (N = 126). All other bilateral connections occurred in less than 5% of hemispheres. Depending on the structures, latencies ranged between 20 and 90 msec, with an average value of 60.2 msec. There were no statistical difference in the proportion of patients showing Engel Class I between patients with and without contralateral temporal connections. No difference was found in the proportion of patients showing bilateral or unilateral seizure onset among patients with and without contralateral temporal projections. The present findings corroborate that the functionality of bilateral temporal connections in humans is limited and does not affect the surgical outcome.

Dynamic directed interictal connectivity in left and right temporal lobe epilepsy.

There is increasing evidence that epileptic activity involves widespread brain networks rather than single sources and that these networks contribute to interictal brain dysfunction. We investigated the fast-varying behavior of epileptic networks during interictal spikes in right and left temporal lobe epilepsy (RTLE and LTLE) at a whole-brain scale using directed connectivity. In 16 patients, 8 with LTLE and 8 with RTLE, we estimated the electrical source activity in 82 cortical regions of interest (ROIs) using high-density electroencephalography (EEG), individual head models, and a distributed linear inverse solution. A multivariate, time-varying, and frequency-resolved Granger-causal modeling (weighted Partial Directed Coherence) was applied to the source signal of all ROIs. A nonparametric statistical test assessed differences between spike and baseline epochs. Connectivity results between RTLE and LTLE were compared between RTLE and LTLE and with neuropsychological impairments. Ipsilateral anterior temporal structures were identified as key drivers for both groups, concordant with the epileptogenic zone estimated invasively. We observed an increase in outflow from the key driver already before the spike. There were also important temporal and extratemporal ipsilateral drivers in both conditions, and contralateral only in RTLE. A different network pattern between LTLE and RTLE was found: in RTLE there was a much more prominent ipsilateral to contralateral pattern than in LTLE. Half of the RTLE patients but none of the LTLE patients had neuropsychological deficits consistent with contralateral temporal lobe dysfunction, suggesting a relationship between connectivity changes and cognitive deficits. The different patterns of time-varying connectivity in LTLE and RTLE suggest that they are not symmetrical entities, in line with our neuropsychological results. The highest outflow region was concordant with invasive validation of the epileptogenic zone. This enhanced characterization of dynamic connectivity patterns could better explain cognitive deficits and help the management of epilepsy surgery candidates.

Increasing structural atrophy and functional isolation of the temporal lobe with duration of disease in temporal lobe epilepsy

Due to pharmacoresistant seizures and the underutilization of surgical treatments, a large number of temporal lobe epilepsy (TLE) patients experience seizures for years or decades. The goal of this study was to generate a predictive model of duration of disease with the least number of parameters possible in order to identify and quantify the significant volumetric and functional indicators of TLE progression. Two cohorts of subjects including 12 left TLE, 21 right TLE and 20 healthy controls (duration = 0) were imaged on a 3T MRI scanner using high resolution T1-weighted structural MRI and 20 min of resting functional MRI scanning. Multivariate linear regression methods were used to compute a predictive model of duration of disease using 49 predictors including functional connectivity and gray matter volumes computed from these images. No model developed from the full set of data accurately predicted the duration of disease across the entire range from 3 to 50 years. We then performed the regression on 35 subjects with durations of disease in the range 10 to 35 years. The resulting predictive model showed that longer durations were associated with reductions in functional connectivity from the ipsilateral temporal lobe to the contralateral temporal lobe, precuneus and mid cingulate, and with decreases in volume of the ipsilateral hippocampus and pallidum. Functional and volumetric parameters accurately predicted duration of disease in TLE. The findings suggest that TLE is associated with a gradual functional isolation and significant progressive structural atrophy of the ipsilateral temporal lobe over years of duration in the range of 10-35 years. Furthermore, these changes can also be detected in the contralateral hemisphere in these patients, but to a lesser degree.

Recurrent glioblastoma multiforme presents as a mirror image in the contralateral temporal lobe

A 44-year-old woman with history of left temporal glioblastoma multiforme (GBM) presented with a generalized seizure and altered mental status. She had undergone surgical resection for the left tem...

Lesion side matters — An fMRI study on the association between neural correlates of watching dynamic fearful faces and their evaluation in patients with temporal lobe epilepsy

Most studies assessing facial affect recognition in patients with TLE reported emotional disturbances in patients with TLE. Results from the few fMRI studies assessing neural correlates of affective face processing in patients with TLE are divergent. Some, but not all, found asymmetrical mesiotemporal activations, i.e., stronger activations within the hemisphere contralateral to seizure onset. Little is known about the association between neural correlates of affect processing and subjective evaluation of the stimuli presented. Therefore, we investigated the neural correlates of processing dynamic fearful faces in 37 patients with mesial temporal lobe epilepsy (TLE; 18 with left-sided TLE (lTLE), 19 with right-sided TLE (rTLE)) and 20 healthy subjects. We additionally assessed individual ratings of the fear intensity and arousal perception of the fMRI stimuli and correlated these data with the activations induced by the fearful face paradigm and activation lateralization within the mesiotemporal structures (in terms of individual lateralization indices, LIs). In healthy subjects, whole-brain analysis showed bilateral activations within a widespread network of mesial and lateral temporal, occipital, and frontal areas. The patient groups activated different parts of this network. In patients with lTLE, we found predominantly right-sided activations within the mesial and lateral temporal cortices and the superior frontal gyrus. In patients with rTLE, we observed bilateral activations in the posterior regions of the lateral temporal lobe and within the occipital cortex. Mesiotemporal region-of-interest analysis showed bilateral symmetric activations associated with watching fearful faces in healthy subjects. According to the region of interest and LI analyses, in the patients with lTLE, mesiotemporal activations were lateralized to the right hemisphere. In the patients with rTLE, we found left-sided mesiotemporal activations. In patients with lTLE, fear ratings were comparable to those of healthy subjects and were correlated with relatively stronger activations in the right compared to the left amygdala. Patients with rTLE showed significantly reduced fear ratings compared to healthy subjects, and we did not find associations with amygdala lateralization. Although we found stronger activations within the contralateral mesial temporal lobe in the majority of all patients, our results suggest that only in the event of left-sided mesiotemporal damage is the right mesial temporal lobe able to preserve intact facial fear recognition. In the event of right-sided mesiotemporal damage, fear recognition is disturbed. This underlines the hypothesis that the right amygdala is biologically predisposed to processing fear, and its function cannot be fully compensated in the event of right-sided mesiotemporal damage.

Frontal hemodynamic changes precede EEG onset of temporal lobe seizures

ObjectiveA preictal state exists minutes or hours prior to the clinical seizure. We investigated whether hemodynamic changes preceding temporal lobe seizures were detectable in frontal scalp recordings using near-infrared spectroscopy (NIRS). Patients undergoing video-EEG telemetry (VET) were studied. MethodsA NIRS sensor was placed over the frontal scalp ipsilateral to the patient’s first recorded seizure. Regional cerebral oxygenation (rSO2) was recorded synchronously with VET data and peripheral oxygen saturation (SaO2). Periictal changes in rSO2 were compared with baseline interictal rSO2. ResultsEleven seizures were recorded in six patients. A mean peak preictal increase in rSO2 of 7.1% from the interictal baseline (p<0.001) occurred at a mean peak latency of 298.9s before seizure onset. rSO2 then decreased around seizure onset. SaO2 nadir occurred at a mean latency of 62s following rSO2 nadir. A postictal increase in rSO2 occurred with a mean duration of about 35min. Periictal rSO2 changes occurred with both ipsi and contralateral temporal lobe seizures. ConclusionWe have shown that preictal changes in cerebral oxygenation occur with a mean peak latency of about 4.98min before seizure onset. SignificanceNIRS has the potential for providing a noninvasively detected signal of an imminent seizure.

Intensity Modulated Radiation Therapy (IMRT) Versus Intensity Modulated Proton Therapy (IMPT) in Low-Grade Gliomas: A Dosimetric Study

To compare intensity-modulated proton therapy (IMPT) and intensity-modulated radiation therapy (IMRT) in patients (pts) with low-grade gliomas (LGG). Eleven pathologically confirmed previously irradiated LGG pts were retrieved and re-planned both with IMRT and IMPT. The dose prescription was 54 Gy in 27 fractions with the following goals: first, compliance of maxDose constraints for primary organs at risk (OARs) (optic nerves, chiasm, retinas, and brainstem); second, ensure target coverage: the percentage of planning target volume (PTV) receiving at least 95% of the prescribed dose (V95) should be ≥99%. Once the previous goals were met, a further effort was made to reduce the dose to secondary OARs: cochlea (meanDose), lens (maxDose), pituitary gland (volume receiving 50 Gy - V50), brain, temporal lobe, and hippocampus (volume receiving 30 and 40 Gy - V30 and V40, respectively). Target conformity and homogeneity were evaluated via conformity index and homogeneity index. Wilcoxon Rank Sum test was performed to determine statistical differences between the techniques and p < 0.05 was considered significant. Both techniques always fulfilled the established constraints for primary OARs. IMPT and IMRT provided same target coverage and conformity while homogeneity was significantly better with IMPT (p = 0.01). With a few exceptions, IMPT systematically provided a lower maxDose to primary OARs with respect to IMRT. However, the differences were statistically significant only for the contralateral retina (p = 0.03). IMRT and IMPT achieved comparable results regarding pituitary gland V50. IMPT significantly reduced the maxDose to omo- and contralateral lens (mean reduction 5.2 and 6.3 Gy, respectively) as well as mean dose to omo- and contralateral cochlea (mean reduction 5.3 and 3.8 Gy). Moreover, IMPT scored significantly better results in terms of brain V30 and V40 (mean reduction 8.9% and 4.1%, respectively) as well as omolateral temporal lobe V30 (mean reduction 19.1%). Even though results were not statistically significant, IMPT performed better than IMRT also for omolateral temporal lobe V40, contralateral temporal lobe V30 and V40 as well as omo- and contralateral hippocampus V30 and V40. IMRT and IMPT provide same target coverage and primary OARs sparing so that a better tumor control and lower primary OARs toxicity cannot be expected with IMPT. IMPT achieves a significant better sparing of secondary OARs and healthy brain. Hence, IMPT could potentially reduce the secondary OARs toxicity and radiation related neurocognitive deficits.