Patterns of default mode network in temporal lobe epilepsy with and without hippocampal sclerosis.

The default mode network (DMN) consists of the deactivation of specific regions during the performance of cognitive tasks and activation during resting or mind wandering. Several pieces of evidence indicate the impairment of DMN in patients with mesial temporal lobe epilepsy (MTLE). However, most of these studies combined different underlying etiologies, failing to disentangle the influence of seizures and presence and side of hippocampal sclerosis (HS). We included 119 patients with MTLE divided into right-HS (n = 42), left-HS (n = 46), and magnetic resonance imaging (MRI)-negative MTLE (n = 31) and controls (n = 59). All underwent resting-state seed-based functional connectivity (FC), with a seed placed at the posterior cingulate cortex (PCC), an essential node for the DMN. To access group inferences, we used an SPM (Statistical Parametric Mapping) full-factorial model to compare patterns of activation using pairwise comparisons among all groups. Our results indicate a different pattern of DMN FC when controlling for side and presence of HS. The group with right-HS had increased FC in the left angular gyrus and the left middle occipital gyrus, when compared to controls, and increased FC of the left hippocampus when compared to the group with left-HS. The MRI-negative group had increased FC of the left hippocampus, left ventral diencephalon, and left fusiform gyrus as compared to left-HS, but did not show any areas of reduced FC compared to controls. By contrast, the group with left-HS did not show areas of increased FC compared to controls or the right-HS and had reduced FC in the left hippocampus compared to controls. Hence, the right-HS presented increased FC in areas related to the DMN in the left hemisphere; the MRI-negative group also showed increased FC in left-sided structures close to temporal lobe when compared to left-HS, probably indicating engagement in a compensatory system. In a subanalysis considering only the MRI-negative with left-sided EEG (electroencephalogram) subgroup, we found differences against controls, with left angular gyrus more connected in the first group, but no significant differences when compared to the group with left-HS. We conclude that the origin of seizures on the left hemisphere seems to engender a less prominent capacity of recruiting other neighbor areas related to DMN as compared to right-HS and controls. Considering recent studies that have revealed the importance of DMN for cognitive skills and memory, our findings may indicate that deficiencies exhibited by patients with left-HS temporal lobe epilepsy (TLE) in connecting to the DMN could be a surrogate marker of their known worse neuropsychological performance. Further studies with direct comparisons between cognitive tests and FC within the DMN are needed to validate these findings, especially for MRI-negative patients. This article is part of the Special Issue "NEWroscience 2018".

Hippocampal atrophy disrupts the language network but not hemispheric language lateralization.

OBJECTIVE: It is still unclear how temporal lobe epilepsy (TLE) with and without hippocampal atrophy (HA) affects cortical language distribution. We aimed to investigate the role of the hippocampus on language lateralization, activation pattern, and functional connectivity (FC) in patients with TLE. METHODS: We investigated 93 patients with TLE-divided into right HA (RHA), left HA (LHA), and negative magnetic resonance imaging (MRI) (non-HA)-and 101 controls using a semantic-language functional MRI (fMRI) task and the Boston Naming Test (BNT). RESULTS: Groups did not differ in the frequency of atypical language lateralization (LL), which correlated differently with handedness in each brain region and group. Blood-oxygen-level dependend (BOLD) activation patterns and region of interest (ROI)-to-ROI FC differed between LHA and controls, as well as between LHA and non-HA patients. In the task activation pattern analysis, there was a decrease in the activation of patients with LHA relative to controls, exactly in the left hippocampus. However, non-HA patients had increased FC relative to controls in the left superior temporal gyrus region. Seed-to-voxel FC demonstrated greater differences between patients and controls and smaller differences among patient groups. The non-HA group was similar to controls, except for increased BOLD activation and increase FC in the superior temporal gyri. RHA and LHA differed from controls in BNT. BNT correlated with fMRI activation in RHA and non-HA groups. SIGNIFICANCE: LHA affected naming performance, fMRI semantic task activation pattern, and FC more than RHA and non-HA. Contrary to our expectations, LHA did not increase the frequency of atypical LL. Regardless of the side, HA impacts negatively on the language network but not on hemispheric language lateralization.

Long-term postoperative atrophy of contralateral hippocampus and cognitive function in unilateral refractory MTLE with unilateral hippocampal sclerosis.

OBJECTIVE: This study aimed to evaluate long-term atrophy in contralateral hippocampal volume after surgery for unilateral MTLE, as well as the cognitive outcome for patients submitted to either selective transsylvian amygdalohippocampectomy (SelAH) or anterior temporal lobe resection (ATL). METHODS: We performed a longitudinal study of 47 patients with MRI signs of unilateral hippocampal sclerosis (23 patients with right-sided hippocampal sclerosis) who underwent surgical treatment for MTLE. They underwent preoperative/postoperative high-resolution MRI as well as neuropsychological assessment for memory and estimated IQ. To investigate possible changes in the contralateral hippocampus of patients, we included 28 controls who underwent two MRIs at long-term intervals. RESULTS: The volumetry using preoperative MRI showed significant hippocampal atrophy ipsilateral to the side of surgery when compared with controls (p<0.0001) but no differences in contralateral hippocampal volumes. The mean postoperative follow-up was 8.7 years (± 2.5 SD; median=8.0). Our patients were classified as Engel I (80%), Engel II (18.2%), and Engel III (1.8%). We observed a small but significant reduction in the contralateral hippocampus of patients but no volume changes in controls. Most of the patients presented small declines in both estimated IQ and memory, which were more pronounced in patients with left TLE and in those with persistent seizures. Different surgical approaches did not impose differences in seizure control or in cognitive outcome. CONCLUSIONS: We observed small declines in cognitive scores with most of these patients, which were worse in patients with left-sided resection and in those who continued to suffer from postoperative seizures. We also demonstrated that manual volumetry can reveal a reduction in volume in the contralateral hippocampus, although this change was mild and could not be detected by visual analysis. These new findings suggest that dynamic processes continue to act after the removal of the hippocampus, and further studies with larger groups may help in understanding the underlying mechanisms.

Carotid stenting versus endarterectomy cognitive outcomes.

BACKGROUND: The objectives are to analyze the impact of carotid revascularization on cognitive performance after a 3-month period in patients, who have undergone carotid artery stenting (CAS) or carotid endarterectomy (CEA), and to compare the cognitive outcomes between these 2 groups of patients. This a nonrandomized and prospective single-center experience. METHODS: This study was performed in the University of Campinas Hospital from January 2010 to January 2012 and included 30 patients with carotid stenosis who received carotid interventions. Nineteen patients received CEA and 11 patients received CAS. Neuropsychologic evaluation included general cognitive, language, visuospatial, attentional, executive function, and memory tests. RESULTS: After the follow-up period, there was improvement in episodic memory, encoding subitem (P = 0.02), and delayed recall (P = 0.02) for the CEA group. The CAS group improved in episodic memory, encoding subitem (P = 0.009), working memory (P = 0.04), and executive functions (P = 0.02). Comparing the techniques, the CAS group showed higher scores only in executive functions (P = 0.02). CONCLUSIONS: Both groups had a similar performance in cognitive tests, comparing preoperative and postoperative results. However, patients who underwent CAS tended to achieve higher scores in executive function and operational memory/attention tests.

Temporopolar amygdalohippocampectomy: seizure control and postoperative outcomes.

OBJECTIVE: The objective of this study was to evaluate the efficacy and safety of a modified surgical approach for the treatment of temporal lobe epilepsy secondary to hippocampal sclerosis (HS). This modified approach, called temporopolar amygdalohippocampectomy (TP-AH), includes a transsylvian resection of the temporal pole and subsequent amygdalohippocampectomy utilizing the limen insula as an anatomical landmark. METHODS: A total of 61 patients who were diagnosed with HS and underwent TP-AH between 2013 and 2017 were enrolled. Patients performed pre- and postoperative diffusion tensor imaging and were classified according to Engel's scale for seizure control. To evaluate the functional preservation of the temporal stem white-matter fiber tracts, the authors analyzed postoperative Humphrey perimetries and pre- and postoperative neurocognitive performance (Rey Auditory Verbal Learning Test [RAVLT], Weschler Memory Scale-Revised [WMS-R], intelligence quotient [IQ], Boston Naming Test [BNT], and semantic and phonemic fluency). Demographic data and surgical complications were also recorded and described. RESULTS: After a median follow-up of 36 ± 16 months, 46 patients (75.4%) achieved Engel class I, of whom 37 (60.6%) were Engel class IA. No significant changes in either the inferior frontooccipital fasciculus and optic radiation tractography were observed postoperatively for both left- and right-side surgeries. Reliable perimetry was obtained in 40 patients (65.6%), of whom 27 (67.5%) did not present any visual field defects (VFDs) attributable to surgery, while 12 patients (30%) presented with quadrant VFD, and 1 patient (2.5%) presented with hemifield VFD. Despite a significant decline in verbal memory (p = 0.007 for WMS-R, p = 0.02 for RAVLT recognition), there were significant improvements in both IQ (p < 0.001) and visual memory (p = 0.007). Semantic and phonemic fluency, and scores on the BNT, did not change postoperatively. CONCLUSIONS: TP-AH provided seizure control similar to historical temporal lobe approaches, with a tendency to preserve the temporal stem and a satisfactory incidence of VFD. Despite a significant decline in verbal memory, there were significant improvements in both IQ and visual memory, along with preservation of executive function. This approach can be considered a natural evolution of the selective transsylvian approach.

Clinical and Imaging Evaluation of Transuncus Selective Amygdalohippocampectomy.

BACKGROUND: Various reports have described the transuncus (TU) approach as a selective route to the amygdala and hippocampus, but this approach has not yet been submitted to solid postoperative imaging analysis. The objective of this study was to evaluate the anatomy, surgical technique, postoperative imaging analysis, and outcome in a series of patients with temporal lobe epilepsy who underwent selective amigdalohippocampectomy via a TU approach. METHODS: This was a prospective study of 25 consecutive patients who underwent selective amigdalohippocampectomy through a TU approach. The temporal stem and temporal pole were evaluated through different modalities of 3-Tesla magnetic resonance imaging, including tractography of optic radiation (OR), uncinate fascicle, and inferior fronto-occipital fascicle. Visual field analysis was performed with automated perimetry. RESULTS: The mean age was 40 ± 8.21 years, and mean follow-up was 26.44 + 12.58 months. Postoperatively, 21 patients (84%) were classified as Engel I (good seizure control). Diffusion tensor imaging (DTI) data showed that 78.2% of patients had some structural damage to the temporal stem and fibers of the uncinate fascicle were identified postoperatively in only 3 patients (13.04%). The inferior fronto-occipital fascicle was identified in 18 patients (78.3%); however, subsequent DTI analysis of the remaining fibers showed them to be damaged. Integrity of the OR did not differ between these 2 groups. CONCLUSIONS: A TU approach is a feasible and efficient approach to selective amigdalohippocampectomy for surgical treatment of temporal lobe epilepsy. Postoperative DTI analysis suggests that a TU approach results in more injury to the temporal stem and its associated white matter fiber tracts than expected by previous anatomic studies; however, it was efficient in preserving OR.

Effects of task complexity on activation of language areas in a semantic decision fMRI protocol.

Language tasks used for clinical fMRI studies may be too complex for some patients with cognitive impairments, and "easier" versions are sometimes substituted, though the effects on brain activity of such changes in task complexity are largely unknown. To investigate these differences, we compared two versions of an fMRI language comprehension protocol, with different levels of difficulty, in 24 healthy right-handed adults. The protocol contrasted an auditory word comprehension task (semantic decision) with a nonspeech control task using tone sequences (tone decision). In the "complex" version (CV), the semantic decision task required two complex semantic decisions for each word, and the tone decision task required the participant to count the number of target tones in each sequence. In the "easy" version (EV), the semantic task required only a single easier decision, and the tone task required only detection of the presence or absence of a target tone in each sequence. The protocols were adapted for a Brazilian population. Typical left hemisphere language lateralization was observed in 92% of participants for both CV and EV using the whole-brain lateralization index, and typical language lateralization was also observed for others regions of interest. Task performance was superior on the EV compared to the CV (p=0.014). There were many common areas of activation across the two version; however, the CV produced greater activation in the left superior and middle frontal giri, angular gyrus, and left posterior cingulate gyrus compared to the EV, the majority of which are areas previously identified with language and semantic processing. The EV produced stronger activation only in a small area in the posterior middle temporal gyrus. These results reveal differences between two versions of the protocol and provide evidence that both are useful for language lateralization and worked well for Brazilian population. The complex version produces stronger activation in several nodes of the semantic network and therefore is elected for participants who can perform well these tasks.

Widespread neuronal damage and cognitive dysfunction in spinocerebellar ataxia type 3.

Previous studies demonstrated cognitive impairments in spinocerebellar ataxia type 3 (SCA3/MJD); however, there is no consensus about the cognitive domains affected and the correlation with structural brain abnormalities. We investigated the neuropsychological profile and 3T-MRI findings, including high-resolution T1-images, diffusion tensor imaging and magnetic resonance spectroscopy of 32 patients with SCA3/MJD and 32 age-, gender- and educational level-matched healthy controls. We reviewed patients' clinical history and CAG repeat length, and performed assessment and rating of ataxia (SARA)-Brazilian version and the neuropsychiatric inventory. Patients presented worse performance in episodic and working memory and Beck inventories (depression and anxiety). SCA3/MJD patients had a reduction of gray matter volume (GM) in the cerebellum, putamen, cingulum, precentral and parietal lobe. A positive correlation was identified between the cognitive findings and GM of temporal, frontal, parietal, culmen and insula. We observed positive correlation between the brainstem's fractional anisotropy and digit span-forward. The following cerebellar metabolite groups (measured relative to creatine) were reduced in patients: N-acetyl-aspartate (NAA), NAA + N-acetyl-aspartate-glutamate and glutamate + glutamine (Glx). We found a positive correlation between Corsi's block-tapping task forward with Glx; semantic verbal fluency with phosphorylcholine and glycerophosphorylcholine; digits span-forward with NAA. The cognitive impairments in SCA3/MJD are associated not only with cerebellar and brainstem abnormalities, but also with neuroimaging evidence of diffuse neuronal and axonal dysfunction, particularly in temporal, frontal, parietal and insular areas.

The useful interaction between functional magnetic resonance imaging and neuropsychology / A relevante interação entre ressonância magnética funcional e neuropsicologia / La relevante interacción entre resonancia magnética funcional y neuropsicología

In this paper, we aimed to elaborate a brief review about the early studies in functional magnetic resonance imaging (fMRI) associated to cognitive tasks, going over the most important researchers in the area, from William James to Seiji Ogawa. Moreover, we discuss studies that used cognitive tasks and fMRI in diseases such as epilepsy, autism, schizophrenia, multiple sclerosis, Parkinson's disease and dementia, in order to demonstrate the current and important interaction between neuropsychology and fMRI. From this review, we concluded that neuropsychology, a of neuroscience used for diagnosing cognitive impairments, can be combined to technologies such as fMRI, producing extremely useful results for experimental and especially clinical contexts...

O objetivo deste artigo foi fazer uma breve revisão acerca de como tiveram início os estudos em imagem de ressonância magnética funcional (RMf) associada a tarefas cognitivas, passando pelos principais pesquisadores na área, desde William James até Seiji Ogawa. Além disso, se relata que foi utilizado RMf e tarefas cognitivas em doenças como epilepsia, autismo, esquizofrenia, esclerose múltipla, doença de Parkinson e demência, a fim de demonstrar a atual e importante interação entre neuropsicologia e RMf. A partir deste estudo, concluímos que a neuropsicologia, uma área da neurociência bastante utilizada para o diagnóstico de prejuízos cognitivos, pode ser com- binada a tecnologias como RMf e produzir resultados de extrema utilidade experimental e principalmente clínica...

El objetivo de este artículo fue el de hacer una breve revisión acerca de cómo tuvieron inicio los estudios en imagen de resonancia magnética funcional (RMf) asociada a tareas cognitivas, pasando por los principales investigadores en el área, desde William James hasta Seiji Ogawa. Además, se relata que fue utilizada RMf y tareas cognitivas en enfermedades como epilepsia, autismo, esquizofrenia, escle- rosis múltiple, enfermedad de Parkinson y demencia, a fin de demostrar la actual e importante interacción entre neuropsicología y RMf. A partir de este estudio, concluimos que la neuropsicología, un área de la neurociencia bastante utilizada para el diagnóstico de deterioro cognitivo, puede ser combinada a tecnologías como RMf y producir resultados de extrema utilidad experimental y principalmente clínica...