Overt speech critically changes lateralization index and did not allow determination of hemispheric dominance for language: an fMRI study

Background Pre-surgical mapping of language using functional MRI aimed principally to determine the dominant hemisphere. This mapping is currently performed using covert linguistic task in way to avoid motion artefacts potentially biasing the results. However, overt task is closer to natural speaking, allows a control on the performance of the task, and may be easier to perform for stressed patients and children. However, overt task, by activating phonological areas on both hemispheres and areas involved in pitch prosody control in the non-dominant hemisphere, is expected to modify the determination of the dominant hemisphere by the calculation of the lateralization index (LI). Objective Here, we analyzed the modifications in the LI and the interactions between cognitive networks during covert and overt speech task. Methods Thirty-three volunteers participated in this study, all but four were right-handed. They performed three functional sessions consisting of (1) covert and (2) overt generation of a short sentence semantically linked with an audibly presented word, from which we estimated the “Covert” and “Overt” contrasts, and a (3) resting-state session. The resting-state session was submitted to spatial independent component analysis to identify language network at rest (LANG), cingulo-opercular network (CO), and ventral attention network (VAN). The LI was calculated using the bootstrapping method. Results The LI of the LANG was the most left-lateralized (0.66 ± 0.38). The LI shifted from a moderate leftward lateralization for the Covert contrast (0.32 ± 0.38) to a right lateralization for the Overt contrast (− 0.13 ± 0.30). The LI significantly differed from each other. This rightward shift was due to the recruitment of right hemispheric temporal areas together with the nodes of the CO. Conclusion Analyzing the overt speech by fMRI allowed improvement in the physiological knowledge regarding the coordinated activity of the intrinsic connectivity networks. However, the rightward shift of the LI in this condition did not provide the basic information on the hemispheric language dominance. Overt linguistic task cannot be recommended for clinical purpose when determining hemispheric dominance for language.

NCOG-17. FACTORS INFLUENCING POOR INDEPENDENCE LEVEL FOLLOWING RESECTION OF THE RIGHT TEMPORO-PARIETAL GLIOBLASTOMAS

In glioma surgeries, cognitive outcomes for the dominant hemisphere have gained much attention compared to the non-dominant hemisphere. For non-dominant hemispheric glioblastomas, we previously observed decreased independence level following glioblastoma resection of the posterior temporal to the parietal lobes. Here, we investigated the reason for the poor Karnofsky Performance Status (KPS) in such glioblastomas. A total of 41 patients with resection of the right cerebral hemispheric primary glioblastoma were enrolled for the study. Several kinds of neuropsychological functions and KPS of the brain regions were evaluated at pre- and postoperative 3 months by performing the Spearman’s correlation analysis and voxel-based lesion symptom mapping (VLSM). Additionally, the correlation between the resected volume of each gyrus or white matter tract and neuropsychological function score was analyzed. KPS at chronic phase (73.6) declined significantly compared with preoperation (81.0, p = 0.020). Functional factors influencing the KPS were general cognitive function, visuospatial cognition, emotion recognition, executive function, and apathy. The VLSM analysis revealed that the resection of the ventral parietal lobe and supramarginal gyrus (VPL-SMG) resulted in significantly poor KPS. Among the functional factors affecting KPS, VPL-SMG resection contributed to significantly lower scores in visuospatial cognition, emotion recognition, and apathy than those without resection (p = 0.0045, 0.047, and 0.0002, respectively). Further, we investigated whether the damage of the VPL-SMG could result in KPS related functional deficit. We found visuospatial cognition related to the posterior occipital lobe, SMG, arcuate fasciculus (AF), and dorsal superior longitudinal fasciculus, emotion recognition to the middle to inferior occipital gyrus and AF, and apathy to the inferior parietal lobe and middle temporal gyrus. We concluded that deficits of visuospatial cognition, emotion recognition, and apathy due to the damage of the cortical and white matter areas, including the VPL-SMG, were responsible for KPS of the non-dominant hemispheric glioblastomas.

Focal Cognitive Syndromes

The neurologic results of cortical lesions reflect the structural properties of the affected region. Lesions affecting primary sensorimotor cortices result in primary sensorimotor deficits that are qualitatively all-or-nothing, such as blindness (hemianopia) and paralysis (hemiparesis). Quantitatively, though, the severity of the deficit depends on the extent of the lesion (so that a hemiparetic patient may not be completely paralyzed but simply weak). Lesions affecting modality-specific association regions result in conceptually more complex disorders that are confined to a single modality, such as nonfluent aphasia (a form of motor speech disorder reflecting the language-dominant hemisphere) or prosopagnosia (a visual disorder impairing the ability to disambiguate visually similar entities, specifically faces, reflecting the “what” visual pathway in inferotemporal cortices).

Brain Symmetry Analysis during the Use of a BCI Based on Motor Imagery for the Control of a Lower-Limb Exoskeleton

Brain–Computer Interfaces (BCI) are systems that allow external devices to be controlled by means of brain activity. There are different such technologies, and electroencephalography (EEG) is an example. One of the most common EEG control methods is based on detecting changes in sensorimotor rhythms (SMRs) during motor imagery (MI). The aim of this study was to assess the laterality of cortical function when performing MI of the lower limb. Brain signals from five subjects were analyzed in two conditions, during exoskeleton-assisted gait and while static. Three different EEG electrode configurations were evaluated: covering both hemispheres, covering the non-dominant hemisphere and covering the dominant hemisphere. In addition, the evolution of performance and laterality with practice was assessed. Although sightly superior results were achieved with information from all electrodes, differences between electrode configurations were not statistically significant. Regarding the evolution during the experimental sessions, the performance of the BCI generally evolved positively the higher the experience was.

Paramedian transparietal approach to a dominant hemisphere intraventricular meningioma: illustrative case

BACKGROUND Meningiomas of the atrium of the lateral ventricle present a unique operative challenge. Parietal transcortical approaches have been described with an oblique approach, but a strictly paramedian approach may offer advantages in a dominant hemisphere atrial meningioma. OBSERVATIONS The patient presented with several weeks of intermittent headaches. Magnetic resonance imaging (MRI) showed an enhancing intraventricular mass in the atrium of the left lateral ventricle. Three-dimensional reconstructions were created from a preoperative MRI, with 1-mm slices for neuronavigation. Diffusion tensor imaging (DTI) was obtained, and tracts were reconstructed in the patient’s three-dimensional brainspace. DTI tractography delineated a paramedian transparietal corridor devoid of functional white matter tracks. The patient was positioned supine, in a semislouch position. A left parietal craniotomy was performed. Neuronavigation identified a gyrus posterior to the sensory cortex, anterior to the optic radiations and medial to superior longitudinal and arcuate fasciculus fiber tracts. The tumor was debulked to allow mobilization to coagulate capsular blood supply. Gross total resection was achieved. The patient was discharged postoperatively on day 3 without neurological deficits. LESSONS A paramedian transparietal approach to a dominant hemisphere meningioma of the lateral ventricle can be a safe and effective way to resect tumors in this anatomically unique operative corridor.

Hemispheric Difference of Regional Brain Function Exists in Patients With Acute Stroke in Different Cerebral Hemispheres: A Resting-State fMRI Study

ObjectiveTo explore the different compensatory mechanisms of brain function between the patients with brain dysfunction after acute ischemic stroke (AIS) in the dominant hemisphere and the non-dominant hemisphere based on Resting-state Functional Magnetic Resonance Imaging (Rs-fMRI).MethodsIn this trial, 15 healthy subjects (HS) were used as blank controls. In total, 30 hemiplegic patients with middle cerebral artery acute infarction of different dominant hemispheres were divided into the dominant hemisphere group (DH) and the non-dominant hemisphere group (NDH), scanned by a 3.0 T MRI scanner, to obtain the amplitude of low-frequency fluctuations (ALFF) and regional homogeneity (ReHo) and compare the differences.ResultsCompared with the HS, increased ALFF values in the brain areas, such as the bilateral midbrain, were observed in DH. Meanwhile decreased ReHo values in the brain areas, such as the right postcentral gyrus (BA3), were also observed. Enhanced ALFF values in the brain areas, such as the left BA6, and enhanced ReHo values in the brain areas, such as the left precuneus, were observed in the NDH. The ALFF and ReHo values of the right BA9 and precentral gyrus were both increased. Compared with DH, the NDH group showed lower ALFF values in the left supplementary motor area and lower ReHo values in the right BA10.ConclusionAfter acute infarction in the middle cerebral artery of the dominant hemisphere, a compensation mechanism is triggered in brain areas of the ipsilateral cortex regulating motor-related pathways, while some brain areas related to cognition, sensation, and motor in the contralateral cortex are suppressed, and the connection with the peripheral brain regions is weakened. After acute infarction in the middle cerebral artery of the non-dominant hemisphere, compensatory activation appears in motor control-related brain areas of the dominant hemisphere. After acute middle cerebral artery infarction in the dominant hemisphere, compared with the non-dominant hemisphere, functional specificity in the bilateral supplementary motor area weakens. After acute middle cerebral artery infarction in different hemispheres, there are hemispheric differences in the compensatory mechanism of brain function.

Ictal Swearing as a Lateralizing Value for the Dominant Hemisphere in Temporal Lobe Epilepsy

Ictal swearing, as an epileptic manifestation, has rarely been reported. Despite its poor localization value and unclear mechanism, several previous studies have reported that it frequently originates from the temporal lobe and more often from the non-dominant hemisphere. Herein, we report a case of a 41-year-old right-handed man with a history of stereotypical manifestation of ictal swearing with a left (dominant) hemisphere origin, confirmed by video electroencephalography monitoring. Reasonable suspicion that repetitive swearing could be a manifestation of seizures is important for clinicians not to misdiagnose the disease.

Clinical, Imaging, and Pathologic Characteristics of Patients With Right Versus Left Hemisphere-Predominant Logopenic Progressive Aphasia

Objective:To assess and compare demographic, clinical, neuroimaging and pathologic characteristics of a cohort of patients with right versus left hemisphere-predominant logopenic progressive aphasia (LPA).Methods:This is a case-control study of patients with LPA who were prospectively followed at Mayo Clinic and underwent an [18F]-fluorodeoxyglucose (FDG)-PET scan. Patients were classified as rLPA if right temporal lobe metabolism was ≥1 standard deviation lower than left temporal lobe metabolism. Patients with rLPA were frequency-matched 3:1 to typical left-predominant LPA based on degree of asymmetry and severity of temporal lobe metabolism. Patients were compared on clinical, imaging (MRI, FDG-PET, amyloid-beta- and tau-PET) and pathologic characteristics.Results:Of 103 prospectively recruited LPA patients, 8 (4 females) were classified as rLPA (7.8%); all rLPA cases were right-handed. rLPA patients had milder aphasia based on the Western Aphasia Battery-Aphasia Quotient (p=0.04) and less frequent phonologic errors (p=0.015). rLPA had shorter survival compared to typical LPA: hazard ratio 4.0(1.2- 12.9), p=0.02. There were no other differences in demographics, handedness, genetics, neurological or neuropsychological tests. Compared to the 24 frequency-matched typical LPA patients, rLPA showed greater frontotemporal hypometabolism of the non-dominant hemisphere on FDG-PET and less atrophy in amygdala and hippocampus of the dominant hemisphere. Autopsy evaluation revealed a similar distribution of pathologic findings in both groups, with Alzheimer’s disease pathologic changes being the most frequent pathology.Conclusions:Right LPA is associated with less severe aphasia but has shorter survival from reported symptom onset than typical LPA, possibly related to greater involvement of the non-dominant hemisphere.

Predictors of surgical outcome among patients with spontaneous supratentorial intracerebral hemorrhage: A prospective single institutional study

Introduction: Intracerebral hemorrhage (ICH) is a potentially devastating neurologic emergency with long-term functional independence achieved in only limited patients with good prognostic factors. The objective of this study is toidentify the predictors of functional outcome in terms of modified Rankin Scale (mRS) following craniotomy and evacuation of spontaneous supratentorial ICH. Methodology: It is a prospective study of forty patients conducted at the College of Medical Sciences (CMS) from May 2019 to April 2020 with three months follow-up. Patients of spontaneous supratentorial ICH with features of raised ICP and deteriorating GCS underwent surgical evacuation. The various predictors of outcome like Glasgow Coma Score (GCS) and pupillary inequality at presentation, age, location of hematoma, clot volume, comorbidities, intra-ventricular extension and involvement of dominant hemisphere were documented and compared with outcome in terms of modified Rankin Scale (mRS). Results: The mortality rate at three months was 25% (32% in deep seated and 13.3% in lobar ICH) and higher in patients with poor GCS and pupillary inequality at presentation, volume >100 ml, intra-ventricular extension and patients undergoing decompressive craniectomy. Twenty patients (50%) had a favorable outcome (mRS 1-3) at follow-up, while 20 (50%) had a poor outcome (mRS 4-6). Unfavorable outcome was significantly higher among deep seated hematoma, age>70 years, poor GCS and pupillary inequality at presentation, clot volume >100ml, pre-existing co-morbidity, patients undergoing decompressive craniectomy and involvement of dominant hemisphere. Conclusion: Surgical evacuation of spontaneous supratentorial ICH is associated with high mortality in patients with poor GCS and pupillary inequality at presentation, and large clot volume with intraventricular extension. However, young patients with good pre-morbid status, moderate volume of hematoma, not involving dominant hemisphere and moderate to good GCS have good functional outcome.