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47 result(s) for "Hermier, Marc"
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Cardiac autonomic responses to cortical electrical stimulation: a SEEG study
•The central autonomic network plays a major role in autonomic cardiac adjustments.•We studied cardiac autonomic reactivity to intracortical stimulations.•A core network within the brain is deeply involved in cardiac regulation.•A broader autonomic network also contributes to cardiac regulation.•This organization illustrates the close connection between heart and cerebral cortex. Recent growing neuroimaging evidence support that a set of cortical regions - the central autonomic network - is involved in autonomic control, but its functional organization remains unclear. We studied the direct autonomic cardiac effects produced by 1500 direct cortical electrical stimulations in 43 patients with epilepsy (32.8 ± 8.6 years old, 19 females) undergoing intracerebral recordings during presurgical evaluation. The time course of RR interval (RRI) reactivity and its variability were studied. Nearly half (48.6 %, n = 729) of the cortical stimulations resulted in a cardiac response, divided almost equally between bradycardia (24.47 %) and tachycardia (24.13 %), with no difference between right and left stimulations. Bradycardia was marked by an increase in parasympathetic heart control (increase in HF power and decrease in LF/HF ratio), while tachycardia was marked by a predominance in sympathetic heart control (decrease in HF power and increase in LF/HF ratio). We individualized a main network, where evoked bradycardia and tachycardia were strong, consisting of amygdala, posterior insula, frontal mesial premotor/prefrontal cortex, and anterior cingulate. Other brain regions were also involved, but to a lesser degree, with regions mostly in the limbic system and neocortex (sensory-motor/premotor and lateral temporal regions). These results highlight a close relationship between cerebral cortex and heart. Two hierarchically ordered networks were identified. A ‘core’ autonomic network strongly involved in cardiovascular regulation, consistent with the classical definition of CAN in functional imaging. But also a more ‘widespread’ autonomic network, both consistent with a major role of the cortex in continuous autonomic cardiac adjustments to high level emotional, cognitive or sensorimotor cortical activities. This study establishes for the first time a functional mapping of cardiac responses evoked by cortical electrical stimulations, and evidenced hierarchically ordered networks that extends the classical model of CAN. [Display omitted]
Visceral and emotional responses to direct electrical stimulations of the cortex
Objective Visceral sensations are bodily symptoms which are component manifestations of emotions frequently reported during epileptic seizures. Nowadays, the underlying mechanism and location of brain areas involved in the processing of these sensations remain unclear. Our objectives were to characterize the type and frequency of visceral and emotional responses evoked by electrical stimulations, to produce a mapping of brain structures involved in their processing, and to assess the link between visceral sensations and emotional feelings. Methods We reviewed 12,088 bipolar stimulations performed in 203 patients during the presurgical evaluation of drug refractory epilepsy. Responses to stimulation were divided into viscero‐sensitive, viscero‐vegetative, and emotional sensations. Univariate analysis and conditional logistic regression were used to assess the association between visceral and emotional sensations and localization of the stimulated contacts. Results In total, 543 stimulations evoked visceral and emotional sensations. Stimulations of operculo‐insulolimbic structures (amygdala, anterior and posterior insula, anterior and mid‐cingulate cortex, hippocampus, parahippocampus, temporal pole, frontal and parietal operculum) were significantly more associated with visceral and emotional sensations than all other cortical regions. Preferential implication of certain brain structures, depending on the type of visceral responses was evidenced: temporo‐mesial structures, insula, and frontoparietal operculum for viscero‐sensitive sensations; amygdala, insula, anterior and mid‐cingulate cortex, and temporal pole for viscero‐vegetative sensations; temporo‐mesial structures, anterior cingulate cortex, and frontal operculum for emotional sensations. Interpretation Our data can help to guide SEEG explorations when visceral or emotional symptoms are part of the ictal semiology. They also bring some insights into the mechanisms of visceroception and the functional significance of the co‐localization of visceral and emotional representations in the human brain.
Comprehensive analysis of early fractional anisotropy changes in acute ischemic stroke
Cerebral ischemia leads to a rapid decrease of the apparent diffusion coefficient. For fractional anisotropy both increase and decrease have been reported in acute ischemic stroke. Aim of this study was to characterize early water diffusion changes in a homogenous group of acute stroke patients and to clarify the issue of early fractional anisotropy changes and their relation to time from symptom onset. MRI data of patients with acute ischemic stroke examined by diffusion tensor imaging within 8h after symptom were analyzed. We calculated fractional anisotropy, eigenvalues and the isotropic and anisotropic components of the diffusion tensor. The values were calculated as ratios between the ischemic lesion and a mirror region in the unaffected side and correlated with clinical parameters. We included 63 patients: 49% female, mean age 69 ± 14 years, median NIHSS on admission 9 (IQR 4-14). For the whole sample, mean fractional anisotropy was increased (ratio: 1.083 ± 0.168), while all other diffusion parameters were decreased. Both the isotropic and anisotropic component of the diffusion tensor were decreased with a more pronounced decrease of the isotropic component (ratios: isotropic = 0.730 ± 0.106, anisotropic = 0.788 ± 0.127; p<0.001). There was no correlation of fractional anisotropy with time from symptom onset. Looking at individual patients, fractional anisotropy was increased in 70%. There were no differences in clinical characteristics between patients with increased and decreased fractional anisotropy. Fractional anisotropy increase in acute stroke results from a more pronounced decrease of the isotropic diffusion component and is not related to time from symptom onset. Thus, fractional anisotropy is not helpful as a surrogate marker of lesion age in the very first hours of stroke.
A Novel De Novo Missense Mutation in KIF1A Associated with Young-Onset Upper-Limb Amyotrophic Lateral Sclerosis
We investigate the etiology of amyotrophic lateral sclerosis (ALS) in a 35-year-old woman presenting with progressive weakness in her left upper limb. Prior to sequencing, a comprehensive neurological work-up was performed, including neurological examination, electrophysiology, biomarker assessment, and brain and spinal cord MRI. Six months before evaluation, the patient experienced weakness and atrophy in her left hand, accompanied by brisk reflexes and Hoffman sign in the same arm. Electroneuromyography revealed lower motor neuron involvement in three body regions. Neurofilament light chains were elevated in her cerebrospinal fluid. Brain imaging showed asymmetrical T2 hyperintensity of the corticospinal tracts and T2 linear hypointensity of the precentral gyri. Trio genome sequencing identified a likely pathogenic de novo variant in the KIF1A gene (NM_001244008.2): c.574A>G, p.(Ile192Val). Pathogenic variants in KIF1A have been associated with a wide range of neurological manifestations called KIF1A-associated neurological diseases (KAND). This report describes a likely pathogenic de novo variant in KIF1A associated with ALS, expanding the phenotypic spectrum of KAND and our understanding of the pathophysiology of ALS.
Diffusion tensor imaging abnormalities of the trigeminal nerve root in patients with classical trigeminal neuralgia: a pre- and postoperative comparative study 4 years after microvascular decompression
BackgroundAs diffusion tensor imaging (DTI) is able to assess tissue integrity, authors used diffusion to detect abnormalities in trigeminal nerves (TGN) in patients with trigeminal neuralgia (TN) caused by neurovascular compression (NVC) who had undergone microvascular decompression (MVD). The authors also studied anatomical TGN parameters (cross-sectional area [CSA] and volume [V]). The study compared pre- and postoperative findings.MethodsUsing DTI sequencing on a 3-T MRI scanner, we measured the fraction of anisotropy (FA) and apparent diffusion coefficient (ADC) of the TGN in 10 patients who had undergone MVD for TN and in 6 normal subjects. We compared data between affected and unaffected nerves in patients and both nerves in normal subjects (controls). We then correlated these data with CSA and V. Data from the affected side and the unaffected side before and 4 years after MVD were compared.ResultsBefore MVD, the FA of the affected side (0.37 ± 0.03) was significantly lower (p < 0.05) compared to the unaffected side in patients (0.48 ± 0.03) and controls (0.52 ± 0.02), and the ADC in the affected side (5.6 ± 0.34 mm2/s) was significantly higher (p < 0.05) compared to the unaffected side in patients (4.26 ± 0.25 mm2/s) and controls (3.84 ± 0.18 mm2/s). Affected nerves had smaller V and CSA compared to unaffected nerves and controls (p < 0.05). After MVD, the FA in the affected side (0.41 ± 0.02) remained significantly lower (p < 0.05) compared to the unaffected side (0.51 ± 0.02), but the ADC in the affected side (4.24 ± 0.34 mm2/s) had become similar (p > 0.05) to the unaffected side (4.01 ± 0.33 mm2/s).ConclusionsDTI revealed a loss of anisotropy and an increase in diffusivity in affected nerves before surgery. Diffusion alterations correlated with atrophic changes in patients with TN caused by NVC. After removal of the compression, the loss of FA remained, but ADC normalized in the affected nerves, suggesting improvement in the diffusion of the trigeminal root.
Brush sign and collateral supply as potential markers of large infarct growth after successful thrombectomy
Objectives To investigate the relationships between brush sign and cerebral collateral status on infarct growth after successful thrombectomy. Methods HIBISCUS-STROKE cohort includes acute ischemic stroke patients treated with thrombectomy after MRI triage and undergoing a day-6 MRI including FLAIR images to quantify final infarct volume (FIV). Successful reperfusion was defined as a modified thrombolysis in cerebral infarction score  ≥ 2B. Infarct growth was calculated by subtracting FIV from baseline ischemic core after co-registration and considered large (LIG) when  > 11.6 mL. Brush sign was assessed on T2*-weighted-imaging and collaterals were assessed using the hypoperfusion intensity ratio, which is the volume of Time-To-Tmax (Tmax)  ≥ 10 s divided by the volume of Tmax  ≥  6 s. Good collaterals were defined by a hypoperfusion intensity ratio  < 0.4. Results One hundred and twenty-nine patients were included, of whom 45 (34.9%) had a brush sign and 63 (48.8%) good collaterals. Brush sign was associated with greater infarct growth ( p  = 0.01) and larger FIV ( p  = 0.02). Good collaterals were associated with a smaller baseline ischemic core ( p  < 0.001), larger penumbra ( p  = 0.04), and smaller FIV ( p  < 0.001). Collateral status was not significantly associated with brush sign ( p  = 0.20) or with infarct growth ( p  = 0.67). Twenty-eight (22.5%) patients experienced LIG. Univariate regressions indicated that brush sign (odds ratio (OR) = 4.8; 95% confidence interval (CI): [1.9;13.3]; p  = 0.004) and hemorrhagic transformation (OR = 1.7; 95%CI: [1.2;2.6]; p  = 0.04) were predictive of LIG. In multivariate regression, only the brush sign remained predictive of LIG (OR = 5.2; 95%CI: [1.8–16.6], p  = 0.006). Conclusions Brush sign is a predictor of LIG after successful thrombectomy and cerebral collateral status is not. Key Points • Few predictors of ischemic growth are known in ischemic stroke patients achieving successful mechanical thrombectomy . • Our results suggest that the brush sign—a surrogate marker of severe hypoperfusion—is independently associated with large ischemic growth (> 11.6 mL) after successful thrombectomy whereas cerebral collateral status does not .
Visualization of Vascular Compression of the Trigeminal Nerve With High-Resolution 3T MRI: A Prospective Study Comparing Preoperative Imaging Analysis to Surgical Findings in 40 Consecutive Patients Who Underwent Microvascular Decompression for Trigeminal Neuralgia
Abstract BACKGROUND: High-resolution three-dimensional (3D) magnetic resonance imaging (MRI) has demonstrated its ability to predict fine trigeminal neurovascular anatomy. OBJECTIVE: To address the predictive value of 3-Tesla (3T) MRI in detecting and assessing features of neurovascular compression (NVC), particularly regarding the degree of compression exerted on the root, in patients who underwent microvascular decompression (MVD) for classic primary trigeminal neuralgia. METHODS: This prospective study includes 40 consecutive patients who underwent MVD for classic primary trigeminal neuralgia. All patients underwent a preoperative 3T MRI with 3D T2-weighted driven equilibrium (DRIVE), 3D time-of-flight (TOF) magnetic resonance angiography (MRA), and 3D T1-weighted gadolinium-enhanced sequences in combination. Evaluations were performed by 2 independent observers and compared with the operative findings. RESULTS: For prediction of NVC, image analysis corresponded with surgical findings in 39 cases. Of the 3 patients in whom image analysis did not show NVC, 2 did not have NVC at the time of intraoperative observation. MRI sensitivity was 97.4% (37/38), and specificity was 100% (2/2). The kappa coefficients (κ) for predicting the offending vessel, its location, and the site of compression were 0.882, 0.813, and 0.942, respectively. Image analysis correctly defined the severity of the compression in 31 of the 37 cases. The κ coefficients predicting the degree of compression were 0.813, 0.833, and 0.852, respectively, for Grades 1 (simple contact), 2 (distortion), and 3 (marked indentation). CONCLUSION: 3T MRI using 3D T2-weighted DRIVE in combination with 3D TOF-MRA and 3D T1-weighted gadolinium-enhanced sequences proved to be reliable in detecting NVC and in predicting the degree of root compression, the outcome being correlated with the latter.
Cerebral collaterals are associated with pre-treatment brain–blood barrier permeability in acute ischemic stroke patients
Introduction To investigate the relationship between collaterals and blood–brain barrier (BBB) permeability on pre-treatment MRI in a cohort of acute ischemic stroke (AIS) patients treated with thrombectomy. Methods We conducted a retrospective analysis of the HIBISCUS-STROKE cohort, a single-center observational study that enrolled patients treated with thrombectomy from 2016 to 2022. Dynamic-susceptibility MRIs were post-processed to generate K2 maps with arrival-time correction, which were co-registered with apparent diffusion coefficient (ADC) maps. The 90th percentile of K2 was extracted from the infarct core—defined by an ADC ≤ 620 × 10 −6  mm 2 /s with manual adjustments—and expressed as a percentage change compared to the contralateral white matter. Collaterals were assessed using pre-thrombectomy digital subtraction arteriography with an ASITN/SIR score < 3 defining poor collaterals. Results Out of 249 enrolled, 101 (40.6%) were included (median age: 72.0 years, 52.5% of males, median NIHSS score at admission: 15.0). Patients with poor collaterals ( n  = 44) had worse NIHSS scores (median: 16.0 vs 13.0, p  = 0.04), larger infarct core volumes (median: 43.7 mL vs 9.5 mL, p  < 0.0001), and higher increases in K2 (median: 346.3% vs 152.7%, p  = 0.003). They were less likely to achieve successful recanalization (21/44 vs 51/57, p  < 0.0001) and experienced more frequent hemorrhagic transformation (16/44 vs 9/57, p  = 0.03). On multiple variable analysis, poor collaterals were associated with larger infarct cores (odds ratio (OR) = 1.12, 95% confidence interval (CI): [1.07, 1.17], p  < 0.0001) and higher increases in K2 (OR = 6.63, 95% CI: [2.19, 20.08], p  = 0.001). Conclusion Poor collaterals are associated with larger infarct cores and increased BBB permeability at admission MRI. Clinical relevance statement Poor collaterals are associated with a larger infarct core and increased BBB permeability at admission MRI of AIS patients treated with thrombectomy. These findings may have translational interests for extending thrombolytic treatment eligibility and developing neuroprotective strategies. Key Points In AIS, collaterals and BBB disruption have been both linked to hemorrhagic transformation . Poor collaterals were associated with larger ischemic cores and increased BBB permeability on pre-treatment MRI . These findings could contribute to hemorrhagic transformation risk stratification, thereby refining clinical decision-making for reperfusion therapies .
Preoperative demonstration of the neurovascular compression characteristics with special emphasis on the degree of compression, using high-resolution magnetic resonance imaging: a prospective study, with comparison to surgical findings, in 100 consecutive patients who underwent microvascular decompression for trigeminal neuralgia
Purpose Surgical outcome after microvascular decompression (MVD) for primary trigeminal neuralgia (TN) has been demonstrated as being related to the characteristics of the neurovascular compression (NVC), especially to the degree of compression exerted on the root. Therefore, preoperative determination of the NVC features could be of great value to the neurosurgeon, for evaluation of conflicting nature, exact localization, direction and degree of compression. This study deals with the predictive value of MRI in detecting and assessing features of vascular compression in 100 consecutive patients who underwent MVD for TN. Methods The study included 100 consecutive patients with primary TN who were submitted to a preoperative 3D MRI 1.5 T with T2 high-resolution, TOF-MRA, and T1-Gadolinium. Image analysis was performed by an independent observer blinded to the operative findings and compared with surgical data. Findings In 88 cases, image analysis showed NVC features that coincided with surgical findings. There were no false-positive results. Among 12 patients that did not show NVC at image analysis, nine did not have NVC at intraoperative observation, resulting in three false-negative cases. MRI sensitivity was 96.7% (88/91) and specificity 100% (9/9). Image analysis correctly identified compressible vessel in 80 of the 91 cases and degree of compression in 77 of the 91 cases. Kappa-coefficient predicting degree of root compression was 0.746, 0.767, and 0.86, respectively, for Grades I (simple contact), II (distortion), and III (marked indentation; p  < 0.01). Conclusion 3D T2 high-resolution in combination with 3D TOF-MRA and 3D T1-Gadolinium proved to be reliable in detecting NVC and in predicting the degree of the root compression.
Novel Intronic Mutation in VMA21 Causing Severe Phenotype of X-Linked Myopathy with Excessive Autophagy—Case Report
X-linked Myopathy with Excessive Autophagy (XMEA) is a rare autophagic vacuolar myopathy caused by mutations in the Vacuolar ATPase assembly factor VMA21 gene; onset usually occurs during childhood and rarely occurs during adulthood. We described a 22-year-old patient with XMEA, whose onset was declared at 11 through gait disorder. He had severe four-limb proximal weakness and amyotrophy, and his proximal muscle MRC score was between 2 and 3/5 in four limbs; creatine kinase levels were elevated (1385 IU/L), and electroneuromyography and muscle MRI were suggestive of myopathy. Muscle biopsy showed abnormalities typical of autophagic vacuolar myopathy. We detected a hemizygous, unreported, intronic, single-nucleotide substitution c.164-20T>A (NM_001017980.4) in intron 2 of the VMA21 gene. Fibroblasts derived from this patient displayed a reduced level of VMA21 transcripts (at 40% of normal) and protein, suggesting a pathogenicity related to an alteration of the splicing efficiency associated with an intron retention. This patient with XMEA displayed a severe phenotype (rapid weakness of upper and lower limbs) due to a new intronic variant of VMA21, related to an alteration in the splicing efficiency associated with intron retention, suggesting that phenotype severity is closely related to the residual expression of the VMA21 protein.