Inter-brain co-activations during mindfulness meditation. Implications for devotional and clinical settings.

Mindfulness meditation usually takes place as personal, introspective activity. It is not known if this practice activates the brain differently when done alone or with someone else. Sixteen couples of expert meditators performed mindfulness-oriented meditation (MOM) and instructed mind-wandering (IMW) tasks in two conditions: once sitting in the same room (SR) and once in two different rooms (DR). Spontaneous electroencephalographic (EEG) data was collected during 7-minute recording sessions in the four experimental settings (MOM/SR, MOM/DR, IMW/SR, IMW/DR). Power in band was computed in separate clusters of independent components of the EEG signals. In addition to significant task effects, found in frontolimbic (MOM > IMW in gamma) and frontoparietal locations (MOM < IMW in theta), significant condition effects were found in frontal (SR > DR in delta) and in temporo-occipital regions (SR > DR in theta and alpha). Moreover, a significant interaction between task and condition revealed higher gamma activity in limbic areas during MOM/SR vs. MOM/DR settings. This effect was not attributable to gender, age nor the meditation expertise of participants. We thus show that the brains of two people work differently when they are doing something together or alone; some of these differences are specific to mindfulness meditation. Implications for devotional and clinical settings are discussed.

Clinical and neurophysiological characterization of muscular weakness in severe COVID-19.

OBJECTIVE: To report clinical and electroneuromyographic (ENMG) characteristics of patients affected by severe COVID-19 infection, evaluated for muscular weakness. MATERIALS AND METHODS: ENMGs performed for evaluation of diffuse weakness in patients who could not be discharged from semi-intensive care COVID unit because of difficulties in ventilation weaning were reviewed. Patients with severe COVID-19 infection who had undergone endotracheal intubation and able to co-operate were considered. ENMG protocol was focused on neurophysiological items that excluded or confirmed critical illness polyneuropathy (CIP), myopathy (CIM), or polyneuromyopathy (CIPM). Standardized clinical evaluation was performed using Medical Research Council (MRC) sum score. RESULTS: Eight patients were included in the study. All presented known risk factors for intensive care unit-acquired weakness (ICU-AW), and none of them had history of underlying neuromuscular disorders. ENMG findings were normal in two patients, while only two patients had an altered MRC sum score (< 48). Neuromuscular involvement was diagnosed in 6/8 patients (75%): 2 had CIP, 1 had possible CIM, 1 had CIPM, while 1 patient, with clinically evident weakness but equivocal ENMG findings, was classified as ICU-AW. Finally, 1 patient was diagnosed with acute demyelinating neuropathy. Patients with neuromuscular involvement were those with longer intubation duration and higher levels of IL-6 at admission. CONCLUSION: Neuromuscular complications are frequent in severe COVID-19 and cannot be excluded by MRC sum scores above 48. Standardized ENMG is helpful in guiding diagnosis when clinical evaluation is not reliable or possible. Elevated IL-6 at admission may be a predictor biomarker of ICU-AW in COVID-19.

Motor or non-motor speech interference? A multimodal fMRI and direct cortical stimulation mapping study.

We retrospectively analyzed data from 15 patients, with a normal pre-operative cognitive performance, undergoing awake surgery for left fronto-temporal low-grade glioma. We combined a pre-surgical measure (fMRI maps of motor- and language-related centers) with intra-surgical measures (MNI-registered cortical sites data obtained during intra-operative direct electrical stimulation, DES, while they performed the two most common language tasks: number counting and picture naming). Selective DES effects along the precentral gyrus/inferior frontal gyrus (and/or the connected speech articulation network) were obtained. DES of the precentral gyrus evoked the motor speech arrest, i.e., anarthria (with apparent mentalis muscle movements). We calculated the number of shared voxels between the lip-tongue and overt counting related- and silent naming-related fMRI maps and the Volumes of Interest (VOIs) obtained by merging together the MNI sites at which a given speech disturbance was observed, normalized on their mean the values (i.e., Z score). Both tongue- and lips-related movements fMRI maps maximally overlapped (Z = 1.05 and Z = 0.94 for lips and tongue vs. 0.16 and -1.003 for counting and naming) with the motor speech arrest seed. DES of the inferior frontal gyrus, pars opercularis and the rolandic operculum induced speech arrest proper (without apparent mentalis muscle movements). This area maximally overlapped with overt counting-related fMRI map (Z = -0.11 and Z = 0.09 for lips and tongue vs. 0.9 and 0.0006 for counting and naming). Interestingly, our fMRI maps indicated reduced Broca's area activity during silent speech compared to overt speech. Lastly, DES of the inferior frontal gyrus, pars opercularis and triangularis evoked variations of the output, i.e., dysarthria, a motor speech disorder occurring when patients cannot control the muscles used to produce articulated sounds (phonemes). Silent object naming-related fMRI map maximally overlapped (Z = -0.93 and Z = -1.04 for lips and tongue vs. -1.07 and 0.99 for counting and naming) with this seed. Speech disturbances evoked by DES may be thought of as selective interferences with specific recruitment of left inferior frontal gyrus and precentral cortex which are differentiable in terms of the specific interference induced.

Risk Factors for Intraoperative Seizures in Glioma Surgery: Electrocorticography Matters.

PURPOSE: Few and contradictory data are available regarding intraoperative seizures during surgery for low-grade gliomas. Aim of this study was to evaluate possible risk factors for the occurrence of IOS. METHODS: The authors performed a retrospective analysis of 155 patients affected by low-grade gliomas and tumor-related epilepsy, who underwent surgery in our Department, between 2007 and 2018. A statistical analysis was performed by means of univariate and multivariate regression to evaluate any possible correlation between seizure occurrence and several demographic, clinical, neurophysiological, and histopathological features. RESULTS: Intraoperative seizure occurred in 39 patients (25.16%) with a total of 62 seizure events recorded. Focal seizures were the prevalent seizure type: among them, 39 seizures did not show motor signs, being those with only electrographic and/or with cognitive features the most represented subtypes. Twenty-six seizures occurring during surgery were not spontaneous: direct cortical stimulation with Penfield paradigm was the most prevalent evoking factor. The univariate analysis showed that the following prognostic factors were statistically associated with the occurrence of intraoperative seizure: the awake technique ( P = 0.01) and the interictal epileptiform discharges detected on the baseline electrocorticography (ECoG) ( P < 0.001). After controlling for confounding factors with multivariate analysis, the awake surgery and the epileptic ECoG pattern kept statistical significance. CONCLUSIONS: The awake surgery procedure and the epileptic ECoG pattern are risk factors for intraoperative seizure. ECoG is mandatory to detect electrographic seizures or seizures without motor signs.

Fast or Slow? A Comparison Between Two Transcranial Electrical Stimulation Techniques for Eliciting Motor-Evoked Potentials During Supratentorial Surgery.

PURPOSE: During intraoperative neurophysiological monitoring of motor pathways, two types of transcranial electrical stimulation are available, i.e., constant-current and constant-voltage stimulation. Few previous studies, performed only during spinal surgery, analyzed and compared them during intraoperative neurophysiological monitoring. The aim of our study was to compare these two stimulation techniques for eliciting motor-evoked potentials during intraoperative neurophysiological monitoring in a group of patients affected by supratentorial lesions. METHODS: Supratentorial lesions from 16 patients were retrospectively collected and analyzed. Motor-evoked potentials were performed only from transcranial electrical stimulation because the inability to place the subdural strip electrodes correctly did not permit to perform direct cortical stimulation. At the beginning of surgery, in each patient, motor-evoked potentials were monitored by using both "fast-charge" constant-voltage and "slow-charge" constant-current stimulation. Several neurophysiological parameters were collected and compared between the two stimulation techniques by means of statistical analysis. RESULTS: "Fast-charge" constant-voltage stimulation allowed statistically higher efficiency rates for eliciting motor-evoked potentials compared with "slow-charge" constant-current stimulation, both for upper and lower limbs. We also found that threshold and maximal charge as well as charge density were significantly lower during constant-voltage stimulation, thus lowering the potential tissue damage. CONCLUSIONS: "Fast-charge" constant-voltage transcranial electrical stimulation is feasible and safe during intraoperative neurophysiological monitoring for supratentorial surgery and may be preferable to "slow-charge" constant-current stimulation.

Multimodal transcutaneous auricular vagus nerve stimulation: An option in the treatment of sleep bruxism in a "polyvagal" context.

OBJECTIVE: To consider the possible role of the vagus nerve (VN) in the pathophysiology of sleep bruxism (SB) and introduce a multimodal protocol of transcutaneous auricular stimulation of the VN in the treatment of SB patients. METHODS: Ten patients with SB underwent four sessions of electric transcutaneous auricular vagus nerve stimulation (ta-VNS) in specific auricular areas. The patients were advised to manually stimulate the same areas between sessions. Masticatory muscle activity and sleep parameters were measured by a polysomnography (PSG) before and after the treatment. Heart rate variability (HRV) parameters were measured during each stimulation. RESULTS: PSG analysis revealed a statistically significant reduction in tonic SB index and tonic contraction time. HRV parameters showed a statistically significant increase in mean values of the vagal tone after each session of stimulation. No side effect was reported. CONCLUSION: The stimulation of the VN might have a role in the treatment of SB.

Real-Time Neuropsychological Testing of Sensorimotor Cognition During Awake Surgery in Precentral and Postsomatosensory Areas.

BACKGROUND: For patients undergoing brain surgery, once primary motor and sensory areas are identified by direct electrical stimulation, resection can be performed in the precentral and postsomatosensory areas while monitoring cognition. For this purpose, we developed a real-time neuropsychological testing (RTNT) protocol tapping sensorimotor cognition. METHODS: We retrospectively reviewed a consecutive series of 57 adult patients with tumors in the precentral and postsomatosensory areas who performed the RTNT sequence. The testing protocol used continuously throughout resection for excisions comprised action verbs, mental rotation of body parts, action imagery, action semantics, ideomotor praxis, and short-term memory. RESULTS: The patients' median performance on RTNT tests was significantly lower for mental rotation and action imagery (χ2 (2) = 55.98, P < 0.001), as well as their minimum value of patients' performance (χ2 (2) = 85.048, P < 0.001) and their delta calculated between the patients' performance at the first versus the last RTNT run (χ2 (2) = 14.33, P < 0.05). Patients showing such decreases in performance on action imagery had lesions overlapping on the right precentral and postcentral gyrus, the supplementary motor area, and the superior and inferior parietal lobe. For the mental rotation task, their maximum lesion overlay included the right cingulum/supplementary motor area and left superior and inferior parietal lobe and medial precuneus. The mean resection extent was 91.15% ± 17.45 and correlated with the number of motor-related positive sites found by the direct electrical stimulation at cortical (r = -0.279, P = 0.020) and white matter (r = -0.417, P = 0.001) level. CONCLUSIONS: The sensory-motor RTNT is performed to assist surgery in the precentral and postsomatosensory areas.

The persistence of seizures after tumor resection negatively affects survival in low-grade glioma patients: a clinical retrospective study.

INTRODUCTION: Seizures are the most common clinical manifestation of low-grade glioma (LGG). Many papers hypothesized an influence of epilepsy on glioma progression. To our knowledge, no clinical study demonstrated a direct relationship between persistence of epileptic seizures after surgery and overall survival (OS) in LGG patients. The present study aims at investigating the correlation between post-operative seizure outcome and survival in tumor-related epilepsy (TRE) patients. METHODS: We performed a retrospective analysis of adult patients affected by TRE who underwent surgery for resection of LGG in a single high-volume neurosurgical center. Seizure outcome was assessed 1 year after surgery and categorized according to Engel classification. Clinical, molecular and radiological features were evaluated in univariate and multivariate analyses to investigate the correlation with OS. RESULTS: A total of 146 patients met the inclusion criteria. Histopathological diagnosis was Diffuse Astrocytoma isocitrate dehydrogenase (IDH) wild type in 16 patients (11%), Diffuse astrocytoma IDH mutated in 89 patients (61%) and oligodendroglioma IDH mutated, 1p 19q codeleted in 41 patients (28%). 1 year after surgery, 103 (70.6%) patients were in Engel class 1. Median duration of follow-up period was 69.5 months. Median OS was 79.3 (72.2-86.4) months in the whole population, while it was 86.8 (78.4-95.2), 63.9 (45.7-82), 63.7 (45.2-82.2) and 47.5 (18.3-76.6) months for patients in Engel class 1, 2, 3 and 4, respectively. In a univariate analysis, Engel class evaluated 1 year after surgery significantly influenced OS (p < 0.01). Multivariate analysis showed that OS was independently associated with extent of resection (p = 0.02), molecular class (p < 0.01) and Engel class (p = 0.04). CONCLUSIONS: Seizure control 1 year after surgery significantly predicted survival of patients affected by LGG-related epilepsy in a large monocentric retrospective series. Future studies are needed to confirm these results and to assess if an epilepsy-surgical therapeutic approach may improve OS.

Neurosurgical lesions to sensorimotor cortex do not impair action verb processing.

There is ongoing debate regarding the role that sensorimotor regions play in conceptual processing, with embodied theories supporting their direct involvement in processing verbs describing body part movements. Patient lesion studies examining a causal role for sensorimotor activation in conceptual task performance have suffered the caveat of lesions being largely diffuse and extensive beyond sensorimotor cortices. The current study addresses this limitation in reporting on 20 pre-operative neurosurgical patients with focal lesion to the pre- and post-central area corresponding to somatotopic representations. Patients were presented with a battery of neuropsychological tests and experimental tasks tapping into motor imagery and verbal conceptual verb processing in addition to neurophysiological measures including DTI, fMRI, and MEP being measured. Results indicated that left tumor patients who presented with a lesion at or near somatotopic hand representations performed significantly worse on the mental rotation hand task and that performance correlated with MEP amplitudes in the upper limb motor region. Furthermore, performance on tasks of verbal processing was within the normal range. Taken together, while our results evidence the involvement of the motor system in motor imagery processes, they do not support the embodied view that sensorimotor regions are necessary to tasks of action verb processing.

Predictors of Postoperative Seizure Outcome in Low Grade Glioma: From Volumetric Analysis to Molecular Stratification.

The importance of the extent of resection (EOR) has been widely demonstrated as the main predictor for survival, nevertheless its effect on tumor related epilepsy is less investigated. A total of 155 patients were enrolled after a first-line surgery for supratentorial Diffuse Low Grade Gliomas (DLGGs). Postoperative seizure outcome was analyzed stratifying the results by tumor volumetric data and molecular markers according to 2016 WHO classification. Receiver operating characteristic (ROC) curves were computed to asses EOR, residual tumor volume, and ΔT2T1 MRI index (expressing the tumor growing pattern) corresponding to optimal seizure outcome. A total of 70.97% of patients were seizure-free 18 months after surgery. Better seizure outcome was observed in IDH1/2 mutated and 1p/19q codeleted subgroup. At multivariate analysis, age (p = 0.014), EOR (p = 0.030), ΔT2T1 MRI index (p = 0.016) resulted as independent predictors of postoperative seizure control. Optimal parameters to improve postoperative seizure outcome were EOR ≥ 85%, ΔT2T1 MRI index ≤ 18 cm3, residual tumor volume ≤ 15 cm3. This study confirms the role of EOR and tumor growing pattern on postoperative seizure outcome independently from the molecular class. Higher ΔT2T1 MRI index, representing the infiltrative component of the tumor, is associated with worse seizure outcome and strengthens the evidence of common pathogenic mechanisms underlying tumor growth and postoperative seizure outcome.

Transient hemi-diaphragmatic palsy following pleural empyema: a pediatric case report.

Phrenic nerve palsy generally is a jatrogenic damage of invasive neck and/or chest procedures in the pediatric age, but it does not represent a common complication of pleural empyema. One case of transient monolateral diaphragmatic paralysis following a decorticated pleural empyema is here reported. Common causes of the present disorder and its possible physiopathologic mechanisms are discussed, too.

Spontaneous eye movements during focused-attention mindfulness meditation.

Oculometric measures have been proven to be useful markers of mind-wandering during visual tasks such as reading. However, little is known about ocular activity during mindfulness meditation, a mental practice naturally involving mind-wandering episodes. In order to explore this issue, we extracted closed-eyes ocular movement measurements via a covert technique (EEG recordings) from expert meditators during two repetitions of a 7-minute mindfulness meditation session, focusing on the breath, and two repetitions of a 7-minute instructed mind-wandering task. Power spectral density was estimated on both the vertical and horizontal components of eye movements. The results show a significantly smaller average amplitude of eye movements in the delta band (1-4 Hz) during mindfulness meditation than instructed mind-wandering. Moreover, participants' meditation expertise correlated significantly with this average amplitude during both tasks, with more experienced meditators generally moving their eyes less than less experienced meditators. These findings suggest the potential use of this measure to detect mind-wandering episodes during mindfulness meditation and to assess meditation performance.

The neural basis of temporal preparation: Insights from brain tumor patients.

When foreperiods (FPs) of different duration vary on a trial-by-trial basis equiprobably but randomly, the RT is faster as the FP increases (variable FP effect), and becomes slower as the FP on the preceding trial gets longer (sequential effects). It is unclear whether the two effects are due to a common mechanism or to two different ones. Patients with lesions on the right lateral prefrontal cortex do not show the typical FP effect, suggesting a deficit in monitoring the FP adequately [Stuss, D. T., Alexander, M. P., Shallice, T., Picton, T. W., Binns, M. A., Macdonald, R., et al. (2005). Multiple frontal systems controlling response speed. Neuropsychologia, 43, 396-417]. The aim of this study was two-fold: (1) to replicate this neuropsychological result testing cerebral tumor patients before and after surgical removal of the tumor located unilaterally in the prefrontal, premotor or parietal cortex, respectively and (2) to investigate whether the sequential effects would change together with the FP effect (supporting single-process accounts) or the two effects can be dissociated across tumor locations (suggesting dual-process views). The results of an experiment with a variable FP paradigm show a significant reduction of the FP effect selectively after excision of tumors on right prefrontal cortex. On the other hand, the sequential effects were reliably reduced especially after surgical removal of tumors located in the left premotor region, despite a normal FP effect. The latter dissociation between the two effects supports a dual-process account of the variable FP phenomena. This study demonstrates that testing acute cerebral tumor patients represents a viable neuropsychological approach for the fractionation and localisation of cognitive processes.

Inhibition of wrong responses and conflict resolution: an electroencephalogram study.

To investigate the neural activity elicited by conflict processes, we recorded event-related potentials during a spatial version of the Simon task. In this task, participants have to release a key according to the direction of an arrow while ignoring the side on which this stimulus is presented. Responses are, nevertheless, faster when stimulus and response side match (spatial compatibility) than when they do not match (spatial incompatibility). Results showed that, in incompatible trials, a negative potential arising before response execution and corresponding to the N2 event-related potential component was elicited. The dipole analysis localized this potential to the anterior cingulate cortex. We suggest that this brain region is involved in the inhibition of incorrect responses in incompatible trials.

MotorBrain: A mobile app for the assessment of users' motor performance in neurology.

BACKGROUND AND OBJECTIVE: Human motor skills or impairments have been traditionally assessed by neurologists by means of paper-and-pencil tests or special hardware. More recently, technologies such as digitizing tablets and touchscreens have offered neurologists new assessment possibilities, but their use has been restricted to a specific medical condition, or to stylus-operated mobile devices. The objective of this paper is twofold. First, we propose a mobile app (MotorBrain) that offers six computerized versions of traditional motor tests, can be used directly by patients (with and without the supervision of a clinician), and aims at turning millions of smartphones and tablets available to the general public into data collection and assessment tools. Then, we carry out a study to determine whether the data collected by MotorBrain can be meaningful for describing aging in human motor performance. METHODS: A sample of healthy participants (N= 133) carried out the motor tests using MotorBrain on a smartphone. Participants were split into two groups (Young, Old) based on their age (less than or equal to 30 years, greater than or equal to 50 years, respectively). The data collected by the app characterizes accuracy, reaction times, and speed of movement. It was analyzed to investigate differences between the two groups. RESULTS: The app does allow measuring differences in neuromotor performance. Data collected by the app allowed us to assess performance differences due to the aging of the neuromuscular system. CONCLUSIONS: Data collected through MotorBrain is suitable to make meaningful distinctions among different kinds of performance, and allowed us to highlight performance differences associated to aging. MotorBrain supports the building of a large database of neuromotor data, which can be used for normative purposes in clinical use.

Post-anoxic status epilepticus: which variable could modify prognosis? A single-center experience.

BACKGROUND: Status epilepticus (SE) is associated with high mortality in post-anoxic coma despite antiepileptic treatment. The aim of our study was to assess the percentage of awakening in a consecutive series of post-anoxic comatose patients with an EEG pattern consistent with SE and to verify any correlation with clinical, neurophysiological or pharmacological parameters. METHODS: We retrospectively analyzed data collected from seventeen patients affected by post-anoxic SE matching them with outcome scores by means of univariate statistical analysis. RESULTS: Four patients were not pharmacologically treated while thirteen patients were treated with a combination of benzodiazepines, antiepileptic or anesthetic drugs: seven patients awakened even if they showed a moderate-severe disability A statistically significant correlation with preserved median nerve cortical somatosensory evoked potentials (SSEP), with the use of anesthetics and with the duration of SE was found. CONCLUSIONS: In post-anoxic coma, SE does not always correlate with poor outcome. In patients with favorable patterns on multimodal prognostication approach, pharmacologic treatment, even aggressive, could be attempted.

Independent Component Decomposition of Human Somatosensory Evoked Potentials Recorded by Micro-Electrocorticography.

High-density surface microelectrodes for electrocorticography (ECoG) have become more common in recent years for recording electrical signals from the cortex. With an acceptable invasiveness/signal fidelity trade-off and high spatial resolution, micro-ECoG is a promising tool to resolve fine task-related spatial-temporal dynamics. However, volume conduction - not a negligible phenomenon - is likely to frustrate efforts to obtain reliable and resolved signals from a sub-millimeter electrode array. To address this issue, we performed an independent component analysis (ICA) on micro-ECoG recordings of somatosensory-evoked potentials (SEPs) elicited by median nerve stimulation in three human patients undergoing brain surgery for tumor resection. Using well-described cortical responses in SEPs, we were able to validate our results showing that the array could segregate different functional units possessing unique, highly localized spatial distributions. The representation of signals through the root-mean-square (rms) maps and the signal-to-noise ratio (SNR) analysis emphasizes the advantages of adopting a source analysis approach on micro-ECoG recordings in order to obtain a clear picture of cortical activity. The implications are twofold: while on one side ICA may be used as a spatial-temporal filter extracting micro-signal components relevant to tasks for brain-computer interface (BCI) applications, it could also be adopted to accurately identify the sites of nonfunctional regions for clinical purposes.

Quantitative Diffusion Tensor Imaging Analysis of Low-Grade Gliomas: From Preclinical Application to Patient Care.

BACKGROUND: Preoperative diffusion tensor tractography (DTT) has recently been used to aid in the mapping of functional pathways to limit damage associated with resection of low-grade gliomas (LGGs). OBJECTIVE: To assess the predictive capacity of DTT as a biomarker of postoperative motor outcomes in patients with LGGs involving the corticospinal tract (CST). CST parameters obtained using a quantitative fiber tracking approach were used to investigate the reliability of the DTT biomarker by comparing their values in the tumoral (Tcst) and healthy (Hcst) hemispheres. METHODS: Thirty-seven patients with LGGs involving the CST were enrolled. Quantification of structural differences between the Tcst and Hcst were analyzed according to the novel biomarker (NF index), defined as follows: (Hcst NF - Tcst NF)/Hcst NF, where NF represents the number of fibers in each region. Logistic regression analysis was used to examine associations among clinical postoperative outcomes and NF index values, tumoral patterns, and premotor/motor evoked potentials. RESULTS: NF values significantly differed between the Tcst and Hcst. Analysis of the NF index showed that patients with a preoperative NF index <0.22 had a significantly lower risk of developing transient postoperative deficits (area under the curve, 0.92; 95% binomial confidence interval, 0.834-1). Patients with less pronounced differences in NF between the Tcst and Hcst also experienced better clinical outcomes. CONCLUSIONS: The NF index may be a useful biomarker for predicting clinical outcomes in patients with LGGs. Furthermore, the NF index may provide a preoperative estimate of the patient's potential for recovery from possible postsurgical neurologic deficits.

Mental rotation in a patient with an implanted electrode grid in the motor cortex.

We investigated the effects of cortical stimulation on mental rotation tasks in a patient with an electrode array placed over his left primary motor cortex. The array was implanted to relieve chronic pain resulting from right brachial plexus damage. Tasks involving motor imagery were slowed down by cortical stimulation, whereas those involving visual imagery were not. When the patient performed the motor-imagery task, the interference effect on response times disappeared if the stimulator was switched off. We also probed two of the sites (anterior-lateral and posterior-medial position), and found that stimulation of the more anterior-lateral one consistently disrupted motor imagery.