The incremental benefit of EUS for the identification of malignancy in indeterminate extrahepatic biliary strictures: A systematic review and meta-analysis.

This systematic review aims to assess the literature to determine the impact of EUS for diagnosing malignancy among indeterminate extrahepatic biliary strictures. A systematic review was performed using MEDLINE, EMBASE, Cochrane, and conference proceedings from inception to July 2016. Pooled results were calculated using random-effects model, and heterogeneity was explored using stratified meta-analysis and meta-regression. The main outcome was the incremental benefit of EUS (IBEUS) for the diagnosis of malignancy among patients who have undergone ERCP with brushing cytology for extrahepatic biliary strictures. Of 3131 identified citations, ten met the inclusion criteria and were included in the final analyses (study periods from 1998 to 2014). Pooled IBEUS estimate with the adjustment for publication bias was 14% (95% confidence interval, 7%-20%). Individual studies demonstrate that the IBEUS is greater for distal biliary strictures or when an extrinsic mass is identified on cross-sectional imaging. EUS increases the identification of malignancy for indeterminate biliary strictures following a nondiagnostic ERCP, particularly those that are distal or related to extrinsic compression.

Specific functional asymmetries of the human visual cortex revealed by functional near-infrared spectroscopy.

Based on multiple invasive reports and neuroimaging studies, it is well established that the cytoarchitecture of the visual cortex is related to its functional organization, namely, its retinotopy. The present study aimed to further investigate retinotopic mapping as well as specific vertical and horizontal functional asymmetries within the human visual cortex using functional near-infrared spectroscopy (fNIRS). Black and white wedge checkerboard stimuli were randomly presented to the four visual field (VF) quadrants of eight healthy adults in order to quantify and compare the localization and the amplitude of hemodynamic cortical responses to each VF quadrant. Results showed the expected activation in the contralateral hemisphere, with respect to the side of the stimulated quadrant. We also measured significantly stronger activations in the upper visual cortex when low hemifield stimuli were presented compared to activations in the lower visual cortex when upper hemifield stimuli were shown, especially when the stimulation was presented in the right visual field. These findings confirm the vertical asymmetry of the visual cortex previously reported by neuroimaging and behavioral studies. More importantly, the present work confirms the reliability of the fNIRS technique for functional mapping of the human brain.

Cumulative effects of concussions in athletes revealed by electrophysiological abnormalities on visual working memory.

Event-related potentials (ERPs) have been useful to detect subtle, pervasive alterations of cognition-related waveforms in athletes with multiple concussions. This study used the sustained posterior contralateral negativity (SPCN) waveform component recorded while participants performed a visual short-term memory task to investigate how working memory (WM) storage capacity was affected among athletes who differed according to their history of sports concussions. Fifty-five university-level football players were assigned to three groups: 1-2 concussion athletes; 3+ concussion athletes; non-concussed athletes. The main finding of the present study was that athletes with a history of three concussions or more exhibited significantly attenuated SPCN amplitude relative to both concussed athletes with only one or two prior concussions and athletes without concussions. The latter finding adds to previous evidence of disproportionately worse outcome in athletes presenting with a history of three or more concussions relative to those with fewer concussions. In addition, SPCN amplitude was found to correlate significantly with a visual memory capacity estimate (K), but this K value did not significantly differ across groups. This suggests that attenuated SPCN amplitude after three or more concussions did not interfere with apparent WM function. Taken together, these findings suggest that the altered neurophysiological index of WM storage might be a more sensitive measure of a latent WM function abnormality which may well worsen with aging, or perhaps additional brain insults.

Electrophysiological abnormalities in well functioning multiple concussed athletes.

OBJECTIVE: The present study was aimed at characterizing the short- and long-term effects of multiple concussions using an electrophysiological approach. METHOD: Participants for this study were recruited from college football teams. They included athletes who never sustained concussions compared to two groups of asymptomatic multiple concussed athletes, one that sustained their last concussion within the year and the other more than 2 years prior to testing. All participants were submitted to an auditory three-tone Oddball paradigm while event-related potentials (ERP) were recorded. RESULTS: Results from ERP recordings reveal significantly reduced P3a and P3b amplitudes in the recent concussed group in the three-tone task compared to control athletes. In contrast, athletes who sustained their concussions more than 2 years prior to testing had equivalent P3a and P3b amplitude to that of controls. CONCLUSION: These findings suggest that, despite functioning normally in their daily lives, concussed athletes still show subtle neuronal changes in information processing. Thus, the persistence of sub-clinical abnormalities on ERP components despite normal overt functioning may indicate sub-optimal compensation in multiple concussed athletes and leave them vulnerable to subsequent concussions.

Near-infrared spectroscopy as an alternative to the Wada test for language mapping in children, adults and special populations.

The intracarotid amobarbital test (IAT) is the most widely used procedure for pre-surgical evaluation of language lateralization in epileptic patients. However, apart from being invasive, this technique is not applicable in young children or patients who present mental retardation and/or language deficits. Functional magnetic resonance imaging (fMRI) is increasingly employed as a non-invasive alternative. Again, this method is more difficult to use with young children, especially hyperactive ones, since they have to remain motionless during data acquisition. The aim of this study was to determine whether near-infrared spectroscopy (NIRS) can be used as an alternative technique to investigate language lateralization in children and special populations. Unlike Wada test, NIRS is non-invasive, and it is more tolerant to movement artefacts than fMRI. In the present study, NIRS data were acquired in four epileptic children, a 12-year-old boy with pervasive developmental disorder and a 3-year-old, healthy child, as well as three healthy and two epileptic adults, while they performed a verbal fluency task and a control task. When applicable, the results were compared to the subjects' fMRI and/or IAT findings. Clear laterality of speech was obtained in all participants, including the two non-epileptic children, and NIRS results matched fMRI and IAT findings. These results, if replicable in larger samples, are encouraging and suggest that NIRS has the potential to become a viable, non-invasive alternative to IAT and fMRI in the determination of speech lateralization in children and clinical populations that cannot be submitted to more invasive techniques.

Neuropsychology: traditional and new methods of investigation.

The neuropsychological assessment is an integral part of the clinical investigation of patients suffering from epilepsy. The aim of the evaluation is to determine disease-related and treatment-related effects on cognition and behavior in order to orient therapeutic interventions, by taking into account the compensatory mechanisms that are available to the patient. Examples of the tests best illustrating the classical neuropsychological protocol are presented. Neuropsychology also plays an important role in the assessment of language lateralization in patients slated for epilepsy surgery. Traditionally, this has been achieved by means of the rather invasive Wada procedure. However, with the advent of new neuroimaging techniques, this procedure is gradually being replaced by minimally invasive or noninvasive methods, such as functional magnetic resonance imaging, positron emission tomography, and optical imaging. In the present paper, we discuss some of the newer techniques that are available to the neuropsychologist for the study of the impact of epilepsy on cerebral functioning.

Neurophysiological anomalies in symptomatic and asymptomatic concussed athletes.

OBJECTIVE: Concussion in sports is a problem of such magnitude that improvements in diagnosis and management are desirable. The aim of the present study was to investigate the effect of concussion on event-related potentials, in symptomatic as well as in asymptomatic athletes. METHODS: Twenty symptomatic and asymptomatic athletes who sustained a concussion were compared with 10 control athletes in a modified auditory Oddball task. The task included a sequence of tones containing standard and deviant stimuli. Participants were asked to respond to the target tone presented in the left ear and to ignore tones presented in the right ear. The electroencephalogram was recorded from 28 electrodes during the task. RESULTS: The results showed a reduction in the amplitude of N1, P2, and P3 components in symptomatic and asymptomatic athletes in comparison with control athletes. No between-group differences were observed in reaction times or in latency of the event-related potentials components, except for P3 latency, in which the controls showed shorter latency than the concussed groups. CONCLUSION: Concussions seem to produce deficits in the early and late stages of auditory information processing, which possibly reflect impaired brain functioning in symptomatic and asymptomatic concussed athletes. The fact that asymptomatic athletes have an electrophysiological profile similar to that of symptomatic athletes challenges the validity of return-to-play guidelines for which the absence of symptoms is a major issue.