A significant proportion of the population suffers from tinnitus, a bothersome auditory phantom perception that can severely alter the quality of life. Numerous experimental studies suggests that a maladaptive plasticity of the auditory and limbic cortical areas may underlie tinnitus. Accordingly, repetitive transcranial magnetic stimulation (rTMS) has been repeatedly used with success to reduce tinnitus intensity. The potential of transcranial direct current stimulation (tDCS), another promising method of noninvasive brain stimulation, to relieve tinnitus has not been explored systematically. In a double-blind, placebo-controlled and balanced order design, 20 patients suffering from chronic untreatable tinnitus were submitted to 20 minutes of 1 mA anodal, cathodal and sham tDCS targeting the left temporoparietal area. The primary outcome measure was a change in tinnitus intensity or discomfort assessed with a Visual Analogic Scale (VAS) change-scale immediately after tDCS and 1 hour later. Compared to sham tDCS, anodal tDCS significantly reduced tinnitus intensity immediately after stimulation; whereas cathodal tDCS failed to do so. The variances of the tinnitus intensity and discomfort VAS change-scales increased dramatically after anodal and cathodal tDCS, whereas they remained virtually unchanged after sham tDCS. Moreover, several patients unexpectedly reported longer-lasting effects (at least several days) such as tinnitus improvement, worsening, or changes in tinnitus features, more frequently after real than sham tDCS. Anodal tDCS is a promising therapeutic tool for modulating tinnitus perception. Moreover, both anodal and cathodal tDCS seem able to alter tinnitus perception and could, thus, be used to trigger plastic changes.

BackgroundTranscranial direct current stimulation (tDCS) is used in human physiological studies and for therapeutic trials in patients with abnormalities of cortical excitability. Its safety profile places tDCS in the pole-position for translating in real-world therapeutic application. However, an episode of transient respiratory depression in a subject receiving tDCS with an extracephalic electrode led to the suggestion that such an electrode montage could modulate the brainstem autonomic centres.We investigated whether tDCS applied over the midline frontal cortex in 30 healthy volunteers (sham n = 10, cathodal n = 10, anodal n = 10) with an extracephalic reference electrode would modulate brainstem activity as reflected by the monitoring and stringent analysis of vital parameters: heart rate (variability), respiratory rate, blood pressure and sympatho-vagal balance.We reasoned that this study could lead to two opposite but equally interesting outcomes: 1) If tDCS with an extracephalic electrode modulated vital parameters, it could be used as a new tool to explore the autonomic nervous system and, even, to modulate its activity for therapeutic purposes. 2) On the opposite, if applying tDCS with an extracephalic electrode had no effect, it could thus be used safely in healthy human subjects. This outcome would significantly impact the field of non-invasive brain stimulation with tDCS. Indeed, on the one hand, using an extracephalic electrode as a genuine neutral reference (as opposed to the classical "bi-cephalic" tDCS montages which deliver bi-polar stimulation of the brain) would help to comfort the conclusions of several modern studies regarding the spatial location and polarity of tDCS. On the other hand, using an extracephalic reference electrode may impact differently on a given cortical target due to the change of direct current flow direction; this may enlarge the potential interventions with tDCS.ResultsWhereas the respiratory frequency decreased mildly over time and the blood pressure increased steadily, there was no differential impact of real (anodal or cathodal) versus sham tDCS. The heart rate remained stable during the monitoring period. The parameters reflecting the sympathovagal balance suggested a progressive shift over time favouring the sympathetic tone, again without differential impact of real versus sham tDCS.ConclusionsApplying tDCS with an extracephalic reference electrode in healthy volunteers did not significantly modulate the activity of the brainstem autonomic centres. Therefore, using an extracephalic reference electrode for tDCS appears safe in healthy volunteers, at least under similar experimental conditions.

No abstract

The prognosis of patients who are admitted to the hospital after cardiac arrest often relies on neurological examination, which could be significantly influenced by the use of sedative drugs or the implementation of targeted temperature management. The need for early and accurate prognostication is crucial as up to 15-20% of patients could be considered as having a poor outcome and may undergo withdrawal of life-sustaining therapies while a complete neurological recovery is still possible. As current practice in Belgium is still based on a very early assessment of neurological function in these patients, the Belgian Society of Intensive Care Medicine created a multidisciplinary Task Force to provide an optimal approach for monitoring and refine prognosis of CA survivors. This Task Force underlined the importance to use a multimodal approach using several additional tools (e.g., electrophysiological tests, neuroimaging, biomarkers) and to refer cases with uncertain prognosis to specialized centers to better evaluate the extent of brain injury in these patients.