Transcranial Random Noise Stimulation Does Not Improve Behavioral and Neurophysiological Measures in Patients with Subacute Vegetative-Unresponsive Wakefulness State (VS-UWS).
Front Hum Neurosci. 2017;11:524
Authors: Mancuso M, Abbruzzese L, Canova S, Landi G, Rossi S, Santarnecchi E
Background: The absence of efficient treatments capable to promote central nervous system recovery in patients in vegetative state (VS) due to a severe acquired brain injury highlights the need of exploring alternative neuromodulatory treatments that can lead to neurobehavioral gains. Some encouraging preliminary observations suggest that transcranial direct current stimulation could be effective in disorders of consciousness (DoC) patients, especially when applied on the dorsolateral prefrontal cortex (DLPFC) in patients with minimally conscious state (MCS) but not in those with VS. Objective: The primary aim of the present study was to verify if the application of transcranial random noise stimulation (tRNS) on the DLPFC might favor improvements of consciousness recovery in subacute VS-UWS. Methods: Nine patients with DoC due to traumatic brain injury (n = 1), anoxia (n = 3), and vascular damage (n = 5), have undergone a randomized, double-blind, sham-controlled, neuromodulatory trial with tRNS of bilateral DLPFC. All patients were in a post-acute phase and the DoC onset ranged from 30 days to 4 months. The diagnosis of DoC was based on internationally established criteria from the Multi-Society Task Force on PVS, and classified as VS or MCS using the JFK Coma Recovery Scale-Revised scores (CRS-R). We used CRS-R, Synek Scale, Ad-Hoc semi-quantitative scale and the Clinical Global Impression-Improvement scale to measure behavioral and electrophysiological changes during tRNS intervention. All patients were also treated with daily conventional rehabilitation treatment. Results: No significant differences emerged between active and sham groups regarding improvements of level of consciousness, as well as on electroencephalographic data. Only one patient showed emergence from VS-UWS, evolving from VS to MCS after the tRNS stimulation, at a distance of 3 weeks from the enrolment into the study. Conclusion: Repeated applications of tRNS of the DLPFC, even if applied in a subacute phase of VS-UWS state, did not modify behavioral and neurophysiological outcomes differently than sham stimulation.
PMID: 29163104 [PubMed]
A new approach for the determination of ECAP thresholds.
Cochlear Implants Int. 2017 Nov 22;:1-11
Authors: Hoth S, Spitzer P, Praetorius M
BACKGROUND: Electrically evoked compound action potentials (ECAPs) of the auditory nerve are routinely recorded for testing the cochlear implant integrity and its functional connection to the auditory system. The response thresholds derived from ECAP recordings are widely used as a helpful guide in the fitting of the dynamic range of electric stimulation, although they may not always predict the behavioral thresholds of individuals well. Conventionally, this threshold is based on the identification of a minimum N peak and maximum P peak and linear extrapolation of the resulting amplitude growth function (AGF). As an alternative, a new procedure involving numeric signal processing and requiring less user intervention is presented here. Data acquisition: In 12 adults implanted with MED-EL FLEX28 electrodes, two series of ECAPs were recorded immediately after implantation: (i) a full profile involving all 12 channels across the whole stimulus range in steps of 200 current units and (ii) a high resolution section (20 records in the immediate neighborhood of the threshold) of the AGF in one selected channel. Data treatment: It was observed that N and P wave latencies do not depend on stimulus intensity. Fixed time windows were hence defined for stimulus plus noise and noise alone regions. In these windows, the variance of the compound signal representing response and noise is extracted, whereas the noise variance is extracted from the tail of the curve following this time window. The base line is corrected by fitting an exponential function to reduce stimulus or amplifier artifacts. The response threshold is then derived from the response to noise ratio which should exceed the limit of 6 dB.
RESULTS: The ECAP thresholds obtained from the new procedure coincide well with those determined by the conventional linear extrapolation of the AGF and they correlate to a greater degree with psychometric thresholds than the existing approach.
CONCLUSIONS: The new ECAP algorithm looks promising and may reduce the need for user intervention in determining thresholds.
PMID: 29161976 [PubMed - as supplied by publisher]
A Gal-MµS Device to Evaluate Cell Migratory Response to Combined Galvano-Chemotactic Fields.
Biosensors (Basel). 2017 Nov 21;7(4):
Authors: Mishra S, Vazquez M
Electric fields have been studied extensively in biomedical engineering (BME) for numerous regenerative therapies. Recent studies have begun to examine the biological effects of electric fields in combination with other environmental cues, such as tissue-engineered extracellular matrices (ECM), chemical gradient profiles, and time-dependent temperature gradients. In the nervous system, cell migration driven by electrical fields, or galvanotaxis, has been most recently studied in transcranial direct stimulation (TCDS), spinal cord repair and tumor treating fields (TTF). The cell migratory response to galvano-combinatory fields, such as magnetic fields, chemical gradients, or heat shock, has only recently been explored. In the visual system, restoration of vision via cellular replacement therapies has been limited by low numbers of motile cells post-transplantation. Here, the combinatory application of electrical fields with other stimuli to direct cells within transplantable biomaterials and/or host tissues has been understudied. In this work, we developed the Gal-MµS device, a novel microfluidics device capable of examining cell migratory behavior in response to single and combinatory stimuli of electrical and chemical fields. The formation of steady-state, chemical concentration gradients and electrical fields within the Gal-MµS were modeled computationally and verified experimentally within devices fabricated via soft lithography. Further, we utilized real-time imaging within the device to capture cell trajectories in response to electric fields and chemical gradients, individually, as well as in combinatory fields of both. Our data demonstrated that neural cells migrated longer distances and with higher velocities in response to combined galvanic and chemical stimuli than to either field individually, implicating cooperative behavior. These results reveal a biological response to galvano-chemotactic fields that is only partially understood, as well as point towards novel migration-targeted treatments to improve cell-based regenerative therapies.
PMID: 29160793 [PubMed - in process]
Sacral neuromodulation and pregnancy: Results of a national survey carried out for the neuro-urology committee of the French Association of Urology (AFU).
Neurourol Urodyn. 2017 Nov 21;:
Authors: Roulette P, Castel-Lacanal E, Sanson S, Caremel R, Phé V, Bart S, Duchêne F, De Sèze M, Even A, Manunta A, Scheiber-Nogueira MC, Mouracade P, Loche CM, Chartier-Kastler E, Ruffion A, Karsenty G, Gamé X
AIMS: To assess the impact of sacral neuromodulation (SNM) on pregnancy and vice-versa, by identifying women who had received SNM for lower-urinary tract symptoms (LUTS) and had become pregnant.
METHODS: A cross-sectional descriptive study was carried out based on responses to an on-line questionnaire sent to practitioners listed on the InterStim enCaptureTM National Registry. Questions were related to pre-pregnancy health and SNM efficacy, deactivation of the device, its impact on LUTS, childbirth, the infant, its reactivation and postpartum effectiveness.
RESULTS: Twenty-seven pregnancies were recorded among 21 women. Six women had had a pregnancy prior to implantation, two of whom had had a c-section. A total of 18.5% of women had the device disabled prior to conception. The others had their device disabled during the first trimester and did not reactivate it before delivery. Complications were reported in 25.9% of pregnancies: six women had urinary infections, including three of the four treated for chronic retention of urine (CRU), and 1 woman had pain at the stimulation site. There were 24 live births (including one premature birth and four c-sections), one spontaneous miscarriage and two voluntary interruptions of pregnancy. No neonatal disorders have been reported. Effectiveness of sacral neuromodulation decreased in 20% in postpartum.
CONCLUSIONS: In 27 pregnancies established during SNM for LUTS, 18.5% of patients deactivated their case before pregnancy and the others switched it off during the first trimester. Three-quarters of women with CRU had urinary infection. No adverse effects on fetuses were found. SNM effectiveness deteriorated in 20% cases after childbirth.
PMID: 29160571 [PubMed - as supplied by publisher]
Delayed access to bilateral input alters cortical organization in children with asymmetric hearing.
Neuroimage Clin. 2018;17:415-425
Authors: Polonenko MJ, Papsin BC, Gordon KA
Bilateral hearing in early development protects auditory cortices from reorganizing to prefer the better ear. Yet, such protection could be disrupted by mismatched bilateral input in children with asymmetric hearing who require electric stimulation of the auditory nerve from a cochlear implant in their deaf ear and amplified acoustic sound from a hearing aid in their better ear (bimodal hearing). Cortical responses to bimodal stimulation were measured by electroencephalography in 34 bimodal users and 16 age-matched peers with normal hearing, and compared with the same measures previously reported for 28 age-matched bilateral implant users. Both auditory cortices increasingly favoured the better ear with delay to implanting the deaf ear; the time course mirrored that occurring with delay to bilateral implantation in unilateral implant users. Preference for the implanted ear tended to occur with ongoing implant use when hearing was poor in the non-implanted ear. Speech perception deteriorated with longer deprivation and poorer access to high-frequencies. Thus, cortical preference develops in children with asymmetric hearing but can be avoided by early provision of balanced bimodal stimulation. Although electric and acoustic stimulation differ, these inputs can work sympathetically when used bilaterally given sufficient hearing in the non-implanted ear.
PMID: 29159054 [PubMed - in process]
Interferential current sensory stimulation, through the neck skin, improves airway defense and oral nutrition intake in patients with dysphagia: a double-blind randomized controlled trial.
Clin Interv Aging. 2017;12:1879-1886
Authors: Maeda K, Koga T, Akagi J
Background: Neuromuscular electrical stimulation with muscle contraction, administered through the skin of the neck, improves a patient's swallowing ability. However, the beneficial effects of transcutaneous electrical sensory stimulation (TESS), without muscle contraction, are controversial. We investigated the effect of TESS, using interferential current, in patients undergoing dysphagia rehabilitation.
Methods: This double-blind, randomized controlled trial involved 43 patients who were prescribed in-hospital dysphagia rehabilitation for ≥3 weeks. Patients were randomly assigned to the sensory stimulation (SS) or sham groups; all received usual rehabilitative care plus 2 weeks of SS or sham intervention. Outcome measures included cough latency times against a 1% citric acid mist, functional oral intake scale (FOIS) scores, and oral nutritional intake - each determined after the second and third week following treatment initiation.
Results: Mean patient age was 84.3±7.5 years; 58% were women. The SS and sham groups had similar baseline characteristics. Changes in cough latency time at 2 weeks (-14.1±14.0 vs -5.2±14.2 s, p=0.047) and oral nutrition intake at 3 weeks (437±575 vs 138±315 kcal/day, p=0.042) improved more in the SS group than in the sham group. Changes in cough frequency and FOIS scores indicated better outcomes in the SS group, based on substantial effect sizes.
Conclusion: TESS, using interferential current through the neck, improved airway defense and nutrition in patients suffering from dysphagia. Further large-scale studies are needed to confirm the technique's effect on swallowing ability.
PMID: 29158670 [PubMed - in process]
Induced cortical responses require developmental sensory experience.
Brain. 2017 Nov 16;:
Authors: Yusuf PA, Hubka P, Tillein J, Kral A
Sensory areas of the cerebral cortex integrate the sensory inputs with the ongoing activity. We studied how complete absence of auditory experience affects this process in a higher mammal model of complete sensory deprivation, the congenitally deaf cat. Cortical responses were elicited by intracochlear electric stimulation using cochlear implants in adult hearing controls and deaf cats. Additionally, in hearing controls, acoustic stimuli were used to assess the effect of stimulus mode (electric versus acoustic) on the cortical responses. We evaluated time-frequency representations of local field potential recorded simultaneously in the primary auditory cortex and a higher-order area, the posterior auditory field, known to be differentially involved in cross-modal (visual) reorganization in deaf cats. The results showed the appearance of evoked (phase-locked) responses at early latencies (<100 ms post-stimulus) and more abundant induced (non-phase-locked) responses at later latencies (>150 ms post-stimulus). In deaf cats, substantially reduced induced responses were observed in overall power as well as duration in both investigated fields. Additionally, a reduction of ongoing alpha band activity was found in the posterior auditory field (but not in primary auditory cortex) of deaf cats. The present study demonstrates that induced activity requires developmental experience and suggests that higher-order areas involved in the cross-modal reorganization show more auditory deficits than primary areas.
PMID: 29155975 [PubMed - as supplied by publisher]
Assessment of Dictyostelium discoideum Response to Acute Mechanical Stimulation.
J Vis Exp. 2017 Nov 09;(129):
Authors: Artemenko Y, Devreotes PN
Chemotaxis, or migration up a gradient of a chemoattractant, is the best understood mode of directed migration. Studies using social amoeba Dictyostelium discoideum revealed that a complex signal transduction network of parallel pathways amplifies the response to chemoattractants, and leads to biased actin polymerization and protrusion of a pseudopod in the direction of a gradient. In contrast, molecular mechanisms driving other types of directed migration, for example, due to exposure to shear flow or electric fields, are not known. Many regulators of chemotaxis exhibit localization at the leading or lagging edge of a migrating cell, as well as show transient changes in localization or activation following global stimulation with a chemoattractant. To understand the molecular mechanisms of other types of directed migration we developed a method that allows examination of cellular response to acute mechanical stimulation based on brief (2 - 5 s) exposure to shear flow. This stimulation can be delivered in a channel while imaging cells expressing fluorescently-labeled biosensors to examine individual cell behavior. Additionally, cell population can be stimulated in a plate, lysed, and immunoblotted using antibodies that recognize active versions of proteins of interest. By combining both assays, one can examine a wide array of molecules activated by changes in subcellular localization and/or phosphorylation. Using this method we determined that acute mechanical stimulation triggers activation of the chemotactic signal transduction and actin cytoskeleton networks. The ability to examine cellular responses to acute mechanical stimulation is important for understanding the initiating events necessary for shear flow-induced motility. This approach also provides a tool for studying the chemotactic signal transduction network without the confounding influence of the chemoattractant receptor.
PMID: 29155792 [PubMed - in process]
Analyzing EEG and MEG signals recorded during tES, a reply.
Neuroimage. 2017 Nov 14;167:53-61
Authors: Noury N, Siegel M
Transcranial Electric Stimulation (tES) is a widely used non-invasive brain stimulation technique. However, strong stimulation artifacts complicate the investigation of neural activity with EEG or MEG during tES. Thus, studying brain signals during tES requires detailed knowledge about the properties of these artifacts. Recently, we characterized the phase- and amplitude-relationship between tES stimulation currents and tES artifacts in EEG and MEG and provided a mathematical model of these artifacts (Noury and Siegel, 2017, and Noury et al., 2016, respectively). Among several other features, we showed that, independent of the stimulation current, the amplitude of tES artifacts is modulated time locked to heartbeat and respiration. In response to our work, a recent paper (Neuling et al., 2017) raised several points concerning the employed stimulation device and methodology. Here, we discuss these points, explain potential misunderstandings, and show that none of the raised concerns are applicable to our results. Furthermore, we explain in detail the physics underlying tES artifacts, and discuss several approaches how to study brain function during tES in the presence of residual artifacts.
PMID: 29155079 [PubMed - as supplied by publisher]