Yuriy P. Danilov

Introduction. Cerebral palsy is one of the most common non-progressive neurological disorders caused by fetal or infant brain injury. Current rehabilitation for children with cerebral palsy involves a series of measures, including physical training, special massage techniques, physiotherapy, treatment by certain positions and postures, use of supporting orthoses and fixation devices for walking, and special orthopedic suits facilitating verticalization and motor activity of a child. Over the last few decades, computerized stimulators and robotics with virtual reality systems have been actively used in neurorehabilitation. However, most of these systems did not show significant efficiency in rehabilitation of children with cerebral palsy. In the last few years, different non-invasive electrostimulation techniques have been considered innovative and can be applied independently or in combination with existing procedures. One of such techniques is translingual neurostimulation. Aim. This study aimed to evaluate the effectiveness of a combination of translingual neurostimulation and physical rehabilitation for children with cerebral palsy. Materials and methods. In this study, we observed 134 children (63 girls and 71 boys) with spastic diplegia aged 2–17 years (mean age is 7.8 years old ± 0.3). Depending on the type of rehabilitation therapy, the patients were divided into two groups: active (main) and control. Active group consisted of 94 children who received standard restorative treatment in combination with translingual neurostimulation, whereas the control group consisted of 40 children who received only standard rehabilitation treatment without translingual neurostimulation. Results. Both groups of patients showed positive dynamics; however, patients in the active group showed greater improvements as evidenced by all grading scales. Improvements were observed in children of all ages, and the results were mostly stable for 12 months. Conclusion. Translingual neurostimulation is a novel approach to neurorehabilitation that shows promising results, in addition to its proven effectiveness and safety. As a result of neurostimulation, the patient’s brain becomes more susceptible to the applied therapeutic procedures aimed at restoring motor control and formation of new motor skills, thereby markedly increasing the effectiveness of neurorehabilitation. This study broadens the perspectives in the use and further development of translingual neurostimulation in rehabilitation of children with cerebral palsy.

Despite growing evidence of a critical link between neuromodulation technologies and neuroplastic recovery, the underlying mechanisms of these technologies remain elusive. To investigate physiological evidence of central nervous system (CNS) changes in humans during translingual neurostimulation (TLNS). We used high-density electroencephalography (EEG) to measure changes in resting brain activity before, during, and after high frequency (HF) and low frequency (LF) TLNS. Wavelet power analysis around Cz and microstate analysis revealed significant changes after 20 min of stimulation compared to baseline. A secondary effect of exposure order was also identified, indicating a differential neuromodulatory influence of HF TLNS relative to LF TLNS on alpha and theta signal power. These results further our understanding of the effects of TLNS on underlying resting brain activity, which in the long-term may contribute to the critical link between clinical effect and changes in brain activity.

Background: This study sought to examine the effect of targeted physical therapy with and without cranial nerve non-invasive neuromodulation (CN-NINM), on the walking ability of people with MS who exhibited a dysfunctional gait. We hypothesized that subjects who received electrical stimulation would have greater improvement than those who had a control device after a 14-week intervention. Gait disturbance is a common problem for people with multiple sclerosis (MS). Current management may include exercise, pharmacology, functional electrical stimulation, compensatory strategies, use of assistive devices, and implanted electrical devices. We have developed an effective rehabilitative strategy using neuromodulation of the cranial nerves via electrical stimulation of the tongue to enhance the plasticity of the brain.Methods: The study is a within-subject blinded randomized control design. Twenty chronic MS subjects with an identified gait disturbance were assigned to either an active or control group. Both groups completed a 14-week intervention program using a standardized combination of exercise and a device that provided electrical stimulation to the tongue. Those in the active group received electrical stimulation on the tongue that they could perceive. Those in the control group used a device that did not provide a physiologically significant stimulus and was not perceivable. Subjects were assessed with the Dynamic Gait Index (DGI).Results: The DGI scores improved for both groups. There were significant between-group differences, with the active group showing statistically greater improvement than the control group mean.Conclusion: People with MS demonstrated improved gait with CN-NINM training in a pilot randomized controlled trial. This study suggests that tongue-based neurostimulation may amplify the benefits of exercise for improving gait in people with chronic MS.

Some individuals with balance impairment have hypersensitivity of the motion-sensitive visual cortices (hMT+) compared to healthy controls. Previous work showed that electrical tongue stimulation can reduce the exaggerated postural sway induced by optic flow in this subject population and decrease the hypersensitive response of hMT+. Additionally, a region within the brainstem (BS), likely containing the vestibular and trigeminal nuclei, showed increased optic flow-induced activity after tongue stimulation. The aim of this study was to understand how the modulation induced by tongue stimulation affects the balance-processing network as a whole and how modulation of BS structures can influence cortical activity. Four volumes of interest, discovered in a general linear model analysis, constitute major contributors to the balance-processing network. These regions were entered into a dynamic causal modeling analysis to map the network and measure any connection or topology changes due to the stimulation. Balance-impaired individuals had downregulated response of the primary visual cortex (V1) to visual stimuli but upregulated modulation of the connection between V1 and hMT+ by visual motion compared to healthy controls ( p ≤1E–5). This upregulation was decreased to near-normal levels after stimulation. Additionally, the region within the BS showed increased response to visual motion after stimulation compared to both prestimulation and controls. Stimulation to the tongue enters the central nervous system at the BS but likely propagates to the cortex through supramodal information transfer. We present a model to explain these brain responses that utilizes an anatomically present, but functionally dormant pathway of information flow within the processing network.

Multivariate analysis of functional magnetic resonance imaging (fMRI) data allows investigations into network behavior beyond simple activations of individual regions. We apply group independent component analysis to fMRI data collected in a previous study looking at the sustained neuromodulatory effects of electrical tongue stimulation in balance-impaired individuals. Twelve subjects with balance disorders viewed optic flow in an fMRI scanner before and after 5 days of electrical tongue stimulation. Nine healthy controls also viewed the visual stimuli but did not receive any stimulation. Multiple regression of the 47 estimated components found two that were modulated by the visual stimuli. Component 7, comprised primarily of the primary visual cortex (V1), responded to all visual stimuli and showed no difference in task-related activity between the healthy controls and the balance-impaired subjects before or after stimulation. Component 11 responded only to motion in the visual field and contained multiple cortical and subcortical regions involved in processing information pertinent to balance. Two-sample t -tests of the calculated signal change revealed that the task-related activity of this network is greater in balance-impaired subjects compared with controls before stimulation ( p =0.02), but that this network hypersensitivity decreases after electrical tongue stimulation ( p =0.001).

This pilot study aimed to show that information-free stimulation of the tongue can improve behavioral measures and induce sustained neuromodulation of the balance-processing network in individuals with balance dysfunction. Twelve balance-impaired subjects received one week of cranial nerve non-invasive neuromodulation (CN-NINM). Before and after the week of stimulation, postural sway and fMRI activation were measured to monitor susceptibility to optic flow. Nine normal controls also underwent the postural sway and fMRI tests but did not receive CN-NINM. Results showed that before CN-NINM balance-impaired subjects swayed more than normal controls as expected (p ≤ 0.05), and that overall sway and susceptibility to optic flow decreased after CN-NINM (p ≤ 0.005 & p ≤ 0.05). fMRI showed upregulation of visual sensitivity to optic flow in balance-impaired subjects that decreased after CN-NINM. A region of interest analysis indicated that CN-NINM may induce neuromodulation by increasing activity within the dorsal pons (p ≤ 0.01).

We have developed a novel, tongue-based electrotactile brain-machine interface. Variability of the tactile sensation intensity across the stimulated area, however, limits the amount of reliable information transmission. We have conducted an experiment to characterize local sensitivity across the region stimulated by the array. From this data we have constructed an iso-intensity algorithm to compensate for the variability in electrotactile sensation levels across the stimulated area of the tongue.