Acute Effect of Single-Session Cerebellar Anodal Transcranial Direct Current Stimulation on Static and Dynamic Balance in Healthy Volunteers.

Several studies have shown the positive effect of cerebellar transcranial direct current stimulation (ctDCS) on balance in patients and older adults. However, in healthy volunteers, the results are conflicting. We aimed to investigate the immediate effect of anodal ctDCS on the dynamic-static balance in healthy, non-athletic young adults due to the possible benefits for sports performance. Twenty-one healthy volunteers participated in two consecutive 20 min sessions of ctDCS (2 mA current intensity), with 1-week intervals (anodal ctDCS-sham ctDCS). Flamingo and Y-Balance tests were used to evaluate the static and dynamic balances before and after the ctDCS. A Continuous Performance Test (CPT) was used to evaluate the changes in sustained attention, impulsivity, and vigilance. A repeated measure analysis of variance (ANOVA) was used to compare the changes in balance scores, reaction time, omission, and commission numbers. There were no statistically significant differences in dynamic and static balance scores and in CPT parameters between conditions. In conclusion, there was no immediate neuromodulation effect of anodal ctDCS to improve balance performance in healthy, young individuals. Furthermore, no evidence was found to support the use of cerebellar tDCS to improve sports performance.

Determination of tibial somatosensory evoked potentials predicts detrusor sphincter dyssynergia in children with neurogenic bladder dysfunction.

INTRODUCTION: Tibial somatosensory evoked potentials (SEP) are used to identify the neurological status and tethered cord (TC) in patients with spina bifida (SB). Its significance in contributing to the interpretation of urodynamics to determine bladder status is unknown. This study aimed to determine the correlation between SEP and urodynamics in children with SB. MATERIAL AND METHODS: SEP and urodynamic results, for differential diagnosis of TC, were evaluated. SEP scores were correlated with urodynamic findings. SEP results were scored from 1 to 6, with 1, denoting a favorable score and 6, an unfavorable score. Age, gender, detrusor, and sphincter activities in urodynamics were noted. Results were analyzed using the χ2 test and logistic regression analysis. Receiver operating characteristic (ROC) curve was formed to get a valid threshold for the SEP score to predict the urodynamic condition. RESULTS: There were 44 SB patients for whom SEP was done for differential diagnosis of TC. Fifteen patients who did not meet the inclusion criteria were excluded from the study. SB aperta was present in 17 patients and occulta in 12, respectively. The patients had a mean age of 6.6 ± 3.2 years. There were 13 boys and 16 girls. A strong correlation was found between high SEP scores and detrusor sphincter dyssynergia (p < 0.001). A SEP score over 3.5 was found to be 93% sensitive and 73% specific to predict this correlation. There was no relationship between detrusor activity and SEP scores (p = 0.18). DISCUSSION: Tibial SEP is an important noninvasive adjunct tool for the diagnosis of TC in patients with SB. Urodynamic studies are the gold standard in the evaluation of bladder status in neurogenic bladder dysfunction due to SB. Detrusor sphincter dyssynergia may be regarded as a sign of severe spinal cord injury in these patients. CONCLUSION: Our findings suggest that in children with neurogenic bladder, high SEP scores may predict the presence of detrusor sphincter dyssynergia but not the status of detrusor function while providing pathophysiological evidence for neural injury.

Physical mechanisms of emerging neuromodulation modalities.

One of the ultimate goals of neurostimulation field is to design materials, devices and systems that can simultaneously achieve safe, effective and tether-free operation. For that, understanding the working mechanisms and potential applicability of neurostimulation techniques is important to develop noninvasive, enhanced, and multi-modal control of neural activity. Here, we review direct and transduction-based neurostimulation techniques by discussing their interaction mechanisms with neurons via electrical, mechanical, and thermal means. We show how each technique targets modulation of specific ion channels (e.g. voltage-gated, mechanosensitive, heat-sensitive) by exploiting fundamental wave properties (e.g. interference) or engineering nanomaterial-based systems for efficient energy transduction. Overall, our review provides a detailed mechanistic understanding of neurostimulation techniques together with their applications toin vitro, in vivo, and translational studies to guide the researchers toward developing more advanced systems in terms of noninvasiveness, spatiotemporal resolution, and clinical applicability.

Neuromodulation of the left auditory cortex with transcranial direct current stimulation (tDCS) has no effect on the categorical perception of speech sounds.

Temporal cue analysis in auditory stimulus is essential in the perception of speech sounds. The effect of transcranial direct current stimulation (tDCS) on auditory temporal processing remains unclear. In this study, we examined whether tDCS applied over the left auditory cortex (AC) has a polarity-specific behavioral effect on the categorical perception of speech sounds whose temporal features are modulated. Sixteen healthy volunteers in each group were received anodal, cathodal, or sham tDCS. A phonetic categorization task including auditory stimuli with varying voice onset time was performed before and during tDCS, and responses were analyzed. No statistically significant difference was observed between groups (anode, cathode, sham) and within the groups (pre-tDCS, during tDCS) in comparisons of the slope parameter of the identification function obtained from the phonetic categorization task data. Our results show that a single-session application of tDCS over the left AC does not significantly affect the categorical perception of speech sounds.

Holmes' Tremor with Shoulder Pain Treated by Deep Brain Stimulation of Unilateral Ventral Intermediate Thalamic Nucleus and Globus Pallidus Internus.

A 21-year-old male was admitted with severe right arm and hand tremors after a thalamic hemorrhage caused by a traffic accident. He was also suffering from agonizing pain in his right shoulder that manifested after the tremor. Neurologic examination revealed a disabling, severe, and irregular kinetic and postural tremor in the right arm during target-directed movements. There was also an irregular ipsilateral rest tremor and dystonic movements in the distal part of the right arm. The amplitude was moderate at rest and extremely high during kinetic and intentional movements. The patient underwent left globus pallidum internus and ventral intermediate thalamic nucleus deep brain stimulation. The patient improved by more than 80% as rated by the Fahn-Tolosa-Marin Tremor Rating Scale and Visual Analog Scale six months after surgery.

The effect of transcranial direct current stimulation on seizure frequency of patients with mesial temporal lobe epilepsy with hippocampal sclerosis.

OBJECTIVES: Transcranial direct current stimulation (tDCS) is a non-invasive and safe method tried in drug-resistant epilepsies, in recent years. Our aim was to evaluate the effect of tDCS in patients diagnosed with mesial temporal lobe epilepsy with hippocampal sclerosis (MTLE-HS) which is a well-known drug-resistant focal epilepsy syndrome. PATIENTS AND METHODS: Twelve MTLE-HS patients diagnosed with their typical clinical, EEG and MRI findings fulfilling the criteria for drug-resistance as suggested by the ILAE commission were included after Ethics Committee approval and their signed consent. All patients received modulated cathodal stimulation; 2mA for 30min on 3 consecutive days. All patients also received sham stimulation with the same electrode positions; designed as 60s stimulation gradually decreasing in 15s with placement of the electrodes for 30min over the stimulation side. They were followed up by standard seizure diaries and their medical treatment was not changed during the study period. Their seizure frequencies both before and after cathodal tDCS and sham stimulation were compared statistically. Adverse effects were also questioned. RESULTS: Mean age of our study group was 35.42±6.96 (6 males; median: 35.50). The mean seizure frequency was 10.58±9.91 (median=8; min-max=2-30) at the baseline and significantly decreased to 1.67±2.50 (median=0.5; min-max=0-8) after cathodal tDCS application (p=0.003). Ten patients (83.33%) had more than 50% decrease in their seizure frequencies after cathodal tDCS. Two patients (16.67%) also showed positive sham effect. Six patients (50%) were seizure-free in the post-cathodal tDCS period of one month. No adverse effect has been reported except tingling sensation during cathodal stimulation. CONCLUSION: Our small series suggested that cathodal tDCS may be used as an additional treatment option in MTLE-HS. It may be tried in TLE-HS patients waiting for or rejecting epilepsy surgery or even with ineffective surgery results. More studies are needed with large series of patients to investigate the effects of tDCS in drug resistant epilepsies.

Transcranial direct current stimulation improves seizure control in patients with Rasmussen encephalitis.

Rasmussen encephalitis is associated with severe seizures that are unresponsive to antiepileptic drugs, as well as immunosuppressants. Transcranial direct current stimulation (t-DCS) is a non-invasive and safe method tried mostly for focal epilepsies with different aetiologies. To date, there is only one published study with two case reports describing the effect of t-DCS in Rasmussen encephalitis. Our aim was to investigate the effect of t-DCS on seizures in Rasmussen encephalitis and to clarify its safety. Five patients (mean age: 19; three females), diagnosed with Rasmussen encephalitis were included in this study. Patients received first cathodal, then anodal (2 mA for 30 minutes on three consecutive days for non-sham stimulations), and finally sham stimulation with two-month intervals, respectively. Three patients received classic (DC) cathodal t-DCS whereas two patients received cathodal stimulation with amplitude modulation at 12 Hz. Afterwards, all patients received anodal stimulation with amplitude modulation at 12 Hz. In the last part of the trial, sham stimulation (a 60-second stimulation with gradually decreasing amplitude to zero in the last 15 seconds) was applied to three patients. Maximum current density was 571 mA/m2 using 70 mm x 50 mm wet sponge electrodes with 2-mA maximum, current controlled stimulator, and maximum charge density was 1028 C/m2 for a 30-minute stimulation period. After cathodal stimulation, all but one patient had a greater than 50% decrease in seizure frequency. Two patients who received modulated cathodal t-DCS had better results. The longest positive effect lasted for one month. A second trial with modulated anodal stimulation and a third with sham stimulation were not effective. No adverse effect was reported with all types of stimulations. Both classic and modulated cathodal t-DCS may be suitable alternative methods for improving seizure outcome in Rasmussen encephalitis patients.

Comparison of Pattern Electroretinography and Optical Coherence Tomography Parameters in Patients with Primary Open-Angle Glaucoma and Ocular Hypertension.

OBJECTIVES: To investigate the correlation of visual field (VF), pattern electroretinography (PERG) and Fourier domain optical coherence tomography (FD-OCT) results in patients with ocular hypertension (OHT) and early primary open-angle glaucoma (POAG). MATERIALS AND METHODS: The study included 72 eyes of 37 patients with early POAG, 76 eyes of 38 patients with OHT, and 60 eyes of 30 controls. All subjects underwent full ophthalmologic examination, VF assessment with 24-2 Humphrey standard automated perimetry (Swedish Interactive Thresholding Algorithm (SITA)-Standard), retinal nerve fiber layer (RNFL) and ganglion cell complex (GCC) thickness measurement with FD-OCT, and PERG P50 and N95 wave latency and amplitude measurements with electroretinography (Nihon Kohden). RESULTS: With the exception of the nasal quadrant, all GCC parameters and RNFL results were significantly lower in the POAG group compared to the OHT and control groups. There was no statistically significant difference between the OHT and control group. PERG amplitudes were lower in the POAG and OHT groups than in the control group. Reduction in N95 amplitude was greater than that of P50 amplitude. No difference was detected in PERG latencies among groups. GCC was significantly correlated with VF and RNFL in the POAG group. CONCLUSION: Significant thinning of the GCC and RNFL occurs in addition to VF pathologies in patients with early POAG, and these examinations should be concomitantly evaluated. During diagnostic assessment of patients with early POAG, GCC and RNFL analysis by FD-OCT are highly effective. GCC is as reliable as RNLF in the early diagnosis of glaucoma and there is a highly significant correlation between them. Dysfunction of ganglion cells in patients with OHT may be detected earlier using PERG amplitude analysis.

Structural and functional comparison of the persistent and resolved amblyopia.

PURPOSE: To assess structural or functional differences of the retina among subjects with persistent and resolved amblyopia. METHODS: Fourteen eyes with persistent amblyopia that did not reach normal visual acuity (VA) levels (≤0.1 LogMAR) despite amblyopia treatment, 18 eyes with resolved amblyopia, and 16 eyes of 16 normal subjects were included. All subjects underwent optical coherence tomography (OCT), pattern visual evoked potential (PVEP), and pattern electroretinography (PERG) evaluation. RESULTS: There was no significant difference in foveal thickness, foveal volume, macular volume, ganglion cell layer thickness, and total and sectorial retinal nerve fiber layer measurements among three groups (p > 0.05). Foveolar thickness was significantly increased in both resolved and persistent amblyopia groups compared with the control group (p = 0.031). However, there was no difference between amblyopic groups (p = 0.98). Although, in the PVEP study, N75 implicit time was found significantly prolonged in both amblyopia groups (p = 0.046), there were no significant differences in P100 implicit time and amplitude among the groups (p > 0.05). PERG amplitude of the persistent group was significantly lower than that of the control group (p = 0.003). There were no significant differences in P50, N95 implicit times among groups (p > 0.05). CONCLUSIONS: In our study, the only significant difference between persistent and resolved amblyopia groups was the initial VA. Neither OCT nor electrophysiological examinations were found to be useful in order to explain why some cases were resistant to the treatment for amblyopia.

The morpho-functional evaluation of retina in amblyopia.

PURPOSE: To investigate the morphological or functional differences of retina in amblyopia. MATERIALS AND METHODS: Forty-one patients with unilateral strabismic, anisometropic or combined amblyopia were included in the study. A control group was composed of 16 normal children. All participants were tested with optical coherence tomography (OCT) and pattern electroretinography (PERG). The findings from amblyopic and nonamblyopic eyes were compared among the amblyopic groups. Also, amblyopic and nonamblyopic eyes were compared with the healthy control eyes. RESULTS: No significant difference was found in OCT parameters for amblyopic and nonamblyopic eyes among the amblyopic groups (p > 0.05). In the combined and anisometropic groups, ganglion cell complex (GCC) was found to be significantly increased in both amblyopic and nonamblyopic eyes compared to the control group (p < 0.05). In strabismic amblyopia, significant reduction in GCC thickness and increase in foveal thickness were found, compared to nonamblyopic eyes (p = 0.019, p = 0.08). There were no significant differences in PERG amplitude and latency between the amblyopic and the nonamblyopic eyes in amblyopic groups (p > 0.05). PERG amplitude in amblyopic eyes was found to be significantly decreased compared with that in normal eyes (p < 0.05). When the nonamblyopic eyes were compared with the control group, only the anisometropic amblyopia group demonstrated significant reduction in amplitude and prolongation in latency (p = 0.002, p = 0.026). CONCLUSION: We found no significant differences in morphological and functional measures among amblyopic groups. However, we detected significant differences in the retinal function and morphology of both amblyopic and nonamblyopic eyes compared with healthy control eyes.