This volume contains two Open Access Chapters. This volume features contributions from activist scholars grappling to understand and alleviate the compound sufferings of women and LGBTIQA+ persons as ...they encounter criminal justice systems in Southeast Asia.
Abstract Background Swallowing problems following stroke may result in increased risk of aspiration pneumonia, malnutrition, and dehydration. Objective/hypothesis Our hypothesis was that three ...neurostimulation techniques would produce beneficial effects on chronic dysphagia following stroke through a common brain mechanism that would predict behavioral response. Methods In 18 dysphagic stroke patients (mean age: 66 ± 3 years, 3 female, time-post-stroke: 63 ± 15 weeks ±SD), pharyngeal electromyographic responses were recorded after single-pulse transcranial magnetic stimulation (TMS) over the pharyngeal motor cortex, to measure corticobulbar excitability before, immediately, and 30 min, after real and sham applications of neurostimulation. Patients were randomized to a single session of either: pharyngeal electrical stimulation (PES), paired associative stimulation (PAS) or repetitive TMS (rTMS). Penetration-aspiration scores and bolus transfer timings were assessed before and after both real and sham interventions using videofluoroscopy. Results Corticobulbar excitability of pharyngeal motor cortex was beneficially modulated by PES, PAS and to a lesser extent by rTMS, with functionally relevant changes in the unaffected hemisphere. Following combining the results of real neurostimulation, an overall increase in corticobulbar excitability in the unaffected hemisphere ( P = .005, F1,17 = 10.6, ANOVA) with an associated 15% reduction in aspiration ( P = .005, z = −2.79) was observed compared to sham. Conclusions In this mechanistic study, an increase in corticobulbar excitability the unaffected projection was correlated with the improvement in swallowing safety ( P = .001, rho = −.732), but modality-specific differences were observed. Paradigms providing peripheral input favored change in neurophysiological and behavioral outcome measures in chronic dysphagia patients. Further larger cohort studies of neurostimulation in chronic dysphagic stroke are imperative.
Background & Aims Patients with stroke experience swallowing problems (dysphagia); increased risk of aspiration pneumonia, malnutrition, and dehydration; and have increased mortality. We investigated ...the behavioral and neurophysiological effects of a new neurostimulation technique (paired associative stimulation PAS), applied to the pharyngeal motor cortex, on swallowing function in healthy individuals and patients with dysphagia from stroke. Methods We examined the optimal parameters of PAS to promote plasticity by combining peripheral pharyngeal (electrical) with cortical stimulation. A virtual lesion was used as an experimental model of stroke, created with 1-Hz repetitive transcranial magnetic stimulation over the pharyngeal cortex in 12 healthy individuals. We tested whether hemispheric targeting of PAS altered swallowing performance before applying the technique to 6 patients with severe, chronic dysphagia from stroke (mean of 38.8 ± 24.4 weeks poststroke). Results Ten minutes of PAS to the unlesioned pharyngeal cortex reversed (bilaterally) the cortical suppression induced by virtual lesion (lesioned: F1,9 = 21.347, P = .001; contralesional: F1,9 = 9.648, P = .013; repeated-measures analysis of variance) compared with sham PAS. It promoted changes in behavior responses measured with a swallowing reaction time task (F1,7 = 21.02, P = .003; repeated-measures analysis of variance). In patients with chronic dysphagia, real PAS induced short-term bilateral changes in the brain; the unaffected pharyngeal cortex had increased excitability ( P = .001; 95% confidence interval, 0.21–0.05; post hoc paired t test) with reduced penetration-aspiration scores and changes in swallowing biomechanics determined by videofluoroscopy. Conclusions The beneficial neurophysiological and behavioral properties of PAS, when applied to unlesioned brain, provide the foundation for further investigation into the use of neurostimulation as a rehabilitative approach for patients with dysphagia from stroke.
Transcranial direct current stimulation (tDCS) is a novel intervention that can modulate brain excitability in health and disease; however, little is known about its effects on bilaterally innervated ...systems such as pharyngeal motor cortex. Here, we assess the effects of differing doses of tDCS on the physiology of healthy human pharyngeal motor cortex as a prelude to designing a therapeutic intervention in dysphagic patients. Healthy subjects (n = 17) underwent seven regimens of tDCS (anodal 10 min 1 mA, cathodal 10 min 1 mA, anodal 10 min 1.5 mA, cathodal 10 min 1.5 mA, anodal 20 min 1 mA, cathodal 20 min 1 mA, Sham) on separate days, in a double blind randomized order. Bihemispheric motor evoked potential (MEP) responses to single-pulse transcranial magnetic stimulation (TMS) as well as intracortical facilitation (ICF) and inhibition (ICI) were recorded using a swallowed pharyngeal catheter before and up to 60 min following the tDCS. Compared with sham, both 10 min 1.5 mA and 20 min 1 mA anodal stimulation induced increases in cortical excitability in the stimulated hemisphere (+44 +/- 17% and +59 +/- 16%, respectively; P < 0.005) whereas only 10 min 1.5 mA cathodal stimulation induced inhibition (-26 +/- 4%, P = 0.02). There were neither contralateral hemisphere changes nor any evidence for ICI or ICF in driving the ipsilateral effects. In conclusion, anodal tDCS can alter pharyngeal motor cortex excitability in an intensity-dependent manner, with little evidence for transcallosal spread. Anodal stimulation may therefore provide a useful means of stimulating pharyngeal cortex and promoting recovery in dysphagic patients.
Inhibitory patterns of repetitive transcranial magnetic stimulation (rTMS) were applied to pharyngeal motor cortex in order
to establish its role in modulating swallowing activity and provide ...evidence for functionally relevant hemispheric asymmetry.
Healthy volunteers underwent single pulse TMS before and for 60 min after differing intensities of 1 Hz rTMS ( n = 9, 6 male, 3 female, mean age 34 ± 3 years) or theta burst stimulation (TBS) ( n = 9, 6 male, 3 female, mean age 37 ± 4 years). Electromyographic responses recorded from pharynx and hand were used as a
measure of cortico-motor pathway excitability. Swallowing behaviour was then examined with a reaction time protocol, before
and for up to 60 min after the most effective inhibitory protocol (1 Hz) applied to each hemisphere. Interventions were conducted
on separate days and compared to sham using ANOVA. Only high intensity 1 Hz rTMS consistently suppressed pharyngeal motor
cortex immediately and for up to 45 min (â34 ± 7%, P ⤠0.001). Adjacent hand and contralateral pharyngeal motor cortex showed no change in response (â15 ± 12%, P = 0.14 and 15 ± 12%, P = 0.45, respectively). When used to unilaterally disrupt each hemisphere, rTMS to pharyngeal motor cortex with the stronger
responses altered normal (â12 ± 3%, P ⤠0.001) and fast (â9 ± 4%, P ⤠0.009) swallow times, not seen following rTMS to the contralateral cortex or after sham. Thus, suppression of pharyngeal
motor cortex to rTMS is intensity and frequency dependent, which when applied to each hemisphere reveals functionally relevant
asymmetry in the motor control of human swallowing.
Background & Aims Excitatory brain stimulation with repetitive transcranial magnetic stimulation (rTMS) has been proposed as a treatment for dysphagia after stroke. Moreover, 1-Hz rTMS can induce a ...“virtual lesion” in the human pharyngeal motor cortex that suppresses brain activity and temporarily disrupts swallowing. We thus examined if rTMS could reverse the disrupted brain and swallowing functions following a unilateral virtual lesion in the pharyngeal motor cortex, such that rTMS might be developed as a therapy. Methods Healthy subjects (n = 23) were given varying conditions of 5-Hz rTMS over the pharyngeal motor cortex to determine the most effective excitatory parameters. Thereafter, a unilateral virtual lesion was made in the pharyngeal motor cortex using 1-Hz rTMS, followed by contralateral active or sham 5-Hz rTMS. Motor evoked potentials and serial swallowing reaction times were recorded before and for 60 minutes postlesion to assess reversibility of the disruption to the brain and swallowing. Results The greatest increase in pharyngeal motor cortex excitability was seen following 250 pulses of 5-Hz rTMS (F(1,11) = 10.3, P = .008), an effect that lasted over 2 hours. In contrast to sham rTMS, active contralateral 5-Hz rTMS completely abolished the cortical suppression induced by the virtual lesion, with effects occurring for up to 50 minutes in both unlesioned (F(1,11) = 6, P = .03) and lesioned (F(1,11) = 67, P < .001) hemispheres. Active rTMS also reversed the changes in swallowing behavior (F(1,8) = 9, P = .018), restoring function to prelesional levels. Conclusions Contralesional-targeted neurostimulation modulates brain activity and swallowing motor behavior after experimental disruption and might be usefully applied in stroke-affected patients as a therapy for dysphagia.
Background & Aims Polymorphisms in brain-derived neurotrophic factor (BDNF) can affect brain and behavioral responses. However, little is known about the effects of a single nucleotide polymorphism ...(SNP) in BDNF , at codon 66 (the Val−Met substitution, detected in approximately 33% of the Caucasian population) on stimulation-induced plasticity in the cortico-bulbar system. We examined whether this SNP influenced outcomes of different forms of neurostimulation applied to the pharyngeal motor cortex. Methods Thirty-eight healthy volunteers were assessed for corticobulbar excitability after single-pulse, transcranial magnetic stimulation of induced pharyngeal electromyographic responses, recorded from a swallowed intraluminal catheter. Thereafter, volunteers were conditioned with pharyngeal electrical stimulation, or 2 forms of repetitive (1 and 5 Hz) transcranial magnetic stimulation (rTMS). Repeated measurements of pharyngeal motor-evoked potentials were assessed with transcranial magnetic stimulation for as long as 1 hour after the 3 forms of neurostimulation and correlated with SNPs at codon 66 of BDNF (encoding Val or Met). Results Pharyngeal electrical stimulation significantly increased the amplitude of motor-evoked potentials in individuals with the SNP that encoded Val66, compared to those that encoded Met66, with a strong GENOTYPE*TIME interaction ( F8,112 = 2.4; P = .018). By contrast, there was a significant reduction in latencies of subjects with the SNP that encoded Met66 after 5-Hz rTMS ( F3,60 = 4.9; P = .04). In addition, the expected inhibitory effect of 1-Hz rTMS on amplitude was not observed in subjects with the SNP that encoded Met66 in BDNF ( F7,140 = 2.23; P = .035). Conclusions An SNP in human BDNF at codon 66 affects plasticity of the pharyngeal cortex to different forms of neurostimulation. Genetic analysis might help select specific forms of neurostimulation as therapeutics for patients with disorders such as dysphagic stroke.
Our objective has been to establish a pro-angiogenic role for exosomes in endometriosis and to determine whether a differential expression profile of cellular and exosomal
microRNAs
(
miRNAs
) exists ...in endometriosis. We performed an in vitro study of human primary endometrial stromal cells (ESCs) and human umbilical vein endothelial cells (HUVECs). We isolated and characterized exosomes from ESCs from five endometriosis patients and five phase-matched controls. Exosomes were characterized by transmission electron microscopy and NanoSight technology.
MiRNA
was assessed by deep sequencing and reverse transcription with quantitative polymerase chain reaction. Exosome uptake studies were achieved by means of confocal microscopy. The pro-angiogenic experiments were executed by treating HUVECs with ESC-derived exosomes. We observed differential profiles of exosomal
miRNA
expression between exosomes derived from endometriosis lesion cells and diseased eutopic stromal cells compared with exosomes derived from control ESCs. We also demonstrated autocrine cellular uptake of exosomes and paracrine functional angiogenic effects of exosomes on HUVECs. The results of this study support the hypothesis that exosomes derived from ESCs play autocrine/paracrine roles in the development of endometriosis, potentially modulating angiogenesis. The broader clinical implications are that Sampson’s theory of retrograde menstruation possibly encompasses the finding that exosomes work as intercellular communication modulators in endometriosis.
Background & Aims Oropharyngeal dysphagia is an important disability that occurs after stroke; it contributes to aspiration pneumonia and death, and current modalities for rehabilitation of dysphagia ...have uncertain efficacy. We therefore examined the role of pharyngeal electrical stimulation (PES) in expediting human swallowing recovery after experimental (virtual) and actual (stroke) brain lesions. Methods First, healthy subjects (n = 13) were given 1-Hz repetitive transcranial magnetic stimulation to induce a unilateral virtual lesion in pharyngeal motor cortex followed by active or sham (control) PES. Motor-evoked potentials and swallow accuracy were recorded before and after the lesion to assess PES response. Thereafter, 50 acute dysphagic stroke patients underwent either a dose-response study, to determine optimal parameters for PES (n = 22), or were assigned randomly to groups given either active or sham (control) PES (n = 28). The primary end point was the reduction of airway aspiration at 2 weeks postintervention. Results In contrast to sham PES, active PES reversed the cortical suppression induced by the virtual lesion ( F7,70 = 2.7; P = .015) and was associated with improvement in swallowing behavior ( F3,42 = 5; P = .02). After stroke, 1 PES treatment each day ( U = 8.0; P = .043) for 3 days ( U = 10.0) produced improved airway protection compared with controls ( P = .038). Active PES also reduced aspiration ( U = 54.0; P = .049), improved feeding status ( U = 58.0; P = .040), and resulted in a shorter time to hospital discharge (Mantel–Cox log-rank test, P = 0.038). Conclusions This pilot study of PES confirms that it is a safe neurostimulation intervention that reverses swallowing disability after virtual lesion or stroke.
Key points
Cortical control of swallowing exhibits functional asymmetry with brain lesions involving the strongest projection being implicated in the pathophysiology of dysphagia after unilateral ...stroke.
Swallowing recovery is associated with neuroplastic adaptation in the unlesioned hemisphere, a process which can be facilitated by excitatory neurostimulation techniques including transcranial direct current stimulation (tDCS).
Unilateral suppression of the strongest pharyngeal motor projection using 1 Hz repetitive transcranial magnetic stimulation (rTMS) can disrupt swallowing neurophysiology and behaviour making it a useful model for trialling novel neurostimulation interventions in healthy subjects.
In this healthy participant study we examined the effects of tDCS after unilateral pre‐conditioning with 1 Hz rTMS to determine its ability to restore swallowing neurophysiology and behaviour.
We show that application of optimised parameters of tDCS (anodal stimulation, 1.5 mA, 10 min) over the unconditioned hemisphere reverses the brain and behavioural consequences of inhibitory pre‐conditioning, supporting the use of tDCS in clinical trials.
The human cortical swallowing system exhibits bilateral but functionally asymmetric representation in health and disease as evidenced by both focal cortical inhibition (pre‐conditioning with 1 Hz repetitive transcranial magnetic stimulation; rTMS) and unilateral stroke, where disruption of the stronger (dominant) pharyngeal projection alters swallowing neurophysiology and behaviour. Moreover, excitatory neurostimulation protocols capable of reversing the disruptive effects of focal cortical inhibition have demonstrated therapeutic promise in post‐stroke dysphagia when applied contralaterally. In healthy participants (n = 15, 8 males, mean age (±SEM) 35 ± 9 years), optimal parameters of transcranial direct current stimulation (tDCS) (anodal, 1.5 mA, 10 min) were applied contralaterally after 1 Hz rTMS pre‐conditioning to the strongest pharyngeal projection. Swallowing neurophysiology was assessed in both hemispheres by intraluminal recordings of pharyngeal motor‐evoked responses (PMEPs) to single‐pulse TMS as a measure of cortical excitability. Swallowing behaviour was examined using a pressure‐based reaction time protocol. Measurements were made before and for up to 60 min post intervention. Subjects were randomised to active or sham tDCS after 1 Hz rTMS on separate days and data were compared using repeated measures ANOVA. Active tDCS increased PMEPs bilaterally (F1,14 = 7.4, P = 0.017) reversing the inhibitory effects of 1 Hz rTMS in the pre‐conditioned hemisphere (F1,14 = 10.1, P = 0.007). Active tDCS also enhanced swallowing behaviour, increasing the number of correctly timed challenge swallows compared to sham (F1,14 = 6.3, P = 0.025). Thus, tDCS to the contralateral pharyngeal motor cortex reverses the neurophysiological and behavioural effects of focal cortical inhibition on swallowing in healthy individuals and has therapeutic potential for dysphagia rehabilitation.
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