Transcranial magnetic stimulation and sleep disorders: pathophysiologic insights

rTMS reduces spatial learning and memory deficits induced by sleep deprivation possibly via suppressing the expression of kynurenine 3-monooxygenase in rats

INTRODUCTION

Impairment of learning and memory caused by sleep deprivation is a common symptom that significantly affects quality of life. Repetitive transcranial magnetic stimulation (rTMS) is a promising approach to exert a positive effect on cognitive impairment. However, there is less known about the mechanism of rTMS for learning and memory induced by chronic REM sleep deprivation (CRSD). This study was to detect the effects of rTMS on spatial learning and memory deficits by CRSD and explore possible mechanism.

METHODS

Sixty male Sprague-Dawley rats were randomly divided into four groups: wide platform (Control), sleep deprivation (SD), sleep deprivation + rTMS (TMS), and sleep deprivation + sham rTMS (Sham-TMS). Morris water maze (MWM) and open field test (OFT) assessed spatial learning and memory and anxiety of rats with pre/post-intervention. Golgi staining and transmission electron microscope (TEM) were used to observe structural variations of synapses in the hippocampus. The alteration in gene expression of different groups was analyzed by RNA-sequencing (RNA-Seq), and the key gene was screened and identified by quantitative polymerase chain reaction (qPCR) and subsequently verified with western blotting and immunofluorescence.

RESULTS

The behavioral test showed spatial learning and memory decreased and anxiety increased in the SD group compared to the Control and TMS groups. Moreover, rTMS improved spine density, ultrastructural damage, and quantities of synapses. In accordance with RNA-Seq, 56 differentially expressed genes (DEGs) were identified by comparing alternations in four groups and concentrated on kynurenine 3-monooxygenase (KMO). The expression of KMO increased significantly in rats of the SD group compared to the Control and TMS groups identified by qPCR, western blotting, and immunofluorescence.

CONCLUSION

1 Hz rTMS alleviated spatial learning and memory deficits induced by CRSD probably via down-regulating the expression of KMO and improving the structure and quantity of synapses in the hippocampus of rats.

Cortical excitability in patients with REM sleep behavior disorder with abnormal TRODAT-1 SPECT scan: an insight into prodromal Parkinson's disease

Introduction

REM Sleep Behavior Disorder (RBD) has been highlighted to identify a patient with prodromal Parkinson's disease (PD). Although many studies focus on biomarkers to predict an RBD patient's evolution from prodromal PD to clinical PD, the neurophysiological perturbation of cortical excitability has not yet been well elucidated. Moreover, no study describes the difference between RBD with and without abnormal TRODAT-1 SPECT.

Methods

By measuring the amplitude of motor evoked potentials (MEP), the cortical excitability changes after transcranial magnetic stimulation (TMS) were evaluated in 14 patients with RBD and eight healthy controls (HC). Seven of the 14 patients with RBD showed abnormal TRODAT-1 (TRA-RBD), and seven were normal (TRN-RBD). The tested parameters of cortical excitability include resting motor threshold (RMT), active motor threshold (AMT), short-interval intracortical inhibition (SICI), intracortical facilitation (ICF), contralateral silence period (CSP), and input-output recruitment curve.

Results

The RMT and AMT showed no difference among the three studied groups. There was only SICI at inter-stimuli-interval 3 ms revealing group differences. The TRA-RBD demonstrated significant differences to HC in these aspects: decreased SICI, increased ICF, shortening of CSP, and augmented MEP amplitude at 100% RMT. Moreover, the TRA-RBD had a smaller MEP facilitation ratio at 50% and 100% of maximal voluntary contraction when compared to TRN-RBD. The TRN-RBD did not present any difference to HC.

Conclusion

We showed that TRA-RBD shared similar cortical excitability changes with clinical PD. These findings would provide further insight into the concept that RBD is the highly prevalent entity in prodromal PD.

Altered functional connectivity of the default mode and frontal control networks in patients with insomnia

AIMS

The purpose of this study was to investigate the association between spontaneous regional activity and brain functional connectivity, which maybe can distinguish insomnia while being responsive to repetitive transcranial magnetic stimulation (rTMS) treatment effects in insomnia patients.

METHODS

Using resting-state functional magnetic resonance imaging data from 38 chronic insomnia patients and 36 healthy volunteers, we compared the amplitude of low-frequency fluctuations (ALFF) between the two groups. Of all the patients with insomnia, 20 received rTMS for 4 weeks, while 18 patients received a 4-week pseudo-stimulation intervention. Seed-based resting-state functional connectivity (RSFC) analysis was conducted from regions with significantly different ALFF values, and the association between RSFC value and Pittsburgh Sleep Quality Index score was determined.

RESULTS

Our results revealed that insomnia patients presented a significantly higher ALFF value in the posterior cingulate cortex (PCC), whereas a significantly lower ALFF value was observed in the superior parietal lobule (SPL). Moreover, significantly reduced RSFC was detected from both PCC to prefrontal cortex connections, as well as from left SPL to frontal pole connections. In addition, RSFC from frontal pole to left SPL negatively predicted sleep quality (PSQI) and treatment response in patients' group.

CONCLUSION

Our findings suggest that disrupted frontoparietal network connectivity may be a biomarker for insomnia in middle-aged adults, reinforcing the potential of rTMS targeting the frontal lobes. Monitoring pretreatment RSFC could offer greater insight into how rTMS treatments are responded to by insomniacs.

Repetitive transcranial magnetic stimulation in primary sleep disorders

Repetitive transcranial magnetic stimulation (rTMS) is a widely used non-invasive neuromodulatory technique. When applied in sleep medicine, the main hypothesis explaining its effects concerns the modulation of synaptic plasticity and the strength of connections between the brain areas involved in sleep disorders. Recently, there has been a significant increase in the publication of rTMS studies in primary sleep disorders. A multi-database-based search converges on the evidence that rTMS is safe and feasible in chronic insomnia, obstructive sleep apnea syndrome (OSAS), restless legs syndrome (RLS), and sleep deprivation-related cognitive deficits, whereas limited or no data are available for narcolepsy, sleep bruxism, and REM sleep behavior disorder. Regarding efficacy, the stimulation of the dorsolateral prefrontal cortex bilaterally, right parietal cortex, and dominant primary motor cortex (M1) in insomnia, as well as the stimulation of M1 leg area bilaterally, left primary somatosensory cortex, and left M1 in RLS reduced subjective symptoms and severity scale scores, with effects lasting for up to weeks; conversely, no relevant effect was observed in OSAS and narcolepsy. Nevertheless, several limitations especially regarding the stimulation protocols need to be considered. This review should be viewed as a step towards the further contribution of individually tailored neuromodulatory techniques for sleep disorders.

Prefrontal brain function in patients with chronic insomnia disorder: A pilot functional near-infrared spectroscopy study

Purpose

Insomnia is one of the most common diseases in elderly patients, which seriously affect the quality of life and psychological state of patients. The purpose of this study was to investigate the changes in the functional network pattern of the prefrontal cortex in patients with chronic insomnia disorder (CID) after taking drugs, using non-invasive and low-cost functional neuroimaging with multi-channel near-infrared spectroscopy (fNIRS).

Methods

All subjects were assessed using the Pittsburgh Sleep Quality Index (PSQI), Hamilton Depression Scale (HAMD), Hamilton Anxiety Scale (HAMA), and fNIRS. The fNIRS assessment consists of two parts: the verbal fluency test (VFT) task state and the resting state, which assessed the differences in prefrontal activation and functional connectivity, respectively.

Results

A total of 30 patients with chronic insomnia disorder (CID) and 15 healthy peers completed the study. During the VFT task, a significantly lower PFC activation was observed in patients with insomnia compared to the control group (P < 0.05). However, the PFC activation in patients taking medication was higher than in patients who did not receive medication. Functional connectivity analysis showed a weaker mean PFC channel connectivity strength in patients with CID who did not receive drug treatment. Drug treatment resulted in enhanced functional connectivity of the prefrontal lobe, especially the DLPFC and frontal poles.

Conclusion

A weak prefrontal cortex response was detected in patients with CID when performing the VFT task, which could be enhanced by taking hypnotics. The weakened right prefrontal lobe network may play a role in the development of CID. fNIRS may serve as a potential tool to assess sleep status and guide drug therapy.

The Sensory Abnormality Mediated Partially the Efficacy of Repetitive Transcranial Magnetic Stimulation on Treating Comorbid Sleep Disorder in Autism Spectrum Disorder Children

Sleep disorder emerges as a common comorbidity in children with autism spectrum disorder (ASD), and the interaction between the core symptoms of ASD and its sleep disorder remains unclear. Repetitive transcranial magnetic stimulation (rTMS) was used on the bilateral dorsolateral prefrontal cortex (DLPFC) to investigate the efficacy of rTMS on the core symptoms of ASD and comorbid sleep problems as well as the mediation role of the ASD symptoms between rTMS intervention and sleep improvement. A total of 41 Chinese children with ASD and who met the criteria in the fifth edition of the American Diagnostic and Statistical Manual of Mental Disorders were recruited, and 39 of them (mean age: 9.0 ± 4.4 years old; the male-female ratio was 3.9: 1) completed the study with the stimulating protocol of high frequency on the left DLPFC and low frequency on the right DLPFC. They were all assessed three times (before, at 4 weeks after, and at 8 weeks after the stimulation) by the Children's Sleep Habits Questionnaire (CSHQ), Strengths and Difficulties Questionnaire (SDQ), Childhood Autism Rating Scale, Repetitive Behavior Questionnaire-2, and Short Sensory Profile (SSP). The repeated-measures ANOVA showed that the main effect of "intervention time" of CSHQ (F = 25.103, P < 0.001), SSP (F = 6.345, P = 0.003), and SDQ (F = 9.975, P < 0.001) was statistically significant. By Bayesian mediation analysis, we only found that the total score of SSP mediated the treating efficacy of rTMS on CSHQ (αβ = 5.11 ± 1.51, 95% CI: 2.50-8.41). The percentage of mediation effect in total effect was 37.94%. Our results indicated the treating efficacy of rTMS modulation on bilateral DLPFC for both autistic symptoms and sleep disturbances. The sensory abnormality of ASD mediated the improvement of rTMS on sleep problems of ASD.

Functional Connectivity Density in the Sensorimotor Area is Associated with Sleep Latency in Patients with Primary Insomnia

OBJECTIVE

It is unclear whether the patterns of functional connectivity density (FCD) differ between patients with primary insomnia (PI) and healthy subjects. In the present study, we investigated the features of FCD in patients with PI using resting-state functional MRI (rsfMRI).

METHODS

rsfMRI datasets of 32 patients with PI and 34 healthy controls (HCs) were obtained using a 3-Tesla scanner. FCD analysis was performed to compare voxels with abnormal whole-brain functional connectivity with other voxels among patients with PI and HCs. Abnormal brain regions were then used as seed points for FC analysis.

RESULTS

Compared with HCs, patients with PI exhibited significantly decreased FCD in the left medial frontal gyrus and increased FCD in the left supplementary motor area (SMA). With the left medial frontal gyrus as the seed point, patients with PI showed decreased FC between the left medial frontal gyrus and the left fusiform gyrus compared with HCs. With the left SMA as the seed point, patients with PI exhibited increased FC between the left SMA and the right anterior cingulate gyrus. Correlation analysis revealed that the increased FCD values in the left SMA were positively correlated with sleep latency in patients with PI.

CONCLUSION

Default-mode network and SMA dysfunctions may be related to the pathophysiology of PI.

Involvement of central sensory pathways in subjects with restless legs syndrome: A neurophysiological study

In patients with restless legs syndrome (RLS) a motor cortical disinhibition has been reported in transcranial magnetic stimulation (TMS) studies, but the neuronal excitability in other cortical areas has been poorly explored. The aim of this study was the functional evaluation of thalamo-cortical circuits and inhibitory cortical responses in the sensory cortex in RLS. We assessed the high-frequency somatosensory evoked potentials (HF-SEP) in sixteen subjects suffering from RLS of different degrees of severity. In patients with severe or very severe RLS we found a significant desynchronization with amplitude reduction of both pre- and post-synaptic HF-SEP bursts, which suggest an impairment in the thalamo-cortical projections and in the cortical inhibitory interneurons activity, respectively. The assessment of the central sensory pathways by means of HF-SEP may shed light on the pathophysiological mechanisms of RLS.

The long-term effect of repetitive transcranial magnetic stimulation in the treatment of intractable insomnia

OBJECTIVE

To explore the differences in clinical efficacy of different courses of repetitive transcranial magnetic stimulation (rTMS) in the treatment of intractable insomnia and the duration of clinical efficacy after cessation of treatment.

METHOD

70 patients with intractable insomnia were randomly divided into 1 treatment course group and 2 treatment courses group. The rTMS course consisted of daily sessions of 1200 stimuli for the r-DLPFC at a frequency of 1 Hz and 800 stimuli for parietal lobe (CPZ) at a frequency of 1 Hz. The pitchburg sleep index (PSQI), Hamilton depression scale (HAMD), Hamilton anxiety scale (HAMA), and cardiopulmonary coupled sleep (CPC) were assessed for 35 patients in each group at baseline, at 2 weeks, and at 1 and 3 months after treatment.

RESULT

The scores of PSQI, HAMD and HAMA in the 2 groups were significantly improved after 1 month of follow-up after rTMS treatment (p < 0.01). The long-term effect of different treatment courses is different. After 2 consecutive courses of treatment, there was still a significant difference between the 3-month follow-up and the pre-treatment period (p < 0.05). However, there was no statistical difference between the 3-month follow-up of one course of treatment and the pre-treatment period. The results of CPC test showed that the improvement of total sleep time (TST), and deep sleep time (DST) was basically consistent with the assessment of PSQI, HAMD and HAMA that the clinical efficacy of the 3-month follow-up was better than that of one course of treatment after 2 consecutive courses of treatment.

CONCLUSION

The treatment of refractory insomnia by rTMS is effective, and the duration of the curative effect is related to the course of treatment. 2 consecutive courses of treatment still have a certain effect after 3 months, which is worthy of clinical promotion.

Transcranial magnetic stimulation therapeutic applications on sleep and insomnia: a review

Repetitive transcranial magnetic stimulation (rTMS) is a neuromodulatory technique approved by the US Food and Drug Administration for use in treatment-resistant major depressive disorder. It works by generating localized magnetic fields that create depolarizing electrical currents in neurons a few centimeters below the scalp. This localized effect is believed to stimulate neural plasticity, activate compensatory processes, and influence cortical excitability. Additionally, rTMS has been used in a variety of clinical trials for neurological and psychiatric conditions such as anxiety, post-traumatic stress disorder and epilepsy. Beneficial effects in sleep parameters have been documented in these trials, as well as in major depressive disorder, and have led to an interest in using rTMS in the field of sleep medicine for specific disorders such as insomnia, hypersomnia, and restless legs syndrome. It is unknown whether rTMS has intrinsically beneficial properties when applied to primary sleep disorders, or if it only acts on sleep through mood disorders. This narrative review sought to examine available literature regarding the application of rTMS for sleep disorder to identify knowledge gaps and inform future study design. The literature in this area remains scarce, with few randomized clinical trials on rTMS and insomnia. Available studies have found mixed results, with some studies reporting subjective sleep improvement while objective improvement is less consistent. Due to the heterogeneity of results and the variations in rTMS protocols, no definitive conclusions have been reached, signaling the need for further research.

The Management and Alternative Therapies for Comorbid Sleep Disorders in Epilepsy

BACKGROUND

There is a complex and interactive relationship between sleep and epilepsy. Sleep disorders are common in patients with epilepsy, and methods for managing sleep disorders in patients with epilepsy are limited.

OBJECTIVE

This review addresses the relationship among sleep, sleep disorders, and epilepsy, focusing on the management of sleep disorders in epilepsy, including some complementary and alternative therapies.

METHODS

The terms related to "sleep" and "epilepsy" were searched in "Pubmed" and "Cochrane Library".

RESULTS

Sleep stages differently affect both seizures and interictal epileptiform discharges. Seizures disrupt sleep architecture greatly, especially when occurring during sleep in the night. Insomnia and obstructive sleep apnea (OSA) are the most frequent types of comorbid sleep disorders in patients with epilepsy. Pharmacological agents with both anti-convulsant and sedative effects are the priorities for comorbid sleep disorders in epilepsy. Continuous positive airway pressure (CPAP) therapy is the most effective non-pharmacological method to improve OSA and reduce seizures. Complementary and alternative therapies such as Chinese traditional medicine, cognitive behavioral therapy, meditation, yoga, neurofeedback, and acupuncture may have benefits in reducing seizures and improving sleep quality simultaneously by alleviating stress and seizure triggers; however, evidence- based therapies are still deficient.

CONCLUSION

Management of sleep disorders in patients with epilepsy is challenging. Large-scale randomized controlled clinical trials are in demand to guide the treatments in the future.

Effect of low frequency repetitive magnetic stimulation at Shenmen (HT7) on sleep quality in patients with chronic insomnia

BACKGROUND

Insomnia is a common, recurrent, and tenacious sleep problem, especially the chronic insomnia. Repetitive transcranial magnetic stimulation (rTMS) at right dorsolateral prefrontal cortex (r-DLPFC) is used in chronic insomnia, and repetitive magnetic stimulation (rMS) at Shenmen (HT7) acupoint may be an alternative approach. However, the efficacy and mechanism of rMS at HT7 acupoint for chronic insomnia has not been confirmed.

METHODS/DESIGN

This is a 3-armed randomized positive-controlled noninferiority clinical trial. We will allocate 45 subjects aged between 18 and 65 years old, diagnosed with initial chronic insomnia over 3 months to 3 groups randomly in a ratio of 1:1:1. Patients in the experimental group will be treated with rMS at HT7 acupoint while the others in the control group will be treated with rTMS at r-DLPFC or waiting treatment. All will be given rMS at HT7 or rTMS at r-DLPFC or no treatment for 10 days, and then received 20-day follow-up. Patients will be evaluated with the insomnia severity index and Pittsburgh sleep quality index for sleep state, Beck Depression Inventory-2nd edition scores for the depression state, Beck anxiety inventory scores for the anxiety state, and Montreal Cognitive Assessment scores for the cognition state before and the 10th day of treatment, 30th day of follow-up; study on mechanisms of rMS will be revealed through the resting motor threshold diversity of the motor cortex before and the 10th day of treatment, 30th day of follow-up. Baseline characteristics of patients will be summarized by groups and compared with Chi-squared for categorical variables, and analysis of variance or Kruskal-Wallis test for the continuous variables. Primary and secondary outcomes according to the measurement times are applicable to univariate repetitive measurement deviation analysis or analysis of variance, or Kruskal-Wallis test.

CONCLUSION

The present study is designed to preliminarily investigate short-term efficacy and mechanism of rMS at HT7 acupoint therapy on chronic insomnia, also to explore the correlation between motor cortex excitability and chronic insomnia. With this research, we are looking forward to find out an appropriate alternative and easy therapy for chronic insomnia individuals compared with rTMS at r-DLPFC.

TRIAL REGISTRATION

The trial was registered on Chinese Clinical Trial Registry (http://www.chictr.org.cn/index.aspx) with the ID ChiCTR1900026844 on October 24, 2019.

Contribution of transcranial magnetic stimulation in restless legs syndrome: pathophysiological insights and therapeutical approaches

Transcranial magnetic stimulation (TMS) may offer a reliable means to characterize significant pathophysiologic and neurochemical aspects of restless legs syndrome (RLS). Namely, TMS has revealed specific patterns of changes in cortical excitability and plasticity, in particular dysfunctional inhibitory mechanisms and sensorimotor integration, which are thought to be part of the pathophysiological mechanisms of RLS rather than reflect a non-specific consequence of sleep architecture alteration. If delivered repetitively, TMS is able to transiently modulate the neural activity of the stimulated and connected areas. Some studies have begun to therapeutically use repetitive TMS (rTMS) to improve sensory and motor disturbances in RLS. High-frequency rTMS applied over the primary motor cortex or the supplementary motor cortex, as well as low-frequency rTMS over the primary somatosensory cortex, seem to have transient beneficial effects. However, further studies with larger patient samples, repeated sessions, an optimized rTMS setup, and clinical follow-up are needed in order to corroborate preliminary results. Thus, we performed a systematic search of all the studies that have used TMS and rTMS techniques in patients with RLS.

The effect of repetitive transcranial magnetic stimulation for insomnia: a systematic review and meta-analysis

BACKGROUND

Repetitive transcranial magnetic stimulation (rTMS) might be a promising technique in treating insomnia. A comprehensive meta-analysis of the available literature is conducted to offer evidence.

OBJECTIVE

To evaluate the efficacy and safety of rTMS for insomnia, either as monotherapy or as a complementary strategy.

METHODS

CENTRAL, PubMed, EMBASE, PsycINFO, CINAHL, PEDro, CBM, CNKI, WANFANG, and VIP were searched from earliest record to August 2019. Randomized control trials (RCTs) published in English and Chinese examining effects of rTMS on patients with insomnia were included. Two authors independently completed the article selection, data extraction and rating. Physiotherapy Evidence Database (PEDro) scale was used to assess the methodological quality of the included studies. The RevMan software was used for meta-analysis. The quality of the evidence was assessed by Grading of Recommendations Assessment, Development and Evaluation (GRADE) approach.

RESULTS

A total of 36 trials from 28 eligible studies were included, involving a total of 2357 adult participants (mean age, 48.80 years; 45.33% males). Compared with sham rTMS, rTMS was associated with improved PSQI total score (SMD -2.31, 95% CI -2.95 to -1.66; Z = 7.01, P < 0.00001) and scores of seven subscales. Compared to other treatment, rTMS as an adjunct to other treatment was associated with improved PSQI total score (SMD -1.44, 95% CI -2.00 to -0.88; Z = 5.01, P < 0.00001), and may have effects on scores of seven subscales. Compared with other treatment, rTMS was associated with improved Pittsburgh sleep quality index (PSQI) total score (SMD -0.63, 95% CI -1.22 to -0.04; Z = 2.08, P = 0.04), and may have a better score in sleep latency, sleep disturbance and hypnotic using of seven subscales. In the three pair of comparisons, the results for polysomnography (PSG) outcomes were varied. In general, rTMS may improve sleep quality through increasing slow wave and rapid eye movement (REM) sleep. The rTMS group was more prone to headache than the sham or blank control group (RR 1.71, 95% CI 1.03 to 2.85; Z = 2.07, P = 0.04). No severe adverse events were reported. Reporting biases and low and very low grade of some evidences should be considered when interpreting the results of this meta-analysis.

CONCLUSIONS

Our findings indicate that rTMS may be a safe and effective option for insomnia. Further international, multicenter, high-quality RCTs with more objective, quality of life related and follow-up assessments are needed.

Sleep quality improves during treatment with repetitive transcranial magnetic stimulation (rTMS) in patients with cocaine use disorder: a retrospective observational study

BACKGROUND

Sleep disturbance is a prominent and common complaint in people with cocaine use disorder (CUD), either during intake or withdrawal. Repetitive transcranial magnetic stimulation (rTMS) has shown promise as a treatment for CUD. Thus, we evaluated the relationship between self-perceived sleep quality and cocaine use pattern variables in outpatients with CUD undergoing an rTMS protocol targeted at the left dorsolateral prefrontal cortex.

METHODS

This is a retrospective observational study including 87 patients diagnosed with CUD according to the DSM-5 criteria. Scores in Pittsburgh Sleep Quality Index (PSQI), Cocaine Craving Questionnaire (CCQ), Beck Depression Inventory-II (BDI-II), Self-rating Anxiety Scale (SAS), and Symptoms checklist 90-Revised (outcome used: Global Severity Index, GSI) were recorded at baseline, and after 5, 30, 60, and 90 days of rTMS treatment. Cocaine use was assessed by self-report and regular urine screens.

RESULTS

Sleep disturbances (PSQI scores > 5) were common in patients at baseline (mean ± SD; PSQI score baseline: 9.24 ± 3.89; PSQI > 5 in 88.5% of patients). PSQI scores significantly improved after rTMS treatment (PSQI score Day 90: 6.12 ± 3.32). Significant and consistent improvements were also seen in craving and in negative-affect symptoms compared to baseline. Considering the lack of a control group, in order to help the conceptualization of the outcomes, we compared the results to a wait-list group (n = 10). No significant improvements were observed in the wait-list group in any of the outcome measures.

CONCLUSIONS

The present findings support the therapeutic role of rTMS interventions for reducing cocaine use and accompanying symptoms such as sleep disturbance and negative-affect symptoms.

TRIAL REGISTRATION

ClinicalTrials.gov.NCT03733821.

Obstructive Sleep Apnea Syndrome: A Preliminary Navigated Transcranial Magnetic Stimulation Study

PURPOSE

An increase in resting motor threshold (RMT), prolonged cortical silent period duration (CSP), and reduced short-latency afferent inhibition (SAI), confirmed with previous transcranial magnetic stimulation (TMS), suggest decreased cortical excitability in obstructive sleep apnea syndrome (OSAS). The present study included MRI of OSAS patients for navigated TMS assessment of the RMT, as an index of the threshold for corticospinal activation at rest, and SAI as an index of cholinergic neurotransmission. We hypothesize to confirm findings on SAI and RMT with adding precision in the targeting of motor cortex in OSAS.

SUBJECTS AND METHODS

After acquiring head MRIs for 17 severe right-handed OSAS and 12 healthy subjects, the motor cortex was mapped with nTMS to assess the RMT and SAI, with motor evoked potentials (MEPs) recorded from the abductor-pollicis brevis (APB) muscle. The 120%RMT intensity was used for the SAI by a paired-pulse paradigm in which the electrical stimulation to the median nerve is followed by magnetic stimulation of the motor cortex at inter-stimulus intervals (ISIs) of 18-28 ms (ISIs_18-28). The SAI control condition included a recording of MEPs without peripheral stimulation. Latency and amplitude of MEP at RMT at 120%RMT for eleven different at ISIs_18-28 were analyzed.

RESULTS

The study showed a significantly lower percentage deviation of MEP amplitude at ISIs_(18-28ms) from the control condition between OSAS and healthy subjects (U=44.0, p=0.01). The intensity of stimulation at RMT was significantly higher in OSAS subjects (U=55.0, p=0.04*). Correlation analysis showed that BMI significantly negatively correlated (ρ=-0.47) with MEP amplitude percentage deviation in OSAS patients.

CONCLUSION

The nTMS study results in increased RMT, and reduced cortical afferent inhibition in OSAS patients for SAI at ISIs_18-28, confirming previous findings of impaired cortical afferent inhibition in OSAS. Future nTMS studies are desirable to elucidate the role of RMT and SAI in diagnostics and treatment of OSAS, and to elucidate the usefulness of nTMS in OSAS research.

The Effect of sequential bilateral low-frequency rTMS over dorsolateral prefrontal cortex on serum level of BDNF and GABA in patients with primary insomnia

OBJECTIVE

This study aimed to investigate the effect of sequential bilateral low-frequency repetitive transcranial magnetic stimulation (rTMS) over dorsolateral prefrontal cortex (DLPFC) on patients with primary insomnia (PI).

METHODS

A total of 32 eligible right-handed participants diagnosed by PI according to International classification of sleep disorders (ICD-3) were recruited into this study. Participants received 10 daily sessions of sequential bilateral 1 Hz rTMS over DLPFC. Before and after the whole procedure of rTMS, patients were assessed by Pittsburgh Sleep Quality Index (PSQI) for the severity of sleep disturbance. Meanwhile, serum concentration of brain-derived neurotrophic factor (BDNF) and gamma-aminobutyric acid (GABA) in patients was measured by ELISA and UPLC, respectively. Moreover, the amplitude of MEPs reflecting the right cortical excitability was examined. Finally, Pearson correlation analysis was performed to evaluate the correlation among the change of these variables.

RESULTS

After rTMS treatment, the PSQI score was markedly decreased as compared to pre-rTMS; the concentrations of serum BDNF and GABA were significantly higher; the amplitude of MEPs was markedly reduced. Pearson correlation analysis revealed that the change of PSQI score was negatively associated with the alteration of serum BDNF level and serum GABA level, and positively associated with the change of MEPs amplitude; the change of MEPs amplitude was negatively associated with fold change in the serum BDNF level and the serum GABA level; the increase in serum GABA level was positively associated with the serum BDNF level.

CONCLUSIONS

A sequential bilateral low-frequency rTMS over DLPFC significantly improves primary insomnia probably by increasing the level of BDNF and GABA in the brain and reducing cortical excitability.

Excessive Daytime Sleepiness in Parkinson's Disease: Clinical Implications and Management

Objective

Excessive daytime sleepiness (EDS) is one of the most common sleep abnormalities in patients with Parkinson's disease (PD), yet its multifactorial etiology complicates its treatment. This review summarized recent studies on the epidemiology, etiology, clinical implications, associated features, and evaluation of EDS in PD. The efficacy of pharmacologic and non-pharmacologic treatments for EDS in PD was also reviewed.

Data Sources

English language articles indexed in PubMed and Cochrane databases and Chinese-language papers indexed in Wanfang and National Knowledge Infrastructure databases that were published between January 1987 and November 2017 were located using the following search terms: "sleepiness", "sleep and Parkinson's disease", and "Parkinson's disease and treatment".

Study Selection

Original research articles and critical reviews related to EDS in PD were selected.

Results

EDS is a major health hazard and is associated with many motor and nonmotor symptoms of PD. Its causes are multifactorial. There are few specific guidelines for the treatment of EDS in PD. It is first necessary to identify and treat any possible factors causing EDS. Recent studies showed that some nonpharmacologic (i.e., cognitive behavioral therapy, light therapy, and repetitive transcranial magnetic stimulation) and pharmacologic (i.e., modafinil, methylphenidate, caffeine, istradefylline, sodium oxybate, and atomoxetine) treatments may be effective in treating EDS in PD.

Conclusions

EDS is common in the PD population and can have an immensely negative impact on quality of life. Its causes are multifactorial, which complicates its treatment. Further investigations are required to determine the safety and efficacy of potential therapies and to develop novel treatment approaches for EDS in PD.

Direct comparison of cortical excitability to transcranial magnetic stimulation in obstructive sleep apnea syndrome and restless legs syndrome

OBJECTIVE

Changes to transcranial magnetic stimulation (TMS) have been reported in obstructive sleep apnea syndrome (OSAS) and restless legs syndrome (RLS), although no direct comparison study is available. The aim of this new investigation is to assess and compare cortical excitability of OSAS and RLS patients using the same methodology and under the same experimental conditions.

METHODS

Fourteen patients with OSAS and 12 with RLS were compared to 14 age-matched controls. All patients were untreated and had a severe degree of disease. Resting motor threshold (rMT), cortical silent period (CSP) and motor evoked potentials MEPs, as well as intracortical inhibition (ICI) and facilitation at interstimulus interval (ISI) of 3 and 10 ms, respectively, were explored from the right first dorsal interosseous muscle, during wakefulness.

RESULTS

rMT was higher in OSAS than in RLS and controls. CSP was shorter in RLS only when compared to apneic patients, whereas it was similar between OSAS and controls. OSAS subjects exhibited slightly prolonged central motor conductivity, whereas MEP amplitude was smaller in both patient groups. The ICI ratio at ISI of 3 ms was decreased in RLS patients only.

CONCLUSIONS

Distinct changes of responses at TMS were found, probably connected with the different neurophysiological substrates underlying OSAS and RLS and could not be interpreted as a mere reflection of the effects of sleep architecture alteration. TMS can be considered an additional tool for the understanding of clinical and pathophysiological aspects of sleep disorders, and possibly for the evaluation of the effect of therapy.

Pharmacological treatment of sleep disorders and its relationship with neuroplasticity

Sleep and wakefulness are regulated by complex brain circuits located in the brain stem, thalamus, subthalamus, hypothalamus, basal forebrain, and cerebral cortex. Wakefulness and NREM and REM sleep are modulated by the interactions between neurotransmitters that promote arousal and neurotransmitters that promote sleep. Various lines of evidence suggest that sleep disorders may negatively affect neuronal plasticity and cognitive function. Pharmacological treatments may alleviate these effects but may also have adverse side effects by themselves. This chapter discusses the relationship between sleep disorders, pharmacological treatments, and brain plasticity, including the treatment of insomnia, hypersomnias such as narcolepsy, restless legs syndrome (RLS), obstructive sleep apnea (OSA), and parasomnias.

Transcranial magnetic stimulation in sleep fragmentation: a model to better understand sleep disorders

OBJECTIVE

To investigate practice-dependent plasticity and cortical inhibition/excitability in good sleepers after a night of sleep fragmentation (SF), by means of transcranial magnetic stimulation (TMS).

METHODS

In basal condition (BC), after a full night of spontaneous sleep, and in fragmented condition (FC), after a fragmented night of sleep, motor evoked potential (MEP) amplitude, motor threshold (MT), silent period (SP), and intracortical inhibition were assessed. In both conditions subjects performed, also, a bimanual motor task: MEPs were recorded before and after exercise, and after rest. We evaluated the presence of post-exercise facilitation and delayed facilitation. Subjects reported their alertness level (Stanford Sleepiness Scale-SSS).

RESULTS

MT and SSS were significantly increased in SF. Instead, no significant differences for MEP amplitude or SP or intracortical inhibition were found. In both conditions post-exercise facilitation and delayed facilitation were present.

CONCLUSION

SF produces disruption of nocturnal sleep and increases daytime sleepiness. Confirmatory features of this clinical behaviour could be that in FC we observed a significant increase in SSS and in MT. SF was unable to modify cortical inhibition\excitability and\or to influence plasticity-related parameters. These results seem inconsistent with some of TMS alterations observed in sleep deprivation (SD) and restless legs syndrome (RLS). We suggest that SD and SF represent different phenomena that can depend on various networks acting on motor cortex. We speculate that alterations in cortical excitability found in RLS are intrinsically related to the underlying disease itself and are not instead directly associated with the SF present in RLS.