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Background: We aimed at evaluating the amplitude changes of the motor evoked potentials (MEPs) induced by of low-frequency (LF) repetitive transcranial magnetic stimulation (rTMS) over the primary motor cortex (M1) in10 patients with primary insomnia (PI) and in 10 age-matched healthy controls., Methods: Median peak-to-peak MEP amplitudes were assessed in all subjects at three times: at baseline (T 0 ), after the first train of a single rTMS session (T 1 ), and after the whole rTMS procedure (T 2 ). This consists of 20 trains of 1 Hz stimulation with 50 stimuli per train and an intertrain interval of 30 s., Results: Resting motor threshold (RMT) and MEPs amplitude did not differ between the two groups at T 0 . A reduction of MEP size was observed at both T 1 and T 2 in all subjects, but this was significantly less pronounced in patients than in control subjects., Conclusions: The lack of MEP inhibition reflects an altered response to LF rTMS in patients with PI. These rTMS findings are indicative of an altered cortical plasticity in inhibitory circuits within M1 in PI. Subjects with PI exhibited an impairment of the LTD-like mechanisms induced by inhibitory rTMS, thus providing further support to the involvement of GABA neurotransmission in the pathophysiology of PI., (Copyright © 2020 Elsevier B.V. All rights reserved.)

In this review, we aimed at identifying the studies that have employed repetitive transcranial magnetic stimulation (rTMS) in patients with sleep disorders. Low-frequency (LF) rTMS stimulating the right dorsolateral prefrontal cortex (DLPFC) or the posterior parietal cortex (PPC) was found to be effective to reduce cortical hyperexcitability and improve the sleep quality in subjects with chronic primary insomnia (PI). Both high-frequency (HF) and LF rTMS applied over the primary motor cortex or the supplementary motor cortex seem to have transient beneficial effects in patients with restless legs syndrome (RLS). Stimulation of upper airway muscles during sleep by isolated TMS and by rTMS twitch can improve airflow dynamics in obstructive sleep apnea syndrome (OSAS) patients without arousal. A single case report study indicates that HF rTMS over the left DLPFC might represent an alternative choice for symptom control in narcoleptic patients with cataplexy, and a pilot study also raises the possibility of therapeutic benefits from rTMS in patients with sleep bruxism. rTMS may also exert intrinsic effects on hypersomnia in depressed adolescents. In conclusion, rTMS may contribute to the development of new non-pharmacological therapeutic options for several sleep disorders. rTMS might be useful as therapeutical tool in particular in patients with PI, RLS, OSAS and narcolepsy, while its effect in other sleep disorders (ie, parasomnias) has not yet been explored. rTMS integrated with clinical, sleep-related, and neuroimaging data may represent an effective tool in modulating cortical excitability and inducing short-term synaptic plasticity. Further studies with larger patient samples, repeated sessions, an optimized rTMS setup, and clinical follow-up warranted to verify the initial findings, and to expand clinical and research interest towards neuromodulation in the different sleep disorders., (Copyright © 2020 Elsevier B.V. All rights reserved.)

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., (Copyright © 2019 Elsevier B.V. All rights reserved.)

Background/objective: Odor identification and discrimination are reduced in subjects with obstructive sleep apnea syndrome (OSAS), but the pathophysiology of the olfactory dysfunction in OSAS is still poorly understood. Experimental evidence suggests that olfactory impairment could be related to central cholinergic dysfunction. Short latency afferent inhibition (SAI) is a paired-pulse transcranial magnetic stimulation (TMS) protocol that gives the opportunity to test an inhibitory cholinergic circuit in the human cerebral motor cortex. The objective of the study was to assess the cholinergic function, as measured by SAI, in OSAS patients with olfactory impairment., Methods: We applied SAI technique in 20 patients with OSAS and in 20 healthy control subjects; SAI values were correlated with the Sniffin' Sticks olfactory test results., Results: SAI was reduced in OSAS patients when compared with control subjects. We also found a strong negative correlation between olfactory parameters and SAI., Conclusions: These findings suggest that cholinergic dysfunction is a robust determinant of hyposmia also in OSAS patients. Reduced SAI values and presence of olfactory impairment might indicate an increased risk of cognitive decline in patients with OSAS., (Copyright © 2017 Elsevier B.V. All rights reserved.)