Equipment for Repetitive Transcranial Magnetic Stimulation

The effect of repetitive transcranial magnetic stimulation on the Hamilton Depression Rating Scale-17 criterion in patients with major depressive disorder without psychotic features: a systematic review and meta-analysis of intervention studies

AIM

In line with the publication of clinical information related to the therapeutic process of repetitive transcranial magnetic stimulation (rTMS) and the updating of relevant treatment guidelines, the present meta-analysis study was designed and conducted to determine the effect of repetitive transcranial magnetic stimulation (rTMS) on the Hamilton Depression Rating Scale-17 (HDRS-17) criterion in patients with major depressive disorder (MDD) without psychotic features.

METHODS

In this study, a systematic search was conducted in electronic databases such as PubMed [Medline], Scopus, Web of Science, Embase, Ovid, Cochrane Library, and ClinicalTrials. gov using relevant keywords. The search period in this study was from January 2000 to January 2022, which was updated until May 2023. Randomized controlled trials (RCTs) that determined the effect of repetitive transcranial magnetic stimulation (rTMS) on the Hamilton Depression Rating Scale-17 (HDRS-17) criterion in patients with major depressive disorder (MDD) without psychotic features were included in the analysis. The quality of the included RCTs was assessed using the Cochrane Risk of Bias checklist. Statistical analyses were performed using STATA (Version 16) and RevMan (Version 5).

RESULTS

Following the combination of results from 16 clinical trial studies in the present meta-analysis, it was found that the mean Hamilton Depression Rating Scale-17 (HDRS-17) in patients with major depressive disorder (MDD) decreases by an average of 1.46 units (SMD: -1.46; % 95 CI: -1.65, -1.27, I square: 45.74%; P heterogeneity: 0.56). Subgroup analysis results indicated that the standardized mean difference of Hamilton Depression Rating Scale-17 (HDRS-17) varied based on the number of treatment sessions: patients receiving 10 or fewer repetitive transcranial magnetic stimulation (rTMS) sessions showed a mean Hamilton Depression Rating Scale-17 (HDRS-17) reduction of 2.60 units (SMD: -2.60; % 95 CI: -2.86, -2.33, I square: 55.12%; P heterogeneity: 0.55), while those receiving 11 to 20 sessions showed a mean Hamilton Depression Rating Scale-17 (HDRS-17) reduction of 0.28 units (SMD: -0.28; % 95 CI: -0.65, -0.09, I square: 39.91%; P heterogeneity: 0.89).

CONCLUSION

In conclusion, our meta-analysis demonstrates the efficacy of repetitive transcranial magnetic stimulation (rTMS) in reducing depressive symptoms in major depressive disorder (MDD) patients. The complex results of subgroup analysis revealed insight on the possible benefits of a more focused strategy with fewer sessions, as well as the impact of treatment session frequency. These findings add to our understanding of repetitive transcranial magnetic stimulation (rTMS) as a therapeutic intervention for the treatment of major depressive illnesses.

A randomized controlled trial of repetitive transcranial magnetic stimulation plus donepezil vs donepezil alone for mild to moderate cognitive impairment due to small vessel cerebrovascular disease

OBJECTIVES

Small vessel cerebrovascular disease (SVCVD) accounts for 35% to 67% of vascular dementias, and may be overlooked by healthcare providers due to its insidious onset. SVCVD involves chronic cerebral ischemia and hypoperfusion, endothelial dysfunction, blood-brain barrier disruption, and interstitial fluid reflux. The purpose of this study was to investigate the clinical efficacy of repetitive transcranial magnetic stimulation (rTMS) combined with donepezil hydrochloride compared to donepezil alone in the treatment of mild-to-moderate cognitive impairment in patients with SVCVD.

MATERIAL AND METHODS

A cohort of 115 individuals with mild-to-moderate cognitive impairment due to SVCVD was purposefully selected and randomized into two groups: a test group and a control group. The test group received a combination of repetitive transcranial magnetic stimulation (rTMS) and oral donepezil hydrochloride (10 mg/day), while the control group received oral donepezil alone (10 mg/day). The Mini-Mental State Examination (MMSE) and Montreal Cognitive Assessment (MoCA) scores were evaluated in both groups prior to and following the interventions.

RESULTS

Following 6 weeks of treatment, both groups demonstrated enhancement in cognitive function. However, a statistically significant difference was observed between the test group and the control group (p < .05 on both the MMSE and the MOCA), favoring the test group.

CONCLUSIONS

Compared to donepezil alone, the combination of repetitive transcranial magnetic stimulation (rTMS) and donepezil has a significantly greater effect on enhancing cognitive function among individuals experiencing mild-to-moderate cognitive impairment resulting from SVCVD.

Transcranial magnetic stimulation set-up for small animals

Transcranial magnetic stimulation (TMS) is widely applied on humans for research and clinical purposes. TMS studies on small animals, e.g., rodents, can provide valuable knowledge of the underlying neurophysiological mechanisms. Administering TMS on small animals is, however, prone to technical difficulties, mainly due to their small head size. In this study, we aimed to develop an energy-efficient coil and a compatible experimental set-up for administering TMS on rodents. We applied a convex optimization process to develop a minimum-energy coil for TMS on rats. As the coil windings of the optimized coil extend to a wide region, we designed and manufactured a holder on which the rat lies upside down, with its head supported by the coil. We used the set-up to record TMS-electromyography, with electromyography recorded from limb muscles with intramuscular electrodes. The upside-down placement of the rat allowed the operator to easily navigate the TMS without the coil blocking their field of view. With this paradigm, we obtained consistent motor evoked potentials from all tested animals.

Repetitive transcranial magnetic stimulation during a spatial memory task leads to a decrease in brain metabolic activity

Repetitive transcranial magnetic stimulation (rTMS) is a non-invasive neuromodulation technique that is able to generate causal-based interferences between brain networks and cognitive or behavioral responses. It has been used to improve cognition in several disease models. However, although its exploration in healthy animals is essential to attribute its pure effect in learning and memory processes, studies in this regard are scarce. We aimed to evaluate whether rTMS leads to memory facilitation in healthy rats, and to explore the brain-related oxidative metabolism. We stimulated healthy Wistar rats with a high-frequency (100 Hz) and low-intensity (0.33 T) protocol during three consecutive days and evaluated the effect on the performance of an allocentric spatial reference learning and memory task. Following the last day of learning, we assessed oxidative brain metabolism through quantitative cytochrome c oxidase (CCO) histochemistry. The results showed that rTMS did not improve spatial memory in healthy rats, but the behavioral outcome was accompanied by a CCO reduction in the prefrontal, retrosplenial, parietal, and rhinal cortices, as well as in the striatum, amygdala, septum, mammillary bodies, and the hippocampus, reflecting a lower metabolic activity. In conclusion, rTMS induces a highly efficient use of brain regions associated with spatial memory.

Repetitive Transcranial Magnetic Stimulation (rTMS) Reverses the Long-term Memory Impairment and the Decrease of Hippocampal Interleukin-10 Levels, both Induced by Neuropathic Pain in Rats

Neuropathic pain (NP) is characterized by the presence of spontaneous pain, allodynia and hyperalgesia. Repetitive transcranial magnetic stimulation (rTMS) is one of neuromodulatory techniques that induces satisfactory NP relief, including that from refractory pain patients. The objective of this study was to evaluate rTMS treatment over long term memory (LTM) and hippocampal BDNF and IL-10 levels in rats submitted to a NP model. A total of 81 adult (60-days old) male Wistar rats were randomly allocated to one of the following 9 experimental groups: control, control + sham rTMS, control + rTMS, sham neuropathic pain, sham neuropathic pain + sham rTMS, sham neuropathic pain + rTMS, neuropathic pain (NP), neuropathic pain + sham rTMS and neuropathic pain + rTMS. Fourteen days after the surgery for chronic constriction injury (CCI) of the sciatic nerve, NP establishment was accomplished. Then, rats were treated with daily 5-minute sessions of rTMS for eight consecutive days. LTM was assessed by the object recognition test (ORT) twenty-four hours after the end of rTMS treatment. Biochemical assays (BDNF and IL-10 levels) were performed in hippocampus tissue homogenates. rTMS treatment reversed the reduction of the discrimination index in the ORT and the hippocampal IL-10 levels in NP rats. This result shows that rTMS reverses the impairment LTM and the increase in the hippocampal IL-10 levels, both induced by NP. Moreover, it appears to be a safe non-pharmacological therapeutic tool since it did not alter LTM and neurochemical parameters in naive animals.

rTMS induces analgesia and modulates neuroinflammation and neuroplasticity in neuropathic pain model rats

Neuropathic pain (NP) is related to the presence of hyperalgesia, allodynia, and spontaneous pain, affecting 7%-10% of the general population. Repetitive transcranial magnetic stimulation (rTMS) is applied for NP relief, especially in patients with refractory pain. As NP response to existing treatments is often insufficient, we aimed to evaluate rTMS treatment on the nociceptive response of rats submitted to an NP model and its effect on pro-and anti-neuroinflammatory cytokine and neurotrophin levels. A total of 106 adult male Wistar rats (60 days old) were divided into nine experimental groups: control, control + sham rTMS, control + rTMS, sham NP, sham neuropathic pain + sham rTMS, sham neuropathic pain + rTMS, NP, neuropathic pain + sham rTMS, and neuropathic pain + rTMS. NP establishment was achieved 14 days after the surgery to establish chronic constriction injury (CCI) of the sciatic nerve. Rats were treated with 5 min daily sessions of rTMS for eight consecutive days. Nociceptive behavior was assessed using von Frey and hot plate tests at baseline, after NP establishment, and post-treatment. Biochemical assays to assess the levels of brain-derived neurotrophic factor (BDNF), tumor necrosis factor-alpha (TNF-α), and interleukin (IL)-10, were performed in the prefrontal cortex (PFC) and spinal cord tissue homogenates. rTMS treatment promoted a partial reversal of mechanical allodynia and total reversal of thermal hyperalgesia induced by CCI. Moreover, rTMS increased the levels of BDNF, TNF-α, and IL-10 in the PFC. rTMS may be a promising tool for the treatment of NP. The alterations induced by rTMS on neurochemical parameters may have contributed to the analgesic effect presented.

Repetitive Transcranial Magnetic Stimulation Modulates Frontal and Temporal Time-Varying EEG Network in Generalized Anxiety Disorder: A Pilot Study

Generalized Anxiety Disorder (GAD) is a highly prevalent yet poorly understood chronic mental disorder. Previous studies have associated GAD with excessive activation of the right dorsolateral prefrontal cortex (DLPFC). This study aimed to investigate the effect of low-frequency repetitive transcranial magnetic stimulation (repetitive TMS, rTMS) targeting the right DLPFC on clinical symptoms and TMS-evoked time-varying brain network connectivity in patients with GAD. Eleven patients with GAD received 1 Hz rTMS treatment targeting the right DLPFC for 10 days. The severity of the clinical symptoms was evaluated using the Hamilton Anxiety Scale (HAMA) and the Hamilton Depression Scale (HAMD) at baseline, right after treatment, and at the one-month follow-up. Co-registration of single-pulse TMS (targeting the right DLPFC) and electroencephalography (TMS-EEG) was performed pre- and post-treatment in these patients and 11 healthy controls. Time-varying brain network connectivity was analyzed using the adaptive directed transfer function. The scores of HAMA and HAMD significantly decreased after low-frequency rTMS treatment, and these improvements in ratings remained at the one-month follow-up. Analyses of the time-varying EEG network in the healthy controls showed a continuous weakened connection information outflow in the left frontal and mid-temporal regions. Compared with the healthy controls, the patients with GAD showed weakened connection information outflow in the left frontal pole and the posterior temporal pole at baseline. After 10-day rTMS treatment, the network patterns showed weakened connection information outflow in the left frontal and temporal regions. The time-varying EEG network changes induced by TMS perturbation targeting right DLPFC in patients with GAD were characterized by insufficient information outflow in the left frontal and temporal regions. Low-frequency rTMS targeting the right DLPFC reversed these abnormalities and improved the clinical symptoms of GAD.