First evidence of long-term effects of transcranial pulse stimulation (TPS) on the human brain

Effects of home-based neurostimulation on outcomes after stroke: a systematic review and meta-analysis

BACKGROUND

Home-based rehabilitation is a cost-effective means of making services available for patients. The aim of this study is to determine the evidence in the literature on the effects of home-based neurostimulation in patients with stroke.

METHOD

We searched PubMED, Embase, Web of Science, Scopus, and CENTRAL for randomized controlled trials on the subject matter using keywords such as stroke, electrical stimulation and transcranial direct current stimulation. Information on participants' characteristics and mean scores on the outcomes of interest were extracted. Risks of bias and methodological quality of the included studies were assessed using Cochrane Risks of bias tool and PEDro scale respectively. The data was analyzed using both narrative and quantitative syntheses. In the quantitative synthesis, meta-analysis was carried out using random effect model analysis.

RESULT

The results showed that, home-based neurostimulation is superior to the control at improving upper limb muscle strength (SMD = 0.72, 95% CI = 0.08 to 1.32, p = 0.03), functional mobility (SMD = -0.39, 95% CI = -0.65 to 0.14, p = 0.003) and walking endurance (SMD = 0.33, 95% CI = 0.08 to 0.59, p = 0.01) post intervention; and upper limb motor function (SMD = 0.9, 95% CI = 0.10 to 1.70, p = 0.03), functional mobility (SMD = -0.30, 95% CI = -0.56 to -0.05, p = 0.02) and walking endurance (SMD = 0.33, 95% CI = 0.08 to 0.59, p = 0.01) at follow-up.

CONCLUSIONS

Home-based neurostimulation can be used to improve upper and lower limb function after stroke.

Current state of clinical ultrasound neuromodulation

Unmatched by other non-invasive brain stimulation techniques, transcranial ultrasound (TUS) offers highly focal stimulation not only on the cortical surface but also in deep brain structures. These unique attributes are invaluable in both basic and clinical research and might open new avenues for treating neurological and psychiatric diseases. Here, we provide a concise overview of the expanding volume of clinical investigations in recent years and upcoming research initiatives concerning focused ultrasound neuromodulation. Currently, clinical TUS research addresses a variety of neuropsychiatric conditions, such as pain, dementia, movement disorders, psychiatric conditions, epilepsy, disorders of consciousness, and developmental disorders. As demonstrated in sham-controlled randomized studies, TUS neuromodulation improved cognitive functions and mood, and alleviated symptoms in schizophrenia and autism. Further, preliminary uncontrolled evidence suggests relieved anxiety, enhanced motor functions in movement disorders, reduced epileptic seizure frequency, improved responsiveness in patients with minimally conscious state, as well as pain reduction after neuromodulatory TUS. While constrained by the relatively modest number of investigations, primarily consisting of uncontrolled feasibility trials with small sample sizes, TUS holds encouraging prospects for treating neuropsychiatric disorders. Larger sham-controlled randomized trials, alongside further basic research into the mechanisms of action and optimal sonication parameters, are inevitably needed to unfold the full potential of TUS neuromodulation.

A systematic review of preclinical and clinical transcranial ultrasound neuromodulation and opportunities for functional connectomics

BACKGROUND

Low-intensity transcranial ultrasound has surged forward as a non-invasive and disruptive tool for neuromodulation with applications in basic neuroscience research and the treatment of neurological and psychiatric conditions.

OBJECTIVE

To provide a comprehensive overview and update of preclinical and clinical transcranial low intensity ultrasound for neuromodulation and emphasize the emerging role of functional brain mapping to guide, better understand, and predict responses.

METHODS

A systematic review was conducted by searching the Web of Science and Scopus databases for studies on transcranial ultrasound neuromodulation, both in humans and animals.

RESULTS

187 relevant studies were identified and reviewed, including 116 preclinical and 71 clinical reports with subjects belonging to diverse cohorts. Milestones of ultrasound neuromodulation are described within an overview of the broader landscape. General neural readouts and outcome measures are discussed, potential confounds are noted, and the emerging use of functional magnetic resonance imaging is highlighted.

CONCLUSION

Ultrasound neuromodulation has emerged as a powerful tool to study and treat a range of conditions and its combination with various neural readouts has significantly advanced this platform. In particular, the use of functional magnetic resonance imaging has yielded exciting inferences into ultrasound neuromodulation and has the potential to advance our understanding of brain function, neuromodulatory mechanisms, and ultimately clinical outcomes. It is anticipated that these preclinical and clinical trials are the first of many; that transcranial low intensity focused ultrasound, particularly in combination with functional magnetic resonance imaging, has the potential to enhance treatment for a spectrum of neurological conditions.

Dynamical and individualised approach of transcranial ultrasound neuromodulation effects in non-human primates

Low-frequency transcranial ultrasound stimulation (TUS) allows to alter brain functioning with a high spatial resolution and to reach deep targets. However, the time-course of TUS effects remains largely unknown. We applied TUS on three brain targets for three different monkeys: the anterior medial prefrontal cortex, the supplementary motor area and the perigenual anterior cingulate cortex. For each, one resting-state fMRI was acquired between 30 and 150 min after TUS as well as one without stimulation (control). We captured seed-based brain connectivity changes dynamically and on an individual basis. We also assessed between individuals and between targets homogeneity and brain features that predicted TUS changes. We found that TUS prompts heterogenous functional connectivity alterations yet retain certain consistent changes; we identified 6 time-courses of changes including transient and long duration alterations; with a notable degree of accuracy we found that brain alterations could partially be predicted. Altogether, our results highlight that TUS induces heterogeneous functional connectivity alterations. On a more technical point, we also emphasize the need to consider brain changes over-time rather than just observed during a snapshot; to consider inter-individual variability since changes could be highly different from one individual to another.

Efficacy and safety of transcranial pulse stimulation in young adolescents with attention-deficit/hyperactivity disorder: a pilot, randomized, double-blind, sham-controlled trial

Background

This is the first study to evaluate the efficacy and safety of transcranial pulse stimulation (TPS) for the treatment of attention-deficit/hyperactivity disorder (ADHD) among young adolescents in Hong Kong.

Methods

This double-blind, randomized, sham-controlled trial included a TPS group and a sham TPS group, encompassing a total of 30 subjects aged 12-17 years who were diagnosed with ADHD. Baseline measurements SNAP-IV, ADHD RS-IV, CGI and executive functions (Stroop tests, Digit Span) and post-TPS evaluation were collected. Both groups were assessed at baseline, immediately after intervention, and at 1-month and 3-month follow-ups. Repeated-measures ANOVAs were used to analyze data.

Results

The TPS group exhibited a 30% reduction in the mean SNAP-IV score at postintervention that was maintained at 1- and 3-month follow-ups.

Conclusion

TPS is an effective and safe adjunct treatment for the clinical management of ADHD.

Clinical trial registration

ClinicalTrials.Gov, identifier NCT05422274.

Non-invasive sound wave brain stimulation with Transcranial Pulse Stimulation (TPS) improves neuropsychiatric symptoms in Alzheimer's disease

BACKGROUND

This study explores Transcranial Pulse Stimulation (TPS) as a potential non-invasive treatment for Alzheimer's disease (AD), focusing on its impact on cognitive functions and behavioral symptoms.

METHODS

In a prospective, one-arm open-label trial, ten patients with mild to moderate dementia due to AD were assessed using the Alzheimer's Disease Assessment Scale (ADAS-Cog), Neuropsychiatric Inventory (NPI), Pfeffer Functional Activities Questionnaire, and Zarit Caregiver Burden Interview. Assessments occurred at 30- and 90-days post-treatment. The TPS protocol consisted of 10 sessions over five weeks, using the Neurolith® device to deliver 6000 focused shockwave pulses at 0.25 mJ/mm2 and a frequency of 4 Hz.

RESULTS

TPS significantly reduced neuropsychiatric symptoms, with NPI scores decreasing by 23.9 points (95% CI: -39.19 to -8.61, p = 0.0042) after 30 days, and by 18.9 points (95% CI: -33.49 to -2.91, p = 0.022) after 90 days. These changes had large effect sizes (Cohen's dz = 1.43 and dz = 0.94, respectively). A decreasing trend was observed in the ADAS-Cog score (-3.6, 95% CI: -7.18 to 0.00, p = 0.05) after 90 days, indicating a potential reduction in cognitive impairment, though not statistically significant.

CONCLUSION

The preliminary results indicate that TPS treatment leads to significant improvement in neuropsychiatric symptoms in AD patients, showing promise as a therapeutic approach for AD. Further research is needed to fully establish its effectiveness, especially concerning cognitive functions.

Novel ultrasound neuromodulation therapy with transcranial pulse stimulation (TPS) in Parkinson's disease: a first retrospective analysis

BACKGROUND

Transcranial Pulse Stimulation (TPS) has been recently introduced as a novel ultrasound neuromodulation therapy with the potential to stimulate the human brain in a focal and targeted manner. Here, we present a first retrospective analysis of TPS as an add-on therapy for Parkinson's disease (PD), focusing on feasibility, safety, and clinical effects. We also discuss the placebo response in non-invasive brain stimulation studies as an important context.

METHODS

This retrospective clinical data analysis included 20 PD patients who received ten sessions of TPS intervention focused on the individual motor network. Safety evaluations were conducted throughout the intervention period. We analyzed changes in motor symptoms before and after TPS treatment using Unified Parkinson's Disease Rating Scale part III (UPDRS-III).

RESULTS

We found significant improvement in UPDRS-III scores after treatment compared to baseline (pre-TPS: 16.70 ± 8.85, post-TPS: 12.95 ± 8.55; p < 0.001; Cohen's d = 1.38). Adverse events monitoring revealed no major side effects.

CONCLUSION

These preliminary findings suggest that TPS can further improve motor symptoms in PD patients already on optimized standard therapy. Findings have to be evaluated in context with the current literature on placebo effects.

Transcranial pulse stimulation in Alzheimer's disease

BACKGROUND

Transcranial pulse stimulation (TPS) is a novel noninvasive ultrasonic brain stimulation that can increase cortical and corticospinal excitability, induce neuroplasticity, and increase functional connectivity within the brain. Several trials have confirmed its potential in treating Alzheimer's disease (AD).

OBJECTIVE

To investigate the effect and safety of TPS on AD.

DESIGN

A systematic review.

METHODS

PubMed, Embase via Ovid, Web of Science, Cochrane Library, CNKI (China National Knowledge Infrastructure), VIP (China Science and Technology Journal Database), and WanFang were searched from inception to April 1, 2023. Study selection, data extraction, and quality evaluation of the studies were conducted by two reviewers independently, with any controversy resolved by consensus. The Methodological Index for Nonrandomized Studies was used to assess the risk of bias.

RESULTS

Five studies were included in this review, with a total of 99 patients with AD. For cognitive performance, TPS significantly improved the scores of the CERAD (Consortium to Establish a Registry for Alzheimer's Disease) test battery, Alzheimer's Disease Assessment Scale (cognitive), Montreal Cognitive Assessment, and Mini-Mental Status Examination. For depressive symptoms, TPS significantly reduced the scores of the Alzheimer's Disease Assessment Scale (affective), Geriatric Depression Score, and Beck Depression Inventory. By functional magnetic resonance imaging, studies have shown that TPS improved cognitive performance in AD patients by increasing functional connectivity in the hippocampus, parahippocampal cortex, precuneus, and parietal cortex, and activating cortical activity in the bilateral hippocampus. TPS alleviated depressive symptoms in AD patients by decreasing functional connectivity between the ventromedial network (left frontal orbital cortex) and the salience network (right anterior insula). Adverse events in this review, including headache, worsening mood, jaw pain, nausea, and drowsiness, were reversible and lasted no longer than 1 day. No serious adverse events or complications were observed.

CONCLUSIONS

TPS is promising in improving cognitive performance and reducing depressive symptoms in patients with AD. TPS may be a safe adjunct therapy in the treatment of AD. However, these findings lacked a sham control and were limited by the small sample size of the included studies. Further research may be needed to better explore the potential of TPS.

PATIENT AND PUBLIC INVOLVEMENT

Patients and the public were not involved in this study.

Decoding motor plans using a closed-loop ultrasonic brain-machine interface

Brain-machine interfaces (BMIs) enable people living with chronic paralysis to control computers, robots and more with nothing but thought. Existing BMIs have trade-offs across invasiveness, performance, spatial coverage and spatiotemporal resolution. Functional ultrasound (fUS) neuroimaging is an emerging technology that balances these attributes and may complement existing BMI recording technologies. In this study, we use fUS to demonstrate a successful implementation of a closed-loop ultrasonic BMI. We streamed fUS data from the posterior parietal cortex of two rhesus macaque monkeys while they performed eye and hand movements. After training, the monkeys controlled up to eight movement directions using the BMI. We also developed a method for pretraining the BMI using data from previous sessions. This enabled immediate control on subsequent days, even those that occurred months apart, without requiring extensive recalibration. These findings establish the feasibility of ultrasonic BMIs, paving the way for a new class of less-invasive (epidural) interfaces that generalize across extended time periods and promise to restore function to people with neurological impairments.

The effectiveness and safety of low-intensity transcranial ultrasound stimulation: A systematic review of human and animal studies

Low-intensity transcranial ultrasound stimulation (LITUS) is a novel non-invasive neuromodulation technique. We conducted a systematic review to evaluate current evidence on the efficacy and safety of LITUS neuromodulation. Five databases were searched from inception to May 31, 2023. Randomized controlled human trials and controlled animal studies were included. The neuromodulation effects of LITUS on clinical or pre-clinical, neurophysiological, neuroimaging, histological and biochemical outcomes, and adverse events were summarized. In total, 11 human studies and 44 animal studies were identified. LITUS demonstrated therapeutic efficacy in neurological disorders, psychiatric disorders, pain, sleep disorders and hypertension. LITUS-related changes in neuronal structure and cortical activity were found. From histological and biochemical perspectives, prominent findings included suppressing the inflammatory response and facilitating neurogenesis. No adverse effects were reported in controlled animal studies included in our review, while reversible headache, nausea, and vomiting were reported in a few human subjects. Overall, LITUS alleviates various symptoms and modulates associated brain circuits without major side effects. Future research needs to establish a solid therapeutic framework for LITUS.

A Bibliometric Analysis for Low-Intensity Ultrasound Study Over the Past Three Decades

Low-intensity ultrasound (LI-US) is a non-invasive stimulation technique that has emerged in recent years and has been shown to have positive effects on neuromodulation, fracture healing, inflammation improvement, and metabolic regulation. This study reports the conclusions of a bibliometric analysis of LI-US. Input data for the period between 1995 and 2022, including 7209 related articles in the field of LI-US, were collected from the core library of the Web of Science (WOS) database. Using these data, a set of bibliometric indicators was obtained to gain knowledge on different aspects: global production, research areas, and sources analysis, contributions of countries and institutions, author analysis, citation analysis, and keyword analysis. This study combined the data analysis capabilities provided by the WOS database, making use of two bibliometric software tools: R software and VOS viewer to achieve analysis and data exploration visualization, and predicted the further development trends of LI-US. It turns out that the United States and China are co-leaders while Zhang ZG is the most significant author in LI-US. In the future, the hot spots of LI-US will continue to focus on parameter research, mechanism discussion, safety regulations, and neuromodulation applications.

The Emergence of Functional Ultrasound for Noninvasive Brain-Computer Interface

A noninvasive brain-computer interface is a central task in the comprehensive analysis and understanding of the brain and is an important challenge in international brain-science research. Current implanted brain-computer interfaces are cranial and invasive, which considerably limits their applications. The development of new noninvasive reading and writing technologies will advance substantial innovations and breakthroughs in the field of brain-computer interfaces. Here, we review the theory and development of the ultrasound brain functional imaging and its applications. Furthermore, we introduce latest advancements in ultrasound brain modulation and its applications in rodents, primates, and human; its mechanism and closed-loop ultrasound neuromodulation based on electroencephalograph are also presented. Finally, high-frequency acoustic noninvasive brain-computer interface is prospected based on ultrasound super-resolution imaging and acoustic tweezers.

Ultrasound Neuromodulation as a New Brain Therapy

Within the last decade, ultrasound has been "rediscovered" as a technique for brain therapies. Modern technologies allow focusing ultrasound through the human skull for highly focal tissue ablation, clinical neuromodulatory brain stimulation, and targeted focal blood-brain-barrier opening. This article gives an overview on the state-of-the-art of the most recent application: ultrasound neuromodulation as a new brain therapy. Although research centers have existed for decades, the first treatment centers were not established until 2020, and clinical applications are spreading rapidly.

Evaluating the efficacy and safety of transcranial pulse stimulation on adolescents with attention deficit hyperactivity disorder: Study protocol of a pilot randomized, double-blind, sham-controlled trial

Background

Traditional treatment alone might not effectively control the severity of attention deficit hyperactivity disorder (ADHD) symptoms. Transcranial pulse stimulation (TPS) is a non-invasive brain stimulation (NIBS) technology used on older adults with mild neurocognitive disorders and adults with major depressive disorder. However, there has been no study conducted on young adolescents with ADHD. This will be the first nationwide study evaluating the efficacy and safety of TPS in the treatment of ADHD among young adolescents in Hong Kong.

Methods

This study proposes a double-blinded, randomized, sham-controlled trial including TPS as an intervention group and a sham TPS group. Both groups will be measured at baseline (T1), immediately after the intervention (T2), and at the 1-month (T3) and 3-month follow-ups (T4).

Recruitment

A total of 30 subjects aged between 12 and 17 years, diagnosed with attention deficit hyperactivity disorder (ADHD), will be recruited in this study. All subjects will be computer randomized into either the intervention group or the sham TPS group on a 1:1 ratio.

Intervention

All subjects in each group will have to undertake functional MRI (fMRI) before and after six 30-min TPS sessions, which will be completed in 2 weeks' time.

Outcomes

Baseline measurements and post-TPS evaluation of the ADHD symptoms and executive functions will also be conducted on all participants. The 1- and 3-month follow-up periods will be used to assess the long-term sustainability of the TPS intervention. For statistical analysis, ANOVA with repeated measures will be used to analyze data. Missing data were managed by multiple imputations. The level of significance will be set to p &lt; 0.05.

Significance of the study

Results emerging from this study will generate new knowledge to ascertain whether TPS can be used as a top-on treatment for ADHD.

Clinical trial registration

clinicaltrails.gov, identifier: NCT05422274.

Noninvasive Brain Stimulation for Neurorehabilitation in Post-Stroke Patients

Characterized by high morbidity, mortality, and disability, stroke usually causes symptoms of cerebral hypoxia due to a sudden blockage or rupture of brain vessels, and it seriously threatens human life and health. Rehabilitation is the essential treatment for post-stroke patients suffering from functional impairments, through which hemiparesis, aphasia, dysphagia, unilateral neglect, depression, and cognitive dysfunction can be restored to various degrees. Noninvasive brain stimulation (NIBS) is a popular neuromodulatory technology of rehabilitation focusing on the local cerebral cortex, which can improve clinical functions by regulating the excitability of corresponding neurons. Increasing evidence has been obtained from the clinical application of NIBS, especially repetitive transcranial magnetic stimulation (rTMS) and transcranial direct current stimulation (tDCS). However, without a standardized protocol, existing studies on NIBS show a wide variation in terms of stimulation site, frequency, intensity, dosage, and other parameters. Its application for neurorehabilitation in post-stroke patients is still limited. With advances in neuronavigation technologies, functional near-infrared spectroscopy, and functional MRI, specific brain regions can be precisely located for stimulation. On the basis of our further understanding on neural circuits, neuromodulation in post-stroke rehabilitation has also evolved from single-target stimulation to co-stimulation of two or more targets, even circuits and the network. The present study aims to review the findings of current research, discuss future directions of NIBS application, and finally promote the use of NIBS in post-stroke rehabilitation.

Low-intensity pulsed ultrasound triggers a beneficial neuromodulation in dementia mice with chronic cerebral hypoperfusion via activation of hippocampal Fndc5/irisin signaling

BACKGROUND

Exercise-related signaling Fndc5/irisin expresses in brain and acts as a crucial regulator of cognitive function, but its detailed roles in vascular dementia (VaD) are still unclear. Low intensity pulsed ultrasound (LIPUS), a novel brain stimulation approach, has been suggested as a promising treatment for dementia. Here, we investigated the activity and efficacy of Fndc5/irisin in experimental VaD, further explored whether the potential effects of LIPUS on VaD is related to Fndc5/irisin.

METHODS

Mouse model of VaD was established with chronic cerebral hypoperfusion (CCH) using bilateral common carotid arteries stenosis (BCAS). Transcranial LIPUS was applied 24 h after BCAS and subsequently daily with a stimulation time of 5 min at an ultrasound pressure of 0.51 MPa for a period of 28 days. The levels of Fndc5/irisin in different brain regions, the hippocampal long-term potentiation and anti-inflammatory cytokines were investigated at day 28 after cognitive evaluation. Global Fndc5 knock-out (F5KO), forced expression or knockdown of Fndc5, and recombinant irisin application were respectively employed for mechanism exploration. The neuron dendritic spine density and astrocyte phenotype were detected in vitro.

RESULTS

Fndc5/irisin was reduced in hippocampus of BCAS mice, forced expression hippocampal Fndc5 or bilateral intrahippocampal injection of recombinant irisin respectively improved hippocampal synaptic plasticity or inflammatory microenvironment, and then alleviated the cognitive impairments. LIPUS existed a positive efficacy in enhancing hippocampal Fndc5/irisin in BCAS mice, thus triggering a beneficial neuromodulation for VaD protection. Importantly, the neurorestorative effects of LIPUS on CCH-induced damages were totally reversed by knockdown the expression of hippocampal Fndc5 in WT mice, or in F5KO mice. Moreover, Fndc5 mediated the upregulated effects of LIPUS on spine density as well as irisin secretion of hippocampal neurons. The neuron-secreted irisin further drove reactive astrocytes to a neuroprotective phenotype.

CONCLUSION

LIPUS induced a neurorestorative stimulation against VaD may be through upregulation of the hippocampal Fndc5/irisin levels. Hippocampal Fndc5/irisin signaling might be a promising strategic target for VaD.

Safety of Clinical Ultrasound Neuromodulation

Transcranial ultrasound holds much potential as a safe, non-invasive modality for navigated neuromodulation, with low-intensity focused ultrasound (FUS) and transcranial pulse stimulation (TPS) representing the two main modalities. While neuroscientific and preclinical applications have received much interest, clinical applications are still relatively scarce. For safety considerations, the current literature is largely based on guidelines for ultrasound imaging that uses various physical parameters to describe the ultrasound pulse form and expected bioeffects. However, the safety situation for neuromodulation is inherently different. This article provides an overview of relevant ultrasound parameters with a focus on bioeffects relevant for safe clinical applications. Further, a retrospective analysis of safety data for clinical TPS applications in patients is presented.

Retrospective real-world pilot data on transcranial pulse stimulation in mild to severe Alzheimer's patients

Introduction

Transcranial pulse stimulation (TPS) is a non-invasive neuromodulation therapy that uses short, repetitive shockwaves through a neuro-navigated device. Current research suggests that these pulses lead to a wide range of vascular, metabolic, and neurotrophic changes. This relatively new CE-marked treatment provided first promising results in a clinical pilot study for improving cognition in mild-to-moderate Alzheimer's. Data from other centers is lacking, so here we analyzed safety and pilot real-world short-term results of TPS from the first center in Germany. To gain information about effects in different stages, patients with not only mild but also moderate-to-severe Alzheimer's were analyzed.

Methods

A total of 11 patients were retrospectively examined for cognitive and emotional function before and after the first stimulation series. The effect was assessed using several neuropsychological tests [Alzheimer's Disease Assessment Scale (ADAS), including the ADAS cognitive score (ADAS Cog) and ADAS affective scores, Mini-Mental Status Examination (MMSE), and Montreal Cognitive Assessment (MoCA)] including in comparison between the groups of mild-to-severe patients. Moreover, subjective improvement of symptom severity, potential effects on depressive symptoms, and side effects were analyzed using Numeric Rating Scales (NRS).

Results

Side effects were rare (in 4% of sessions) with moderate subjective severity and only transient. Patients significantly improved in the ADAS and ADAS Cog, while there was no significant effect in MMSE and MoCA. Patients' self-reported symptom severity improved significantly. The depressive symptoms measured in an ADAS subscale also improved significantly. Statistical data analyses revealed no significant correlation of clinical improvement with baseline symptom severity.

Conclusion

TPS might be a safe and promising add-on therapy for Alzheimer's, even for moderate-to-severe patients. More research on long-term effects in patients as well as studies with sham control groups is needed. Moreover, translational research on the mechanisms of action and effects on cerebral network physiology will be needed to understand this new neuromodulation technique.

Functional Specificity of TPS Brain Stimulation Effects in Patients with Alzheimer's Disease: A Follow-up fMRI Analysis

Introduction

Transcranial pulse stimulation (TPS) has been recently introduced as a novel clinical brain stimulation technique based on highly focused ultrasound pressure pulses. In a first pilot study on clinical effects of navigated and focused ultrasound neuromodulation, a dichotomy of functional effects was found: patients with Alzheimer’s disease improved cognition and language but deteriorated with visuo-constructive functions.

Methods

We analyzed changes in functional connectivity measured with functional magnetic resonance imaging (fMRI) using graph analysis of a visuo-constructive network in 18 patients with Alzheimer’s disease. We calculated the network’s global efficiency and tested for correlation with visuo-constructive test scores to explain this dichotomy.

Results

Important visuo-constructive network nodes were not stimulated in the pilot setting and correspondingly global efficiency of a visuo-constructive network was decreased after TPS therapy, compatible with a natural progress of the disease. A correlation between visuo-constructive scores and changes in global efficiency was found.

Conclusion

Results argue for a high functional specificity of ultrasound-based neuromodulation with TPS.

Over the last decade, there has been growing interest in ultrasound-based non-invasive brain stimulation techniques in neuroscience and as a potential therapy for disorders of the brain. Transcranial pulse stimulation (TPS) has been introduced as an innovative neuromodulation technique, applying ultrashort pressure pulses through the skull into neural tissue with 3D navigation in real time. In the first clinical pilot study, patients suffering from Alzheimer’s disease showed an increase in memory and language functions for up to 3 months after TPS therapy. However, visuo-constructive capacities (e.g., copying a geometrical figure) worsened. Notably, brain areas relevant for such processes had been left out during stimulation. This begged the question whether the brain areas that were targeted for brain stimulation as well as functional changes could explain this diverse response pattern. We therefore analyzed functional magnetic resonance data from patients. Specifically, we compared graph theoretical functional connectivity measures in a visuo-constructive network before and after TPS therapy. We found a decrease in connectivity in a central network node, which also correlated with visuo-constructive test scores. This deterioration is likely associated with normal disease progression. Together with the already reported improvement in global cognitive functions, these results argue for a functional specific effect of TPS.

Human Ultrasound Neuromodulation: State of the Art

The first human applications of ultrasound in medicine date back to 1939, when Reimar Pohlmann (Berlin, Germany) published data on therapy of neuralgia with ultrasound [...]