Ultrasound Blood-Brain Barrier Opening and Aducanumab in Alzheimer's Disease.

Antiamyloid antibodies have been used to reduce cerebral amyloid-beta (Aß) load in patients with Alzheimer's disease. We applied focused ultrasound with each of six monthly aducanumab infusions to temporarily open the blood-brain barrier with the goal of enhancing amyloid removal in selected brain regions in three participants over a period of 6 months. The reduction in the level of Aß was numerically greater in regions treated with focused ultrasound than in the homologous regions in the contralateral hemisphere that were not treated with focused ultrasound, as measured by fluorine-18 florbetaben positron-emission tomography. Cognitive tests and safety evaluations were conducted over a period of 30 to 180 days after treatment. (Funded by the Harry T. Mangurian, Jr. Foundation and the West Virginia University Rockefeller Neuroscience Institute.).

Ultrasound-mediated blood-brain barrier opening uncovers an intracerebral perivenous fluid network in persons with Alzheimer's disease.

BACKGROUND: Focused ultrasound (FUS)-mediated blood-brain barrier (BBB) opening is under investigation as a therapeutic modality for neurodegeneration, yet its effects in humans are incompletely understood. Here, we assessed physiologic responses to FUS administered in multifocal brain sites of persons with Alzheimer's disease (AD). METHODS: At a tertiary neuroscience institute, eight participants with AD (mean age 65, 38% F) enrolled in a phase 2 clinical trial underwent three successive targeted BBB opening procedures at 2 week intervals using a 220 kHz FUS transducer in combination with systemically administered microbubbles. In all, 77 treatment sites were evaluated and encompassed hippocampal, frontal, and parietal brain regions. Post-FUS imaging changes, including susceptibility effects and spatiotemporal gadolinium-based contrast agent enhancement patterns, were analyzed using serial 3.0-Tesla MRI. RESULTS: Post-FUS MRI revealed expected intraparenchymal contrast extravasation due to BBB opening at all targeted brain sites. Immediately upon BBB opening, hyperconcentration of intravenously-administered contrast tracer was consistently observed around intracerebral veins. Following BBB closure, within 24-48 h of FUS intervention, permeabilization of intraparenchymal veins was observed and persisted for up to one week. Notably, extraparenchymal meningeal venous permeabilization and associated CSF effusions were also elicited and persisted up to 11 days post FUS treatment, prior to complete spontaneous resolution in all participants. Mild susceptibility effects were detected, however no overt intracranial hemorrhage or other serious adverse effects occurred in any participant. CONCLUSIONS: FUS-mediated BBB opening is safely and reproducibly achieved in multifocal brain regions of persons with AD. Post-FUS tracer enhancement phenomena suggest the existence of a brain-wide perivenous fluid efflux pathway in humans and demonstrate reactive physiological changes involving these conduit spaces in the delayed, subacute phase following BBB disruption. The delayed reactive venous and perivenous changes are consistent with a dynamic, zonal exudative response to upstream capillary manipulation. Further preclinical and clinical investigations of these FUS-related imaging phenomena and of intracerebral perivenous compartment changes are needed to elucidate physiology of this pathway as well as biological effects of FUS administered with and without adjuvant neurotherapeutics. TRIAL REGISTRATION: ClinicalTrials.gov identifier: NCT03671889, registered 9/14/2018.

Focused ultrasound-mediated blood-brain barrier opening in Alzheimer's disease: long-term safety, imaging, and cognitive outcomes.

OBJECTIVE: MRI-guided low-intensity focused ultrasound (FUS) has been shown to reversibly open the blood-brain barrier (BBB), with the potential to deliver therapeutic agents noninvasively to target brain regions in patients with Alzheimer's disease (AD) and other neurodegenerative conditions. Previously, the authors reported the short-term safety and feasibility of FUS BBB opening of the hippocampus and entorhinal cortex (EC) in patients with AD. Given the need to treat larger brain regions beyond the hippocampus and EC, brain volumes and locations treated with FUS have now expanded. To evaluate any potential adverse consequences of BBB opening on disease progression, the authors report safety, imaging, and clinical outcomes among participants with mild AD at 6-12 months after FUS treatment targeted to the hippocampus, frontal lobe, and parietal lobe. METHODS: In this open-label trial, participants with mild AD underwent MRI-guided FUS sonication to open the BBB in ß-amyloid positive regions of the hippocampus, EC, frontal lobe, and parietal lobe. Participants underwent 3 separate FUS treatment sessions performed 2 weeks apart. Outcome assessments included safety, imaging, neurological, cognitive, and florbetaben ß-amyloid PET. RESULTS: Ten participants (range 55-76 years old) completed 30 separate FUS treatments at 2 participating institutions, with 6-12 months of follow-up. All participants had immediate BBB opening after FUS and BBB closure within 24-48 hours. All FUS treatments were well tolerated, with no serious adverse events related to the procedure. All 10 participants had a minimum of 6 months of follow-up, and 7 participants had a follow-up out to 1 year. Changes in the Alzheimer's Disease Assessment Scale-cognitive and Mini-Mental State Examination scores were comparable to those in controls from the Alzheimer's Disease Neuroimaging Initiative. PET scans demonstrated an average ß-amyloid plaque of 14% in the Centiloid scale in the FUS-treated regions. CONCLUSIONS: This study is the largest cohort of participants with mild AD who received FUS treatment, and has the longest follow-up to date. Safety was demonstrated in conjunction with reversible and repeated BBB opening in multiple cortical and deep brain locations, with a concomitant reduction of ß-amyloid. There was no apparent cognitive worsening beyond expectations up to 1 year after FUS treatment, suggesting that the BBB opening treatment in multiple brain regions did not adversely influence AD progression. Further studies are needed to determine the clinical significance of these findings. FUS offers a unique opportunity to decrease amyloid plaque burden as well as the potential to deliver targeted therapeutics to multiple brain regions in patients with neurodegenerative disorders.

Non-invasive vagus nerve stimulation for prevention of migraine: The multicenter, randomized, double-blind, sham-controlled PREMIUM II trial.

AIM: Evaluate the efficacy and safety of non-invasive vagus nerve stimulation for migraine prevention. METHODS: After completing a 4-week diary run-in period, adults who had migraine with or without aura were randomly assigned to receive active non-invasive vagus nerve stimulation or sham therapy during a 12-week double-blind period. RESULTS: Of 336 enrolled participants, 113 (active, n = 56; sham, n = 57) completed ≥70 days of the double-blind period and were ≥66% adherent with treatment, comprising the prespecified modified intention-to-treat population. The COVID-19 pandemic led to early trial termination, and the population was ∼60% smaller than the statistical target for full power. Mean reduction in monthly migraine days (primary endpoint) was 3.12 for the active group and 2.29 days for the sham group (difference, -0.83; p = 0.2329). Responder rate (i.e. the percentage of participants with a ≥50% reduction in migraine days) was greater in the active group (44.87%) than the sham group (26.81%; p = 0.0481). Prespecified subgroup analysis suggested that participants with aura responded preferentially. No serious device-related adverse events were reported. CONCLUSIONS: These results suggest clinical utility of non-invasive vagus nerve stimulation for migraine prevention, particularly for patients who have migraine with aura, and reinforce the well-established safety and tolerability profile of this therapy.Trial Registration: ClinicalTrials.gov (NCT03716505).

Prevalence of Occipital Neuralgia at a Community Hospital-based Headache Clinic.

BACKGROUND: Occipital neuralgia (ON) is a paroxysmal disorder involving lancinating pain that originates in the neck or skull base with superior radiation toward the apex. ON more commonly occurs in patients with other coexisting headache disorders. There are limited data regarding the prevalence of ON. This study aims to demonstrate the prevalence of ON in a community hospital-based headache clinic. METHODS: This IRB-approved retrospective study was conducted at the Cambridge Health Alliance Headache Clinic. Medical records of patients presenting with headache as a chief complaint were reviewed from January 2010 to September 2015. RESULTS: Of 800 study patients, 81% were females (n = 648). A total of 195 patients were diagnosed with ON, and 146 patients had a positive occipital Tinel sign on examination. Isolated ON was present in 15.38% (n = 30) of patients. Multiple regression analysis demonstrated that the odds of ON were higher in patients with chronic migraine vs episodic migraine (adjusted odds ratio = 2.190 [95% confidence interval: 1.364-3.515]), even when adjusted for significant covariates. CONCLUSION: ON occurred in nearly 25% of patients presenting with a chief complaint of headache to a community hospital-based headache clinic. Among patients with ON, 15% presented with ON as the chief complaint without another coexisting headache disorder. As such, up to 85% of ON cases occurred in patients having an additional headache type. Approximately 75% of patients with ON had a positive occipital Tinel sign on examination. Elevated body mass index, higher age at presentation, and chronic migraine increased the odds of having ON. Undiagnosed or inadequate treatment of ON can increase the frequency and intensity of other comorbid headache disorders.

Blood-Brain Barrier Opening with MRI-guided Focused Ultrasound Elicits Meningeal Venous Permeability in Humans with Early Alzheimer Disease.

Background Opening of the blood-brain barrier (BBB) induced with MRI-guided focused ultrasound has been shown in experimental animal models to reduce amyloid-ß plaque burden, improve memory performance, and facilitate delivery of therapeutic agents to the brain. However, physiologic effects of this procedure in humans with Alzheimer disease (AD) require further investigation. Purpose To assess imaging effects of focused ultrasound-induced BBB opening in the hippocampus of human participants with early AD and to evaluate fluid flow patterns after BBB opening by using serial contrast-enhanced MRI. Materials and Methods Study participants with early AD recruited to a Health Insurance Portability and Accountability Act-compliant, prospective, ongoing phase II clinical trial (ClinicalTrials.gov identifier, NCT03671889) underwent three separate focused ultrasound-induced BBB opening procedures that used a 220-kHz transducer with a concomitant intravenous microbubble contrast agent administered at 2-week intervals targeting the hippocampus and entorhinal cortex between October 2018 and May 2019. Posttreatment effects and gadolinium-based contrast agent enhancement patterns were evaluated by using 3.0-T MRI. Results Three women (aged 61, 72, and 73 years) consecutively enrolled in the trial successfully completed repeated focused ultrasound-induced BBB opening of the hippocampus and entorhinal cortex. Postprocedure contrast enhancement was clearly identified within the targeted brain volumes, indicating immediate spatially precise BBB opening. Parenchymal enhancement resolved within 24 hours after all treatments, confirming BBB closure. Transient perivenous enhancement was consistently observed during the acute phase after BBB opening. Notably, contrast enhancement reappeared in the perivenular regions after BBB closure. This imaging marker is consistent with blood-meningeal barrier permeability and persisted for 24-48 hours before spontaneous resolution. No evidence of intracranial hemorrhage or other adverse effect was identified. Conclusion MRI-guided focused ultrasound-induced blood-brain barrier opening was safely performed in the hippocampi of three participants with Alzheimer disease without any adverse effects. Posttreatment MRI reveals a unique spatiotemporal contrast enhancement pattern that suggests a perivenular immunologic healing response downstream from targeted sites. © RSNA, 2021 Online supplemental material is available for this article. See also the editorial by Klibanov in this issue.

ß-Amyloid Plaque Reduction in the Hippocampus After Focused Ultrasound-Induced Blood-Brain Barrier Opening in Alzheimer's Disease.

The blood-brain barrier (BBB) limits therapeutic delivery in Alzheimer's disease (AD) and other neurological disorders. Animal models have demonstrated safe BBB opening and reduction in ß-amyloid plaque with focused ultrasound (FUS). We recently demonstrated the feasibility, safety, and reversibility of FUS-induced BBB opening in the hippocampus and entorhinal cortex in six participants with early AD. We now report the effect of BBB opening with FUS treatment on ß-amyloid plaque. Six participants underwent 18F-Florbetaben PET scan at baseline and 1 week after the completion of the third FUS treatment (60 days interval). PET analysis comparing the hippocampus and entorhinal cortex in the treated and untreated hemispheres revealed a decrease in the ratio of 18F-Florbetaben ligand binding. The standard uptake value ratios (SUVr) reduction ranged from 2.7% to 10% with an average of 5.05% (±2.76) suggesting a decrease in ß-amyloid plaque.

Novel TMS for Stroke and Depression (NoTSAD): Accelerated Repetitive Transcranial Magnetic Stimulation as a Safe and Effective Treatment for Post-stroke Depression.

Background: Post-stroke depression (PSD) affects up to 50% of stroke survivors, reducing quality of life, and increasing adverse outcomes. Conventional therapies to treat PSD may not be effective for some patients. Repetitive transcranial magnetic stimulation (rTMS) is well-established as an effective treatment for Major Depressive Disorder (MDD) and some small trials have shown that rTMS may be effective for chronic PSD; however, no trials have evaluated an accelerated rTMS protocol in a subacute stroke population. We hypothesized that an accelerated rTMS protocol will be a safe and viable option to treat PSD symptoms. Methods: Patients (N = 6) with radiographic evidence of ischemic stroke within the last 2 weeks to 6 months with Hamilton Depression Rating Scale (HAMD-17) scores >7 were recruited for an open label study using an accelerated rTMS protocol as follows: High-frequency (20-Hz) rTMS at 110% resting motor threshold (RMT) was applied to the left dorsolateral prefrontal cortex (DLPFC) during five sessions per day over four consecutive days for a total of 20 sessions. Safety assessment and adverse events were documented based on the patients' responses following each day of stimulation. Before and after the 4-days neurostimulation protocol, outcome measures were obtained for the HAMD, modified Rankin Scale (mRS), functional independence measures (FIM), and National Institutes of Health Stroke Scales (NIHSS). These same measures were obtained at 3-months follow up. Results: HAMD significantly decreased (Wilcoxon p = 0.03) from M = 15.5 (2.81)-4.17 (0.98) following rTMS, a difference which persisted at the 3-months follow-up (p = 0.03). No statistically significant difference in FIM, mRS, or NIHSS were observed. No significant adverse events related to the treatment were observed and patients tolerated the stimulation protocol well overall. Conclusions: This pilot study indicates that an accelerated rTMS protocol is a safe and viable option, and may be an effective alternative or adjunctive therapy for patients suffering from PSD. Future randomized, controlled studies are needed to confirm these preliminary findings. Clinical Trial Registration: https://clinicaltrials.gov/ct2/show/NCT04093843.

Non-invasive vagus nerve stimulation for primary headache: A clinical update.

BACKGROUND: Non-invasive vagus nerve stimulation (nVNS) is a proven treatment for cluster headache and migraine. Several possible mechanisms of action by which nVNS mitigates headache have been identified. METHODS: We conducted a narrative review of recent scientific and clinical research into nVNS for headache, including findings from mechanistic studies and their possible relationships to the clinical effects of nVNS. RESULTS: Findings from animal and human studies have provided possible mechanistic explanations for nVNS efficacy in headache involving four core areas: Autonomic nervous system functions; cortical spreading depression inhibition; neurotransmitter regulation; and nociceptive modulation. We discuss how overlap and interplay among these areas may underlie the utility of nVNS in the context of clinical evidence supporting its safety and efficacy as acute and preventive therapy for both cluster headache and migraine. Possible future nVNS applications are also discussed. CONCLUSION: Significant progress over the past several years has yielded valuable mechanistic and clinical evidence that, combined with the excellent safety and tolerability profile of nVNS, suggests that it should be considered a first-line treatment for both acute and preventive treatment of cluster headache, an effective option for acute treatment of migraine, and a highly relevant, practical option for migraine prevention.

Noninvasive hippocampal blood-brain barrier opening in Alzheimer's disease with focused ultrasound.

The blood-brain barrier (BBB) presents a significant challenge for treating brain disorders. The hippocampus is a key target for novel therapeutics, playing an important role in Alzheimer's disease (AD), epilepsy, and depression. Preclinical studies have shown that magnetic resonance (MR)-guided low-intensity focused ultrasound (FUS) can reversibly open the BBB and facilitate delivery of targeted brain therapeutics. We report initial clinical trial results evaluating the safety, feasibility, and reversibility of BBB opening with FUS treatment of the hippocampus and entorhinal cortex (EC) in patients with early AD. Six subjects tolerated a total of 17 FUS treatments with no adverse events and neither cognitive nor neurological worsening. Post-FUS contrast MRI revealed immediate and sizable hippocampal parenchymal enhancement indicating BBB opening, followed by BBB closure within 24 h. The average opening was 95% of the targeted FUS volume, which corresponds to 29% of the overall hippocampus volume. We demonstrate that FUS can safely, noninvasively, transiently, reproducibly, and focally mediate BBB opening in the hippocampus/EC in humans. This provides a unique translational opportunity to investigate therapeutic delivery in AD and other conditions.

Unique Considerations for Special Populations in Episodic Migraine: the Underserved.

PURPOSE OF REVIEW: People with migraine disease face many challenges, and these challenges can be magnified when someone is part of an "underserved" population. We set out to examine various categories of "underserved" populations, consider the unique challenges faced by these groups, and discuss mechanisms to mitigate these challenges as much as possible. RECENT FINDINGS: Very little research has been performed to specifically evaluate underserved populations related to people with migraine disease. Recent research has shown the overall limitations of limited numbers of physicians with specialty training in headache disorders, and the socioeconomic implications of migraine disease have long been reported. Even the definition of "underserved" is not completely clear. We undertook to define this concept in the setting of migraine disease, breaking into different categories, including financial, geographic, and cultural/racial. Each underserved population has both shared and unique challenges, and in reality, given the paucity of medical expertise throughout the United States, one could make the argument that nearly all people with migraine disease are at risk for being underserved. In the future, epidemiologic as well as therapeutic research should incorporate analyses of these and any other underserved population to improve the application of study results across broad and varied populations whose commonality, in many cases, ends with sharing the same disease.

Enhanced motor function and its neurophysiological correlates after navigated low-frequency repetitive transcranial magnetic stimulation over the contralesional motor cortex in stroke.

BACKGROUND: The net effect of altered interhemispheric interactions between homologous motor cortical areas after unilateral stroke has been previously reported to contribute to residual hemiparesis. Using this framework, we hypothesized that navigated 1 Hz repetitive transcranial magnetic stimulation (rTMS) over the contralesional hemisphere would induce a stronger physiological and behavioural response in patients with residual motor deficit than in healthy subjects, because an imbalance in interhemispheric excitability may underlie motor dysfunction. METHODS: Navigated rTMS was conducted in 8 chronic stroke patients (67.50±13.77 years) and in 8 comparable normal subjects (57.38±9.61 years). We evaluated motor function (Finger tapping, Nine Hole Peg test, Strength Index and Reaction Time) as well as the excitatory and inhibitory function (resting motor threshold, motor evoked potential amplitude, intra-cortical inhibition and facilitation, and silent period) of the stimulated and non-stimulated motor cortex before and after navigated rTMS. RESULTS: rTMS induced an increase in excitability in the ipsilesional (non-stimulated) motor cortex and led to improved performance in the finger tapping task and pinch force task. These physiological and behavioral effects were more prominent (or robust) in the group of stroke patients than in the control group. CONCLUSION: Navigated low-frequency rTMS involving precise and consistent targeting of the contralesional hemisphere in stroke patients enhanced the cortical excitability of the ipsilesional hemisphere and the motor response of the hemiparetic hand.

Abnormal Mechanisms of Plasticity and Metaplasticity in Autism Spectrum Disorders and Fragile X Syndrome.

OBJECTIVES: Multiple lines of evidence from genetic linkage studies to animal models implicate aberrant cortical plasticity and metaplasticity in the pathophysiology of autism spectrum disorder (ASD) and fragile X syndrome (FXS). However, direct experimental evidence of these alterations in humans with these disorders is scarce. Transcranial magnetic stimulation (TMS) is a noninvasive tool for probing mechanisms of plasticity and metaplasticity in vivo, in humans. The aim of the current study was to examine mechanisms of plasticity and metaplasticity in humans with ASD and FXS. We employed a repetitive TMS protocol developed specifically to probe cortical plasticity, namely continuous theta burst stimulation (cTBS). METHODS: We applied a 40-second train of cTBS to primary motor cortex (M1) to healthy control participants and individuals with ASD or FXS, and we measured the cTBS-induced modulation in motor-evoked potentials (MEPs) in a contralateral intrinsic hand muscle. Each participant completed two sessions of the same protocol on two consecutive days. The degree of modulation in MEPs after cTBS on the first day was evaluated as a putative index of cortical plasticity. Examination of the changes in the effects of cTBS on the second day, as conditioned by the effects on the first day, provided an index of metaplasticity, or the propensity of a given cortical region to undergo plastic change based on its recent history. RESULTS: After a 40-second cTBS train, individuals with ASD show a significantly longer duration of suppression in MEP amplitude as compared with healthy controls, whereas individuals with FXS show a significantly shorter duration. After a second train of cTBS, 24 hours later, the ASD group was indistinguishable from the control group, and while in the FXS group MEPs were paradoxically facilitated by cTBS. CONCLUSION: These findings offer insights into the pathophysiology of ASD and FXS, specifically providing direct experimental evidence that humans with these disorders show distinct alterations in plasticity and metaplasticity, consistent with the findings in animal models. If confirmed in larger test-retest studies, repeated TMS measures of plasticity and metaplasticity may provide a valuable physiologic phenotype for ASD and FXS.

Detailed analysis of allergic cutaneous reactions to spinal cord stimulator devices.

The use of spinal cord stimulation (SCS) devices to treat chronic, refractory neuropathic pain continues to expand in application. While device-related complications have been well described, inflammatory reactions to the components of these devices remain underreported. In contrast, hypersensitivity reactions associated with other implanted therapies, such as endovascular and cardiac rhythm devices, have been detailed. The purpose of this case series is to describe the clinical presentation and course of inflammatory reactions as well as the histology of these reactions. All patients required removal of the entire device after developing inflammatory reactions over a time course of 1-3 months. Two patients developed a foreign body reaction in the lead insertion wound as well as at the implantable pulse generator site, with histology positive for giant cells. One patient developed an inflammatory dermatitis on the flank and abdomen that resolved with topical hydrocortisone. "In vivo" testing with a lead extension fragment placed in the buttock resulted in a negative reaction followed by successful reimplantation of an SCS device. Inflammatory reactions to SCS devices can manifest as contact dermatitis, granuloma formation, or foreign body reactions with giant cell formation. Tissue diagnosis is essential, and is helpful to differentiate an inflammatory reaction from infection. The role of skin patch testing for 96 hours may not be suited to detect inflammatory giant cell reactions that manifest several weeks post implantation.

Insights on the neural basis of motor plasticity induced by theta burst stimulation from TMS-EEG.

Transcranial magnetic stimulation (TMS) is a useful tool to induce and measure plasticity in the human brain. However, the cortical effects are generally indirectly evaluated with motor-evoked potentials (MEPs) reflective of modulation of cortico-spinal excitability. In this study, we aim to provide direct measures of cortical plasticity by combining TMS with electroencephalography (EEG). Continuous theta-burst stimulation (cTBS) was applied over the primary motor cortex (M1) of young healthy adults, and we measured modulation of (i) MEPs, (ii) TMS-induced EEG evoked potentials (TEPs), (iii) TMS-induced EEG synchronization and (iv) eyes-closed resting EEG. Our results show the expected cTBS-induced decrease in MEP size, which we found to be paralleled by a modulation of a combination of TEPs. Furthermore, we found that cTBS increased the power in the theta band of eyes-closed resting EEG, whereas it decreased single-pulse TMS-induced power in the theta and alpha bands. In addition, cTBS decreased the power in the beta band of eyes-closed resting EEG, whereas it increased single-pulse TMS-induced power in the beta band. We suggest that cTBS acts by modulating the phase alignment between already active oscillators; it synchronizes low-frequency (theta and/or alpha) oscillators and desynchronizes high-frequency (beta) oscillators. These results provide novel insight into the cortical effects of cTBS and could be useful for exploring cTBS-induced plasticity outside of the motor cortex.

Transcranial brain stimulation: clinical applications and future directions.

Noninvasive brain stimulation is a valuable investigative tool and has potential therapeutic applications in cognitive neuroscience, neurophysiology, psychiatry, and neurology. Transcranial magnetic stimulation (TMS) is particularly useful to establish and map causal brain-behavior relations in motor and nonmotor cortical areas. Neuronavigated TMS is able to provide precise information related to the individual's functional anatomy that can be visualized and used during surgical interventions and critically aid in presurgical planning, reducing the need for riskier and more cumbersome intraoperative or invasive mapping procedures. This article reviews methodological aspects, clinical applications, and future directions of TMS-based mapping.

State-dependency effects on TMS: a look at motive phosphene behavior.

Transcranial magnetic stimulation (TMS) is a non-invasive neurostimulatory and neuromodulatory technique that can transiently or lastingly modulate cortical excitability (either increasing or decreasing it) via the application of localized magnetic field pulses. Within the field of TMS, the term state dependency refers to the initial, baseline condition of the particular neural region targeted for stimulation. As can be inferred, the effects of TMS can (and do) vary according to this primary susceptibility and responsiveness of the targeted cortical area. In this experiment, we will examine this concept of state dependency through the elicitation and subjective experience of motive phosphenes. Phosphenes are visually perceived flashes of small lights triggered by electromagnetic pulses to the visual cortex. These small lights can assume varied characteristics depending upon which type of visual cortex is being stimulated. In this particular study, we will be targeting motive phosphenes as elicited through the stimulation of V1/V2 and the V5/MT+ complex visual regions.

Transcranial magnetic stimulation provides means to assess cortical plasticity and excitability in humans with fragile x syndrome and autism spectrum disorder.

Fragile X Syndrome (FXS) is the most common heritable cause of intellectual disability. In vitro electrophysiologic data from mouse models of FXS suggest that loss of fragile X mental retardation protein affects intracortical excitability and synaptic plasticity. Specifically, the cortex appears hyperexcitable, and use-dependent long-term potentiation (LTP) and long-term depression (LTD) of synaptic strength are abnormal. Though animal models provide important information, FXS and other neurodevelopmental disorders are human diseases and as such translational research to evaluate cortical excitability and plasticity must be applied in the human. Transcranial magnetic stimulation paradigms have recently been developed to non-invasively investigate cortical excitability using paired pulse stimulation, as well as LTP- and LTD-like synaptic plasticity in response to theta burst stimulation (TBS) in vivo in the human. TBS applied on consecutive days can be used to measure metaplasticity (the ability of the synapse to undergo a second plastic change following a recent induction of plasticity). The current study investigated intracortical inhibition, plasticity and metaplasticity in full mutation females with FXS, participants with autism spectrum disorders (ASD), and neurotypical controls. Results suggest that intracortical inhibition is normal in participants with FXS, while plasticity and metaplasticity appear abnormal. ASD participants showed abnormalities in plasticity and metaplasticity, as well as heterogeneity in intracortical inhibition. Our findings highlight the utility of non-invasive neurophysiological measures to translate insights from animal models to humans with neurodevelopmental disorders, and thus provide direct confirmation of cortical dysfunction in patients with FXS and ASD.

Low and therapeutic doses of antidepressants are associated with similar response in the context of multimodal treatment of pain.

BACKGROUND: Antidepressants are prescribed in a wide range of doses to treat both depression and chronic pain, with optimal psychopharmacology individualized for each patient. In the past decade more antidepressants from different chemical classes have become available and are being used for the treatment of both chronic pain and depression. OBJECTIVE: To review the utilization pattern changes and compare response rates of different classes and doses of antidepressants for various pain conditions in the context of multimodal therapies. DESIGN: Chart review. METHODS: We reviewed 5,916 records at an outpatient multidisciplinary pain center. Of these, 379 records were for patients diagnosed with cancer pain. Because the mechanisms and treatment approaches to cancer pain can differ greatly from non-cancer chronic pain, these records were excluded from the analysis. We assessed 1,506 medical records for patients with chronic non-caner pain who had used at least one antidepressant, with the main outcome measure being the Numeric Rating Pain Scale, 0-10. RESULTS: Of the 5,916 charts reviewed, 1,506 (25.4%) chronic non-cancer pain charts recorded the prescription of at least one antidepressant. Most patients received a combination of medications and procedures. Of the 450 patients receiving secondary amines, favorable responses were recorded for 340 (76%) patients, while 103 (23%) did not respond and 7 had unknown responses. Of the 492 patients receiving tertiary amines, favorable responses were recorded for 375 (76%) patients, while 113 (23%) did not respond, and 4 had unknown responses. Of the 533 patients receiving SSRI/SNRIs, favorable responses were recorded for 382 (72%) patients, while 147 (28%) did not respond, and 4 had unknown responses. Of the 369 patients receiving atypical antidepressants, favorable responses were recorded for 272 (74%) patients, while 94 (25%) did not respond, and 3 had unknown responses. LIMITATIONS: A retrospective study design and the use of antidepressants as a part of multimodal treatment of pain. CONCLUSION: The data suggest that in the context of multimodal treatment for chronic pain, antidepressant therapy at both low and therapeutic doses demonstrates similar response rates. Tricyclic antidepressants (TCAs), which include secondary and tertiary amines, as well as SSRI/SNRIs and atypicals, all appear to show similar favorable response rates.