Search

Background Transcranial focused ultrasound (tFUS) is a noninvasive brain stimulation method that may modulate deep brain structures. This study investigates whether sonication of the right anterior thalamus would modulate thermal pain thresholds in healthy individuals. Methods We enrolled 19 healthy individuals in this three-visit, double-blind, sham-controlled, crossover trial. Participants first underwent a structural MRI scan used solely for tFUS targeting. They then attended two identical experimental tFUS visits (counterbalanced by condition) at least one week apart. Within the MRI scanner, participants received two, 10-min sessions of either active or sham tFUS spread 10 min apart targeting the right anterior thalamus [fundamental frequency: 650 kHz, Pulse repetition frequency: 10 Hz, Pulse Width: 5 ms, Duty Cycle: 5%, Sonication Duration: 30s, Inter-Sonication Interval: 30 s, Number of Sonications: 10, ISPTA.0 995 mW/cm2, ISPTA.3 719 mW/cm2, Peak rarefactional pressure 0.72 MPa]. The primary outcome measure was quantitative sensory thresholding (QST), measuring sensory, pain, and tolerance thresholds to a thermal stimulus applied to the left forearm before and after right anterior thalamic tFUS. Results The right anterior thalamus was accurately sonicated in 17 of the 19 subjects. Thermal pain sensitivity was significantly attenuated after active tFUS. The pre-post x active-sham interaction was significant (F(1,245.95) = 4.03, p = .046). This interaction indicates that in the sham stimulation condition, thermal pain thresholds decreased 1.08 °C (SE = 0.28) pre-post session, but only decreased .51 °C (SE = 0.30) pre-post session in the active stimulation group. Conclusions Two 10-min sessions of anterior thalamic tFUS induces antinociceptive effects in healthy individuals. Future studies should optimize the parameter space, dose and duration of this effect which may lead to multi-session tFUS interventions for pain disorders.

While electroencephalogram (EEG) burst-suppression is often induced therapeutically using sedatives in the intensive care unit (ICU), there is hitherto no evidence with respect to its association to outcome in moderate-to-severe neurological patients. We examined the relationship between sedation-induced burst-suppression (SIBS) and outcome at hospital discharge and at 6-month follow up in patients surviving moderate-to-severe traumatic brain injury (TBI). For each of 32 patients recovering from coma after moderate-to-severe TBI, we measured the EEG burst suppression ratio (BSR) during periods of low responsiveness as assessed with the Glasgow Coma Scale (GCS). The maximum BSR was then used to predict the Glasgow Outcome Scale extended (GOSe) at discharge and at 6 months post-injury. A multi-model inference approach was used to assess the combination of predictors that best fit the outcome data. We found that BSR was positively associated with outcomes at 6 months (P = 0.022) but did not predict outcomes at discharge. A mediation analysis found no evidence that BSR mediates the effects of barbiturates or propofol on outcomes. Our results provide initial observational evidence that burst suppression may be neuroprotective in acute patients with TBI etiologies. SIBS may thus be useful in the ICU as a prognostic biomarker.

Electroencephalography (EEG), easily deployed at the bedside, is an attractive modality for deriving quantitative biomarkers of prognosis and differential diagnosis in severe brain injury and disorders of consciousness (DOC). Prior work by Schiff has identified four dynamic regimes of progressive recovery of consciousness defined by the presence or absence of thalamically-driven EEG oscillations. These four predefined categories (ABCD model) relate, on a theoretical level, to thalamocortical integrity and, on an empirical level, to behavioral outcome in patients with cardiac arrest coma etiologies. However, whether this theory-based stratification of patients might be useful as a diagnostic biomarker in DOC and measurably linked to thalamocortical dysfunction remains unknown. In this work, we relate the reemergence of thalamically-driven EEG oscillations to behavioral recovery from traumatic brain injury (TBI) in a cohort of N = 38 acute patients with moderate-to-severe TBI and an average of 1 week of EEG recorded per patient. We analyzed an average of 3.4 hr of EEG per patient, sampled to coincide with 30-min periods of maximal behavioral arousal. Our work tests and supports the ABCD model, showing that it outperforms a data-driven clustering approach and may perform equally well compared to a more parsimonious categorization. Additionally, in a subset of patients (N = 11), we correlated EEG findings with functional magnetic resonance imaging (fMRI) connectivity between nodes in the mesocircuit-which has been theoretically implicated by Schiff in DOC-and report a trend-level relationship that warrants further investigation in larger studies.

Objective Transcranial Focused Ultrasound (tFUS) is a promising new potential neuromodulation tool. However, the safety of tFUS neuromodulation has not yet been assessed adequately. Patients with refractory temporal lobe epilepsy electing to undergo an anterior temporal lobe resection present a unique opportunity to evaluate the safety and efficacy of tFUS neuromodulation. Histological changes in tissue after tFUS can be examined after surgical resection, while further potential safety concerns can be assessed using neuropsychological testing. Methods Neuropsychological functions were assessed in eight patients before and after focused ultrasound sonication of the temporal lobe at intensities up to 5760 mW/cm2. Using the BrainSonix Pulsar 1002, tFUS was delivered under MR guidance, using the Siemens Magnetom 3T Prisma scanner. Neuropsychological changes were assessed using various batteries. Histological changes were assessed using hematoxylin and eosin staining, among others. Results With respect to safety, the histological analysis did not reveal any detectable damage to the tissue, except for one subject for whom the histology findings were inconclusive. In addition, neuropsychological testing did not show any statistically significant changes in any test, except for a slight decrease in performance on one of the tests after tFUS. Significance This study supports the hypothesis that low-intensity Transcranial Focused Ultrasound (tFUS) used for neuromodulation of brain circuits at intensities up to 5760 mW/cm2 may be safe for use in human research. However, due to methodological limitations in this study and inconclusive findings, more work is warranted to establish the safety. Future directions include greater number of sonications as well as longer exposure at higher intensity levels to further assess the safety of tFUS for modulation of neuronal circuits.

Introduction: In multiple animal models of ischemic stroke, cerebellar fastigial nucleus stimulation (FNS) via implanted electrode has been shown to exert strong neuroprotective and collateral enhancement effects. Translational studies of FNS have been precluded due to the invasive nature of direct electrical stimulation. Recently, low-intensity focused ultrasound pulsation (LIFUP) has been used to stimulate deep hemispheric targets. Identifying achievable anatomic trajectories for LIFUP delivery is required for human trials. Method: Sagittal brain MRI T1 from 10 patients were analyzed. Potential pathways from the suboccipital (SO) region (transducer placement site) to the roof of the 4 th ventricle (location of FN) were traced, evaluating paths both via the thinnest portion of the occipital bone (OB) and via the transforaminal window (TFW). Interindividual variations in trajectory distances (cm), thickness of the OB through which the beam passes (cm), and the projected neck flexion degree from neutral position required to achieve a TFW path were measured. Results: An achievable anatomic pathway for stimulation of the FN via LIFUP was identified in 100% of patients (Fig 1). In standard MR positioning, 90% had an available path through thin portions of the OB and 10% had a projected path through TFW. The mean distance from the skin at the SO region to the roof of 4 th ventricle/FN was 7.2 cm (± 0.64cm). The mean OB thickness traversed by the beam was 0.3cm (±0.1). The projected required neck flexion to enable a TFW in all subjects was mean 9.3° (±5°). Conclusions: The distance for the LIFUP beam to travel from skin surface to FN via a suboccipital approach is well within the LIFUP penetration depth and all individuals had an accessible trajectory via the TFW through attainable degrees of head flexion, affording minimal ultrasonic energy dispersion and maximal focality. Ultrasound stimulation of fastigial nucleus is a feasible treatment strategy in human acute ischemic stroke.

A 29-year-old woman presented with head and neck dystonia, as well as functional seizures. The patient was an active military service member with a history of combat-related trauma. Resting blood oxygen level dependent (BOLD) functional MRI (fMRI) scans of the brain demonstrated an increased anterior cingulate component of the salience network and hyper-connectivity between the insula and cingulate. Following neurological and psychiatric evaluation, she was diagnosed with dissociative post-traumatic stress disorder, partially presenting as a functional movement disorder. Inhibitory repetitive transcranial magnetic stimulation (rTMS) was prescribed with the anterior cingulate as the primary target, and supplementary motor and premotor cortices as secondary targets. The treatment was intended to suppress tremors both directly and indirectly. Thirty-six sessions later, her symptoms were in remission, and she returned to active duty. This case demonstrates the potential efficacy of fMRI-guided rTMS in the treatment of dissociative PTSD.