Characterization of Blood-Brain Barrier Opening Induced by Transcranial Histotripsy in Murine Brains

OBJECTIVE

Transcranial histotripsy has shown promise as a non-invasive neurosurgical tool, as it has the ability to treat a wide range of locations in the brain without overheating the skull. One important effect of histotripsy in the brain is the blood-brain barrier (BBB) opening (BBBO) at the ablation site, but there is a knowledge gap concerning the extent of histotripsy-induced BBBO. Here we describe induction of BBBO by transcranial histotripsy and use of magnetic resonance imaging (MRI) and histology to quantify changes in BBBO at the periphery of the histotripsy ablation zone over time in the healthy mouse brain.

METHODS

An eight-element, 1 MHz histotripsy transducer with a focal distance of 32.5 mm was used to treat the brains of 23 healthy female BL6 mice. T1-gadolinium (T1-Gd) MR images were acquired immediately following histotripsy treatment and during each of the subsequent 4 wk to quantify the size and intensity of BBB leakage.

RESULTS

The T1-Gd MRI results revealed that the hyperintense BBBO volume increased over the first week and subsided gradually over the following 3 wk. Histology revealed complete loss of tight junction proteins and blood vessels in the center of the ablation region immediately after histotripsy, partial recovery in the periphery of the ablation zone 1 wk following histotripsy and near-complete recovery of tight junction complex after 4 wk.

CONCLUSION

These results provide the first evidence of transcranial histotripsy-induced BBBO and repair at the periphery of the ablation zone.

The role of endoscopic endonasal salvage surgery in recurrent or residual craniopharyngioma after a transcranial approach: a systematic review

BACKGROUND

The management of craniopharyngiomas is challenging due to their high rate of recurrence following resection. Excision of recurrent tumors poses further surgical challenges due to loss of arachnoidal planes and adherence to anatomical structures. The endoscopic endonasal approach (EEA) offers a favorable alternative to transcranial approaches for primary craniopharyngiomas. However, the safety and efficacy of EEA for recurrent tumors, specifically after a prior transcranial approach, needs further investigation.

METHODS

We performed a systematic review using PubMed to develop a database of cases of recurrent craniopharyngiomas previously treated with a transcranial approach.

RESULTS

Fifteen articles were included in this review with a total of 75 cases. There were 50 males and 25 females with a mean age of 38 years (range 2-80). One prior transcranial surgery was done in 80.0% of cases, while 8.0% had two and 12.0% had more than two prior surgeries. Radiotherapy after transcranial resection was given in 18 cases (24.0%). Following EEA, vision improved in 60.0% of cases, and vision worsened in 8.6% of the cases. Of cases, 64.4% had pre-existing anterior hypopituitarism, and 43.8% had diabetes insipidus prior to EEA. New anterior hypopituitarism and diabetes insipidus developed in 24.6% and 21.9% of cases, respectively following EEA. Gross total resection (GTR) was achieved in 64.0%, subtotal resection in 32.0%, and partial resection in 4.0% revision EEA cases. GTR rate was higher in cases with no prior radiotherapy compared to cases with prior radiotherapy (72.0% vs 39.0%, p = 0.0372). The recurrence rate was 17.5% overall but was significantly lower at 10.0% following GTR (p = 0.0019). The average follow-up length was 41.2 months (range, 1-182 months).

CONCLUSION

The EEA can be utilized for resection of recurrent or residual craniopharyngiomas previously managed by a transcranial approach.

Hemodynamic predictors of early neurological deterioration and clinical outcome after endovascular treatment in large artery occlusion

Objective

Half of the patients with acute large artery occlusion (LAO) have poor outcomes after endovascular treatment (EVT). Early complications such as cerebral edema and symptomatic intracranial hemorrhage (sICH) can lead to early neurological deterioration (END), which correlates with hemodynamics. This study aimed to identify the hemodynamic predictors of END and outcomes in LAO patients after EVT.

Methods

A total of 76 patients with anterior circulation LAO who underwent EVT and received transcranial Doppler (TCD) monitoring were included. Bilateral middle cerebral artery (MCA) blood flow velocities (BFVs) were measured repeatedly within 1 week. Mean flow velocities (MFV) and MFV index (ipsilateral MFV/contralateral MFV) were calculated. The primary outcome was the incidence of END within 72 h. The secondary outcome was the functional outcome at 90 days-a good outcome was defined as a modified Rankin scale (mRS) score of 0-2, while a poor outcome was defined as an mRS score of 3-6.

Results

A total of 13 patients (17.1 %) experienced END within 72 h, including 5 (38.5 %) with cerebral edema, 5 (38.5 %) with sICH, and 3 (23.0 %) with infarct progression. Multivariable logistic regression analysis showed that a higher 24 h MFV index was independently associated with END (aOR 10.5; 95 % CI 2.28-48.30, p = 0.003) and a poor 90-day outcome (aOR 5.10; 95 % CI 1.38-18.78, p = 0.014). The area under the receiver operating characteristic (ROC) curve (AUC) of the 24 h MFV index for predicting END was 0.807 (95 % CI 0.700-0.915, p = 0.0005), the sensitivity was 84.6 %, and the specificity was 66.7 %. At the 1-week TCD follow-up, patients who had poor 90-day outcomes showed significantly higher 1-week iMFV [73.5 (58.4-99.0) vs. 57.7 (45.3-76.3), p = 0.004] and MFV index [1.24 (0.98-1.57) vs.1.0 (0.87-1.15) p = 0.007]. A persistent high MFV index (PHMI) was independently associated with a poor outcome (aOR 7.77, 95 % CI 1.81-33.3, p = 0.006).

Conclusion

TCD monitoring within 24 h after EVT in LAO patients can help predict END, while dynamic follow-up within 1 week is valuable in predicting clinical outcomes.

Neuromodulation in migraine

The International Neuromodulation Society defines therapeutic neuromodulation as the alteration of nerve activity through targeted delivery of a stimulus, such as electrical stimulation or chemical agents, to specific neurological sites in the body. Neuromodulation for the treatment of migraine is an evolving field offering further insight into the pathophysiology of migraine as well as advanced therapeutics. Central and peripheral neuronal targets have been explored in the efforts to reduce the frequency and severity of attacks. Invasive and noninvasive techniques have been developed, targeting either the central or peripheral nervous system. Noninvasive central neuromodulation techniques have the benefit of a low side effect profile in addition to higher level of evidence for use thanks to sham-controlled trials; however, these modalities are less clinically available for use. Noninvasive transcutaneous neuromodulation techniques that target the peripheral nervous system have provided devices that are available over the counter or by prescription. Several of these devices are effective for abortive and preventive treatment of migraine. Invasive techniques such as cranial nerve stimulation with implanted stimulator devices or spinal cord stimulation may be used for more aggressive management in patients refractory to other treatments. Overall, neuromodulation techniques can be particularly beneficial for medically complex or refractory patients, those that prefer nonmedication options, and those that have experienced adverse effects from medications.

Recent advances in light energy biotherapeutic strategies with photobiomodulation on central nervous system disorders

Transcranial photobiomodulation refers to irradiation of the brain through the skull using low-intensity red or near-infrared light, which is the most commonly studied method of light energy biotherapy for central nervous system disorders. The absorption of photons by specific chromophores within the cell elevates ATP synthesis, reduces oxidative stress damage, alleviates inflammation or mediates the activation of transcription factors and signaling mediators through secondary mediators, which in turn trigger downstream signaling pathways to cause a series of photobiological effects including upregulation of neurotrophic factors. Multiple mechanisms are simultaneously involved in the pathological process of central nervous system disorders. The pleiotropic treatment of transcranial photobiomodulation towards multiple targets plays a beneficial role in improving hemodynamics, neural repair and improving behaviors in central nervous system disorders such as ischemic stroke, traumatic brain injury, neurodegenerative diseases, epilepsy and depression. This review mainly introduces the mechanism and recent preclinical and clinical advances of transcranial photobiomodulation for central nervous system disorders, which will provide a reference for clinicians to understand and engage in related studies, and calls for more and larger studies to validate and develop a wider application of transcranial photobiomodulation in central nervous system.

Transcranial photobiomodulation ameliorates midbrain and striatum neurochemical impairments and behavioral deficits in reserpine-induced parkinsonism in rats

Photobiomodulation (PBM) of deep brain structures through transcranial infrared irradiation might be an effective treatment for Parkinson's disease (PD). However, the mechanisms underlying this intervention should be elucidated to optimize the therapeutic outcome and maximize therapeutic efficacy. The present study aimed at investigating the oxidative stress-related parameters of malondialdehyde (MDA), nitric oxide (NO), and reduced glutathione (GSH) and the enzymatic activities of sodium-potassium-ATPase (Na+, K+-ATPase), Acetylcholinesterase (AChE), and monoamine oxidase (MAO) and monoamine levels (dopamine (DA), norepinephrine (NE) and serotonin (5-HT) in the midbrain and striatum of reserpine-induced PD in an animal model treated with PBM. Furthermore, the locomotor behavior of the animals has been determined by the open field test. Animals were divided into three groups; the control group, the PD-induced model group, and the PD-induced model treated with the PBM group. Non-invasive treatment of animals for 14 days with 100 mW, 830 nm laser has demonstrated successful attainment in the recovery of oxidative stress, and enzymatic activities impairments induced by reserpine (0.2 mg/kg) in both midbrain and striatum of adult male Wistar rats. PBM also improved the decrease in DA, NE, and 5-HT in the investigated brain regions. On a behavioral level, animals showed improvement in their locomotion activity. These findings have shed more light on some mechanisms underlying the treatment potential of PBM and displayed the safety, easiness, and efficacy of PBM treatment as an alternative to pharmacological treatment for PD.

Impaired Dynamic Cerebral Autoregulation in Patients With Cerebral Venous Sinus Thrombosis: Evaluation Using Transcranial Doppler and Silent Reading Stimulation

OBJECTIVE

Cerebral venous sinus thrombosis (CVST) may impair dynamic cerebral autoregulation (dCA) of the middle cerebral artery (MCA). However, most studies have focused on dCA of the MCA; a few studies are based on the posterior cerebral artery (PCA) during silent reading and neurovascular coupling (NVC). This study explored the effects of CVST on dCA of the MCA and PCA during silent reading and NVC.

METHODS

From January 2021 to August 2022, 60 CVST patients and 30 controls were enrolled in this study. Non-invasive continuous beat-to-beat blood pressure, cerebral blood flow velocity and other associated information on the MCA and PCA during silent reading were collected using a transcranial Doppler. NVC assessment was performed by opening and closing the eyes periodically based on voice prompts, and eye-opening visual stimulation was achieved by silently reading Chinese tourism materials. Visual stimulation signals can selectively activate Brodmann's areas 17, 18, and 19 of the occipital when reading silently with open eyes, prompting them to release neurotransmitters and dilate PCA. dCA was determined by transfer function analysis.

RESULTS

In dCA of the PCA during silent reading, the CVST group's very low frequency phase was lower than that of the control group (p = 0.047). In NVC, the difference in the indexes of the cerebrovascular conductance and visually evoked flow response of the CVST group were lower than those of the control group (p = 0.017 and p = 0.019, respectively).

CONCLUSION

Compared with the control group, dCA and NVC of the PCA during silent reading were impaired in CVST patients.

Evaluation of ultrasound sensors for transcranial photoacoustic sensing and imaging

Photoacoustic imaging through skull bone causes strong attenuation and distortion of the acoustic wavefront, which diminishes image contrast and resolution. As a result, transcranial photoacoustic measurements in humans have been challenging to demonstrate. In this study, we investigated the acoustic transmission through the human skull to design an ultrasound sensor suitable for transcranial PA imaging and sensing. We measured the frequency dependent losses of human cranial bones ex vivo, compared the performance of a range of piezoelectric and optical ultrasound sensors, and imaged skull phantoms using a PA tomograph based on a planar Fabry-Perot sensor. All transcranial photoacoustic measurements show the typical effects of frequency and thickness dependent attenuation and aberration associated with acoustic propagation through bone. The performance of plano-concave optical resonator ultrasound sensors was found to be highly suitable for transcranial photoacoustic measurements.

Histotripsy Treatment of Murine Brain and Glioma: Temporal Profile of Magnetic Resonance Imaging and Histological Characteristics Post-treatment

OBJECTIVE

Currently, there is a knowledge gap in our understanding of the magnetic resonance imaging (MRI) characteristics of brain tumors treated with histotripsy to evaluate treatment response as well as treatment-related injuries. Our aim was to bridge this gap by investigating and correlating MRI with histological analysis after histotripsy treatment of mouse brain with and without brain tumors and evaluating the evolution of the histotripsy ablation zone on MRI over time.

METHODS

An eight-element, 1 MHz histotripsy transducer with a focal distance of 32.5 mm was used to treat orthotopic glioma-bearing mice and normal mice. The tumor burden at the time of treatment was ∼5 mm3. T2, T2*, T1 and T1-gadolinium (Gd) MR images and histology of the brain were acquired on days 0, 2 and 7 for tumor-bearing mice and days 0, 2, 7, 14, 21 and 28 post-histotripsy for normal mice.

RESULTS

T2 and T2* sequences most accurately correlated with histotripsy treatment zone. The treatment-induced blood products, T1 along with T2, revealed blood product evolution from oxygenated, de-oxygenated blood and methemoglobin to hemosiderin. And T1-Gd revealed the state of the blood-brain barrier arising from the tumor or histotripsy ablation. Histotripsy leads to minor localized bleeding, which resolves within the first 7 d as evident on hematoxylin and eosin staining. By day 14, the ablation zone could be distinguished only by the macrophage-laden hemosiderin, which resides around the ablation zone, rendering the treated zone hypo-intense on all MR sequences.

CONCLUSION

These results provide a library of radiological features on MRI sequences correlated to histology, thus allowing for non-invasive evaluation of histotripsy treatment effects in in vivo experiments.

Global sonication of the human intracranial space via a jumbo planar transducer

Contrary to conditioning a Focused Ultrasound (FUS) beam to sonicate a localized region of the human brain, the goal of this investigation was to explore the prospect of distributing homogeneous ultrasound energy over the entire brain space with a large cranium-wide ultrasound beam. Recent ultrasound preclincal studies utilizing large or whole brain stimulation regions create a demand for expanding the treatment envelope of transcranial pulsed-low intensity ultrasound towards Global Brain Sonication (GBS) for potential human investigation. Here, we conduct ultrasound field characterizations when transmitting pulsed ultrasound through human skull specimens using a 1-3 piezocomposite planar transducer operating at 464 kHz with an active single-element surface of 30 × 30 cm. Through computational simulation and hydrophone scanning methodology, ultrasound wave behavior and dose homogeneity in the brain space were evaluated under various trajectories of sonication using the planar transducer. Clinically relevant pulse parameters used for transcranial therapeutic ultrasound applications were used in the experiments. Simulations and empirical testing revealed that dose homogeneity and acoustic intensity over the brain space are influenced by sonication trajectory, skull lens effects, and acoustic wave reflections. The transducer can emit a spatial peak pulse average intensity of 4.03 W/cm² (0.24 MPa) measured in the free-field at 464 kHz with electrical power of 1 kW. The simulation showed that approximately 99 % of the cranial volume was exposed with <30 % of the maximum external acoustic intensity being transmitted into the skull. The transmission loss across all sonication trajectories is similar to previously reported FUS studies. A marker for GBS dose homogeneity is introduced to score the ultrasound pressure field uniformity in the intracranial space. Results of this study identify the initial challenges of exposing the entire human brain space with ultrasound using a large cranium-wide sonication beam intended for global brain therapeutic modulation.

Evaluation of a Novel Acoustic Coupling Medium for Human Low-Intensity Focused Ultrasound Neuromodulation Applications

OBJECTIVE

Single-element low-intensity focused ultrasound (LIFU) is an emerging form of human neuromodulation. Current coupling methods are impractical for clinical bedside use. Here, we evaluate commercially available high-viscosity gel polymer matrices as couplants for human LIFU neuromodulation applications.

METHODS

We first empirically tested the acoustic transmission of three densities at 500 kHz and then subjected the gel with the least acoustic attenuation to further tests of the effect of thickness, frequency, de-gassing and production variability.

RESULTS

The highest-density gel had the lowest acoustic attenuation (3.3%) with low lateral (<0.5 mm) and axial (<2 mm) beam distortion. Different thicknesses of the gel up to 10 mm did not appreciably affect results. The gel polymers exhibited frequency-dependent attenuation at 1 and 3 MHz up to 86.6%, as well as significant beam distortion >4 mm. Poor de-gassing methods also increased pressure attenuation at 500 kHz up to 59.6%. Standardized methods of making these gels should be established to reduce variability.

CONCLUSION

Commercially available de-gassed, high-density gel matrices are a low-cost, easily malleable, low-attenuation and distortion medium for the coupling of single-element LIFU transducers for human neuromodulation applications at 500 kHz.

Non-invasive neuromodulation of sub-regions of the human insula differentially affect pain processing and heart-rate variability

The insula is a portion of the cerebral cortex folded deep within the lateral sulcus covered by the overlying opercula of the inferior frontal lobe and superior portion of the temporal lobe. The insula has been parsed into sub-regions based upon cytoarchitectonics and structural and functional connectivity with multiple lines of evidence supporting specific roles for each of these sub-regions in pain processing and interoception. In the past, causal interrogation of the insula was only possible in patients with surgically implanted electrodes. Here, we leverage the high spatial resolution combined with the deep penetration depth of low-intensity focused ultrasound (LIFU) to non-surgically modulate either the anterior insula (AI) or posterior insula (PI) in humans for effect on subjective pain ratings, electroencephalographic (EEG) contact head evoked potentials (CHEPs) and time-frequency power as well as autonomic measures including heart-rate variability (HRV) and electrodermal response (EDR). N = 23 healthy volunteers received brief noxious heat pain stimuli to the dorsum of their right hand during continuous heart-rate, EDR and EEG recording. LIFU was delivered to either the AI (anterior short gyrus), PI (posterior longus gyrus) or under an inert sham condition time-locked to the heat stimulus. Results demonstrate that single-element 500 kHz LIFU is capable of individually targeting specific gyri of the insula. LIFU to both AI and PI similarly reduced perceived pain ratings but had differential effects on EEG activity. LIFU to PI affected earlier EEG amplitudes around 300 milliseconds whereas LIFU to AI affected EEG amplitudes around 500 milliseconds. In addition, only LIFU to the AI affected HRV as indexed by an increase in standard deviation of N-N intervals (SDNN) and mean HRV low frequency power. There was no effect of LIFU to either AI or PI on EDR or blood pressure. Taken together, LIFU looks to be an effective method to individually target sub-regions of the insula in humans for site-specific effects on brain biomarkers of pain processing and autonomic reactivity that translates to reduced perceived pain to a transient heat stimulus. These data have implications for the treatment of chronic pain and several neuropsychological diseases like anxiety, depression and addiction that all demonstrate abnormal activity in the insula concomitant with dysregulated autonomic function.

Sustained modulation of primate deep brain circuits with focused ultrasonic waves

BACKGROUND

Transcranial focused ultrasound has the potential to noninvasively modulate deep brain circuits and impart sustained, neuroplastic effects.

OBJECTIVE

Bring the approach closer to translations by demonstrating sustained modulation of deep brain circuits and choice behavior in task-performing non-human primates.

METHODS

Low-intensity transcranial ultrasound of 30 s in duration was delivered in a controlled manner into deep brain targets (left or right lateral geniculate nucleus; LGN) of non-human primates while the subjects decided whether a left or a right visual target appeared first. While the animals performed the task, we recorded intracranial EEG from occipital screws. The ultrasound was delivered into the deep brain targets daily for a period of more than 6 months.

RESULTS

The brief stimulation induced effects on choice behavior that persisted up to 15 minutes and were specific to the sonicated target. Stimulation of the left/right LGN increased the proportion of rightward/leftward choices. These effects were accompanied by an increase in gamma activity over visual cortex. The contralateral effect on choice behavior and the increase in gamma, compared to sham stimulation, suggest that the stimulation excited the target neural circuits. There were no detrimental effects on the animals' discrimination performance over the months-long course of the stimulation.

CONCLUSION

This study demonstrates that brief, 30-s ultrasonic stimulation induces neuroplastic effects specifically in the target deep brain circuits, and that the stimulation can be applied daily without detrimental effects. These findings encourage repeated applications of transcranial ultrasound to malfunctioning deep brain circuits in humans with the goal of providing a durable therapeutic reset.

Combined transcranial and transnasal endoscopic approach in transnasal-penetrating intracranial injury: A rare case report

INTRODUCTION

Transnasal-penetrating intracranial injuries are rare traumatic brain injuries that can cause serious and fatal brain damage and a high mortality rate and necessitate immediate multidisciplinary surgical management. We describe an uncommon case whereby a patient who presented with an accidental penetrating injury of the brain was found to have a wooden transnasal-penetrating intracranial object.

CASE PRESENTATION

A 28-year-old man consulted an ear, nose, and throat (ENT) surgeon after complaints of headache for two days, a history of epistaxis, and vomitus. The right side of the nose had been punctured by wood as a result of falling from a motorcycle. A computed tomography (CT) scan led to diagnosis of a transnasal penetrating intracranial injury. Removal of the transcranial foreign body was carried out jointly by a neurosurgeon and ENT surgeon. Postoperatively, antibiotics were given for 14 days, and the patient was discharged without neurological deficit.

CLINICAL DISCUSSION

Early diagnostic procedures, such as CT scan of the skull to assess trajectory and extent of vascular and brain tissue injury, are required for appropriate surgical planning and post-operative treatment of such patients. Surgery was performed by combined transcranial and transnasal endoscopy to identify the skull base, dura mater defect, and brain tissue damage. Removal of the corpus alienum by transnasal endoscopy yielded a good outcome.

CONCLUSION

Combined transcranial and transnasal endoscopic approach showed better result than transcranial approach only. The wooden foreign body can be completely eliminated transnasally without active bleeding using this approach. The patient was discharged with good outcome.

Study of the latency of transcranial motor evoked potentials in spinal cord monitoring during surgery for adolescent idiopathic scoliosis

OBJECTIVE

An increase in the latency of a motor evoked potential might be as significant as a decrease in amplitude to predict a significant and clinically symptomatic neurological injury in spinal surgery for adolescent idiopathic scoliosis. The aim of the study was to investigate the impact of monitoring of latency of motor evoked potentials during spinal surgery for adolescent idiopathic scoliosis by describing intraoperative data.

METHODS

Preoperative recordings of 50 patients undergoing posterior spinal fusion for idiopathic scoliosis were studied. Latencies of appearance of the motor evoked potential curves on the right and left side were recorded for each group of muscles at several key moments during the procedure (basal, before the first implant, before and after corrective maneuvers).

RESULTS

Mean latencies were approximately the same in each muscle group on the right and the left side, before and after correction. There was no significant increase in latency during surgery. Overall results showed that the measured latency did not differ significantly between the two age groups (p=0.07). Negative correlation between height and the means of latencies was recorded in the abductor pollicis brevis and abductor digiti minimi (r=0.4; p=0.009), rectus femoris (r=0.4; p=0.01), tibialis anterior (r=0.4; p=0.007), and abductor hallucis (r=0.5; p=0.0004). No significant correlation was found between age and intraoperative parameters.

CONCLUSION

Intraoperative latency could be a reliable intraoperative monitoring criteria with low variability, that might be used to predict postoperative motor deficits in surgery for adolescent idiopathic scoliosis.

Comparison between extended transsphenoidal and transcranial surgery for craniopharyngioma: focus on hypothalamic function and obesity

PURPOSE

Patients suffering from craniopharyngiomas currently have good survival rates, but long-term sequelae, such as development of obesity, worsen their quality of life. Optimal treatment is still controversial and changed during the decades, becoming less aggressive. Transcranial (TC) surgery was the first approach to be used, followed by extended transsphenoidal (eTNS) access. This study aims to compare the two approaches in terms of risk of hypothalamic damage leading to obesity.

METHODS

This is a monocentric retrospective analysis of post-puberal patients treated for primary craniopharyngioma. Postoperative obesity and percentual postsurgical BMI variation were considered proxy for hypothalamic function and used to fit regression models with basal BMI, type of surgery, tumor volume and hypothalamic involvement (anterior vs. anteroposterior).

RESULTS

No difference in radicality was observed between the two approaches; eTNS was more effective in ameliorating visual function but was significantly associated with CSF leaks. The TC approach was associated with a higher incidence of diabetes insipidus. Regression analysis showed only tumor volume and basal BMI resulted as independent predictors for both postoperative obesity (respectively, OR 1.15, P = 0.041, and OR 1.57, P < 0.001) and percentual BMI variation (respectively, + 0.92%, P = 0.005, and - 1.49%, P = 0.001).

CONCLUSIONS

Larger lesions portend a higher risk to develop postoperative obesity, independently of hypothalamic involvement. Interestingly, basal BMI is independent of lesional volume and is associated with postoperative obesity, but lesser postoperative BMI variation. The surgical approach does not influence the obesity risk. However, eTNS proves valid in managing large tumors with important hypothalamic invasion.

Electric hearing and tinnitus suppression by noninvasive ear stimulation

While noninvasive brain stimulation is convenient and cost effective, its utility is limited by the substantial distance between scalp electrodes and their intended neural targets in the head. The tympanic membrane, or eardrum, is a thin flap of skin deep in an orifice of the head that may serve as a port for improved efficiency of noninvasive stimulation. Here we chose the cochlea as a target because it resides in the densest bone of the skull and is adjacent to many deep-brain-stimulation structures. We also tested the hypothesis that noninvasive electric stimulation of the cochlea may restore neural activities that are missing in acoustic stimulation. We placed an electrode in the ear canal or on the tympanic membrane in 25 human adults (10 females) and compared their stimulation efficiency by characterizing the electrically-evoked auditory sensation. Relative to ear canal stimulation, tympanic membrane stimulation was four times more likely to produce an auditory percept, required eight times lower electric current to reach the threshold and produced two-to-four times more linear suprathreshold responses. We further measured tinnitus suppression in 14 of the 25 subjects who had chronic tinnitus. Compared with ear canal stimulation, tympanic membrane stimulation doubled both the probability (22% vs. 55%) and the amount (-15% vs. -34%) of tinnitus suppression. These findings extended previous work comparing evoked perception and tinnitus suppression between electrodes placed in the ear canal and on the scalp. Together, the previous and present results suggest that the efficiency of conventional scalp-based noninvasive electric stimulation can be improved by at least one order of magnitude via tympanic membrane stimulation. This increased efficiency is most likely due to the shortened distance between the electrode placed on the tympanic membrane and the targeted cochlea. The present findings have implications for the management of tinnitus by offering a potential alternative to interventions using invasive electrical stimulation such as cochlear implantation, or other non-invasive transcranial electrical stimulation methods.

Utilization of the 1064 nm Wavelength in Photobiomodulation: A Systematic Review and Meta-Analysis

Introduction: Photobiomodulation or low-level laser therapy (LLLT;<0.5 W) has been used as a non-invasive treatment for various medical indications. Short (visible; 635-650 nm) and longer (invisible; 810-850 nm and 915-980 nm) near-infrared wavelengths have been commonly used, but power setting deficiencies or incorrect wavelength settings can cause negative outcomes. The 1064 nm wavelength as the longest wavelength is a relative newcomer in high-powered (>0.5 W) laser photobiomodulation therapy (HPL-PBMT) with unique biophysical characteristics. Methods: A comprehensive search of 2016-2021 PubMed, Google Scholar, and Cochrane databases for "photobiomodulation" restricted to clinical trials for patients with a medical diagnosis was done. "1064 nm" content was identified and restricted to high-powered lasers (>0.5 watt). Cohen's d was calculated for the effect size and the difference was determined as a measure of relative 1064 nm HPL-PBMT efficacy. Results: The 22 independent studies meeting inclusion criteria focused on knee arthropathies, spine, shoulder/elbow, wound, gynecological, or osteoporosis with evaluation of pain, function, quality of life, range of motion (ROM), and anatomy. Pain was reduced with statistical significance (P<0.05) in 90% of study assessments (n=20) and 100% of studies focused on the knee (n=6). Of 18 studies assessing functional outcome measures, 100% demonstrated statistically significant improvements. Follow-up assessments up to 6 months in 5 knee arthritis studies revealed long-term pain reduction after cessation of treatment. Improvements in wound healing, bone mineral density, and knee cartilage thickness were demonstrated. The largest effect sizes observed were pain reduction in knee arthritis (average Cohen's d effect size=2.46). Conclusion: These studies have established that 1064 nm HPL-PBMT can effectively reduce pain, increase ROM, increase functional scores, and increase the quality of life for knee osteoarthritis and spinal disorders, with limitations. More studies are needed for clinical validation of single-trial data detecting changes in musculoskeletal conditions, cartilage thickness and bone density.

Repair of Giant Anterior Skull Base Encephalocele Containing Intralesional Eloquent Brain: Technical Note

BACKGROUND

Encephaloceles are herniations of intracranial neural tissue and meninges through defects in the skull. Basal encephaloceles are rare anterior skull base defects incident in 1 in 35,000 live births. Sphenoethmoidal encephaloceles are even more uncommon, with an incidence of 1 in 700,000 live births. Anterior skull base encephaloceles may be life-threatening in infants, presenting as airway obstruction and respiratory compromise. They can also present with cerebrospinal fluid (CSF) rhinorrhea, purulent nasal drainage, or meningitis.

OBJECTIVE

To report a novel technique for repairing a giant sphenoethmoidal encephalocele containing eloquent neural tissue.

METHODS

A 16-mo-old girl presented with progressive airway obstruction from a giant sphenoethmoidal encephalocele that filled her oral cavity. She had multiple congenital anomalies including agenesis of the corpus callosum and cleft lip and palate. Computed tomography showed complete absence of the bony anterior cranial base, and magnetic resonance imaging demonstrated the presence of the pituitary gland and hypothalamus in the hernia sac.

RESULTS

We repaired the encephalocele using a combined microsurgical and endoscopic multidisciplinary approach working through transcranial, transnasal, and transpalatal corridors. The procedure was completed in a single stage, during which the midline cleft lip was also repaired. The child made an excellent neurological and aesthetic recovery with preservation of pituitary and hypothalamic function, without evidence of CSF fistula.

CONCLUSION

The authors describe a novel multidisciplinary technique for treating a giant sphenoethmoidal encephalocele containing eloquent brain. The cleft lip was also repaired at the same time. The ability to work through multiple corridors can enhance the safety and efficacy of an often-treacherous operative endeavor.

Identification of intracranial hemorrhage progression by transcranial point-of-care ultrasound in a patient with prior hemicraniectomy: a case report

Transcranial ultrasound has been described as a tool to identify intracranial pathology, however, it is seldom used in the adult patient population due to poor imaging windows and rapid availability of more advanced imaging such as CT and MRI. We report a unique population in which transcranial ultrasound may be beneficial: those with a history of hemicraniectomy. We present a case of a 65-year-old male with a history of hemicraniectomy who suffered head trauma after a fall from his wheelchair. An initial non-contrast head CT scan identified an intracranial hemorrhage. Point-of-care bedside transcranial ultrasound was able to identify the progression of intracranial hemorrhage, which was confirmed by interval head CT. This prompted repeat CT imaging followed by neurosurgical intervention with the placement of an external ventricular drain in the right lateral ventricle. While ultrasound is unlikely to replace the need for more advanced imaging in these patients, point-of-care transcranial ultrasound may be a useful tool that can be employed rapidly at the bedside for interval screening in patients with hemicraniectomy and concern for new or worsening intracranial hemorrhage.

The effect of tDCS applied to the dorsolateral prefrontal cortex on cycling performance and the modulation of exercise induced pain

Transcranial direct current stimulation (tDCS) is a neuromodulatory tool purported to enhance endurance performance through reducing fatigue related perceptions, including exercise-induced pain (EIP). We examined whether tDCS of the left DLPFC (1) can reduce EIP during a fixed intensity cycling trial (FI), (2) can improve cycling time trial (TT) performance, and (3) whether this was affected by a bilateral or an extracephalic montage. This investigation was comprised of two parts (study one and two). In both studies, participants completed a 10-minute FI trial and a 15-minute TT after 10 min of 2 mA anodal left DLPFC tDCS, SHAM or no stimulation. In study one, 11 participants received tDCS via a bilateral montage. In study two, 20 participants received tDCS using an extracephalic montage. Pain was recorded throughout the FI and TT trials, with power output (PO) monitored during the TT. Study one saw no significant changes in pain (tDCS 4.3 ± 2.0; SHAM 4.0 ± 1.8; control 3.8 ± 1.4) during the FI trial and no significant differences in distance covered, pain or PO in the TT. In study two there were no differences in pain reported in the FI trial, or distance covered (P = 0.239), pain or PO in the TT. In summary, tDCS of the DLPFC did not induce analgesia and provided no ergogenic effect for TT performance, moreover these observations were consistent across both the extracephalic and bilateral montage. These findings are in line with an increasing number of studies demonstrating the inconsistent effects of tDCS.

Identification of brain structures and blood vessels by conventional ultrasound in rats

BACKGROUND

Ultrasound is a safe, non-invasive and affordable imaging technique for the visualization of internal structures and the measurement of blood velocity using Doppler imaging. However, despite all these advantages, no study has identified the structures of the rat brain using conventional ultrasound.

METHODS

A 13 MHz high frequency transducer was used to identify brain structures in the rat. The enlargement of the transcranial window was performed gradually using the ultrasound directly on the skin of the animal, then against the skull, then through a delimited craniotomy and finally through a complete craniotomy.

RESULTS

Our results showed that ultrasound allowed the identification of cerebral ventricles and subarachnoid cisterns, as well as the analysis of real-time monitoring of cerebral blood flow in the main brain arteries of the rat.

COMPARISON WITH EXISTING METHODS

Ultrasound is a tool with the potential to identify brain structures and blood vessels. In contrast to MRI, transcranial ultrasound is a fast, non-invasive, well tolerated and low-cost method and can be done at the bedside.

CONCLUSION

In the present study, we described an atlas of the main brain structures as well as the main vasculature in the rat using ultrasound. This technique could be applied in animal models of various neurological diseases.

Does photobiomodulation influence the resting-state brain networks in young human subjects?

Using fMRI (functional magnetic resonance imaging), we explored the effect of transcranial photobiomodulation on four major resting-state brain networks, namely the sensorimotor, salience, default mode and central executive networks, in normal young subjects. We used a vielight transcranial device (810 nm) and compared the scans in 20 subjects (mean age 30.0 ± 2.8 years) after active- and sham-photobiomodulation sessions. Four sets of analysis-independent components, network connectivity, infra-slow oscillatory power and arterial spin labelling-were undertaken. Our results showed that when comparing pre- with post-active and pre- with post-sham photobiomodulation scans, there were no substantial differences in activity across any of the four resting-state networks examined, indicating no clear photobiomodulation effect. When taken together with previous findings, we suggest that the impact of photobiomodulation becomes much clearer only after brain circuitry is altered, for example, after a neurone undergoes some change in its equilibrium or homeostasis, either during pathology or ageing, or during a change in functional activity when individuals are engaged in a specific task (e.g. evoked brain activity).

Effect of primary motor cortex excitability changes after quadripulse transcranial magnetic stimulation on kinesthetic sensitivity: A preliminary study

Muscle spindles provide the greatest contribution to kinesthetic perception. Primary motor cortex (M1) excitability changes in parallel with the intensity of kinesthetic perception inputs from muscle spindles; M1 is therefore involved in kinesthetic perception. However, the causal relationship between changes in kinesthetic sensitivity and M1 excitability is unclear. The purpose of this study was to test whether artificially and sustainably modulated M1 excitability causes changes in kinesthetic sensitivity in healthy individuals. We evaluated motor evoked potentials (MEP) in Experiment 1 and joint motion detection thresholds (JMDT) in Experiment 2 before and after quadripulse transcranial magnetic stimulation (QPS). Nine healthy right-handed male volunteers were recruited. In each experiment, participants received QPS or sham stimulation (Sham) on separate days. MEP amplitude and JMDT were recorded before and at 0, 15, 30, 45, and 60 min after QPS and Sham. Our results showed that M1 excitability and kinesthetic sensitivity increased after QPS, whereas neither changed after Sham. In the five subjects who participated in both experiments, there was a significant moderate correlation between M1 excitability and kinesthetic sensitivity. Thus, the long-lasting change in kinesthetic sensitivity may be due to changes in M1 excitability. In addition, M1 may play a gain adjustment role in the neural pathways of muscle spindle input.

Evaluation of the Uncertainty of Passive Cavitation Measurements for Blood-Brain Barrier Disruption Monitoring

Exposure to ultrasound combined with intravenous injection of microbubbles is a technique that can be used to temporarily disrupt the blood-brain barrier. Transcranial monitoring of cavitation can be done with one or more passive cavitation detectors (PCDs). However, the positioning of the PCDs relative to the cavitation site and the attenuation of these signals by the skull are two sources of error in the quantification of cavitation activity. The aim of this study was to evaluate in vitro the amplitude variation of cavitation signals that can be expected for an excised porcine skull model. The variation caused by the relative positioning of the PCD with respect to the cavitation site was quantified. A position-based correction of the signal amplitude was evaluated. Pig skull samples were used to assess variation in signal amplitude caused by bone. The overall coefficient of variation of the signals owing to these measurement biases was estimated at 30.8%.

Near-infrared Deep Brain Stimulation in Living Mice

Optogenetics has revolutionized the experimental interrogation of neural circuits in the past decade and holds potential for the treatment of neurological disorders. However, optogenetic stimulation of deep brain neurons requires the insertion of invasive optical fibers because the activating blue-green light cannot penetrate deep inside brain tissue. Here we describe a minimally invasive technique for the stimulation of deep brain neurons by transcranial near-infrared light (NIR), where upconversion nanoparticles (UCNPs) are used as optogenetic actuators to locally convert NIR into visible light. We detail the protocol to use locally injected UCNPs to stimulate dopamine neurons in the ventral tegmental area (VTA) of anesthetized mice by transcranial NIR.

Tuberculum sellae meningiomas

Tuberculum sellae meningiomas are challenging tumors that can cause significant morbidity for patients because of their proximity to critical neurovascular structures. By studying the anatomy of the tuberculum, the manner in which these tumors grow and cause deficits becomes apparent, as also the challenges associated with surgical removal and management. The necessary preoperative workup and grading scales for preoperative evaluation of tuberculum meningiomas are discussed. Traditional open cranial approaches for resection are discussed and contrasted with the endoscopic endonasal approach. Finally, postoperative management, patient outcomes, and adjuvant therapy for management of residual tumor are considered.

Quality of life and emotional burden after transnasal and transcranial anterior skull base surgery

OBJECTIVE

To analyze psychopathological outcome and health-related quality of life (QOL) for cohorts of patients undergoing transcranial or transnasal anterior skull base surgery.

METHODS

A prospective study of patients undergoing elective surgery for various entities of the anterior skull base was performed. Evaluation for depression (ADS-K score) and anxiety (PTSS, STAI-S, STAI-T, and ASI-3 scores) was done before surgery, at 3 and 12 months after surgery. The correlation between preoperative psychological burden and postoperative quality of life as measured by the SF-36 and EuroQol questionnaires was analyzed. Incidence and influence of these psychiatric comorbidities on clinical outcome were examined and compared between transnasal and transcranial subgroups.

RESULTS

We included 54 patients scheduled for surgery of a pituitary adenoma or meningioma of the anterior skull base between January 2013 and July 2017. Of these, a cohort of 40 (74.1%) completed follow-up interviews after 3 and 12 months. There were 60.0% female patients, median age was 57 years. 57.5% of patients had a meningioma and were operated transcranially, while 42.5% of patients received transnasal surgery for pituitary adenoma. The proportion of pathological anxiety scores significantly decreased from 75.0 to 45.0% (p = 0.002), without difference between transnasal and transcranial subgroups. After 3 months, mean EuroQol VAS score non-significantly increased by 0.07 (p = 0.236) across the entire cohort without significant difference between transcranial and transnasal subgroups (p = 0.478). The transnasal cohort tended to score higher in anxiety scores, whereas the transcranial cohort demonstrated higher depression scores without significant difference, respectively. The individually declared emotional burden significantly decreased from 6.7 to 4.0 on the ten-point Likert scale (p < 0.001) equally for both subgroups (transnasal, - 2.3; transcranial, - 3.0; p = 0.174). On last examination, about half of the patients in each subgroup (41.2% vs. 52.2%; p = 0.491) expressed a considerable recovery of preoperative bodily complaints such as headaches, dizziness, and unrest defined as a score of at least 8 on the Likert scaled item.

CONCLUSION

Both transnasal and transcranial approaches yield favorable postoperative QOL and psychopathological outcomes. The postoperative increase in QOL is partly influenced by preoperative expression of mental distress, which tends to resolve postoperatively.

Quantitative Anatomical Comparison of Anterior, Anterolateral and Lateral, Microsurgical and Endoscopic Approaches to the Middle Cranial Fossa

OBJECTIVE

To quantitatively compare different microsurgical and endoscopic approaches to the middle cranial fossa in a preclinical setting with a novel, computer-based research method.

METHODS

Different approaches were performed bilaterally in 5 head and neck specimens that underwent high-resolution computed tomography scans: 5 transcranial anterolateral (supraorbital, mini-pterional, pterional, pterional-transzygomatic, fronto-temporal-orbito-zygomatic) without and with anterior clinoidectomy; 2 transcranial lateral (subtemporal and subtemporal-transzygomatic); 2 endoscopic transnasal (transpterygoid, transpterygoid to infratemporal fossa); 2 endoscopic transorbital (superior eyelid and inferolateral), and endoscopic transmaxillary. A dedicated navigation system was used to quantify surgical working volumes and exposure of different areas of the middle cranial fossa (ApproachViewer, part of GTx-Eyes II, University Health Network, Toronto, Canada). Statistical analysis was performed using a mixed linear model with bootstrap resampling.

RESULTS

Endoscopic transnasal and fronto-temporal-orbito-zygomatic approaches with anterior clinoidectomy showed the largest surgical volumes. Endoscopic approaches allowed a wider exposure of medial anatomical surfaces (e.g., the petrous apex) compared with transcranial ones. Transcranial approaches with larger craniotomies allowed the widest exposure of superomedial anatomical structures (e.g., roof of cavernous sinus). The resection of the zygomatic arch allowed exposure of more medial surfaces with an inferior to superior trajectory.

CONCLUSIONS

This study implemented a novel neuronavigation-based research method to quantitatively compare different approaches to the middle cranial fossa; its results might guide, after consideration of clinical implications, the choice of the neurosurgical approach to different areas of this complex skull base region.

Short-term Effects of Transcranial Near-Infrared Photobiomodulation on Motor Performance in Healthy Human Subjects: An Experimental SingleBlind Randomized Clinical Trial

Introduction: Transcranial near-infrared photobiomodulation (NIR-PBM) is a new noninvasive procedure which transcranially applies a near-infrared wavelength to the scalp with a laser or a light-emitting diode (LED) source. Improvement in the neurological or psychological symptoms has been reported following light irradiation. However, to our knowledge, there is no study to investigate the effects of transcranial NIR-PBM on motor performance directly. Therefore, the objective of this study was to investigate the short-term effects of transcranial NIR-PBM on motor performance in healthy human subjects. Methods: In this experimental single-blind randomized clinical trial study, 56 right-handed healthy participants, whose ages ranged from 18 to 30, were randomly assigned to (1) Real transcranial NIR-PBMC3 group (n=14), (2) Sham transcranial NIR-PBMC3 group (n=14), (3) Real transcranial NIR-PBMC4 group (n=14), and (4) Sham transcranial NIR-PBMC4 group (n=14). We applied the 808 nm laser with irradiation energy density of 60 J/cm² and power density of 200 mw/cm² to the C3 or C4 points of the scalp. The number of finger taps as an indicator of motor performance was assessed by the finger-tapping test (FTT) before and after irradiation of transcranial NIR-PBM on the corresponding points of the scalp for 5 minutes. Results: The results showed that the number of finger taps in both right and left hands following the use of transcranial NIR-PBM in the real transcranial NIR-PBMC3 group significantly increased (P<0.05). Conclusion: We concluded that using transcranial NIR-PBM with a laser source on C3 point of the motor cortex in right-handed healthy people can increase the number of finger taps in both hands as an indicator of motor performance improvement.

Transcranial focused ultrasound pulsation suppresses pentylenetetrazol induced epilepsy in vivo

BACKGROUND

Epilepsy is a neurological disorder characterized by abnormal neuron discharge, and one-third of epilepsy patients suffer from drug-resistant epilepsy (DRE). The current management for DRE includes epileptogenic lesion resection, disconnection, and neuromodulation. Neuromodulation is achieved through invasive electrical stimulus including deep brain stimulation, vagus nerve stimulation, or responsive neurostimulation (RNS). As an alternative therapy, transcranial focused ultrasound (FUS) can transcranially and non-invasively modulate neuron activity.

OBJECTIVE

This study seeks to verify the use of FUS pulsations to suppress spikes in an acute epileptic small-animal model, and to investigate possible biological mechanisms by which FUS pulsations interfere with epileptic neuronal activity.

METHODS

The study used a total of 76 Sprague-Dawley rats. For the epilepsy model, rats were administered pentylenetetrazol (PTZ) to induce acute epileptic-like abnormal neuron discharges, followed by FUS exposure. Various ultrasound parameters were set to test the epilepsy-suppressing effect, while concurrently monitoring and analyzing electroencephalogram (EEG) signals. Animal behavior was monitored and histological examinations were conducted to evaluate the hazard posed by ultrasound exposure and the expression of neuronal activity markers. Western blotting was used to evaluate the correlation between FUS-induced epileptic suppression and the PI3K-mTOR signaling pathway.

RESULTS

We observed that FUS pulsations effectively suppressed epileptic activity and observed EEG spectrum oscillations; the spike-suppressing effect depended on the selection of ultrasound parameters and highly correlated with FUS exposure level. Expression level changes of c-Fos and GAD65 were confirmed in the cortex and hippocampus, indicating that FUS pulsations deactivated excitatory cells and activated GABAergic terminals. No tissue damage, inflammatory response, or behavioral abnormalities were observed in rats treated with FUS under these exposure parameters. We also found that the FUS pulsations down-regulated the S6 phosphorylation and decreased pAKT expression.

CONCLUSION

Our results suggest that pulsed FUS exposure effectively suppresses epileptic spikes in an acute epilepsy animal model, and finds that ultrasound pulsation interferes with neuronal activity and affects the PTZ-induced PI3K-Akt-mTOR pathway, which might help explain the mechanism underlying ultrasound-related epileptic spike control.

Polymethyl Methacrylate Cranioplasty Is an Effective Ultrasound Window to Explore Intracranial Structures: Preliminary Experience and Future Perspectives

OBJECTIVE

To evaluate the feasibility of transcranial sonography in patients harboring polymethylmethacrylate cranioplasties (PMMA-CP) and explore whether this material is a valid sonic window to explore intracerebral structures.

METHODS

In 6 patients, we performed transcranial sonography (TCS), using the PMMA-CP as sonic window. To test the reliability of ultrasound images, we collected several quantitative and qualitative measurements of intracranial structures and compared these sonographic images with standard computed tomography (CT) scan images.

RESULTS

We found that PMMA-CP is a very good sonic window and allowed us to obtain very good quality echographic images of intracranial structures, as shown by the comparison of measurements with CT scan, which were very reliable. The main drawback was related to the shape (i.e., the curvature) of the cranial flap, which hindered the ultrasound probe from correctly adhering to the scalp.

CONCLUSIONS

Although limited by the restricted number of cases, this preliminary experience represents the first available data about the serial use of TCS using PMMA-CP as window. These results open the path to the routine use of TCS to longitudinally control patients already harboring PMMA-CP. More, we here discuss its potential role in globally reducing the number of follow-up CT and magnetic resonance imaging scans required in different type of patients and pathologies.

Impaired cerebral autoregulation is associated with brain dysfunction in patients with sepsis

Background

Sepsis-associated brain dysfunction (SABD) is associated with high morbidity and mortality. The pathophysiology of SABD is multifactorial. One hypothesis is that impaired cerebral autoregulation (CAR) may result in brain hypoperfusion and neuronal damage leading to SABD.

Methods

We studied 100 adult patients with sepsis (July 2012–March 2017) (age = 62 [52–71] years; Acute Physiology and Chronic Health Evaluation II score on admission = 21 [15–26]). Exclusion criteria were acute or chronic intracranial disease, arrhythmias, extracorporeal membrane oxygenation, and known intra- or extracranial supra-aortic vessel disease. The site of infection was predominantly abdominal (46%) or pulmonary (28%). Transcranial Doppler was performed, insonating the left middle cerebral artery with a 2-MHz probe. Middle cerebral artery blood flow velocity (FV) and arterial blood pressure (ABP) signals were recorded simultaneously; Pearson’s correlation coefficient (mean flow index [Mxa]) between ABP and FV was calculated using MATLAB. Impaired CAR was defined as Mxa > 0.3.

Results

Mxa was 0.29 [0.05–0.62]. CAR was impaired in 50 patients (50%). In a multiple linear regression analysis, low mean arterial pressure, history of chronic kidney disease and fungal infection were associated with high Mxa. SABD was diagnosed in 57 patients (57%). In a multivariable analysis, altered cerebral autoregulation, mechanical ventilation and history of vascular disease were independent predictors of SABD.

Conclusions

Cerebral autoregulation was altered in half of the patients with sepsis and was associated with the development of SABD. These findings support the concept that cerebral hypoxia could contribute to the development of SABD.

Electronic supplementary material

The online version of this article (10.1186/s13054-018-2258-8) contains supplementary material, which is available to authorized users.

Effectiveness of tDCS augmentation for co-morbid obsessive compulsive disorder in chronic schizophrenia: A case report

Management of obsessive compulsive disorder (OCD) remains a challenge, particularly in individuals having co-existing psychotic symptoms. Even in patients with schizophrenia having a fair to good response in psychotic symptoms, these obsessive-compulsive symptoms defy response to antipsychotic and anti-obsessive pharmaco-therapeutic approach to a great extent. Recently developed neuromodulation techniques such as transcranial direct current stimulation (tDCS) can serve a viable and effective approach to manage such cases. The present paper documents the first utilization of tDCS (cathode: supplementary motor area; anode: right occipital cortex) as an add-on approach to pharmacotherapy to manage co-morbid OCD in a case of chronic schizophrenia.

Selective Mapping of Deep Brain Stimulation Lead Currents Using Acoustoelectric Imaging

We describe a new application of acoustoelectric imaging for non-invasive mapping of the location, magnitude and polarity of current generated by a clinical deep brain stimulation (DBS) device. Ultrasound at 1MHz was focused near the DBS device as short current pulses were injected across different DBS leads. A recording electrode detected the high-frequency acoustoelectric interaction signal. Linear scans of the US beam produced time-varying images of the magnitude and polarity of the induced current, enabling precise localization of the DBS leads within 0.70mm, a detection threshold of 1.75mA at 1 MPa and a sensitivity of 0.52 ± 0.07 μV/(mA*MPa). Monopole and dipole configurations in saline were repeated through a human skullcap. Despite 13.8-dB ultrasound attenuation through bone, acoustoelectric imaging was still >10dB above background with a sensitivity of 0.56 ± 0.10 μV/(mA*MPa). This proof-of-concept study indicates that selective mapping of lead currents through a DBS device may be possible using non-invasive acoustoelectric imaging.

Olfactory groove and tuberculum sellae meningioma resection by endoscopic endonasal approach versus transcranial approach: A systematic review and meta-analysis of comparative studies

Intracranial meningiomas such as olfactory groove meningioma (OGM) and tuberculum sellae meningioma (TSM) arising at the anterior skull base are amenable to surgical resection. Traditionally, this has been achieved by transcranial approaches (TCAs), however, there has been an evolution in an endoscopic endonasal approach (EEA) within recent years. The aim of this systematic review and meta-analysis was to determine if the EEA was superior to the TCA in managing these anterior skull base meningioma based on comparative studies only, and highlight the limitations of the current literature. Searches of seven electronic databases from inception to April 2018 were conducted following Preferred Reporting Items for Systematic reviews and Meta-Analyses (PRISMA) guidelines. There were 1479 articles identified for screening. Data were extracted and analyzed using meta-analysis of proportions. A total of 10 comparative studies satisfied criteria for inclusions. Resection by the EEA resulted in significantly less likelihood of worse vision (OR, 0.318; p = 0.039) when compared to TCA in OGM. However, EEA resulted also in significantly greater likelihoods of olfactory loss in OGM (OR, 4.511; p = 0.038) and TSM (OR, 3.075; p = 0.017), and CSF leak (OR, 3.854; p = 0.013) in TSM. In terms of surgical and prognosis outcomes, there was no statistically significant trend in favor of either approach in OGM or TSM. The EEA appears to confer a different postoperative complication profile when compared to the TCA in resecting OGM vs TSM which validates previous case-series comparisons. There is a need for longer-term studies that are larger, prospective, randomized in order to fully elucidate efficacy given slow tendency for progression of meningioma in order to develop a more rigorous approach selection algorithm.

[Staged transcranial and transsphenoidal surgery for giant pituitary adenomas: a retrospective study of 21 cases]

Objective: To investigate the effect of the second-stage transcranial and transsphenoidal approach for giant pituitary tumors. Methods: A retrospective review of 21 patients, who had undergone the transcranial surgery and then transsphenoidal surgery for giant pituitary adenomas from 2012 to 2015 in the neurosurgery department of West China Hospital, was performed. Visual findings, endocrine presentation, complications, and tumor types were collected. All data were based on clinical feature, MRI, and follow-up. Results: Among the 21 cases, gross total resection of tumor was achieved in 7 of all patients, subtotal in 11, and partial in 3. No intracranial hemorrhage or death occurred postoperatively. Postoperative infectionoccurred in one patient and cerebrospinal fluid leakage occurred in 3 patients. Four patients recovered after treatment. Conclusion: According to the clinical feature and MRI, it is safe and effective to choose the transcranial surgery and then transsphenoidal surgery for specific giant pituitary adenomas, which can improve treatment effects and reduce postoperative complications.

The Effects of Repetitive Transcranial Magnetic Stimulation at Dorsolateral Prefrontal Cortex in the Treatment of Migraine Comorbid with Depression: A Retrospective Open Study

Objective

The literature on managing migraine non-responsive to pharmacological approaches and that co-occurring with depression is scanty. The comorbid condition predicts a poorer prognosis for migraine as well as depression. The present report assesses efficacy and tolerability of high frequency repetitive transcranial magnetic stimulation (rTMS) over left dorsolateral prefrontal cortex as a treatment modality for migraine with comorbid depression.

Methods

The current retrospective chart review assesses effectiveness of high frequency rTMS over left dorsolateral prefrontal cortex as a treatment modality to manage migraine occurring comorbid with depression in 14 subjects.

Results

The mean scores on Migraine Disability Assessment Test (MIDAS) and depression rating scale reduced significantly from 21.14±3.01 and 20.71±3.95 at baseline to 13.93±6.09 and 14.21±5.52 respectively, after rTMS. There was significant improvement in migraine frequency, severity and functional disability assessed using MIDAS scores (p＜0.05) following high frequency rTMS compared to baseline.

Conclusion

There is a role of applying rTMS as a potential therapeutic modality in the integrated management of a distinct subgroup of migraine patients with comorbid depression.

Transcranial magnetic stimulation in migraine prophylaxis

Transcranial Magnetic Stimulation (TMS) is a non-invasive brain stimulation method used worldwide to make causality-based inferences about brain-behavior interactions, assess cortical reactivity, and map functionally relevant brain regions inducing a controlled current pulse in a specific cortical area. Clinical applications of TMS have shown promising results in the treatment of a vast number of psychiatric and neurological conditions such as headache disorders - migraine being one of the most encountered. In patients with migraine, the pharmacologic therapy is divided in urgent/ abortive treatment of the attack and prophylactic one. As first-line drugs simple analgesics and non-steroidal inflammatory are preferred. Nevertheless, many individuals continue to have attacks refractory to various prophylactic and/or abortive therapies, while others are at high risk of developing medication overuse headache. Among non-pharmacologic therapies TMS has been broadly studied as a preventive migraine treatment with good outcome results. Abbreviations: DLPFC - Dorsolateral prefrontal cortex, FDA - United States Food and Drug Administration, HF-TMS - High frequency transcranial magnetic stimulation, TMS - Transcranial magnetic stimulation, rTMS - Repetitive transcranial magnetic stimulation.

Delayed Visual Loss Following Transcranial Surgery for Tuberculum Sella Meningioma

Postoperative visual loss is a dreaded complication following transcranial excision of tuberculum sella meningioma. Visual deterioration is commonly noticed immediately after surgery, and delayed deterioration after 72 h is uncommon. We report a case of delayed postoperative deterioration in a 48-year-old female and discuss the possible mechanisms.

Transcranial Functional Ultrasound Imaging in Freely Moving Awake Mice and Anesthetized Young Rats without Contrast Agent

Functional ultrasound (fUS) imaging by ultrasensitive Doppler detection of blood volume was previously reported to measure adult rat brain activation and functional connectivity with unmatched spatiotemporal sampling (100 μm, 1 ms), but skull-induced attenuation of ultrasonic waves imposed skull surgery or contrast agent use. Also, fUS feasibility remains to be validated in mice, a major pre-clinical model organism. In the study described here, we performed full-depth ultrasensitive Doppler imaging and 3-D Doppler tomography of the entire mouse brain under anesthesia, non-invasively through the intact skull and skin, without contrast agents. Similar results were obtained in anesthetized young rats up to postnatal day 35, thus enabling longitudinal studies on postnatal brain development. Using a newly developed ultralight ultrasonic probe and an optimized ultrasonic sequence, we also performed minimally invasive full-transcranial fUS imaging of brain vasculature and whisker stimulation-induced barrel cortex activation in awake and freely moving mice, validating transcranial fUS for brain imaging, without anesthesia-induced bias, for behavioral studies.

New horizons for focused ultrasound (FUS) - therapeutic applications in neurodegenerative diseases

Access to the CNS and delivery of therapeutics across the blood-brain barrier remains a challenge for most treatments of major neurological diseases such as AD or PD. Focused ultrasound represents a potential approach for overcoming these barriers to treating AD and PD and perhaps other neurological diseases. Ultrasound (US) is best known for its imaging capabilities of organs in the periphery, but various arrangements of the transducers producing the acoustic signal allow the energy to be precisely focused (F) within the skull. Using FUS in combination with MRI and contrast agents further enhances accuracy by providing clear information on location. Varying the acoustic power allows FUS to be used in applications ranging from imaging, stimulation of brain circuits, to ablation of tissue. In several transgenic mouse models of AD, the use of FUS with microbubbles reduces plaque load and improves cognition and suggests the need to investigate this technology for plaque removal in AD. In PD, FUS is being explored as a way to non-invasively ablate the brain areas responsible for the tremor and dyskinesia associated with the disease, but has yet to be utilized for non-invasive delivery of putative therapeutics. The FUS approach also greatly increases the range of possible CNS therapeutics as it overcomes the issues of BBB penetration. In this review we discuss how the characteristics and various applications of FUS may advance the therapeutics available for treating or preventing neurodegenerative disorders with an emphasis on treating AD and PD.

How to deal with giant pituitary adenomas: transsphenoidal or transcranial, simultaneous or two-staged?

Giant pituitary adenomas (diameter >4 cm) are a challenge to treat, and there is no consensus on the optimal surgical strategy. We report here our experience in surgical management of these lesions. Adult patients with giant pituitary adenomas (n = 62; 54 non-functioning and eight hormone-secreting adenomas) who underwent surgical resection at our hospital from 2009 to 2015 were retrospectively reviewed. Surgical and clinical outcomes were analyzed. Single transsphenoidal and transcranial approaches were used in 43 (69.4%) and four (6.5%) patients, respectively. A combined transsphenoidal and transcranial approach was used in 13 patients (20.9%) and in two patients (3.2%), a transcranial procedure was followed 3 months later by a transsphenoidal approach. Greater than 90% resection was achieved in 47 cases (75.8%). During a mean follow-up period of 46.9 months, 49 patients (79%) showed improved visual impairment scores, while none experienced visual deterioration. There was no post-operative hemorrhage or mortality. A total of 27 patients (43.5%) received adjuvant medical and/or radiation therapy. At last follow-up, eight patients (12.9%) had recurrence. For giant pituitary adenoma, the transsphenoidal and transcranial approaches should be combined flexibly based on the characteristics of the tumor. In certain cases, a simultaneous combined approach can maximize tumor extirpation and lower the risk of swelling and bleeding of the residual tumor.

Microsurgical removal of craniopharyngioma: endoscopic and transcranial techniques for complication avoidance

Craniopharyngioma remains a challenging entity for neurosurgeons because of its midline, deep seated location and intimate relationship with critical neurovascular structures. Although gross total resection is ideal, the need to reduce surgical morbidity and preserve quality of life has led to a number of neurosurgical approaches which have attained this goal. Here we discuss the commonly used approaches for surgical resection and highlight technical considerations to reduce the potential of complications. We also discuss the mutually exclusive underlying genetic lesions in different histopathological subtypes that will likely lead to future treatment options for these tumors.

Transcranial functional ultrasound imaging of the brain using microbubble-enhanced ultrasensitive Doppler

Functional ultrasound (fUS) is a novel neuroimaging technique, based on high-sensitivity ultrafast Doppler imaging of cerebral blood volume, capable of measuring brain activation and connectivity in rodents with high spatiotemporal resolution (100 μm, 1 ms). However, the skull attenuates acoustic waves, so fUS in rats currently requires craniotomy or a thinned-skull window. Here we propose a non-invasive approach by enhancing the fUS signal with a contrast agent, inert gas microbubbles. Plane-wave illumination of the brain at high frame rate (500 Hz compounded sequence with three tilted plane waves, PRF = 1500Hz with a 128 element 15 MHz linear transducer), yields highly-resolved neurovascular maps. We compared fUS imaging performance through the intact skull bone (transcranial fUS) versus a thinned-skull window in the same animal. First, we show that the vascular network of the adult rat brain can be imaged transcranially only after a bolus intravenous injection of microbubbles, which leads to a 9 dB gain in the contrast-to-tissue ratio. Next, we demonstrate that functional increase in the blood volume of the primary sensory cortex after targeted electrical-evoked stimulations of the sciatic nerve is observable transcranially in presence of contrast agents, with high reproducibility (Pearson's coefficient ρ = 0.7 ± 0.1, p = 0.85). Our work demonstrates that the combination of ultrafast Doppler imaging and injection of contrast agent allows non-invasive functional brain imaging through the intact skull bone in rats. These results should ease non-invasive longitudinal studies in rodents and open a promising perspective for the adoption of highly resolved fUS approaches for the adult human brain.

•

We combined ultrafast sensitive Doppler with contrast-enhanced ultrasound imaging.

•

We retrieved highly-resolved neurovascular transcranial maps with contrast agents.

•

The presence of microbubbles compensates for the attenuation from the skull.

•

fUS is sensitive to the local hyperemia in the rat brain through the skull with microbubbles.

•

Transcranial fUS imaging allows non-invasive functional brain studies in rodents.

Transcranial direct middle meningeal artery puncture for the onyx embolization of dural arteriovenous fistula involving the superior sagittal sinus

A 66-year-old woman presented with intermittent paraparesis and generalized tonic-clonic seizure. Cerebral angiography demonstrated dural arteriovenous fistula (AVF) involving superior sagittal sinus (SSS), which was associated with SSS occlusion on the posterior one third. The dural AVF was fed by bilateral middle meningeal arteries (MMAs), superficial temporal arteries (STAs) and occipital arteries with marked retrograde cortical venous reflux. Transfemoral arterial Onyx embolization was performed through right MMA and STA, but it was not successful, which resulted in partial obliteration of dural AVF because of tortuous MMA preventing the microcatheter from reaching the fistula closely enough. Second procedure was performed through left MMA accessed by direct MMA puncture following small decortications of cranium overlying the MMA using diamond drill one week later. Microcatheter could be located far distally to the fistula through 5 F sheath placed into the MMA and complete obliteration of dural AVF was achieved using 3.9 cc of Onyx.

Randomized Sham Controlled Double-blind Trial of Repetitive Transcranial Magnetic Stimulation for Adults With Severe Tourette Syndrome

BACKGROUND

A small proportion of individuals with Tourette syndrome (TS) have a lifelong course of illness that fails to respond to conventional treatments. Open label studies have suggested that low frequency (1-Hz) repetitive transcranial magnetic stimulation (rTMS) targeting the supplementary motor area (SMA) may be effective in reducing tic severity.

OBJECTIVE/HYPOTHESIS

To examine the efficacy of rTMS over the SMA for TS in a randomized double-blind sham-controlled trial (RCT).

METHODS

We conducted a two-site RCT-rTMS with 20 adults with severe TS for 3 weeks. Treatment consisted of 15 sessions (1-Hz; 30 min; 1800 pulses per day) of active or sham rTMS at 110% of the motor threshold over the SMA. A subsequent 3 week course of active rTMS treatment was offered.

RESULTS

Of the 20 patients (16 males; mean age of 33.7 ± 12.2 years), 9 received active and 11 received sham rTMS. After 3 weeks, patients receiving active rTMS showed on average a 17.3% reduction in the YGTSS total tic score compared to a 13.2% reduction in those receiving sham rTMS, resulting in no statistically significant reduction in tic severity (P = 0.27). An additional 3 week open label active treatment for those patients (n = 7) initially randomized to active rTMS resulted in a significant overall 29.7% reduction in tic severity compared to baseline (P = 0.04).

CONCLUSION

This RCT did not demonstrate efficacy of 3-week SMA-targeted low frequency rTMS in the treatment of severe adult TS. Further studies using longer or alternative stimulation protocols are warranted.

First noninvasive thermal ablation of a brain tumor with MR-guided focused ultrasound

Magnetic resonance-guided focused ultrasound surgery (MRgFUS) allows for precise thermal ablation of target tissues. While this emerging modality is increasingly used for the treatment of various types of extracranial soft tissue tumors, it has only recently been acknowledged as a modality for noninvasive neurosurgery. MRgFUS has been particularly successful for functional neurosurgery, whereas its clinical application for tumor neurosurgery has been delayed for various technical and procedural reasons. Here, we report the case of a 63-year-old patient presenting with a centrally located recurrent glioblastoma who was included in our ongoing clinical phase I study aimed at evaluating the feasibility and safety of transcranial MRgFUS for brain tumor ablation. Applying 25 high-power sonications under MR imaging guidance, partial tumor ablation could be achieved without provoking neurological deficits or other adverse effects in the patient. This proves, for the first time, the feasibility of using transcranial MR-guided focused ultrasound to safely ablate substantial volumes of brain tumor tissue.

A two-site pilot randomized 3 day trial of high dose left prefrontal repetitive transcranial magnetic stimulation (rTMS) for suicidal inpatients

BACKGROUND

Suicide attempts and completed suicides are common, yet there are no proven acute medication or device treatments for treating a suicidal crisis. Repeated daily left prefrontal repetitive transcranial magnetic stimulation (rTMS) for 4-6 weeks is a new FDA-approved treatment for acute depression. Some open-label rTMS studies have found rapid reductions in suicidality.

DESIGN

This study tests whether a high dose of rTMS to suicidal inpatients is feasible and safe, and also whether this higher dosing might rapidly improve suicidal thinking. This prospective, 2-site, randomized, active sham-controlled (1:1 randomization) design incorporated 9 sessions of rTMS over 3 days as adjunctive to usual inpatient suicidality treatment. The setting was two inpatient military hospital wards (one VA, the other DOD).

PATIENTS

Research staff screened approximately 377 inpatients, yielding 41 adults admitted for suicidal crisis. Because of the funding source, all patients also had either post-traumatic stress disorder, mild traumatic brain injury, or both.

TMS METHODS

Repetitive TMS (rTMS) was delivered to the left prefrontal cortex with a figure-eight solid core coil at 120% motor threshold, 10 Hertz (Hz), 5 second (s) train duration, 10 s intertrain interval for 30 minutes (6000 pulses) 3 times daily for 3 days (total 9 sessions; 54,000 stimuli). Sham rTMS used a similar coil that contained a metal insert blocking the magnetic field and utilized electrodes on the scalp, which delivered a matched somatosensory sensation.

MAIN OUTCOME MEASURE

Primary outcomes were the daily change in severity of suicidal thinking as measured by the Beck Scale of Suicidal Ideation (SSI) administered at baseline and then daily, as well as subjective visual analog scale measures before and after each TMS session. Mixed model repeated measures (MMRM) analysis was performed on modified intent to treat (mITT) and completer populations.

RESULTS

This intense schedule of rTMS with suicidal inpatients was feasible and safe. Minimal side effects occurred, none differing by arm, and the 3-day retention rate was 88%. No one died of suicide within the 6 month followup. From the mITT analyses, SSI scores declined rapidly over the 3 days for both groups (sham change -15.3 points, active change -15.4 points), with a trend for more rapid decline on the first day with active rTMS (sham change -6.4 points, active -10.7 points, P = 0.12). This decline was more pronounced in the completers subgroup [sham change -5.9 (95% CI: -10.1, -1.7), active -13 points (95% CI: -18.7, -7.4); P = 0.054]. Subjective ratings of 'being bothered by thoughts of suicide' declined non-significantly more with active rTMS than with sham at the end of 9 sessions of treatment in the mITT analysis [sham change -31.9 (95% CI: -41.7, -22.0), active change -42.5 (95% CI: -53.8, -31.2); P = 0.17]. There was a significant decrease in the completers sample [sham change -24.9 (95% CI: -34.4, -15.3), active change -43.8 (95% CI: -57.2, -30.3); P = 0.028].

CONCLUSIONS

Delivering high doses of left prefrontal rTMS over three days (54,000 stimuli) to suicidal inpatients is possible and safe, with few side effects and no worsening of suicidal thinking. The suggestions of a rapid anti-suicide effect (day 1 SSI data, Visual Analogue Scale data over the 3 days) need to be tested for replication in a larger sample.

TRIAL REGISTRATION

ClinicalTrials.gov Identifier: NCT01212848, TMS for suicidal ideation.