Contralateral Area Research Articles

The pH sensitivity of APT-CEST using phosphorus spectroscopy as a reference method.

The pH value is a potential physiological marker for clinical diagnosis as it is altered in pathologies such as tumors. While intracellular pH can be measured noninvasively via phosphorus spectroscopy (31 P MRSI), Amide Proton Transfer-Chemical Exchange Saturation Transfer (APT-CEST) MRI has been suggested as an alternative method for pH quantification. To assess the suitability of APT-CEST contrast for pH quantification, two approaches (magnetization transfer ratio asymmetry [MTRasym ] and Lorentzian difference analysis [LDA]) for analyzing the Z-spectrum have been correlated with pH values obtained by 31 P MRSI. Fourteen patients with glioblastoma and 12 healthy controls were included. In contrast to MTRasym , the LDA is modeling the direct water saturation and the semi-solid magnetization transfer, allowing a separate evaluation of the aliphatic nuclear Overhauser effect and the APT-CEST. The results of our study show that the pH values obtained by 31 P MRSI correspond well with both methods describing the APT-CEST contrast. Two-sample t-test showed significant differences in MTRasym , LDA and pH obtained by 31 P MRSI for regions of interest in glioblastoma, contralateral control areas and normal appearing white matter (P<0.001). A slightly improved correlation between the amide signal and pH was found after performing LDA (r=0.78) compared with MTRasym (r=0.70). While both methods can be used to monitor pH changes, the LDA approach appears to be better suited.

Impaired functional connectivity of limbic system in migraine without aura.

Aberrant functional connectivity of brain networks has been demonstrated in migraine sufferers. Functional magnetic resonance imaging (fMRI) may illustrate altered connectivity in patients suffering from migraine without aura (MwoA). Here, we applied a seed-based approach based on limbic regions to investigate disrupted functional connectivity between spontaneous migraine attacks. Resting-state fMRI data were obtained from 28 migraine patients without aura and 23 well-matched healthy controls (HC). The functional connectivity of the limbic system was characterized using a seed-based whole-brain correlation method. The resulting functional connectivity measurements were assessed for correlations with other clinical features. Neuropsychological data revealed significantly increased connectivity between the limbic system (bilateral amygdala and right hippocampus) and left middle occipital gyrus (MOG), and a positive correlation was revealed between disease duration and connective intensity of the left amygdala and the ipsilateral MOG. There was decreased functional connectivity between the right amygdala and contralateral orbitofrontal cortex (OFC). In addition, resting-state fMRI showed that, compared to HC, patients without aura had significant functional connectivity consolidation between the bilateral hippocampus and cerebellum, and a negative correlation was detected between scores on the headache impact test (HIT) and connectivity intensity of the right hippocampus and bilateral cerebellum. There was decreased functional connectivity between the left hippocampus and three brain areas, encompassing the bilateral inferior parietal gyri (IPG) and contralateral supplementary motor area (SMA). There were no structural differences between the two groups. Our data suggest that migraine patients have disrupted limbic functional connectivity to pain-related regions of the modulatory and encoding cortices, which are associated with specific clinical characteristics. Disturbances of resting-state functional connectivity may play a key role in neuropathological features, perception and affection of migraine. The current study provides further insights into the complex scenario of migraine mechanisms. .

Effects of rTMS and intensive rehabilitation in Parkinson's Disease on learning and retention.

Movement is accompanied by modulation of oscillatory activity in different ranges over the sensorimotor areas. This increase is more evident in normal subjects and less in patients with Parkinson's Disease (PD), a disorder associated with deficits in the formation of new motor skills. Here, we investigated whether such EEG changes improved in a group of PD patients, after two different treatments and whether this relates to performance. Subjects underwent either a session of 5 Hz repetitive Transcranial Magnetic Stimulation (rTMS) over the right posterior parietal cortex or a 4-week Multidisciplinary Intensive Rehabilitation Treatment (MIRT). We used a reaching task with visuo-motor adaptation to a rotated display in incremental 10° steps up to 60°. Retention of the learned rotation was tested before and after either intervention over two consecutive days. High-density EEG was recorded throughout the testing. We found that patients adapted their movements to the rotated display similarly to controls, although retention was poorer. Both rTMS and MIRT lead to improvement in retention of the learned rotation. Mean beta modulation levels changed significantly after MIRT and not after rTMS. These results suggest that rTMS produced local improvement reflected in enhanced short-term skill retention; on the other hand, MIRT determined changes across the contralateral sensorimotor area, reflected in beta EEG changes.

A computational pipeline to find lobule-specific electric field distribution during non-invasive cerebellar stimulation.

Cerebellar Transcranial direct current stimulation (ctDCS) of cerebellar lobules is challenging due to the complexity of the cerebellar structure. Therefore, we present a freely available computational pipeline to determine the subject-specific lobule-specific electric field distribution during ctDCS. The computational pipeline isolates subject-specific cerebellar lobules based on a spatially unbiased atlas template (SUIT) for the cerebellum, and then calculates the lobule-specific electric field distribution during ctDCS. The computational pipeline was tested using Colin27 Average Brain. The 5 cm × 5 cm anode was placed 3 cm lateral to inion, and the same sized cathode was placed on the contralateral supra-orbital area (called Manto montage) and buccinators muscle (called Celnik montage). A published 4x1 HD-ctDCS electrode montage was also implemented for a comparison using analysis of variance. The electric field strength of both the Celnik and the Manto montages affected the lobules Crus II, VIIb, VIII, and IX of the targeted cerebellar hemispheres while Manto montage had a more bilateral effect. The HD-ctDCS montage primarily affected the lobules Crus I, Crus II, VIIb of the targeted cerebellar hemisphere. Our freely available subject-specific computational modeling pipeline can be used to analyze lobulespecific electric field distribution to select an optimal ctDCS electrode montage.

Selective spatial attention involves two alpha-band components associated with distinct spatiotemporal and functional characteristics

Attention is crucial for efficiently coordinating resources over multiple objects in a visual scene. Recently, a growing number of studies suggest that attention is implemented through a temporal organization process during which resources are dynamically allocated over a multitude of objects, yet the associated neural evidence, particularly in low-level sensory areas, is still limited. Here we used EEG recordings in combination with a temporal response function (TRF) approach to examine the spatiotemporal characteristics of neuronal impulse response in covert selective attention. We demonstrate two distinct alpha-band components – one in post-central parietal area and one in contralateral occipital area – that are involved in coordinating neural representations of attended and unattended stimuli. Specifically, consistent with previous findings, the central alpha-band component showed enhanced activities for unattended versus attended stimuli within the first 200 ms temporal lag of TRF response, suggesting its inhibitory function in attention. In contrast, the contralateral occipital component displayed relatively earlier activation for the attended than unattended one in the TRF response. Furthermore, the central component but not the occipital component was correlated with attentional behavioral performance. Finally, the parietal area exerted directional influences on the occipital activity through alpha-band rhythm. Taken together, spatial attention involves two hierarchically organized alpha-band components that are associated with distinct spatiotemporal characteristics and presumably play different functions.

P34-F Cooling the skin for assessing trigeminal small-fibre function

Background To investigate whether cold thermal cutaneous stimulation evokes reproducible CEPs from the trigeminal territory and may prove a reliable diagnostic tool in facial neuropathic pain. Methods Using a novel device consisting of micro-Peltier elements able to steep cooling ramps of up to −300°C/s we recorded cold evoked potentials after stimulation of the supraorbital and perioral regions in 15 healthy participants and in two patients with exemplary facial neuropathic pain conditions. In healthy participants and in patients we also compared cold evoked potentials with laser evoked potentials. Results In healthy participants cold stimulation evoked reproducible scalp potentials, similar to those elicited by laser pulses, though with a latency 30-ms longer, consisting of a vertex complex, preceded by a negative component over the contralateral temporal areas. Unlike LEPs, perioral cold stimulation did not yield shorter latency and larger amplitude CEPs than supraorbital stimulation. In patients with facial neuropathic pain, cold evoked potential recording showed the selective damage of cold pathways, providing complementary information to laser evoked potential recording. Conclusion Our clinical and neurophysiological study shows that this new device, evoking reproducible scalp potentials, provides reliable information on trigeminal cold small-fibres and might be useful for investigating patients with facial neuropathic pain.

Neural Activations Associated With Friction Stimulation on Touch-Screen Devices.

Tactile sensation largely influences human perception, for instance when using a mobile device or a touch screen. Active touch, which involves tactile and proprioceptive sensing under the control of movement, is the dominant tactile exploration mechanism compared to passive touch (being touched). This paper investigates the role of friction stimulation objectively and quantitatively in active touch tasks, in a real human-computer interaction on a touch-screen device. In this study, 24 participants completed an active touch task involved stroking the virtual strings of a guitar on a touch-screen device while recording the electroencephalography (EEG) signal. Statistically significant differences in beta and gamma oscillations in the middle frontal and parietal areas at the late period of the active touch task are found. Furthermore, stronger beta event-related desynchronization (ERD) and rebound in the presence of friction stimulation in the contralateral parietal area are observed. However, in the ipsilateral parietal area, there is a difference in beta oscillation only at the late period of the motor task. As for implicit emotion communication, a significant increase in emotional responses for valence, arousal, dominance, and satisfaction is observed when the friction stimulation is applied. It is argued that the friction stimulation felt by the participants' fingertip in a touch-screen device further induces cognitive processing compared to the case when no friction stimulation is applied. This study provides objective and quantitative evidence that friction stimulation is able to affect the bottom-up sensation and cognitive processing.

Effects of Focal Vibration over Upper Limb Muscles on the Activation of Sensorimotor Cortex Network: An EEG Study

Studying the therapeutic effects of focal vibration (FV) in neurorehabilitation is the focus of current research. However, it is still not fully understood how FV on upper limb muscles affects the sensorimotor cortex in healthy subjects. To explore this problem, this experiment was designed and conducted, in which FV was applied to the muscle belly of biceps brachii in the left arm. During the experiment, electroencephalography (EEG) was recorded in the following three phases: before FV, during FV, and two minutes after FV. During FV, a significant lower relative power at C3 and C4 electrodes and a significant higher connection strength between five channel pairs (Cz-FC1, Cz-C3, Cz-CP6, C4-FC6, and FC6-CP2) in the alpha band were observed compared to those before FV. After FV, the relative power at C4 in the beta band showed a significant increase compared to its value before FV. The changes of the relative power at C4 in the alpha band had a negative correlation with the relative power of the beta band during FV and with that after FV. The results showed that FV on upper limb muscles could activate the bilateral primary somatosensory cortex and strengthen functional connectivity of the ipsilateral central area (FC1, C3, and Cz) and contralateral central area (CP2, Cz, C4, FC6, and CP6). These results contribute to understanding the effect of FV over upper limb muscles on the brain cortical network.

Xenon improves long-term cognitive function, reduces neuronal loss and chronic neuroinflammation, and improves survival after traumatic brain injury in mice

BackgroundXenon is a noble gas with neuroprotective properties that can improve short and long-term outcomes in young adult mice after controlled cortical impact. This follow-up study investigates the effects of xenon on very long-term outcomes and survival. MethodsC57BL/6N young adult male mice (n=72) received single controlled cortical impact or sham surgery and were treated with either xenon (75% Xe:25% O2) or control gas (75% N2:25% O2). Outcomes measured were: (i) 24 h lesion volume and neurological outcome score; (ii) contextual fear conditioning at 2 weeks and 20 months; (iii) corpus callosum white matter quantification; (iv) immunohistological assessment of neuroinflammation and neuronal loss; and (v) long-term survival. ResultsXenon treatment significantly reduced secondary injury (P<0.05), improved short-term vestibulomotor function (P<0.01), and prevented development of very late-onset traumatic brain injury (TBI)-related memory deficits. Xenon treatment reduced white matter loss in the contralateral corpus callosum and neuronal loss in the contralateral hippocampal CA1 and dentate gyrus areas at 20 months. Xenon's long-term neuroprotective effects were associated with a significant (P<0.05) reduction in neuroinflammation in multiple brain areas involved in associative memory, including reduction in reactive astrogliosis and microglial cell proliferation. Survival was improved significantly (P<0.05) in xenon-treated animals compared with untreated animals up to 12 months after injury. ConclusionsXenon treatment after TBI results in very long-term improvements in clinically relevant outcomes and survival. Our findings support the idea that xenon treatment shortly after TBI may have long-term benefits in the treatment of brain trauma patients.

Functional imaging localization of complex organic hallucinations

ABSTRACTBackground: fMRI of mental phenomena is quite difficult to perform because lack of patient’s cooperation or because the symptoms are stable. In some exceptional cases, however, fMRI and DTI are capable to provide insights on the anatomy of organic hallucinations. Methods: In this report we describe a 14-year-old boy with a left fronto-dorsal tumor who experienced chronic complex brief, frequent and repetitive complex visual and auditory hallucinations. His clinical picture included multiple and severe social and mood problems. During a presurgical fMRI mapping the patient complained of having the visual and auditory hallucinations. A block-design FMRI paradigm was obtained from the event timecourse. Deterministic DTI of the brain was obtained seeding the lesion as ROI. The patient underwent surgery and electrocorticography of the lesional area. Results: The fMRI of the hallucinations showed activation in the left inferior frontal gyrus (IFG) and the peri-lesional area. The tractography of the tumor revealed structural aberrant connectivity to occipital and temporal areas in addition to the expected connectivity with the IFG via the aslant fasciculus and homotopic contralateral areas. Intraoperative EEG demonstrated epileptic discharges in the tumor and neighboring areas. After resection, the patient’s hallucinations stopped completely. He regained his normal social life and recover his normal mood. He remained asymptomatic for 90 days. Afterwards, hallucinations reappeared but with less intensity. Conclusions: To our knowledge, this is the first reported case of combined functional and structural connectivity imaging demonstrating brain regions participating in a network involved in the generation of complex auditory and visual hallucinations.

Meta-analysis of RCTs on the effect of vestibulodynia treatment on female sexual function

Vulvodynia and vestibulodynia affect to some 10% of women, tend to be recurrent, and alter sexual function. A large number of treatments have been suggested, although clinical results are controversial. We carried out a systematic review and meta-analysis of randomized clinical trials (RCTs) to assess changes in sexual function with different treatments. Five datafiles were searched without language restriction, for RCTs comparing any clinical intervention as compared to placebo, sham intervention, or no therapy, until October 2018. The authors independently evaluated eligibility based on articles’ titles, abstracts, and full-text articles. A total of 304 unique records were found, and four RCTs provided information about six interventions: (i) Transcranial direct current stimulation (intensity = 2 mA) for 20 minutes, 10 sessions over a two-weeks period, with the anode positioned over the primary motor cortex, and the cathode, over the contralateral supraorbital area; (ii) transcutaneous electrical nerve stimulation twice a week delivered through a vaginal probe, 20 sessions (10 weeks); (iii) 20 units of botulinum toxin A in 0.5 mL injected symmetrically in the muscle bulbospongiosus; (iv) topical lidocaine; (v) oral desimipramine; and (vi) combined topical lidocaine + oral desimipramine. Sexual function assessment was performed with the Female Sexual Function Index (FSFI), the Index of Sexual Satisfaction (ISS), and the Female Sexual Dysfunction (FSD). Random effects meta-analyses with the inverse variance method were used to evaluate the effects of interventions on outcomes. Effects were expressed as mean differences (MD) and their 95% confidence intervals (CI). There were significant increases in FSFI scores (n = 3 interventions; MD = 5.60; 95%CI 0.98 to 10.22; I2 = 57%; p = 0.02); and for the ISS (n = 3 interventions; MD = −5.14; 95%CI −5.14; 95% CI −9.52 to −0.75; I2 = 51%; p = 0.02). There was not significant difference using the FSD (n = 2 interventions; MD = −3. 69: 95%CI = −2.81 to 10.20; I2 = 0%; p = 0.27). Further studies are needed to confirm found trends to identify the appropriate treatment for vestibulodynia.

Biportal Endoscopic Spinal Surgery for Lumbar Spinal Stenosis.

Biportal endoscopic spinal surgery (BESS) is a minimally invasive spinal surgery, which is basically similar to microscopic spinal surgery in terms of the use of floating technique and technically similar to conventional percutaneous endoscopic spinal surgery in terms of the use of endoscopic or arthroscopic instruments. Using two independent portals (viewing and working) and maintaining a certain distance from the bony and neural structures allow closer access to the target lesion through a panoramic view by free handling of the scope and instruments rather than through a fixed view by docking into the Kambin’s triangle. Minimally invasive surgery allows for reduced dissection and inevitable muscle injury, preserving stability and reducing risks of restabilization. The purpose of fusion surgery is the same as that of the three surgical techniques stated above. Its wider range of view helps to overcome limitations of conventional endoscopic spinal surgery and to supplement the weak points of microscopic spinal surgery, such as limited working space in a tubular retractor and difficulty in accessing the contralateral area. This technique provides an alternative to unilateral or bilateral decompression of lumbar central spinal stenosis, foraminal stenosis, low-grade spondylolisthesis, and adjacent segment degeneration. Early clinical outcomes are promising despite potential for complications, such as dural tearing and postoperative epidural hematoma, similar to other procedures. Merits of BESS include decreased postoperative infection rate due to continuous irrigation throughout the procedure and decreased need for fusion surgery for one- or two-level lumbar stenosis by wide sublaminar and foraminal decompression with minimal sacrifice of stabilizing structures.

A New Light-Emitting, Fabric-Based Device for Photodynamic Therapy of Actinic Keratosis: Protocol for a Randomized, Controlled, Multicenter, Intra-Individual, Phase II Noninferiority Study (the Phosistos Study).

BackgroundActinic keratosis (AK) is a common early in situ skin carcinoma caused by long-term sun exposure and usually develops on sun-exposed skin areas. Left untreated, AK may progress to squamous cell carcinoma. To prevent such risk, most clinicians routinely treat AK. Therapy options for AK include cryotherapy, topical treatments, curettage, excision surgery, and photodynamic therapy (PDT).ObjectiveThe aim of this study is to assess the noninferiority, in terms of efficacy at 3 months, of a PDT protocol involving a new light-emitting device (PDT using the Phosistos protocol [P-PDT]) compared with the conventional protocol (PDT using the conventional protocol [C-PDT]) in the treatment of AK.MethodsIn this randomized, controlled, multicenter, intra-individual, phase II noninferiority clinical study, subjects with AK of the forehead and scalp are treated with P-PDT on one area and with C-PDT on the contralateral area. In both areas, lesions are prepared and methyl aminolevulinate (MAL) is applied. Thirty minutes after MAL application, the P-PDT area is exposed to red light at low irradiance (1.3 mW/cm2) for 2.5 hours so that a light dose of 12 J/cm2 is achieved. In the control area (C-PDT area), a 37 J/cm2 red light irradiation is performed 3 hours after MAL application. Recurrent AK at 3 months is retreated. The primary end point is the lesion complete response rate at 3 months. Secondary end points include pain scores at 1 day, local tolerance at 7 days, lesion complete response rate at 6 months, cosmetic outcome at 3 and 6 months, and patient-reported quality of life and satisfaction throughout the study. A total of 45 patients needs to be recruited.ResultsClinical investigations are complete: 46 patients were treated with P-PDT on one area (n=285 AK) and with C-PDT on the contralateral area (n=285 AK). Data analysis is ongoing, and statistical results will be available in the first half of 2019.ConclusionsIn case of noninferiority in efficacy and superiority in tolerability of P-PDT compared with C-PDT, P-PDT could become the treatment of choice for AK.Trial RegistrationClinicalTrials.gov NCT03076892; https://clinicaltrials.gov/ct2/show/NCT03076892 (Archived by WebCite at http://www.webcitation.org/779qqVKek)International Registered Report Identifier (IRRID)DERR1-10.2196/12990

Intermittent Theta-Burst Stimulation Reverses the After-Effects of Contralateral Virtual Lesion on the Suprahyoid Muscle Cortex: Evidence From Dynamic Functional Connectivity Analysis.

Contralateral intermittent theta burst stimulation (iTBS) can potentially improve swallowing disorders with unilateral lesion of the swallowing cortex. However, the after-effects of iTBS on brain excitability remain largely unknown. Here, we investigated the alterations of temporal dynamics of inter-regional connectivity induced by iTBS following continuous TBS (cTBS) in the contralateral suprahyoid muscle cortex. A total of 20 right-handed healthy subjects underwent cTBS over the left suprahyoid muscle motor cortex and then immediately afterward, iTBS was applied to the contralateral homologous area. All of the subjects underwent resting-state functional magnetic resonance imaging (Rs-fMRI) pre- and post-TBS implemented on a different day. We compared the static and dynamic functional connectivity (FC) between the post-TBS and the baseline. The whole-cortical time series and a sliding-window correlation approach were used to quantify the dynamic characteristics of FC. Compared with the baseline, for static FC measurement, increased FC was found in the precuneus (BA 19), left fusiform gyrus (BA 37), and right pre/post-central gyrus (BA 4/3), and decreased FC was observed in the posterior cingulate gyrus (PCC) (BA 29) and left inferior parietal lobule (BA 39). However, in the dynamic FC analysis, post-TBS showed reduced FC in the left angular and PCC in the early windows, and in the following windows, increased FC in multiple cortical areas including bilateral pre- and postcentral gyri and paracentral lobule and non-sensorimotor areas including the prefrontal, temporal and occipital gyrus, and brain stem. Our results indicate that iTBS reverses the aftereffects induced by cTBS on the contralateral suprahyoid muscle cortex. Dynamic FC analysis displayed a different pattern of alteration compared with the static FC approach in brain excitability induced by TBS. Our results provide novel evidence for us in understanding the topographical and temporal aftereffects linked to brain excitability induced by different TBS protocols and might be valuable information for their application in the rehabilitation of deglutition.

Cerebellar Lobules Optimal Stimulation (CLOS): A Computational Pipeline to Optimize Cerebellar Lobule-Specific Electric Field Distribution.

ObjectiveCerebellar transcranial direct current stimulation (ctDCS) is challenging due to the complexity of the cerebellar structure which is reflected by the well-known variability in ctDCS effects. Therefore, our objective is to present a freely available computational modeling pipeline for cerebellar lobules’ optimal stimulation (CLOS).MethodsCLOS can optimize lobule-specific electric field distribution following finite element analysis (FEA) using freely available computational modeling pipelines. We modeled published ctDCS montages with 5 cm × 5 cm anode placed 3 cm lateral to inion, and the same sized cathode was placed on the: (1) contralateral supra-orbital area (called Manto montage), and (2) buccinators muscle (called Celnik montage). Also, a published (3) 4×1 HD-ctDCS electrode montage was modeled. We also investigated the effects of the subject-specific head model versus Colin 27 average head model on lobule-specific electric field distribution. Three-way analysis of variance (ANOVA) was used to determine the effects of lobules, montage, and head model on the electric field distribution. The differences in lobule-specific electric field distribution across different freely available computational pipelines were also evaluated using subject-specific head model. We also presented an application of our computational pipeline to optimize a ctDCS electrode montage to deliver peak electric field at the cerebellar lobules VII-IX related to ankle function.ResultsEta-squared effect size after three-way ANOVA for electric field strength was 0.05 for lobule, 0.00 for montage, 0.04 for the head model, 0.01 for lobule∗montage interaction, 0.01 for lobule∗ head model interaction, and 0.00 for montage∗head model interaction. The electric field strength of both the Celnik and the Manto montages affected the lobules Crus I/II, VIIb, VIII, and IX of the targeted cerebellar hemisphere where Manto montage had a spillover to the contralateral cerebellar hemisphere. The 4×1 HD-ctDCS montage primarily affected the lobules Crus I/II of the targeted cerebellar hemisphere. All three published ctDCS montages were found to be not optimal for ankle function (lobules VII-IX), so we presented a novel HD-ctDCS electrode montage.DiscussionOur freely available CLOS pipeline can be leveraged to optimize electromagnetic stimulation to target cerebellar lobules related to different cognitive and motor functions.

10 Hz tACS Over Somatosensory Cortex Does Not Modulate Supra-Threshold Tactile Temporal Discrimination in Humans.

Perception of physical identical stimuli can differ over time depending on the brain state. One marker of this brain state can be neuronal oscillations in the alpha band (8–12 Hz). A previous study showed that the power of prestimulus alpha oscillations in the contralateral somatosensory area negatively correlate with the ability to temporally discriminate between two subsequent tactile suprathreshold stimuli. That is, with high alpha power subjects were impaired in discriminating two stimuli and more frequently reported to perceive only one stimulus. While this previous study found correlative evidence for a role of alpha oscillations on tactile temporal discrimination, here, we aimed to study the causal influence of alpha power on tactile temporal discrimination by using transcranial alternating current stimulation (tACS). We hypothesized that tACS in the alpha frequency should entrain alpha oscillations and thus modulate alpha power. This modulated alpha power should alter temporal discrimination ability compared to a control frequency or sham. To this end, 17 subjects received one or two electrical stimuli to their left index finger with different stimulus onset asynchronies (SOAs). They reported whether they perceived one or two stimuli. Subjects performed the paradigm before (pre), during (peri), and 25 min after tACS (post). tACS was applied to the contralateral somatosensory-parietal area with either 10, 5 Hz or sham on three different days. We found no significant difference in discrimination abilities between 10 Hz tACS and the control conditions, independent of SOAs. In addition to choosing all SOAs as the independent variable, we chose individually different SOAs, for which we expected the strongest effects of tACS. Again, we found no significant effects of 10 Hz tACS on temporal discrimination abilities. We discuss potential reasons for the inability to modulate tactile temporal discrimination abilities with tACS.

Unusual conservative treatment of a complicated pacemaker pocket infection: a case report

BackgroundFor patients with complicated generator pocket infection, expert consensuses universally advocate complete device and leads removal followed by delayed replacement on the contralateral side. We cured our patient by partial generator removal and reimplantation of sterilized pulse generator on the ipsilateral side. We also performed a literature review about incomplete removal therapy for the management of cardiac implantable electronic device infection.Case presentationAn 86-year-old Chinese Han man was diagnosed as having third-degree atrioventricular block and received a permanent double-chamber pacemaker in his left prepectoral area 15 years ago. Nine years later, the entire system was removed because of confirmed infection, and a new device was reimplanted in the contralateral area. He developed skin necrosis around the pacemaker pocket after 1 year, and his generator was renewed without leads extraction at another medical center. He was subsequently admitted several times for surgical tissue debridement at another institution due to extended skin necrosis. At the time of the new admission, he had severe infection, heart failure, and hypoalbuminemia. He was diagnosed as having complicated pacemaker pocket infection. Our preferred treatment strategy was for complete removal of both the generator and transvenous pacing leads, and we intended to implant an epicardial pacemaker in our patient if necessary. However, he rejected the treatment strategy and firmly refused to replace his generator. We had to attempt a novel pacemaker-preserving strategy considering our patient’s severe comorbidities. Finally, we cured him by partial generator removal and reimplantation of the sterilized pulse generator on the ipsilateral side. There was no sign of wound dehiscence or infection during a 6-month follow-up.ConclusionsWe would posit that partial removal of infected generators combined with conservative treatment may be a proper treatment of complicated generator pocket infection, especially for those who are susceptible to cardiac complications. Reimplantation of a sterilized pulse generator on the ipsilateral side may be an option if patients reject a new device and contralateral vascular condition is not really suitable. Opting for such treatment should be at the consideration of the primary care physician based on the condition of the patient.

Contralateral segmental transcutaneous electrical nerve stimulation inhibits nociceptive flexion reflex in healthy participants.

Transcutaneous electrical nerve stimulation (TENS) is a non-invasive treatment to relieve pain. Contralateral TENS (i.e. TENS administered to the contralateral side of a painful body part) is beneficial when TENS cannot be directly applied to pain site, such as in cases of trauma. Although TENS produces segmental analgesia in an ipsilateral limb, it has been unclear whether TENS produces higher analgesic effects in the contralateral segmental area. The aim of the present study was to investigate the analgesic effects of TENS in contralateral segmental or extra-segmental areas on physiological and subjective pain outcomes, using a nociceptive flexion reflex (NFR) method. We randomly allocated 60 healthy participants to three groups: contralateral segmental TENS (CS-TENS); contralateral extra-segmental TENS (CE-TENS); and contralateral placebo TENS (CP-TENS). CS-TENS was applied to right superficial sural nerve and CE-TENS was applied to the right superficial femoral nerve, each for 30minutes. The magnitude of the NFR elicited by electrical stimulation of the left sural nerve was measured at baseline and at three subsequent 10-minute intervals. Subjective pain intensity was measured simultaneously with a visual analogue scale (VAS). At 30min, the NFR magnitude of CS-TENS group was significantly lower than that of the CP-TENS group (p=0.021). There were no significant differences in VAS scores among the groups at any time point. Our findings suggest that CS-TENS inhibited NFR. Although there was no significant between-group difference in subjective pain intensity, factors such as a placebo effect probably impacted it. Our findings provide support for the contralateral approach at stimulation sites when TENS cannot be directly administered to a pain site (e.g. due to disease or trauma).

Dorsal root entry zone ablation for lower limb pain after thoracolumbar spine fracture

Objective To evaluate the efficacy and safety of dorsal root entry zone (DREZ) ablation surgery in the treatment of lower limb pain after thoracolumbar fracture, and to analyze the underlying mechanism of lower limb pain. Methods From October 2011 to December 2016, a total of 20 patients with lower limb pain after thoracolumbar fracture were treated with DREZ ablation in the spinal cord segment corresponding to the dermatome of the pain territory at Department of Functional Neurosurgery, Xuanwu Hospital, Capital Medical University. The relationship between the segments of the spinal cord injury, sensory level, and area of pain was analyzed retrospectively. The efficacy (overall VAS score improvement more than 50%, no more analgesics needed) and safety of the operation were evaluated according to the postoperative pain relief and complications. Results The segments of spine injuries were T12-L3, and the pain territory was distributed at T11-S2, which lied 2-6 segments higher than that of the injured spinal cord segment. Spinal cord and nerve root were severely injured at the fractured vertebra level. The corresponding spinal cord segments of the pain territory dermatome were moderately atrophied and in 12 cases the corresponding nerve roots were avulsed from the spinal cord. Eighteen patients was pain free right after the operation, 2 cases with pain relieve rate less than 50%. 1 case developed pain recurrence after 3 months. The effective rate on time interval with immediate, 3months and 1 year after operation was 18/20, 17/20, 17/20 respectively. Seven patients had developed transient stabbing pain within the upper boundary of the ablated segment. Two patients who underwent unilateral DREZ lesion developed irritant pain in the contralateral lower extremity area after the operation. Conclusions Chronic neuropathic pain of the lower limb due to thoracolumbar fracture seems more likely to be caused by nerve root injury instead of spinal cord injury. DREZ ablation is safe and effective for those patterns of pain. Key words: Spinal fractures; Spinal cord injuries; Neurosurgical procedures; Neuropathic pain; Dorsal root entry zone

The value of diffusion tensor tractography delineating corticospinal tract in glioma in rat: validation via correlation histology.

BackgroundAn assessment of the degree of white matter tract injury is important in neurosurgical planning for patients with gliomas. The main objective of this study was to assess the injury grade of the corticospinal tract (CST) in rats with glioma using diffusion tensor imaging (DTI).MethodsA total 17 rats underwent 7.0T MRI on day 10 after tumor implantation. The apparent diffusion coefficient (ADC) and fractional anisotropy (FA) were acquired in the tumor, peritumoral and contralateral areas, and the ADC ratio (ipsilateral ADC/contralateral ADC) and rFA (relative FA = ipsilateral FA/contralateral FA) in the peritumoral areas were measured. The CST injury was divided into three grades and delineated by diffusion tensor tractography reconstruction imaging. The fiber density index (FDi) of the ipsilateral and contralateral CST and rFDi (relative FDi = ipsilateral FDi/contralateral FDi) in the peritumoral areas were measured. After the mice were sacrificed, the invasion of glioma cells and fraction of proliferating cells were observed by hematoxylin-eosin and Ki67 staining in the tumor and peritumoral areas. The correlations among the pathology results, CST injury grade and DTI parameter values were calculated using a Spearman correlation analysis. One-way analysis of variance was performed to compare the different CST injury grade by the rFA, rFDi and ADC ratio values.ResultsThe tumor cells and proliferation index were positively correlated with the CST injury grade (r = 0.8857, 0.9233, P < 0.001). A negative correlation was demonstrated between the tumor cells and the rFA and rFDi values in the peritumoral areas (r = −0.8571, −0.5588), and the proliferation index was negatively correlated with the rFA and rFDi values (r = −0.8571, −0.5588), while the ADC ratio was not correlated with the tumor cells or proliferation index. The rFA values between the CST injury grades (1 and 3, 2 and 3) and the rFDi values in grades 1 and 3 significantly differed (P < 0.05).ConclusionsDiffusion tensor imaging may be used to quantify the injury degrees of CST involving brain glioma in rats. Our data suggest that these quantitative parameters may be used to enhance the efficiency of delineating the relationship between fiber tracts and malignant tumor.