Direct cortical stimulation with cylindrical depth electrodes in the interhemispheric fissure for leg motor evoked potential monitoring

ObjectiveTo evaluate cylindrical depth electrodes in the interhemispheric fissure as an alternative to subdural strip electrodes for direct cortical stimulation (DCS) leg motor evoked potential (MEP) monitoring.MethodsA cylindrical depth electrode was positioned in the interhemispheric fissure of 37 patients who underwent supratentorial brain surgery. Leg sensory and motor cortices were localized by highest tibial nerve somatosensory evoked potential amplitude and lowest DCS leg MEP threshold; the lowest-threshold electrode was then used for DCS leg MEP monitoring.ResultsIntraoperative leg MEPs were obtained from all the patients in the series. The mean intensity applied for leg MEP monitoring with the cylindrical depth electrode was 15.2 ± 4.0 mA. No complications secondary to neurophysiological monitoring were detected.ConclusionsLower extremity MEPs were consistently recorded using a multi-contact cylindrical depth electrode in the interhemispheric fissure by DCS.SignificanceCylindrical depth electrodes may be a safe and effective alternative for DCS in the interhemispheric fissure, where subdural strips are difficult to place.     

Exendin-4 attenuates pain-induced cognitive impairment by alleviating hippocampal neuroinflammation in a rat model of spinal nerve ligation

Glucagon-like peptide-1 receptor has anti-apoptotic,anti-inflammatory,and neuroprotective effects.It is now recognized that the occurrence and development of chronic pain are strongly associated with anti-inflammatory responses;however,it is not clear whether glucagon-like peptide-1 receptor regulates chronic pain via anti-inflammatory mechanisms.We explored the effects of glucagon-like peptide-1 receptor on nociception,cognition,and neuroinflammation in chronic pain.A rat model of chronic pain was established using left L5 spinal nerve ligation.The glucagon-like peptide-1 receptor agonist exendin-4 was intrathecally injected into rats from 10 to 21 days after spinal nerve ligation.Electrophysiological examinations showed that,after treatment with exendin-4,paw withdrawal frequency of the left limb was significantly reduced,and pain was relieved.In addition,in the Morris water maze test,escape latency increased and the time to reach the platform decreased following exendin-4 treatment.Immunohistochemical staining and western blot assays revealed an increase in the numbers of activated microglia and astrocytes in the dentate gyrus of rat hippocampus,as well as an increase in the expression of tumor necrosis factor alpha,interleukin 1 beta,and interleukin 6.All of these effects could be reversed by exendin-4 treatment.These findings suggest that exendin-4 can alleviate pain-induced neuroinflammatory responses and promote the recovery of cognitive function via the glucagon-like peptide-1 receptor pathway.All experimental procedures and protocols were approved by the Experimental Animal Ethics Committee of Renmin Hospital of Wuhan University of China(approval No.WDRM 20171214)on September 22,2017.     

Oxime K074 – in vitro and in silico reactivation of acetylcholinesterase inhibited by nerve agents and pesticides

Abstract

Oxime K074 was formerly considered to be a lead structure for design of novel oximes for reactivation of tabun-inhibited acetylcholinesterase (AChE). In this study, we are summarizing its reactivation activity in case of other nerve agents (sarin, cyclosarin, VX and Russian VX) and pesticides (chlorpyrifos, methylchlorpyrifos and DDVP). For this purpose, standard in vitro method using rat brain homogenate was used. As resulted, oxime K074 was able to reactivate brain ChE (cholinesterases) inhibited by all used nerve agents and pesticides excluding cyclosarin-inhibited ChE. Only slight modification in structure of sarin (isopropyl moiety) and cyclosarin (cyclohexyl moiety) caused extraordinary differences in the reactivation of acetylcholinesterase inhibited by these nerve agents. Obtained molecular docking results suggest that the oxime K074 interacts very well with the inhibitors addressed in this work, and the data obtained by the QM/MM approach showed a good correlation with our experimental results of reactivation rate (%) by the oxime K074.     

A systematic review of the complications of high-risk third molar removal and coronectomy: development of a decision tree model and preliminary health economic analysis to assist in treatment planning

Coronectomy is an alternative surgical technique for the management of high-risk third molars. It involves the removal of the crown of a tooth and the deliberate retention of the roots, thereby avoiding injury to the inferior alveolar nerve (IAN). Previous studies have suggested that it reduces the risk of nerve injury when compared with surgical extraction. The purpose of this study was to systematically review the incidence of complications following coronectomy such as IAN injury, pain, dry socket, infection, root migration, and need for re-operation. A comparative cost analysis of coronectomy and surgical extraction was done based on the results of the review. This provides an insight into the economic implications of the two procedures. A search through the MEDLINE database via Ovid, PubMed, Scopus, EMBASE via Ovid, and Web of Science, was carried out to extract randomised and non-randomised controlled trials. Four studies fulfilled the inclusion criteria. A meta-analysis was conducted to measure the overall effect of each outcome. The pooled odds ratio (OR) for IAN injury was 0.16 (95% CI 0.01 to 0.39). Coronectomy reduced this risk by 84%. Dry socket may occur less frequently following coronectomy whereas infection did not show a higher incidence with either intervention. Root migration was found to occur in 13%–85% of cases and the average incidence of re-operation was 2.2%. The ratio of the average costs was 1.12 favouring coronectomy if cone-beam computed tomography (CBCT) was not done prior to the procedure. If a scan was taken routinely for coronectomy, the cost ratio marginally favoured extraction. Coronectomy reduced the risk of nerve injury in high-risk third molars. Definitive conclusions, however, cannot be made for outcomes such as the need for re-operation, which may alter the cost ratio of coronectomy:extraction, as higher quality studies with longer follow-up are needed.     

Toward the establishment of neurophysiological indicators for neuropsychiatric disorders using transcranial magnetic stimulation‐evoked potentials: A systematic review

Transcranial magnetic stimulation (TMS) can depolarize the neurons directly under the coil when applied to the cerebral cortex, and modulate the neural circuit associated with the stimulation site, which makes it possible to measure the neurophysiological index to evaluate excitability and inhibitory functions. Concurrent TMS and electroencephalography (TMS‐EEG) has been developed to assess the neurophysiological characteristics of cortical regions other than the motor cortical region noninvasively. The aim of this review is to comprehensively discuss TMS‐EEG research in the healthy brain focused on excitability, inhibition, and plasticity following neuromodulatory TMS paradigms from a neurophysiological perspective. A search was conducted in PubMed to identify articles that examined humans and that were written in English and published by September 2018. The search terms were as follows: (TMS OR ‘transcranial magnetic stimulation’) AND (EEG OR electroencephalog*) NOT (rTMS OR ‘repetitive transcranial magnetic stimulation’ OR TBS OR ‘theta burst stimulation’) AND (healthy). The study presents an overview of TMS‐EEG methodology and neurophysiological indices and reviews previous findings from TMS‐EEG in healthy individuals. Furthermore, this review discusses the potential application of TMS‐EEG neurophysiology in the clinical setting to study healthy and diseased brain conditions in the future. Combined TMS‐EEG is a powerful tool to probe and map neural circuits in the human brain noninvasively and represents a promising approach for determining the underlying pathophysiology of neuropsychiatric disorders.