Intraoperative Stimulation Research Articles

Subcortical stimulation mapping of descending motor pathways for perirolandic gliomas: assessment of morbidity and functional outcome in 702 cases.

Herein, the authors report their experience with intraoperative stimulation mapping to locate the descending subcortical motor pathways in patients undergoing surgery for hemispheric gliomas within or adjacent to the rolandic cortex, with particular description of the morbidity and functional outcomes associated with this technique. This is a retrospective analysis of patients who, in the period between 1997 and 2016, had undergone resection of hemispheric perirolandic gliomas within or adjacent to descending motor pathways. Data regarding intraoperative stimulation mapping and patient postoperative neurological status were collected. Of 702 patients, stimulation mapping identified the descending motor pathways in 300 cases (43%). A new or worsened motor deficit was seen postoperatively in 210 cases (30%). Among these 210 cases, there was improvement in motor function to baseline levels by 3 months postoperatively in 161 cases (77%), whereas the deficit remained in 49 cases (23%). The majority (65%) of long-term deficits (persisting beyond 3 months) were mild or moderate (antigravity strength or better). On multivariate analysis, patients in whom the subcortical motor pathways had been identified with stimulation mapping during surgery were more likely to develop an additional and/or worsened motor deficit postoperatively than were those in whom the subcortical pathways had not been found (45% vs 19%, respectively, p < 0.001). This difference remained when considering the likelihood of a long-term deficit (i.e., persisting > 3 months; 12% vs 3.2%, p < 0.001). A higher tumor grade and the presence of a preoperative motor deficit were also associated with higher rates of motor deficits persisting long-term. A region of restricted diffusion adjacent to the resection cavity was seen in 20 patients with long-term deficits (41%) and was more common in cases in which the motor pathways were not identified (69%). Long-term deficits that occur in settings in which the subcortical motor pathways are not identified seem in large part due to ischemic injury to descending tracts. Stimulation mapping allows surgeons to identify the descending motor pathways during resection of tumors in perirolandic regions and to attain an acceptable rate of morbidity in these high-risk cases.

Somatotopy and Organization of Spinothalamic Tracts in the Human Cervical Spinal Cord.

Understanding spinothalamic tract anatomy may improve lesioning and outcomes in patients undergoing percutaneous cordotomy. To investigate somatotopy and anatomical organization of spinothalamic tracts in the human cervical spinal cord. Patients with intractable cancer pain undergoing cordotomy underwent preoperative and postoperative quantitative sensory testing for sharp pain and heat pain on day 1 and 7 after cordotomy. Intraoperative sensory stimulation was performed with computed tomography (CT) imaging to confirm the location of the radiofrequency electrode during cordotomy. Postoperative magnetic resonance (MR) imaging was performed to define the location of the lesion. Twelve patients were studied, and intraoperative sensory stimulation combined with CT imaging revealed a somatotopy where fibers from the legs were posterolateral to fibers from the hand. Sharpness detection thresholds were significantly elevated in the area of maximum pain on postoperative day 1 (P=.01). Heat pain thresholds for all areas were not elevated significantly on postoperative day 1, or postoperative day 7. MR imaging confirmed that the cordotomy lesion was in the anterolateral quadrant, and in this location the lesion had a sustained effect on sharp pain but a transient impact on heat pain. In the high cervical spinal cord, spinothalamic fibers mediating sharp pain for the arms are located ventromedial to fibers for the legs, and these fibers are spatially distinct from fibers that mediate heat pain.

Intraoperative test stimulation of the subthalamic nucleus aids postoperative programming of chronic stimulation settings in Parkinson's disease

BackgroundIt is unknown whether intraoperative testing during awake Deep Brain Stimulation (DBS) of the subthalamic nucleus (STN) can be used to postoperatively identify the best settings for chronic stimulation. ObjectiveTo determine whether intraoperative test stimulation is indicative of postoperative stimulation results. MethodsRecords of consecutive Parkinson's Disease patients who received STN DBS between September 2012 and December 2017 were retrospectively analyzed. The best depth identified after intraoperative stimulation via the microelectrode's stimulation tip was compared with the depth of the contact selected for chronic stimulation after a standard monopolar contact review. Moreover, thresholds for induction of clinical effects (optimal improvement of rigidity and induction of side-effects) were compared between stimulation at the postoperatively selected contact and at the corresponding intraoperative depth. ResultsRecords of 119 patients were analyzed (mean (SD) age 60.5 (6.5) years, 31.9% female, 238 STNs). In 75% of cases, the postoperatively selected contact corresponded with the intraoperative depth with the largest therapeutic window or was immediately dorsal to it. Higher stimulation intensities were required postoperatively than intraoperatively to relieve rigidity (p = 0.002) and induce capsular side-effects (p = 0.016). ConclusionIn the majority of cases, the postoperative contact for chronic stimulation was at a similar level or immediately dorsal with respect to the identified best intraoperative depth. Postoperatively, relief of rigidity and induction of capsular side-effects occur at higher stimulation intensities than during intraoperative test stimulation.

High-field intraoperative MRI and glioma surgery: results after the first 100 consecutive patients.

High-field intraoperative MRI (IoMRI) is part of the neurosurgical armamentarium to improve the extent of glioma resection (EOR). To report our oncological and functional outcomes using IoMRI for neuronavigated glioma surgery. In this prospective monocentric study, we reported 100 consecutive adult patients operated on for glioma using IoMRI with neuronavigation, under general anesthesia without intraoperative stimulation, from July 2014 to April 2017. The volumetric evaluation was based on the FLAIR hypersignal for non-enhancing tumors after Gadolinium infusion and on the T1 hypersignal after Gadolinium infusion for enhancing tumors. We evaluated the surgical workflow, the EOR and the clinical outcomes (using Karnofsky performance score (KPS)). Sixty-nine patients underwent one IoMRI, and 31 from two IoMRI controls. At first IoMRI, the median tumor residue was higher in the FLAIR group than in the T1G+ group whereas no more difference was reported after the second IoMRI between the 2 groups (p = 0.56). Additional resection was performed 6 times more frequently in the FLAIR group (OR = 5.7, CI (1.9-17)). The median EOR was 100% (IQR, 93.6-100) whatever the tumor type (first surgery or recurrence) and location. Higher residues were reported only in the insula area (p = 0.004). The median KPS was 90 (IQR, 80-100) at discharge, 3, 6 and 12months after surgery, with no statistical difference between low- and high-grade gliomas (p = 0.34). IoMRI neuronavigated surgery provided maximal EOR whatever the type of glioma and location. IoMRI was all the more useful for non- or minimally enhancing tumors. The step by step surgical resection, introducing the concept of "staged volume" surgery, ensured a high security for the surgeon and low permanent morbidity for the patients.

Tu1924 – Ameliorating Effects and Mechanisms of Intra-Operative Vagal Nerve Stimulation on Postopearive Recovery After Sleeve Gastrectomy in Rats

Tu1924 – Ameliorating Effects and Mechanisms of Intra-Operative Vagal Nerve Stimulation on Postopearive Recovery After Sleeve Gastrectomy in Rats

193 – Acceleration of Postoperative Recovery with Brief Intraoperative Vagal Nerve Stimulation Mediated Via the Autonomic Mechanism

193 – Acceleration of Postoperative Recovery with Brief Intraoperative Vagal Nerve Stimulation Mediated Via the Autonomic Mechanism

Anatomical variability of the arcuate fasciculus: a systematical review.

The arcuate fasciculus (AF) is a white matter fibers tract that links the lateral temporal with the frontal cortex. The AF can be divided into three components: two superficial indirect short tracts (anterior and posterior) and one deep direct long tract. Both DTI and white matter dissections studies find differences regarding the anatomy of the AF, especially its cortical connections. This paper aims at providing a comprehensive anatomical classification of the AF, using the terminologia anatomica. Articles (n = 478) were obtained from a systematical PRISMA review. Studies which focused on primates, unhealthy subjects, as well as studies without cortical termination description and review articles were excluded from the analysis. One hundred and ten articles were retained for full-text examination, of which 19 finally fulfilled our criteria to be included in this review. We classified main descriptions and variations of each segment of the AF according to fiber orientation and cortical connections. Three types of connections were depicted for each segment of the AF. Concerning the anterior segment, most of the frontal fibers (59.35%) ran from the ventral portion of the precentral gyrus and the posterior part of the pars opercularis, to the supramarginal gyrus (85.0%). Main fibers of the posterior segment of the AF ran from the posterior portion of the middle temporal gyrus (100%) to the angular gyrus (92.0%). In main descriptions of the long segment of the AF, fibers ran from both the ventral portion of the precentral gyrus and posterior part of the pars opercularis (63.9%) to the middle and inferior temporal gyrus (60.3%). Minor subtypes were described in detail in the article. We provide a comprehensive classification of the anatomy of the AF, regarding the orientation and cortical connections of its fibers. Although fiber orientation is very consistent, cortical endings of the AF may be different from one study to another, or from one individual to another which is a key element to understand the anatomical basis of current models of language or to guide intraoperative stimulation during awake surgery.

Continuous Intraoperative Nerve Stimulation for Monitoring of Left Recurrent Laryngeal Nerve during Thoracoscopic Esophagectomy

Continuous Intraoperative Nerve Stimulation for Monitoring of Left Recurrent Laryngeal Nerve during Thoracoscopic Esophagectomy

Integrated datasets of normalized brain with functional localization using intra-operative electrical stimulation.

The purpose of this study was to transform brain mapping data into a digitized intra-operative MRI and integrated brain function dataset for predictive glioma surgery considering tumor resection volume, as well as the intra-operative and postoperative complication rates. Brain function data were transformed into digitized localizations on a normalized brain using a modified electric stimulus probe after brain mapping. This normalized brain image with functional information was then projected onto individual patient's brain images including predictive brain function data. Log data were successfully acquired using a medical device integrated into intra-operative MR images, and digitized brain function was converted to a normalized brain data format in 13 cases. For the electrical stimulation positions in which patients showed speech arrest (SA), speech impairment (SI), motor and sensory responses during cortical mapping processes in awake craniotomy, the data were tagged, and the testing task and electric current for the stimulus were recorded. There were 13 SA, 7 SI, 8 motor and 4 sensory responses (32 responses) in total. After evaluation of transformation accuracy in 3 subjects, the first transformation from intra- to pre-operative MRI using non-rigid registration was calculated as 2.6 ± 1.5 and 2.1 ± 0.9mm, examining neighboring sulci on the electro-stimulator position and the cortex surface near each tumor, respectively; the second transformation from pre-operative to normalized brain was 1.7 ± 0.8 and 1.4 ± 0.5mm, respectively, representing acceptable accuracy. This image integration and transformation method for brain normalization should facilitate practical intra-operative brain mapping. In the future, this method may be helpful for pre-operatively or intra-operatively predicting brain function.

Towards Machine Learning Prediction of Deep Brain Stimulation (DBS) Intra-operative Efficacy Maps.

Deep brain stimulation (DBS) has the potential to improve the quality of life of people with a variety of neurological diseases. A key challenge in DBS is in the placement of a stimulation electrode in the anatomical location that maximizes efficacy and minimizes side effects. Pre-operative localization of the optimal stimulation zone can reduce surgical times and morbidity. Current methods of producing efficacy probability maps follow an anatomical guidance on magnetic resonance imaging (MRI) to identify the areas with the highest efficacy in a population. In this work, we propose to revisit this problem as a classification problem, where each voxel in the MRI is a sample informed by the surrounding anatomy. We use a patch-based convolutional neural network to classify a stimulation coordinate as having a positive reduction in symptoms during surgery. We use a cohort of 187 patients with a total of 2,869 stimulation coordinates, upon which 3D patches were extracted and associated with an efficacy score. We compare our results with a registration-based method of surgical planning. We show an improvement in the classification of intraoperative stimulation coordinates as a positive response in reduction of symptoms with AUC of 0.670 compared to a baseline registration-based approach, which achieves an AUC of 0.627 (p < 0.01). Although additional validation is needed, the proposed classification framework and deep learning method appear well-suited for improving pre-surgical planning and personalize treatment strategies.

Reduction of Side Effects by Segmented Electrodes in Case of Subthalamic Nucleus Deep Brain Stimulation in Parkinson Disease: A Case Report.

Patients suffering treatment resistant Parkinson´s disease (PD) are potential candidates for deep brain stimulation (DBS). Commonly most implanted electrodes have a cylindrical shape with quadripolar electrode contacts and generate a symmetrical stimulation field around the lead. To reduce side effects through activation of neighboring fibers a new electrode design with segmented contacts was developed and enables a better adaption of the field of stimulation as well as a multi-target stimulation to improve therapeutic benefits. We report about a 51-year-old male patient with a 15-year history of treatment-refractory PD, who was implanted with bilateral segmented electrodes in the subthalamic nucleus (STN) with St. Jude Medical Infinity™ DBS System (Abbott/St. Jude Medical, Saint Paul, Minnesota, USA). Despite a clear mood-enhancing effect, stimulation with ring electrodes caused motor side effects including rigor and speech disorder. With segmented electrodes an effective and gentle stimulation was achieved. The stimulation of the anterior segments in the central position of the electrode in the STN showed no side-effects and allowed a reduction of initial symptoms in an low stimulation amplitude. Despite precise preoperatively planning and intraoperative trial stimulation, side effects of STN stimulation are very common. The application of segmented electrodes permits more options to reduce side effects rather than using ring electrodes. Studies with larger samples sizes are needed to establish the optional DBS electrode.

Human caudate nucleus subdivisions in tinnitus modulation.

The object of this study was to define caudate nucleus locations responsive to intraoperative direct electrical stimulation for tinnitus loudness modulation and relate those locations to functional connectivity maps between caudate nucleus subdivisions and auditory cortex. Six awake study participants who underwent bilateral deep brain stimulation (DBS) electrode placement in the caudate nucleus as part of a phase I clinical trial were analyzed for tinnitus modulation in response to acute stimulation at 20 locations. Resting-state 3-T functional MRI (fMRI) was used to compare connectivity strength between centroids of tinnitus loudness-reducing or loudness-nonreducing caudate locations and the auditory cortex in the 6 DBS phase I trial participants and 14 other neuroimaging participants with a Tinnitus Functional Index > 50. Acute tinnitus loudness reduction was observed at 5 caudate locations, 4 positioned at the body and 1 at the head of the caudate nucleus in normalized Montreal Neurological Institute space. The remaining 15 electrical stimulation interrogations of the caudate head failed to reduce tinnitus loudness. Compared to the caudate head, the body subdivision had stronger functional connectivity to the auditory cortex on fMRI (p < 0.05). Acute tinnitus loudness reduction was more readily achieved by electrical stimulation of the caudate nucleus body. Compared to the caudate head, the caudate body has stronger functional connectivity to the auditory cortex. These first-in-human findings provide insight into the functional anatomy of caudate nucleus subdivisions and may inform future target selection in a basal ganglia-centric neuromodulation approach to treat medically refractory tinnitus.Clinical trial registration no.: NCT01988688 (clinicaltrials.gov).

Tractography Verified by Intraoperative Magnetic Resonance Imaging and Subcortical Stimulation During Tumor Resection Near the Corticospinal Tract

Tractography is a popular tool for visualizing the corticospinal tract (CST). However, results may be influenced by numerous variables, eg, the selection of seeding regions of interests (ROIs) or the chosen tracking algorithm. To compare different variable sets by correlating tractography results with intraoperative subcortical stimulation of the CST, correcting intraoperative brain shift by the use of intraoperative MRI. Seeding ROIs were created by means of motor cortex segmentation, functional MRI (fMRI), and navigated transcranial magnetic stimulation (nTMS). Based on these ROIs, tractography was run for each patient using a deterministic and a probabilistic algorithm. Tractographies were processed on pre- and postoperatively acquired data. Using a linear mixed effects statistical model, best correlation between subcortical stimulation intensity and the distance between tractography and stimulation sites was achieved by using the segmented motor cortex as seeding ROI and applying the probabilistic algorithm on preoperatively acquired imaging sequences. Tractographies based on fMRI or nTMS results differed very little, but with enlargement of positive nTMS sites the stimulation-distance correlation of nTMS-based tractography improved. Our results underline that the use of tractography demands for careful interpretation of its virtual results by considering all influencing variables.

Intraoperative Neurophysiological Monitoring of the Phrenic Nerve: Utility and Descriptions of the Technique

In surgical procedures of the supraclavicular and lateral cervical regions, as well as in cardiac and mediastinal surgeries, diaphragm function can be compromised by the risk of injury to the phrenic nerve and/or the C4 root. There are few publications that treat the intraoperative stimulation of these nerve structures to evaluate their functionality and, to our knowledge, until now it has not been hypothesized about whether it is possible to reduce the injury rates, which reach 26% in some cardiac surgery studies.We describe the technique used for the neurophysiological monitoring of the phrenic nerve. Also, its usefulness and advantages over other techniques are discussed.We conclude that, with the increasing incorporation in recent years of intraoperative neurophysiological monitoring, its application to the phrenic nerve is possible in procedures with a risk of injury and, thus, the reduction of iatrogenic injury rates may be feasible.

The ERP of slow cortial potential resting-state networks from ECoG in intraoperative mapping of motor related cortices

Objective To explore the sensitivity and specificity of electrocorticography (ECoG) in intraoperative mapping of motor cortices with the event-related potential (ERP) of slow cortical potential resting-state networks. Methods Thirteen patients with brain lesions near eloquent areas who were admitted to Department of Neurosurgery, Guangzhou General Hospital of Guangzhou Military Command from December 2014 to June 2016 were treated under awake craniotomy. The motor-related cortices were detected by intraoperative direct electrical stimulation. The ECoG were collected from patients in resting state. The ERP of slow cortical potential resting-state networks was analyzed. The sensitivity and specificity of ECoG in mapping of motor cortices were evaluated. Results Motor areas were identified by DES in all patients. The ERP of slow cortical potential resting-state networks was significant and regarded as the specific rhythm of motor cortex. When the threshold of ERP of the specific rhythm was chosen as 1.6, this method showed the optimal sensitivity (90.6%) and modest specificity (59.2%) compared with the other threshold. Conclusion Data analysis of the ERP of slow cortical potential resting-state networks from ECoG can be used to map motor areas intraoperatively, which is expected as a new adjunct to DES for intraoperative mapping. Key words: Brain diseases; Electrocorticography; Slow cortial potential; Mapping of motor cortices

Autonomic arousal elicited by subcallosal cingulate stimulation is explained by white matter connectivity

BackgroundSubcallosal cingulate deep brain stimulation (SCC DBS) is an experimental treatment for severe depression. Surgery is performed with awake patients and intraoperative stimulation produces acute behavioral responses in select contacts. While there have been reports on the relationship between acute intraoperative behaviors and their relation to the location of the contacts, there are no descriptions of the physiological changes that accompany them. ObjectiveThe present study sought to examine these physiological readouts, and their association with the anatomical substrates that generated them. MethodsNine patients with severe, treatment-resistant depression were tested intraoperatively. The stimulation protocol consisted of 12 three-minute, sham-controlled, double-blind trials. Changes in heart rate and skin conductance were recorded during each stimulation cycle. Probabilistic tractography between the stimulated contacts and predefined regions of the mood regulation network was performed. ResultsAcute intraoperative SCC stimulation produced increases in autonomic sympathetic response that correlated with the salience of the behavioral responses. The autonomic changes were observed within seconds of initiating acute stimulation and prior to verbalization of subjective experiences. The probabilistic tractography analysis suggested that structural connectivity between the stimulated area and the midcingulate cortex is the primary pathway that mediates autonomic responsivity to SCC DBS. ConclusionsThese findings demonstrate that acute SCC stimulation produces autonomic and behavioral changes in the operating room that are explained by the modulation of networks associated with long term antidepressant response. Intraoperative autonomic recordings paired with careful behavioral observations and precise anatomical mapping aid in the identification and classification of the intraoperative phenomena.

Influence of stimulus presentation rate on intraoperative ECAP thresholds in cochlear implant users

Objective: The objective is to evaluate the influence of the presentation rate on intraoperative ECAP thresholds in cochlear implant users.Design: The design was data on the ECAP thresholds (t-NRT) as well as the behavioural T- and C-levels have been collected in CI patients of a quaternary otologic referral centre. Measurements of the tNRT thresholds were performed intraoperatively for 250 Hz and 80 Hz presentation rates and correlated to the stabilised T- and C-levels measured at the 5th fitting session, 4-6 months after surgery.Study sample: There was a study sample of 35 consecutive CI patients. All patients were users of the Nucleus 24RECA (Freedom) or Nucleus CI512 cochlear implants with the Contour Advance-of-Stylet electrode.Results: The result showed that the t-NRT thresholds were higher for the 250 Hz pulse rate typically used during the intraoperative stimulation under general anaesthesia than for the 80 Hz rate used typically during the postoperative fitting sessions. This difference was more pronounced for the basal electrodes where it exceeded 10 current levels (CL). Pearson’s correlation coefficients between the t-NRT-measurements and the stabilised T- and C-levels r ranged between 0.34 and 0.47.Conclusion: In conclusion, the magnitude of the ECAP thresholds (t-NRT) recorded intraoperatively depends significantly on the stimulus presentation rate.

Corticomotoneuronal Model for Intraoperative Neurophysiological Monitoring During Direct Brain Stimulation.

Intraoperative neurophysiological monitoring during brain surgery uses direct cortical stimulation to map the motor cortex by recording muscle activity induced by the excitation of alpha motor neurons (MNs). Computational models have been used to understand local brain stimulation. However, a computational model revealing the stimulation process from the cortex to MNs has not yet been proposed. Thus, the aim of the current study was to develop a corticomotoneuronal (CMN) model to investigate intraoperative stimulation during surgery. The CMN combined the following three processes into one system for the first time: (1) induction of an electric field in the brain based on a volume conductor model; (2) activation of pyramidal neuron (PNs) with a compartment model; and (3) formation of presynaptic connections of the PNs to MNs using a conductance-based synaptic model coupled with a spiking model. The implemented volume conductor model coupled with the axon model agreed with experimental strength-duration curves. Additionally, temporal/spatial and facilitation effects of CMN synapses were implemented and verified. Finally, the integrated CMN model was verified with experimental data. The results demonstrated that our model was necessary to describe the interaction between frequency and pulses to assess the difference between low-frequency and multi-pulse high-frequency stimulation in cortical stimulation. The proposed model can be used to investigate the effect of stimulation parameters on the cortex to optimize intraoperative monitoring.

Is awake brain surgery in high-grade glioma patients and a severe aphasia feasible? A case study.

Is awake brain surgery in high-grade glioma patients and a severe aphasia feasible? A case study.

Stimulation Contractility Gradient of a Neuromuscular Choristoma Within the Sciatic Nerve: 2-Dimensional Operative Video.

Neuromuscular choristoma (NMC) is a rare congenital nerve lesion that is classified by the presence of heterotopic muscle fibers intercalated within nerve fascicles.1 The presence of NMC typically causes progressive neuropathy and bony/soft tissue undergrowth, often leading to a shortened atrophic limb.2,3 The typical appearance of NMC on magnetic resonance imaging is an enlarged fusiform nerve that exhibits minimal gadolinium enhancement.4 While there is increasing documentation of pathognomonic clinical and radiographic features for various diffuse fusiform peripheral nerve lesions, nerve biopsy is still occasionally required for some patients given the rarity of these diseases and progressive neuropathic features.The intraoperative appearance of NMC and its unique electrical stimulation properties are quite interesting. Intrafascicular replacement of nerve by skeletal muscle gives the nerve a red beefy color and causes the fascicles to contract with electrical stimulation.5 In this video, we demonstrate the intraoperative appearance and contractile properties of NMC in a 60-yr-old woman with progressive sciatic neuropathy. Histologic and immunohistochemical studies identified a gradient of intralesional mature skeletal muscle within the NMC, with substantially fewer desmin-positive skeletal muscle fibers in the distal aspect. A gradient of contractility with intraoperative stimulation seemed to correlate with this pathology. These findings suggest that the lesional extent of NMC may not be clinically or grossly evident, reflecting a varying distribution of skeletal muscle within the affected nerve.The Mayo Clinic Institutional Review Board Office for Human Research Protection does not require approval for single participant case studies. The subject involved in this study was not identifiable and the general surgical consent form included permission for intraoperative photos and video.