Intraoperative Stimulation Research Articles

Assesment of Functional Results for the Lesions Located in Eloquent Areas with Using Intraoperative Cortical-Subcortical Stimulation and Cortical Mapping.

To assess the classical and functional imaging features of patients with pathology located in the eloquent areas of the brain who were admitted to our centre between October 2012 and February 2018. We also studied intraoperative somatosensory evoked potential (SEP), motor evoked potentials (MEP), phase reversal, cortical mapping, the extent of resection and the calculation of postoperative morbidity. We compared our results with previous studies in which this technique was not used. The patient records of 163 patients were reviewed retrospectively after approval by the institutional ethics committee and comparisons were made with reports in the literature. The lesion was localised in the visual cortex in eight of the 163 patients. We did not encounter any abnormality in the VEP recordings, so the surgeries were continued. The remaining 155 cases were followed by intraoperative SEP and MEP monitoring. We observed a greater than 50% decrease in the amplitude and an increase in latencies that was greater than 10% in intraoperative MEP and SEP monitoring in 24 patients of 155. Although 8 of 24 patients with abnormal SEP and MEP values were corrected with manuveurs, 6 patients developed increased neurological deficits postoperatively. In conclusion, all of these methods should not be seen as competitive with each other; they could be considered as complementary. All of these methods are helpful for a surgical team regarding loss of neurological function. The rate of loss might be up to 100% and irreversible despite corrective maneveurs.

Intraoperative Use of Functional MRI for Surgical Decision Making after Limited or Infeasible Electrocortical Stimulation Mapping.

Functional magnetic resonance imaging (fMRI) is becoming widely recognized as a key component of preoperative neurosurgical planning, although intraoperative electrocortical stimulation (ECS) is considered the gold standard surgical brain mapping method. However, acquiring and interpreting ECS results can sometimes be challenging. This retrospective study assesses whether intraoperative availability of fMRI impacted surgical decision-making when ECS was problematic or unobtainable. Records were reviewed for 191 patients who underwent presurgical fMRI with fMRI loaded into the neuronavigation system. Four patients were excluded as a bur-hole biopsy was performed. Imaging was acquired at 3 Tesla and analyzed using the general linear model with significantly activated pixels determined via individually determined thresholds. fMRI maps were displayed intraoperatively via commercial neuronavigation systems. Seventy-one cases were planned ECS; however, 18 (25.35%) of these procedures were either not attempted or aborted/limited due to: seizure (10), patient difficulty cooperating with the ECS mapping (4), scarring/limited dural opening (3), or dural bleeding (1). In all aborted/limited ECS cases, the surgeon continued surgery using fMRI to guide surgical decision-making. There was no significant difference in the incidence of postoperative deficits between cases with completed ECS and those with limited/aborted ECS. Preoperative fMRI allowed for continuation of surgery in over one-fourth of patients in which planned ECS was incomplete or impossible, without a significantly different incidence of postoperative deficits compared to the patients with completed ECS. This demonstrates additional value of fMRI beyond presurgical planning, as fMRI data served as a backup method to ECS.

Evaluation for Late Nerve Transfer Surgery in Spinal Cord Injury: Predicting the Degree of Lower Motor Neuron Injury

Nerve transfer surgery is used to restore upper extremity function following cervical spinal cord injury (SCI) with substantial variation in outcomes. The injury pattern in SCI is complex and can include isolated upper motor neuron (UMN) and combined UMN/lower motor neuron (LMN) dysfunction. The purpose of the study was to determine the most effective diagnostic technique for determining suitable candidates for nerve transfer surgery in SCI. Medical records were reviewed of patients who had nerve transfers to restore upper extremity function in SCI. Data collected included (1) preoperative clinical examination and electrodiagnostic testing; (2) intraoperative neuromuscular stimulation (NMS); and (3) nerve histopathology. Preoperative, intraoperative, and postoperative data were compared to identify predictors of isolated UMN versus combined UMN/LMN injury patterns. The study sample included 22 patients with 50 nerve transfer surgeries and included patients ranging from less than 1 year to over a decade post-SCI. Normal recipient nerve conduction studies (NCS) before surgery corresponded to the intraoperative presence of recipient NMS and postoperative histopathology that showed normal nerve architecture. Conversely, abnormal recipient NCS before surgery corresponded with the absence of recipient NMS during surgery and patterns of denervation on postoperative histopathology. Normal donor preoperative manual muscle testing corresponded with the presence of donor NMS during surgery and normal nerve architecture on postoperative histopathology. An EMG of corresponding musculature did not correspond with intraoperative donor or recipient NMS or histopathological findings. NCS better predict patterns of injury in SCI than EMG. This is important information for clinicians evaluating people for late nerve transfer surgery even years post-SCI. Diagnostic II.

The Use Of Fasial Stımilator in Cochlear implant and Fasial Tumor Surgery

Objective: Our aim in conducting this clinical study that project was to investigate the surgical safety of facial nerve monitoring along with its effects on the duration of the operation in otologic and neurotologic surgery. Methods: We have used intraoperative monitoring and stimulation of facial nerve function routinely in 161 cochlear surgery, and 10 neurotologic cases. Statistical study was performed only in otologic patients. The 171 patients who underwent surgery, of the remaning 30 otologic surgery cases were randomly selected that were monitered. The remaining 30 otologic surgery cases were not monitored and compared statistically for the duration of the operation and the emerging complications. Results: Of the study patients; no responses were detected in seven despite the stimulation. Response occurred only after increasing the amplitude of the stimulation current in two patients. In the remaining 162 patients, the responses were detected. Of the seven patients, in whom no responses were detected; electrode contact was lost in three, nerve fatigue was found in two, and muscle-relaxant use for anesthesia was detected in one patient; while, no causes were identified in one patient. Despite the presence of responses, a transient postoperative paresis was observed in one patient. In cochlear implant patients, the mean duration of surgery was 2.35 hours without monitoring; whereas, it was 1.45 hours in monitored patients. Conclusion: We are of the opinion that this technological method may contribute significantly to obtaining electrophysiologic data, as well as ensuring the safety of the operation and reducing the complication rates.

Neurophysiological monitoring of tongue muscle activation during hypoglossal nerve stimulation.

Upper airway stimulation for obstructive sleep apnea (OSA) via implantable hypoglossal nerve stimulation (HGNS) reduces airway obstruction by selectively stimulating nerve fibers that innervate muscles that produce tongue protrusion, while avoiding fibers that produce tongue retraction. This selective stimulation likely depends upon the location, intensity, and type of electrical stimulation delivered. This study investigates the impact of changing stimulation parameters on tongue muscle activation during HGNS using intraoperative nerve integrity monitoring in conjunction with electromyography (EMG). Prospective case series. Ten patients undergoing unilateral HGNS implantation for OSA in a university hospital setting were studied. Data included EMG responses in tongue muscles that produce protrusion (genioglossus), retraction (styloglossus/hyoglossus), and stiffening (transverse/vertical) in response to intraoperative bipolar probe electrical stimulation of lateral and medial branches of the hypoglossal nerve (HGN) and to implantable pulse generator (IPG) unipolar and bipolar settings after placement of the stimulation cuff. Stimulation of medial division HGN branches resulted in EMG responses in genioglossus muscles, but not in styloglossus/hyoglossus muscles, whereas stimulation of the lateral division HGN branches drove responses in styloglossus/hyoglossus muscles. Variable responses in transverse/vertical muscles were observed with stimulation of lateral and medial division branches. After electrode cuff placement, unipolar and bipolar HGN stimulation configurations of IPG resulted in unique patterns of muscle activation. The relative activation of extrinsic and intrinsic tongue musculature by HGNS is determined by stimulus location, intensity, and type. Intraoperative neurophysiological monitoring of tongue muscle activation enables proper electrode cuff placement and may provide essential data for stimulus optimization. 4 Laryngoscope, 130:1836-1843, 2020.

Cognitive functioning in patients with low-grade glioma: effects of hemispheric tumor location and surgical procedure.

The authors evaluated the cognitive performance of patients with low-grade glioma (LGG) before and after surgery, and specifically investigated 1) the effects of hemispheric tumor location and 2) the type of surgery (either with or without intraoperative stimulation mapping [ISM]). Patients underwent neuropsychological assessment 1 day before (T0) and 3 months after (T3) surgery. ISM targeted motor and/or language functions, but no other cognitive functions. Using 2-way mixed ANOVAs, differences between groups (i.e., for patients with right- vs left-sided lesions and normative controls [NCs], and also for patients operated on with vs without ISM and NCs), effects over time (T0-T3), and interaction effects in cognitive functioning were explored. Individual changes over time were assessed with reliable change indices for each neuropsychological test. In total, 77 patients with LGG were included (38 and 39 patients with right- and left-sided lesions, respectively; and 42 patients with and 35 patients without ISM). The majority of patients who were operated on with ISM had left-sided lesions. Patients with right- and left-sided lesions scored significantly lower on 6 and 3 out of 8 tests, respectively, compared to NCs. No significant differences between hemispheric groups were found at T0 or at T3. Patients with left-sided lesions showed significant deterioration of performance on verbal memory and sustained attention over time. Patients who underwent operation with versus without ISM scored significantly lower on 6 and 3 out of 8 tests, respectively, compared to NCs. Patients in the ISM group scored significantly lower on the Stroop test, shifting attention test, and verbal fluency test than patients without ISM. Also, the ISM group showed a significant decline in mean cognitive flexibility and sustained attention performance over time. Cognitive impairments were found in patients irrespective of hemispheric tumor location, whereby patients who were operated on with ISM performed slightly worse after surgery than patients without ISM. The authors conclude that there is room for improvement of cognitive functioning in surgically treated patients with LGG. The use of specific tests for higher cognitive functions during surgery may potentially improve functional outcome, but that is to be determined in future studies and balanced against oncological outcome. Implementation of neuropsychological assessments into the clinical management of patients with LGG should be encouraged, to inform and alert patients and clinicians on the status of cognitive functioning.

Impact of Multi-modality Monitoring Using Direct Electrical Stimulation to Determine Corticospinal Tract Shift and Integrity in Tumors using the Intraoperative MRI.

Preserving the integrity of the corticospinal tract (CST) while maximizing the extent of tumor resection is one of the key principles of brain tumor surgery to prevent new neurologic deficits. Our goal was to determine the impact of the use of perioperative diffusion tensor imaging (DTI) fiber-tracking protocols for location of the CSTs, in conjunction with intraoperative direct electrical stimulation (DES) on patient neurologic outcomes. The role of combining DES and CST shift in intraoperative magnetic resonance imaging (iMRI) to enhance extent of resection (EOR) has not been studied previously. A total of 53 patients underwent resection of tumors adjacent to the motor gyrus and the underlying CST between June 5, 2009, and April 16, 2013. All cases were performed in the iMRI (BrainSuite 1.5 T). Preoperative DTI mapping and intraoperative cortical and subcortical DES including postoperative DTI mapping were performed in all patients. There were 32 men and 21 women with 40 high-grade gliomas (76%), 4 low-grade gliomas (8%), and 9 (17%) metastases. Thirty-four patients (64%) were newly diagnosed, and 19 (36%) had a previous resection. There were 31 (59%) right-sided and 22 (42%) left-sided tumors. Eighteen patients (34%) had a re-resection after the first intraoperative scan. Most patients had motor-only mapping, and one patient had both speech and motor mapping. Relative to the resection margin, the CST after the first iMRI was designated as having an outward shift (OS), inward shift (IS), or no shift (NS). A gross total resection (GTR) was achieved in 41 patients (77%), subtotal resection in 4 (7.5%), and a partial resection in 8 (15%). Eighteen patients had a re-resection, and the mean EOR increased from 84% to 95% (p = 0.002). Of the 18 patients, 7 had an IS, 8 an OS, and in 3 NS was noted. More patients in the OS group had a GTR compared with the IS or NS groups (p = 0.004). Patients were divided into four groups based on the proximity of the tumor to the CST as measured from the preoperative scan. Group 1 (32%) included patients whose tumors were 0 to 5 mm from the CST based on preoperative scans; group 2 (28%), 6 to 10 mm; group 3 (13%), 11 to 15 mm; and group 4 (26%), 16 to 20 mm, respectively. Patients in group 4 had fewer neurologic complications compared with other groups at 1 and 3 months postoperatively (p = 0.001 and p = 0.007, respectively) despite achieving a similar degree of resection (p = 0.61). Furthermore, the current of intraoperative DES was correlated to the distance of the tumor to the CST, and the regression equation showed a close linear relationship between the two parameters. Combining information about intraoperative CST and DES in the iMRI can enhance resection in brain tumors (77% had a GTR). The relative relationship between the positions of the CST to the resection cavity can be a dynamic process that could further influence the surgeon's decision about the stimulation parameters and EOR. Also, the patients with an OS of the CST relative to the resection cavity had a GTR comparable with the other groups.

Safe marginal resection of atypical neurofibromas in neurofibromatosis type 1.

Patients with neurofibromatosis type 1 (NF1) are predisposed to visceral neurofibromas, some of which can progress to premalignant atypical neurofibromas (ANFs) and malignant peripheral nerve sheath tumors (MPNSTs). Though subtotal resection of ANF may prevent malignant transformation and thus deaths with no neural complications, local recurrences require reoperation. The aim of this study was to assess the surgical morbidity associated with marginal resection of targeted ANF nodules identified via preoperative serial volumetric MRI and 18F-FDG-PET imaging. The authors analyzed clinical outcomes of 16 NF resections of 21 tumors in 11 NF1 patients treated at the NIH Clinical Center between 2008 and 2018. Preoperative volumetric growth rates and 18F-FDG-PET SUVMax (maximum standardized uptake value within the tumor) of the target lesions and any electromyographic or nerve conduction velocity abnormalities of the parent nerves were measured and assessed in tandem with postoperative complications, histopathological classification of the resected tumors, and surgical margins through Dunnett's multiple comparisons test and t-test. The surgical approach for safe marginal resection of ANF was also described. Eleven consecutive NF1 patients (4 male, 7 female; median age 18.5 years) underwent 16 surgical procedures for marginal resections of 21 tumors. Preoperatively, 13 of the 14 (93%) sets of serial MRI studies and 10 of the 11 (91%) 18F-FDG-PET scans showed rapid growth (≥ 20% increase in volume per year) and avidity (SUVMax ≥ 3.5) of the identified tumor, respectively (median tumor size 48.7 cm3; median growth rate 92% per year; median SUVMax 6.45). Most surgeries (n = 14, 88%) resulted in no persistent postoperative parent nerve-related complications, and to date, none of the resected tumors have recurred. The median length of postoperative follow-up has been 2.45 years (range 0.00-10.39 years). Histopathological analysis confirmed significantly greater SUVMax among the ANFs (6.51 ± 0.83, p = 0.0042) and low-grade MPNSTs (13.8, p = 0.0001) than in benign neurofibromas (1.9). This report evaluates the utility of serial imaging (MRI and 18F-FDG-PET SUVMax) to successfully detect ANF and demonstrates that safe, fascicle-sparing gross-total, extracapsular resection of ANF is possible with the use of intraoperative nerve stimulation and microdissection of nerve fascicles.

Effectiveness of Intraoperative Laser Acupuncture Combined with Antiemetic Drugs for Prevention of Postoperative Nausea and Vomiting.

Introduction: Postoperative nausea and vomiting (PONV) are frequent in patients undergoing laparoscopic cholecystectomy. The aim of this study is to evaluate the effectiveness of intraoperative laser acupuncture stimulation of Pericardium 6 (PC6) and Large Intestine 4 (LI4) acupoints combined with antiemetic drug prophylaxis on PONV. Methods: A total of 88 patients, scheduled for laparoscopic cholecystectomy, were assigned into 2 groups. Group I received bilateral laser acupuncture on PC6 and LI4 acupoints after induction of anesthesia and also received antiemetic drug (metoclopramide) prophylaxis. Patients in Group II received only antiemetic drug prophylaxis. Nausea and vomiting frequencies and need for rescue antiemetic drug (ondansetron) were recorded after extubation, at 30th minute at recovery room and at 6th hour at ward. Results: The incidence of nausea and rescue antiemetic drug need was higher at postoperative 6th hour in Group II. Vomiting was not different in groups at any time. Conclusion: Intraoperative laser acupuncture stimulation of PC6 and LI4 acupoints combined with antiemetic drug prophylaxis decreases nausea and rescue antiemetic drug need in late postoperative period in patients undergoing laparoscopic cholecystectomy.

Auditory Intraoperative Stimulation Effects on Pain and Agitation at Awakening (AUDIOPAW)

Auditory Intraoperative Stimulation Effects on Pain and Agitation at Awakening (AUDIOPAW)

Midline suboccipital craniotomy and direct stimulation for a dorsally exophytic brainstem tumor.

Dorsally exophytic brainstem tumors arise from within the brainstem itself. As the tumor grows, it pulls eloquent tissue with it, resulting in a shape that is analogous to the sides of a volcano. Rather than a resection that is flush with the brainstem being performed, this functional tissue on the lateral edges of the tumor must be identified and preserved in order to avoid postoperative deficits. The authors describe a midline, suboccipital approach with the use of intraoperative direct stimulation to identify and preserve functional tissue innervating the palate during the resection of a dorsally exophytic medullary tumor.The video can be found here: https://youtu.be/qbk2DvInO8o.

Microsurgical resection of a glioblastoma multiforme of the medulla oblongata with intraoperative subcortical stimulation and mapping.

Primary glioblastoma multiforme tumors of the medulla oblongata are rare, especially in the adult population. Perhaps due to this rarity, we are not aware of any previous reports addressing the resection of these tumors or their clinical outcomes.In this surgical video, we present a 43-year-old man with a 1-month history of left-sided paresthesia. The paresthesia initiated in the left hand, along with weakness and reduced fine motor control, and then spread to the entire left side of the body. He had recent weight loss, imbalance, difficulty in swallowing, and hoarseness in his voice. He also had a diminished gag reflex, and significant atrophy of the right side of the tongue with an accompanying deviation of the uvula and fasciculations of the tongue. MRI showed an infiltrative expansile mass within the medulla with peripheral enhancement and central necrosis. In T2/FLAIR sequences, a hyperintense signal extended superiorly into the left inferior aspect of the pons and left inferior cerebellar peduncle and inferiorly into the upper cervical cord.The decision was made to proceed with surgical resection. The patient underwent a midline suboccipital craniotomy with C1 laminectomy for surgical resection of this infiltrative expansile intrinsic mass in the medulla oblongata, with concurrent monitoring of motor and somatosensory evoked potentials and monitoring of lower cranial nerves IX, X, XI, and XII. A gross-total resection of the enhancing portion of the tumor was performed, along with a subtotal resection of the nonenhancing portion. The surgery and postoperative course were uneventful. Histopathology revealed a grade IV astrocytoma. The patient received radiation therapy.In this surgical video, we demonstrate important steps for the microsurgical resection of this challenging glioblastoma multiforme of the medulla oblongata.The video can be found here: https://youtu.be/QHbOVxdxbeU.

ReStNeuMap: a tool for automatic extraction of resting-state functional MRI networks in neurosurgical practice.

Resting-state functional MRI (rs-fMRI) represents a promising and cost-effective alternative to task-based fMRI for presurgical mapping. However, the lack of clinically streamlined and reliable rs-fMRI analysis tools has prevented wide adoption of this technique. In this work, the authors introduce an rs-fMRI processing pipeline (ReStNeuMap) for automatic single-patient rs-fMRI network analysis. The authors provide a description of the rs-fMRI network analysis steps implemented in ReStNeuMap and report their initial experience with this tool after performing presurgical mapping in 6 patients. They verified the spatial agreement between rs-fMRI networks derived by ReStNeuMap and localization of activation with intraoperative direct electrical stimulation (DES). The authors automatically extracted rs-fMRI networks including eloquent cortex in spatial proximity with the resected lesion in all patients. The distance between DES points and corresponding rs-fMRI networks was less than 1 cm in 78% of cases for motor, 100% of cases for visual, 87.5% of cases for language, and 100% of cases for speech articulation mapping. The authors' initial experience with ReStNeuMap showed good spatial agreement between presurgical rs-fMRI predictions and DES findings during awake surgery. The availability of the rs-fMRI analysis tools for clinicians aiming to perform noninvasive mapping of brain functional networks may extend its application beyond surgical practice.

Inhibition of Manual Movements at Speech Arrest Sites in the Posterior Inferior Frontal Lobe.

Intraoperative stimulation of the posterior inferior frontal lobe (IFL) induces speech arrest, which is often interpreted as demonstration of essential language function. However, prior reports have described "negative motor areas" in the IFL, sites where stimulation halts ongoing limb motor activity. To investigate the spatial and functional relationship between IFL speech arrest areas and negative motor areas (NMAs). In this retrospective cohort study, intraoperative stimulation mapping was performed to localize speech and motor function, as well as arrest of hand movement, hand posture, and guitar playing in a set of patients undergoing awake craniotomy for dominant hemisphere pathologies. The incidence and localization of speech arrest and motor inhibition was analyzed. Eleven patients underwent intraoperative localization of speech arrest sites and inhibitory motor areas. A total of 17 speech arrest sites were identified in the dominant frontal lobe, and, of these, 5 sites (29.4%) were also identified as NMAs. Speech arrest and arrest of guitar playing was also evoked by a single IFL site in 1 subject. Inferior frontal gyrus speech arrest sites do not function solely in speech production. These findings provide further evidence for the complexity of language organization, and suggest the need for refined mapping strategies that discern between language-specific sites and inhibitory motor areas.

Imaging Predictors for Significant Lower Motor Neuron Injury in Traumatic Cervical Spinal Cord Injury

Abstract INTRODUCTION Traumatic spinal cord injury (SCI) results in loss of both white and grey matter in the spinal cord and adjacent to the site of impact. Loss of gray matter within the injured area leads to lower motor neuron (LMN) injury, due to direct destruction of the alpha motor neurons and associated axonal loss within the adjacent peripheral nerves. The extent of gray matter loss can be discrete, or it can extend multiple levels from the site of impact. Since these changes can become irreversible within a year after injury, early identification of significant LMN injury in patients with traumatic SCI allows them to benefit from available reconstructive surgeries before the window for reinnervation closes. METHODS In this single-center retrospective study the charts of 21 previously healthy individuals aged 15 to 50 yr who suffered traumatic SCI with AIS C4-C8 A-D classification and hand functional impairment, without concomitant peripheral nerve or brachial plexus injury, were reviewed. Magnetic resonance (MR) images of cervical spine, obtained within 6 wk from the injury, were reviewed to identify structural imaging characteristics that correspond to gray matter destruction. Severity of LMN injury predicted by imaging findings was compared with the results of compound muscle action potential (CMAP), motor unit potential (MUP), intraoperative stimulation, and Medical Research Council (MRC) grading of the major muscle groups of the upper extremity. RESULTS The extent of LMN injury as determined by electrophysiological evaluations and intraoperative stimulation could be predicted with some degree of specificity by the preoperative imaging findings. CONCLUSION In this study, simple imaging biomarkers indicate the extent of LMN injury in patients with traumatic SCI. By noting the extent of soft tissue damage within the injured metamere of the spinal cord, the degree of lower motor neuron injury can be anticipated and thus appropriate triage performed.

Fascicle Sparing Capsular Resections of Atypical Neurofibromas in Neurofibromatosis 1

Abstract INTRODUCTION Neurofibromatosis type 1 (NF1) patients are predisposed to neurofibromas (NF), which can progress to premalignant atypical neurofibromas (ANF) and malignant peripheral nerve sheath tumors (MPNST). Subtotal resection of ANF may prevent metastases and deaths, but local recurrences require reoperation. Here, we assess the surgical morbidity associated with gross total, extracapsular resection of targeted ANF nodules identified via serial volumetric magnetic resonance imaging (MRI) and 18F-FDG-PET imaging. METHODS We retrospectively analyzed the clinical outcomes of 11 NF1 patients following 16 NF surgical resections of 21 tumors at the NIH Clinical Center between 2008 and 2018. Preoperative volumetric growth rates and 18F-FDG-PET SUVMAX of the target lesions were measured and assessed in tandem with postoperative complications, histopathological classification of the resected tumors, and surgical margins through Dunnett's multiple comparison tests and t-tests. RESULTS Preoperatively, 13 of the 14 (93%) sets of serial preoperative MRI scans showed rapid growth ( = 20% increase in volume per year), and 10 of the 11 (91%) 18F-FDG-PET scans indicated increased positron emission tomography (PET) avidity (median SUVMax = 6.45). Gross total, extracapsular resections of the targeted neurofibroma nodules were annotated by the surgeon in all 16 (100%) surgeries, and most surgeries (n = 14, 88%) resulted in no persistent postoperative parent nerve-related complications. SUVMax was significantly greater in the ANF (6.51 ± 0.83, P = .0042) and low grade MPNST (13.8, P = .0001) strata than in the benign NF (1.9) stratum. To date, none of the resected NF have recurred. CONCLUSION This study confirms that the combination of increased 18F-FDG-PET SUVMax, rapid growth, and pain can serve as reliable indicators of atypical transformation and the need for surgical intervention. We also demonstrate the ability to achieve safe, fascicle-sparing gross total, extracapsular resection of ANF using intraoperative nerve stimulation, histological verification, and continued monitoring for tumor recurrence.

A Surgical Mouse Model for Advancing Laryngeal Nerve Regeneration Strategies.

Iatrogenic recurrent laryngeal nerve (RLN) injury is a morbid complication of anterior neck surgical procedures. Existing treatments are predominantly symptomatic, ranging from behavioral therapy to a variety of surgical approaches. Though laryngeal reinnervation strategies often provide muscle tone to the paralyzed vocal fold (VF), which may improve outcomes, there is no clinical intervention that reliably restores true physiologic VF movement. Moreover, existing interventions neglect the full cascade of molecular events that affect the entire neuromuscular pathway after RLN injury, including the intrinsic laryngeal muscles, synaptic connections within the central nervous system, and laryngeal nerve anastomoses. Systematic investigations of this pathway are essential to develop better RLN regenerative strategies. Our aim was to develop a translational mouse model for this purpose, which will permit longitudinal investigations of the pathophysiology of iatrogenic RLN injury and potential therapeutic interventions. C57BL/6J mice were divided into four surgical transection groups (unilateral RLN, n = 10; bilateral RLN, n = 2; unilateral SLN, n = 10; bilateral SLN, n = 10) and a sham surgical group (n = 10). Miniaturized transoral laryngoscopy was used to assess VF mobility over time, and swallowing was assessed using serial videofluoroscopy. Histological assays were conducted 3months post-surgery for anatomical investigation of the larynx and laryngeal nerves. Eight additional mice underwent unilateral RLN crush injury, half of which received intraoperative vagal nerve stimulation (iVNS). These 8 mice underwent weekly transoral laryngoscopy to investigate VF recovery patterns. Unilateral RLN injury resulted in chronic VF immobility but only acute dysphagia. Bilateral RLN injury caused intraoperative asphyxiation and death. VF mobility was unaffected by SLN transection (unilateral or bilateral), and dysphagia (transient) was evident only after bilateral SLN transection. The sham surgery group retained normal VF mobility and swallow function. Mice that underwent RLN crush injury and iVNS treatment demonstrated accelerated and improved VF recovery. We successfully developed a mouse model of iatrogenic RLN injury with impaired VF mobility and swallowing function that can serve as a clinically relevant platform to develop translational neuroregenerative strategies for RLN injury.

Ventral Precentral Fiber Intersection Area: A Central Hub in the Connectivity of Perisylvian Associative Tracts

The ventral part of the precentral gyrus is considered one of the most eloquent areas. However, little is known about the white matter organization underlying this functional hub. To analyze the subcortical anatomy underlying the ventral part of the precentral gyrus, ie, the ventral precentral fiber intersection area (VPFIA). Eight human hemispheres from cadavers were dissected, and 8 healthy hemispheres were studied with diffusion tensor imaging tractography. The tracts that terminate at the ventral part of the precentral gyrus were isolated. In addition, 6 surgical cases with left side gliomas close to the VPFIA were operated awake with intraoperative electrical stimulation mapping. The connections within the VPFIA are anatomically organized along an anteroposterior axis: the pyramidal pathway terminates at the anterior bank of the precentral gyrus, the intermediate part is occupied by the long segment of the arcuate fasciculus, and the posterior bank is occupied by the anterior segment of the arcuate fasciculus. Stimulation of the VPFIA elicited speech arrest in all cases. The present study shows strong arguments to sustain that the fiber organization of the VPFIA is different from the classical descriptions, bringing new light for understanding the functional role of this area in language. The VPFIA is a critical neural epicenter within the perisylvian network that may represent the final common network for speech production, as it is strategically located between the termination of the dorsal stream and the motor output cortex that directly control speech muscles.

Nerves in the Areas Posterior to the Prostate Base Contribute to Erectile Function: An Intraoperative Electrical Stimulation Assessment

To confirm the distribution of functional nerves involved in erectile function at the posterior of the prostate base, intraoperative nerve stimulation was performed during robot-assisted radical prostatectomy (RARP) METHODS: Several points at the posterior of the prostate and the posterolateral typical neurovascular bundle (NVB) were electrically stimulated at the level of the prostate base during RARP in patients with clinically localized prostate cancer. The prostate pedicle (PP), medial side of the PP (MPP), Denonvilliers' fascia (DF), and typical NVB were stimulated using bipolar electrodes. The changes in pressure at the middle of the urethra were measured using an inserted balloon-catheter to detect the increase in cavernosal pressure. Although the study included only 12 patients, each stimulation of the PP, MPP, and NVB induced evident urethral pressure responses in all patients. The median amplitude of the pressure responses was 5.49 (IQR 3.11-8.42), 6.00 (IQR 3.70-8.30), and 3.22 (IQR 2.48-7.19) cm H2O at the PP, MPP, and NVB, respectively. The amplitude of responses at the PP and MPP was not small compared with the responses at the typical NVB. Stimulations at the DF induced unstable weak urethral response alone or no response in all patients. We showed that electrostimulation of the PP and MPP increases the cavernosal pressure similar to the typical NVB stimulation. These findings indicate that maximal preservation of the tissues at the posterior area of the prostate base can contribute to optimal recovery of postoperative erectile function after nerve-sparing RARP.

A System for Combined Laser Doppler Flowmetry and Microelectrode Recording during Deep Brain Stimulation Implantation.

Microelectrode recording (MER) and intraoperative test stimulations are commonly used during stereotactic implantation of deep brain stimulation (DBS) electrodes but they can increase the risk of hemorrhage. The aim of the study is to present and evaluate a system combining laser Doppler flowmetry (LDF) and MER. An optical probe was designed with an inner metal tube for the microelectrode. Calibration of the MER-LDF probe in a standard microsphere solution showed expected LDF pattern. No interferences of the MER probe with the LDF signals could be observed. LDF was also acquired in one Parkinson patient undergoing DBS implantation. LDF data were obtained along the precalculated trajectory i.e. from cortex towards the target in the subthalamic nucleus (STN). Results demonstrated the technical feasibility of the combined MER-LDF probe during in-vitro experiences and in one patient. The perfusion signal representing the microcirculation showed stable values with clear peaks from each heartbeat. This agreed with previous investigation using an optical probe without the MER function. Due to the forward-looking probe design, this new technology has a high potential to avoid vessels during MER recording. In addition, it could be possible to detect changes in microcirculatory blood flow during stimulation.