Intraoperative Stimulation Research Articles

Surgical Management of Parkinson’s Disease: The Role of Lesioning Procedures in Developing Countries in the Modern Era

BACKGROUND: The known loss of dopaminergic cells in the pars-compacta of the substantia nigra that is the hallmark of PD. The cellular pathophysiology of the motor dysfunction is beginning to be better understood, thereby providing a stronger scientific rationale for surgical interventions. Yet, to date, there are no treatments that prevent, halt, or cure PD. Surgical strategies, offer symptomatic relief or control of motor complications associated with drug treatment.
 Both pallidotomy and thalamotomy were extensively used in the treatment of PD in the1950’s and 1960’s. With the introduction of levodopa (L-dopa) in the1960’s and the realization of its striking benefits, surgery was almost abandoned and used only for patients with severe tremor. Surgical therapy is now being used earlier and more often. There are currently three brain regions being considered as targets for functional neurosurgery for PD (other than transplantation). Either CNS lesions (thalamotomy, pallidotomy or subthalamic nucleus lesions) or deep brain stimulation [DBS]. These targets are: The ventral intermediate nucleus of the thalamus (Vim), the internal segment of the Globus Pallidus (GPi) and the subthalamic nucleus (STN).
 OBJECTIVE: To assess the outcome (3 months & 6 months) of lesioning procedures in parkinson’s disease (PD) patients meeting the inclusion criteria.
 METHODS: A prospective clinical study conducted on 10 IPD patients during the period from October 2018 to March 2021 at Cairo University Hospitals. This study was concerned to improve the motor symptoms of IPD patients by stereotactic radiofrequency ablative procedures. Cases were restricted to 10 patients due to the Covid-19 pandemic and restriction of elective cases for chronic patients at Cairo University hospitals.
 RESULTS: In our study we operated upon 10 IPD patients who were meeting our selection criteria by ablative procedures contralateral to parkinsonian symptoms.
 Age of the patients ranged 17 – 70y with mean of 50.5 ± 16.35 y with predominance in males representing 6 patients. Mean duration of Parkinson`s disease according to history ranged from 2 to 12 y with mean of 8 ± 3.1 years. Patients were divided into three groups according to their presentation and the operation done for them. Thalamotomy group: Pre-operatively, the UPDRS III off & on respectively was 24.4/15.2 and post-operatively was 13/7.4 with improvement 47% / 51%. The tremor subscore was 5.4/2.8 pre-operatively and 1.4/0.8 post-operatively with average of 72% improvement. The UPDRS II pre was 17.2/11.6 and post it became 10.6/7 with 39% improvement. Modified H&Y 2.4/1.7 pre & post-operatively (29% improvement). Pallidotomy group: Pre-operatively, the UPDRS III off & on respectively was 38.5/23.5 and post-operatively was 28/16 with improvement 27% / 32%. The rigidity subscore was 5/2.5 pre-operatively and 2/1 post-operatively with average of 60% improvement. The bradykinesia subscore was 9/5.5 pre-operatively and 5.5/2.5 post-operatively with average of 47% improvement. The dyskinesia subscore was 4.5 pre-operatively and 1.2 post-operatively with average of 71% improvement. The UPDRS II pre was 22/12.5 and post it became 16/10 with 25% improvement. Modified H&Y 2.75/2.25 pre & post-operatively (18% improvement). Combined group: Pre-operatively, the UPDRS III off & on respectively was 41.33/28.67 and post-operatively was 15.67/11.33 with improvement 62% /60%. The rigidity subscore was 5/3.33 pre-operatively and 1.67/1 post-operatively with average of 68% improvement. The bradykinesia subscore was 10/6 pre-operatively and 4/1.33 post-operatively with average of 72% improvement. The UPDRS II pre was 28.33/19.33 and post it became 16.33/10.67 with 43% improvement. Modified H&Y 2.83/2 pre & post-operatively (29% improvement). Postoperatively, there was a high significant statistical finding in all clinical score and subscore of parkinsonian symptoms.
 CONCLUSION: The study concludes that lesioning procedure should be revisited globally using the modern techniques of targeting and controlled thermal lesion protocols guided by capsular somatotopy and intraoperative macroelectrode stimulation, that will improve the outcome dramatically. Ablative procedures proved their efficacy in controlling motor symptoms of IPD and their cost-benefit in low & middle-income nations.

Intraoperative seizure outcome of levetiracetam combined with perampanel therapy in patients with glioma undergoing awake brain surgery.

This study aimed to evaluate the efficacy of levetiracetam (LEV) combined with perampanel (PER) therapy for intraoperative seizure treatment to determine whether a combination of LEV and PER can aid in the prevention of intraoperative intractable seizures during awake surgery. The authors performed a retrospective cohort study in 78 consecutive patients with glioma who underwent awake surgery using intraoperative direct electrical stimulation mapping. To prevent intraoperative seizures, 50 patients were treated with the antiepileptic drug LEV only (LEV group) from January 2017 to January 2019, while the remaining 28 patients were treated with LEV plus PER (LEV + PER group) between March 2019 and January 2020. LEV (1000-3000 mg) and/or PER (2-4 mg) were administered before the surgery. Preoperative seizures with International League Against Epilepsy (ILAE) class II-VI occurred in 44% of the patients in the LEV group and in 35.7% of patients in the LEV + PER group, with no significant difference between groups (p = 0.319). Total intraoperative seizures occurred in 18 patients (36.0%) in the LEV therapy group and in 2 patients (7.1%) in the LEV + PER group (p = 0.009). Of these, there were no patients (0%) with intractable seizures in the LEV + PER group. Regarding factors that influence intraoperative seizures in glioma patients during awake brain surgery, multivariate logistic regression models revealed that the occurrence of intraoperative seizures was significantly related to the involvement of motor-related regions (positive vs negative, HR 6.98, 95% CI 1.71-28.56, p = 0.007), preoperative seizure (ILAE class II-VI vs ILAE class I, HR 4.44, 95% CI 1.22-16.11, p = 0.024), and LEV + PER group (positive vs negative, HR 0.07, 95% CI 0.01-0.44, p = 0.005). Treatment-related adverse effects were rare and mild, including sleepiness, tiredness, and dizziness in both treatment groups. This study demonstrates that LEV + PER therapy is significantly associated with a lower risk of intraoperative seizures compared with LEV therapy alone in patients with glioma during awake brain mapping. These findings will help neurosurgeons conduct safe and reliable awake surgeries and reduce the rate of intraoperative intractable seizures during such procedures.

Posterolateral trans dentate approach to anterior extensive extramedullary tumor of the cervical spine in a pediatric case: how I do it.

Extramedullary anterior cervical canal tumors can be challenging lesions to reach. The posterolateral trans dentate approach offers an alternative route. Classic posterior laminoplasty is done to expose the medulla; the dentate ligament is identified as a fibrous structure running from the lateral pial surface of the medulla to the lateral dura between nerve roots spaces. Once the ligament is cut, the medulla can be gently rotated to access the anterior cervical canal. Intraoperative neurophysiological stimulation is mandatory. This approach allows a safe route, without the need for corpectomies. It should be considered especially in children where multilevel corpectomies could be challenging.

Premature atrial stimulation accentuates conduction abnormalities in cardiac surgery patients that develop postoperative atrial fibrillation

Backgroundpostoperative atrial fibrillation (POAF) is a common cardiac surgery complication that is associated with increased complications and negative outcomes, but the association between presurgical atrial conduction abnormalities and POAF has not been investigated clinically during premature atrial S1S2 stimulation. This clinical study sought to examine whether intraoperative premature atrial stimulation reveals increased areas of slowed and/or blocked conduction in patients that develop POAF. MethodsHigh-density intraoperative epicardial left atrial mapping was conducted in 20 cardiac surgery patients with no prior history of atrial fibrillation (AF). In 20 patients, 6 (30%) developed POAF. A flexible-array of 240-electrodes was placed on the posterior left atrial wall in between the pulmonary veins. Activation maps were generated for sinus and premature atrial S1S2 stimulated beats. The area of conduction block (CB), conduction delay (CD) and the combination of both (CDCB) for conduction velocity < 0.1, 0.1 ≤ x < 0.2 and < 0.2 m/s, respectively were quantified. ResultsFor a premature atrial S2 beat with shortest cycle length captured, conduction velocity maps revealed a significantly higher area for CD (13.19 ± 6.59 versus 6.06 ± 4.22 mm2, p = 0.028) and CDCB (17.36 ± 8.75 versus 7.41 ± 6.39 mm2, p = 0.034), and a trend toward a larger area for CB (4.17 ± 3.66 versus 1.34 ± 2.86 mm2, p = 0.063) in patients who developed POAF in comparison to those that remained in the sinus. Sinus and S1 paced beats did not show substantial differences in abnormal conduction areas between patients with and without POAF. ConclusionIn comparison to sinus and S1 beats, premature atrial S2 beats accentuate conduction abnormalities in the posterior left atrial wall of cardiac surgery patients that developed POAF.

P03.05 The use of subcortical intraoperative electrical stimulation mapping for assessment of executive functions: A summary of the evidence so far

Abstract BACKGROUND Over the past years, the functional subcortical architecture of the brain has been increasingly acknowledged in neurosurgical planning. A method to study anatomo-functional correlations is direct electrical stimulation (DES). DES is widely used by neurosurgeons and considered as a reliable tool to minimize the occurrence of permanent postoperative motor, language and visual deficits. In recent years, DES has also been used for mapping of other cognitive functions, such as executive functions. MATERIAL AND METHODS We systematically summarized the evidence so far from DES studies on subcortical pathways that are involved in the following three executive functions: (1) inhibitory control, (2) working memory and (3) cognitive flexibility. RESULTS We only found twelve articles that reported on intraoperative electrical stimulation of white matter pathways to map executive functions and explicitly clarified which subcortical tract was stimulated. The results indicate that the second branch of the right superior longitudinal fasciculus (SLF-II) is involved in inhibitory control, the first branch of the right superior longitudinal fasciculus (SLF-I) and the third branch of the left superior longitudinal fasciculus (SLF-III) are involved in working memory and the cingulum is involved in cognitive flexibility. CONCLUSION We were unable to draw any specific conclusions, nor unequivocally established the pathways involved in executive functions due to heterogenous study characteristics, methods and tasks, and the limited number of studies that assessed these relationships. Clearly, neurosurgical groups are exploring novel methods to assess cognition during awake neurosurgery, but are far from consensus on indications and protocols, which complicated the comparison and summarization of findings. We will discuss possible approaches for future research to obtain converging and more definite evidence for the involvement of subcortical pathways in specific executive functions.

Science, Medicine, and the Anesthesiologist

Science, Medicine, and the Anesthesiologist

Intraoperative brain mapping during awake surgery in symptomatic supratentorial cavernomas

BackgroundComplete resection of symptomatic supratentorial cavernoma (SCA) and removal of the surrounding gliotic area is recommended to minimize the risk of persistent seizures or (re)bleeding. Surgery of SCA located in an eloquent area, can carry out severe postoperative neurological morbidity. We report a study aimed to assess feasibility, extent of resection and outcome after surgical removal of CA by cortico-subcortical intraoperative brain stimulation (ioBS) in the awake patient. MethodsSix patients diagnosed of symptomatic SCA located on an eloquent area and operated on while awake under local anaesthesia ioBS, were included. Preoperative planning included neuropsychologic assessment of language-related functions, sociocognitive functions and executive functions. Intraoperatively, we recorded the results achieved in the planned neuropsychological tasks when stimulation was applied (cortical and subcortical). Postoperative control 3D MRI was scheduled at 1 month after surgery to calculate extent of resection. Neuropsychological assessment at 6 months after surgery was performed in all cases. ResultsSix patients (5 females, 1 male) aged 24–48 years were included in our study. Locations of the lesions were right insular (n=1), left insular (n=1), left temporo-insular (n=1), left temporal (n=2) and left frontal (n=1). In all patients, positive findings were obtained during ioBS. In 5 patients, complete surgical resection was achieved. Two patients had postoperative transient neurological deficits, one case of hemiparesis, one case of dysnomia, both cleared over a 6-month period. Clinical follow-up revealed that all patients experienced complete recovery from preoperative symptoms within a year and five patients with seizures showed marked improvement and eventually quit antiepileptic drugs. Neuropsychological assessment at 6 months provided normal results compared to preoperative baseline in all domains. ConclusionsOur study suggests that ioBS in the awake surgery of symptomatic SCA located in eloquent areas, allows to increase the rate of complete resection, minimizing postoperative neurological and neuropsychological deficit, and improving postoperative seizures control.

Risk Factors and Characteristics of Intraoperative Seizures During Awake Craniotomy: A Retrospective Cohort Study of 562 Consecutive Patients With a Space-occupying Brain Lesion.

Intraoperative seizures (IOSs) during awake craniotomy (AC) are associated with significant morbidity. The reported incidence of IOS is between 3% and 30%. The aim of this study was to identify risk factors for IOS during AC for elective resection or biopsy of a space-occupying brain lesion. In this retrospective study, we reviewed the records of all awake craniotomies performed by a single neurosurgeon at a single university hospital between July 2006 and December 2018. IOS was defined as a clinically apparent seizure that occurred in the operating room and was documented in the medical records. Explanatory variables were chosen based on previously published literature on risk factors for IOS. Five hundred and sixty-two patients had a total of 607 AC procedures during the study period; 581 cases with complete anesthesia records were included in analysis. Twenty-nine (5.0%) IOS events were reported during 29 (5%) awake craniotomies. Most seizures (27/29; 93%) were focal in nature and did not limit planned intraoperative stimulation mapping. Variables associated with IOS at a univariate P -value <0.1 (frontal location of tumor, preoperative radiotherapy, preoperative use of antiepileptic drugs, intraoperative use of dexmedetomidine, and intraoperative stimulation mapping) were included in a multivariable logistic regression. Frontal location of tumor (adjusted odds ratio: 5.68, 95% confidence interval: 2.11-15.30) and intraoperative dexmedetomidine use (adjusted odds ratio: 2.724, 95% confidence interval: 1.24-6.00) were independently associated with IOS in the multivariable analysis. This study identified a low incidence (5%) of IOS during AC. The association between dexmedetomidine and IOS should be further studied in randomized trials as this is a modifiable risk factor.

Enhanced Fiber Tractography Using Edema Correction: Application and Evaluation in High-Grade Gliomas.

A limitation of diffusion tensor imaging (DTI)-based tractography is peritumoral edema that confounds traditional diffusion-based magnetic resonance metrics. To augment fiber-tracking through peritumoral regions by performing novel edema correction on clinically feasible DTI acquisitions and assess the accuracy of the fiber-tracks using intraoperative stimulation mapping (ISM), task-based functional magnetic resonance imaging (fMRI) activation maps, and postoperative follow-up as reference standards. Edema correction, using our bi-compartment free water modeling algorithm (FERNET), was performed on clinically acquired DTI data from a cohort of 10 patients presenting with suspected high-grade glioma and peritumoral edema in proximity to and/or infiltrating language or motor pathways. Deterministic fiber-tracking was then performed on the corrected and uncorrected DTI to identify tracts pertaining to the eloquent region involved (language or motor). Tracking results were compared visually and quantitatively using mean fiber count, voxel count, and mean fiber length. The tracts through the edematous region were verified based on overlay with the corresponding motor or language task-based fMRI activation maps and intraoperative ISM points, as well as at time points after surgery when peritumoral edema had subsided. Volume and number of fibers increased with application of edema correction; concordantly, mean fractional anisotropy decreased. Overlay with functional activation maps and ISM-verified eloquence of the increased fibers. Comparison with postsurgical follow-up scans with lower edema further confirmed the accuracy of the tracts. This method of edema correction can be applied to standard clinical DTI to improve visualization of motor and language tracts in patients with glioma-associated peritumoral edema.

Directional Deep Brain Stimulation of the Posteromedial Hypothalamus for Refractory Intermittent Explosive Disorder: A Case Series Using a Novel Neurostimulation Device and Intraoperative Microdialysis

Intermittent explosive disorder (IED) is a psychiatric disorder characterized by recurrent outbursts of aggressive behavior. Deep brain stimulation (DBS) in the posteromedial nucleus of the hypothalamus (pHyp) is an alternative therapy for extreme cases and shows promising results. Intraoperative microdialysis can help elucidate the neurobiological mechanism of pHyp-DBS. We sought to evaluate efficacy and safety of pHyp-DBS using 8-contact directional leads in patients with refractory IED (rIED) and the accompanying changes in neurotransmitters. This was a prospective study in which patients with a diagnosis of rIED were treated with pHyp-DBS for symptom alleviation. Bilateral pHyp-DBS was performed with 8-contact directional electrodes. Follow-up was performed at 3, 6, and 12 months after surgery. Four patients (3 men, mean age 27 ± 2.8 years) were included. All patients were diagnosed with rIED and severe intellectual disability. Two patients had congenital rubella, one had a co-diagnosis of infantile autism, and the fourth presented with drug-resistant epilepsy. There was a marked increase in the levels of gamma-aminobutyric acid and glycine during intraoperative stimulation. The average improvement in aggressive behavior in the last follow-up was 6 points (Δ: 50%, P= 0.003) while also documenting an important improvement of the Short Form Health Survey in all domains except bodily pain. No adverse events associated with pHyp-DBS were observed. This is the first study to show the safety and beneficial effect of directional lead pHyp-DBS in patients with rIED and to demonstrate the corresponding mechanism of action through increases in gamma-aminobutyric acid and glycine concentration in the pHyp.

Endoscopic transcanal facial nerve decompression in Bell's palsy: A pilot study

PurposeTo explore the surgical effects of endoscopic facial nerve decompression in Bell's palsy. Materials and methodsThis retrospective study included 15 patients with Bell's palsy. All had grade VI (House-Brackmann grading system) complete unilateral facial paralysis before surgery and a >95% reduction in amplitude on electroneurography testing compared to the unaffected side. Their MRI results indicated perineural edema in the geniculate ganglion area. Endoscopic decompression surgery was performed soon after they presented at our hospital. The time between onset of facial paralysis and surgery ranged from 25 to 93 days. All patients had no relevant surgical history or ear diseases. ResultsAt 1-year follow-up, 13 of the 15 (87%) patients had recovered to normal or near-normal facial function (House-Brackmann grade I-II), and all patients had reached House-Brackmann grade III or lower facial function. No obvious air-bone gap or sensorineural hearing loss occurred after surgery, and there were no severe complications or synkinesis. ConclusionsEndoscopic transcanal facial nerve decompression provides a less traumatic and improved exposure of the geniculate ganglion, and may also help prevent permanent severe facial sequela. Results of intraoperative facial nerve stimulation may be related to the length of time required for recovery. The optimal time of surgery after onset of paralysis needs to be investigated further, to identify a post-drug surgical therapy which may be more acceptable for patients. Patients' response to conservative treatments should be assessed as soon as possible so as not to delay surgery.

Mapping of Motor Function with Neuronavigated Transcranial Magnetic Stimulation: A Review on Clinical Application in Brain Tumors and Methods for Ensuring Feasible Accuracy.

Navigated transcranial magnetic stimulation (nTMS) has developed into a reliable non-invasive clinical and scientific tool over the past decade. Specifically, it has undergone several validating clinical trials that demonstrated high agreement with intraoperative direct electrical stimulation (DES), which paved the way for increasing application for the purpose of motor mapping in patients harboring motor-eloquent intracranial neoplasms. Based on this clinical use case of the technique, in this article we review the evidence for the feasibility of motor mapping and derived models (risk stratification and prediction, nTMS-based fiber tracking, improvement of clinical outcome, and assessment of functional plasticity), and provide collected sets of evidence for the applicability of quantitative mapping with nTMS. In addition, we provide evidence-based demonstrations on factors that ensure methodological feasibility and accuracy of the motor mapping procedure. We demonstrate that selection of the stimulation intensity (SI) for nTMS and spatial density of stimuli are crucial factors for applying motor mapping accurately, while also demonstrating the effect on the motor maps. We conclude that while the application of nTMS motor mapping has been impressively spread over the past decade, there are still variations in the applied protocols and parameters, which could be optimized for the purpose of reliable quantitative mapping.

Diffusion tractography for awake craniotomy: accuracy and factors affecting specificity

IntroductionDespite evidence of correspondence with intraoperative stimulation, there remains limited data on MRI diffusion tractography (DT)’s sensitivity to predict morbidity after neurosurgical oncology treatment. Our aims were: (1) evaluate DT against subcortical stimulation mapping and performance changes during and after awake neurosurgery; (2) evaluate utility of early post-operative DT to predict recovery from post-surgical deficits.MethodsWe retrospectively reviewed our first 100 awake neurosurgery procedures using DT- neuronavigation. Intra-operative stimulation and performance outcomes were assessed to classify DT predictions for sensitivity and specificity calculations. Post-operative DT data, available in 51 patients, were inspected for tract damage.Results91 adult brain tumor patients (mean 49.2 years, 43 women) underwent 100 awake surgeries with subcortical stimulation between 2014 and 2019. Sensitivity and specificity of pre-operative DT predictions were 92.2% and 69.2%, varying among tracts. Post-operative deficits occurred after 41 procedures (39%), but were prolonged (> 3 months) in only 4 patients (4%). Post-operative DT in general confirmed surgical preservation of tracts. Post-operative DT anticipated complete recovery in a patient with supplementary motor area syndrome, and indicated infarct-related damage to corticospinal fibers associated with delayed, partial recovery in a second patient.ConclusionsPre-operative DT provided very accurate predictions of the spatial location of tracts in relation to a tumor. As expected, however, the presence of a tract did not inform its functional status, resulting in variable DT specificity among individual tracts. While prolonged deficits were rare, DT in the immediate post-operative period offered additional potential to monitor neurological deficits and anticipate recovery potential.

The PROGRAM study: awake mapping versus asleep mapping versus no mapping for high-grade glioma resections: study protocol for an international multicenter prospective three-arm cohort study

IntroductionThe main surgical dilemma during glioma resections is the surgeon’s inability to accurately identify eloquent areas when the patient is under general anaesthesia without mapping techniques. Intraoperative stimulation mapping (ISM)...

MR Tractography-Based Targeting and Physiological Identification of the Cuneiform Nucleus for Directional DBS in a Parkinson's Disease Patient With Levodopa-Resistant Freezing of Gait.

BackgroundFreezing of gait (FOG) is a debilitating motor deficit in a subset of Parkinson’s Disease (PD) patients that is poorly responsive to levodopa or deep brain stimulation (DBS) of established PD targets. The proposal of a DBS target in the midbrain, known as the pedunculopontine nucleus (PPN), to address FOG was based on its observed neuropathology in PD and its hypothesized involvement in locomotor control as a part of the mesencephalic locomotor region (MLR). Initial reports of PPN DBS were met with enthusiasm; however, subsequent studies reported mixed results. A closer review of the MLR basic science literature, suggests that the closely related cuneiform nucleus (CnF), dorsal to the PPN, may be a superior site to promote gait. Although suspected to have a conserved role in the control of gait in humans, deliberate stimulation of a homolog to the CnF in humans using directional DBS electrodes has not been attempted.MethodsAs part of an open-label Phase 1 clinical study, one PD patient with predominantly axial symptoms and severe FOG refractory to levodopa therapy was implanted with directional DBS electrodes (Boston Science Vercise CartesiaTM) targeting the CnF bilaterally. Since the CnF is a poorly defined reticular nucleus, targeting was guided both by diffusion tensor imaging (DTI) tractography and anatomical landmarks. Intraoperative stimulation and microelectrode recordings were performed near the targets with leg EMG surface recordings in the subject.ResultsPost-operative imaging revealed accurate targeting of both leads to the designated CnF. Intraoperative stimulation near the target at low thresholds in the awake patient evoked involuntary electromyography (EMG) oscillations in the legs with a peak power at the stimulation frequency, similar to observations with CnF DBS in animals. Oscillopsia was the primary side effect evoked at higher currents, especially when directed posterolaterally. Directional DBS could mitigate oscillopsia.ConclusionDTI-based targeting and intraoperative stimulation to evoke limb EMG activity may be useful methods to help target the CnF accurately and safely in patients. Long term follow-up and detailed gait testing of patients undergoing CnF stimulation will be necessary to confirm the effects on FOG.Clinical Trial RegistrationClinicaltrials.gov identifier: NCT04218526.

Can we routinely identify the external branch of the superior laryngeal nerves with neural monitoring?: a prospective report on 176 consecutive nerves at risk

The external branch of the superior laryngeal nerve (EBSLN) provides motor function to the cricothyroid muscle (CTM). EBSLN damage produces changes in voice quality and projection. Intraoperative neuromonitoring (IONM) in thyroid surgery aims to optimize EBSLN control during dissection. We prospectively collected the data of 88 consecutive patients who underwent total thyroidectomy with IONM from July 2019 to December 2019. IONM was offered in the intermittent mode of application. We routinely searched for the EBSLN electromyographic (EMG) signal before (S1) and after (S2) dissection of the superior vascular peduncle. In the absence of the EMG signal, we observed the CTM twitch. We identified 141 (80%) S1 EMG signals, while we recorded the CTM twitch in 15 cases (8.5%). In 20 (11.3%) cases, we were unable to identify the EMG signal. Analysing the S2 results, we found loss of EBSLN signal in 11/141 cases (7.8%) identified with IONM in pre-dissection stimulation. Among the 20 cases without pre-dissection identification (we had not identified the external branch of the superior laryngeal nerve or the muscle twitch), in the post-dissection evaluation, we confirmed the loss of signal in 17 of 20 cases, equal to 85% (p < 0.001). Our data clearly show that intraoperative stimulation and recognition of EBSLN, performed before any dissection manoeuvre to the superior vascular thyroid pole, leads to a much higher rate of nerve conservation.

Effects of Intraoperative Auditory Stimulation on Pain and Agitation on Awakening After Pediatric Adenotonsillectomy

Severe pain on awakening (POA) and emergence delirium (ED) are common following pediatric adenotonsillectomy. Effective preventive interventions are lacking. To determine the effects of intraoperative auditory stimulation on reduction of POA and ED after pediatric adenotonsillectomy. Single-center, double-blinded, 4-armed, randomized clinical trial of children undergoing adenotonsillectomy from March 2018 to May 2019 at a tertiary care pediatric referral center. Children were randomized to 1 of the following groups: auditory stimulation with music, auditory stimulation with noise, ambient noise insulation with masking earplugs, and a control group receiving no intervention. Ear inserts were placed in the operating room once general anesthesia was administered. Stimulation parameters were based on the preoperative audiological evaluation and the appropriate fitting of the transduction system, including ambient noise level monitoring. The primary outcome was POA levels measured on 10-point scales according to age-appropriate validated tools. The secondary outcome was ED levels assessed according to the Pediatric Anesthesia Emergence Delirium 20-point scale. A total of 104 consecutive healthy children (median [interquartile range] age at surgery, 5.0 [3.8-6.4] years) were included in the analysis. Music had a large effect size on POA (0.63; 98% CI, 0.43-0.84) and a medium effect size on ED (0.47; 98% CI, 0.21-0.75), while noise had a medium effect size on POA (0.47; 98% CI, 0.22-0.73) and a large effect size on ED (0.63; 98% CI, 0.44-0.85) compared with controls. The earplugs group showed a small effect size on POA and ED. Considering a clinically meaningful threshold of greater than 4 for POA and 10 or greater for ED at dichotomized analysis, a large effect size was achieved by music (1.39; odds ratio [OR], 0.08; 98% CI, 0.02-0.29; and 0.84; OR, 0.22; 98% CI, 0.06-0.75, respectively) and noise (0.97; OR, 0.17; 98% CI, 0.05-0.6; and 1.48; OR, 0.07; 98% CI, 0.02-0.26, respectively), while earplugs resulted in a small effect size. In this randomized clinical trial, children undergoing adenotonsillectomy who received intraoperative auditory stimulation demonstrated a clinically meaningful decrease in POA and ED in the immediate postoperative period. Further research is needed to assess whether intraoperative auditory stimulation may decrease POA and ED in children undergoing other types of surgical procedures. ClinicalTrials.gov Identifier: NCT04112979.

Pre-surgical fMRI Localization of the Hand Motor Cortex in Brain Tumors: Comparison Between Finger Tapping Task and a New Visual-Triggered Finger Movement Task.

Introduction: Pre-surgical mapping is clinically essential in the surgical management of brain tumors to preserve functions. A common technique to localize eloquent areas is functional magnetic resonance imaging (fMRI). In tumors involving the peri-rolandic regions, the finger tapping task (FTT) is typically administered to delineate the functional activation of hand-knob area. However, its selectivity may be limited. Thus, here, a novel cue-induced fMRI task was tested, the visual-triggered finger movement task (VFMT), aimed at eliciting a more accurate functional cortical mapping of the hand region as compared with FTT.Method: Twenty patients with glioma in the peri-rolandic regions underwent pre-operative mapping performing both FTT and VFMT. The fMRI data were analyzed for surgical procedures. When the craniotomy allowed to expose the motor cortex, the correspondence with intraoperative direct electrical stimulation (DES) was evaluated through sensitivity and specificity (mean sites = 11) calculated as percentage of true-positive and true-negative rates, respectively.Results: Both at group level and at single-subject level, differences among the tasks emerged in the functional representation of the hand-knob. Compared with FTT, VFMT showed a well-localized activation within the hand motor area and a less widespread activation in associative regions. Intraoperative DES confirmed the greater specificity (97%) and sensitivity (100%) of the VFMT in determining motor eloquent areas.Conclusion: The study provides a novel, external-triggered fMRI task for pre-surgical motor mapping. Compared with the traditional FTT, the new VFMT may have potential implications in clinical fMRI and surgical management due to its focal identification of the hand-knob region and good correspondence to intraoperative DES.

Transcavernous Approach to the Anteromedial Triangle for Residual Functional Pituitary Adenoma.

Surgical treatment of functional pituitary adenomas is as rule performed by transsphenoidal approach. However, when then lesion invades the parasellar structures and the cavernous sinus, the transsphenoidal removal of these adenomas is usually incomplete. In this video, we present the technical nuances of a transcavernous approach to the anterio-medial triangle for the resection of a residual functional pituitary adenoma. The patient is a 40-year-old male who was diagnosed with growth hormone secreting pituitary macroadenoma. He underwent two transsphenoidal resections in 2013 and 2016 with a small residue in the left cavernous sinus. Subsequently, due to a failure of biochemical remission despite medical management, a transcranial transcavernous surgery was performed. Brain magnetic resonance imaging showed a mass in the roof of the left cavernous sinus, located at the level of the anteromedial triangle, adherent to the clinoidal segment of the internal carotid artery (ICA). The computed tomographic scan showed an osteolysis of the inferior surface of the anterior clinoidal process. After performing an extended pterional craniotomy and an extradural clinoidectomy, the cleavage plane is extended between the temporal dura and the inner layer of the lateral wall of the cavernous sinus. Intraoperative Doppler and stimulation are used to localize the clinoidal segment of the ICA and the third cranial nerve, delimiting the anteromedial triangle. The lesion is progressively dissected and removed. An optic neuropexy with the previously harvested fat is performed in case of a complementary radio surgical treatment. The patient had an uneventful postoperative course and showed a biochemical remission at the 3-month follow-up. The link to the video can be found at: https://youtu.be/oHfugVtU-Nc .

The quantitative evaluation of cortico-spinal tract involvement in malignant intracerebral tumors

The aim of the study was development of the method for preoperative quantitative evaluation of pyramidal tract and tumor relationship in malignant intracerebral tumors.Materials and methods. The retrospective analysis of 62 patients underwent surgery at the Department of Neurosurgery of Privolzhsky Research Medical University in 2017–2019, was performed. The patients were divide in 3 groups: metastatic brain tumor (n = 16); contrast-enhanced gliomas (grade III–IV); contrast-nonenhanced gliomas (grade II–III). The following protocol was implemented for all patients: preoperative DTI-tractography; intraoperative direct subcortical electrical stimulation with fixation of the minimum current intensity at receiving the motor response; pre- and postoperative motor function assessment using MRC-scale. Tract Involvement Index (TII) based on the ratio of the perimeter of the part of the tract involvement in pathological MRI-signal to its cross-section area was calculated using image processing of preoperative MRI and MRI-tractography data.Results. The association between TII values (from 0 to 1.75) and the severity of pre-operative paresis was demonstrated. We have discovered that the greater value of the pyramidal TII was corresponded to the greater severity of the paresis in MRC (p &lt;0.001, n = 62). The analysis of TII values and intraoperative motor direct subcortical mapping results showed an increase in risk of contact with a tract at higher TII value (B0 = −1.6; Bi = 6.61; χ2 = 30.53; n = 62, p &lt;0.001). The TII demonstrates better prognostic value in patients without radiation therapy in anamnesis.Conclusions. The method for preoperative quantitative evaluation of pyramidal tract and tumor relationship using TII calculation can provide additional information for planning surgical treatment in patients with intracerebral tumors without radiation treatment in the history.