Permanent Postoperative Deficits Research Articles

NCMP-20. FACTORS RELATED TO PERMANENT AND TEMPORARY MOTOR DEFICITS IN PATIENTS UNDERGOING GLIOMA RESECTION: A SYSTEMATIC REVIEW AND META-ANALYSIS

Abstract Standard of care treatment for virtually all glioma subtypes starts with maximal safe resection. However, resections that result in motor deficits can negate any survival benefit from surgery and diminish quality of life. Because current evidence on functional outcomes following glioma resection often conflicts and is limited to a small number of case series, retrospective analyses, and reviews, here we performed the first PRISMA-compliant systematic review and meta-analysis of currently published data to identify factors related to permanent and temporary motor deficits after surgery. We searched Ovid Medline, Scopus, Web of Science, CINAHL/EBSCO, PsychInfo, Cochrane and Wiley for studies reporting motor outcomes following surgical resection of glioma. Outcomes were stratified by patient/tumor characteristics, pre-operative condition, and intra-operative factors for both permanent (≥3 months postop) and temporary (<3 months postop) motor deficits. Generalized estimating equations were used to generate odds ratios and 95% confidence intervals. A total of 1,162 titles and abstracts were reviewed for eligibility resulting in the evaluation of 211 full-text articles. Data were extracted from 55 studies including 1,801 patients with 223 (12%) permanent postoperative motor deficits, 428 (24%) temporary motor deficits, and the remaining 1,150 (64%) without motor deficit. Pre-operative deficit was the strongest predictor of permanent post-operative motor deficit (OR 10.56, CI 5.20-21.45, p=7.2E-11), while high pre-operative Karnofsky Performance Scale (KPS) (OR 0.98, CI 0.97-0.99, p=0.036) and subcortical tumor location (OR 0.15, CI 0.025-0.90, p=0.038) were associated with no permanent deficit. Supratotal resection was significantly associated with temporary motor deficits (OR 3.54E+12, CI 3.53+E13-3.56E+17, p<2E-16), and asleep craniotomies were associated with no deficit (OR 1.68E-01, CI 4.93E-02–5.71E-01, p=0.0043). Ultimately, this study represents the largest analysis of motor outcome data in glioma surgery to date.

Multimodal intraoperative neurophysiological monitoring may better predict postoperative distal upper extremities’ complex-functional outcome than spinal and muscular motor evoked potentials alone in high-cervical intramedullary spinal cord tumor surgery

ObjectiveD-wave can safely monitor the corticospinal-tract (CST)-function regarding gross-motor outcome of lower extremities, but it is still unknown whether i)D-wave can also safely monitor the gross-motor outcome of distal upper extremities in those patients undergoing high-cervical intramedullary-spinal-cord-tumor (IMSCT)-resection (enabling epidural D-wave-placement below C5) and ii)multimodal IONM can also predict fine-motor/complex hand function. MethodsWe prospectively assessed 20 patients undergoing IMSCT-surgery above the C4/5-level with multimodal IONM (D-wave/mMEPs/EMG/SSEPs). Detailed gross-/fine-motor and complex hand function was assessed pre- and postoperatively and during long-term follow-up (mean:29.5 ± 18.8 months) and correlated with IONM-findings. ResultsD-wave monitoring was without intraoperative critical changes in all patients and none had any permanent postoperative gross-motor deficits. However, D-wave did not allow to predict the occurrence of mild permanent postoperative deficits affecting fine-motor function which was the case in 8% for distal upper extremities. The complex distal upper extremities’ function assessed by Nine-Hole-Peg-Test (reflecting the complex motor/sensory interaction for hand-usability) was permanently deteriorated in 15% postoperatively and only the combination of D-wave/mMEPs/EMG/SSEPs was able to provide a viable predictive power (specificity:79%/sensitivity:43%). ConclusionsIn high-cervical IMSCT-surgery, unimpaired D-wave reliably predicts preserved gross-motor function, but fails to sufficiently cover distal upper extremities’ fine-motor/complex function. SignificanceOur study underlines the importance of multimodal IONM for fine-motor/complex hand function.

Observations from the first 100 cases of intraoperative MRI – experiences, trends and short-term outcomes

BackgroundWe sought to analyze, in well-defined clinical setting, the first 100 patients treated at the intraoperative MRI (iMRI) hybrid surgical theatre at our facility in a population-based setting to evaluate which pathologies are best approached with iMRI assisted surgeries, as this is not yet clearly defined.MethodsPatients undergoing surgery in the 3T iMRI hybrid surgical theatre at our neurosurgical department between December 2017 to May 2021 were included after informed consent. Demographic, clinical, surgical, histological, radiological and outcome parameters, as well as variables related to iMRI, were retrospectively collected and analyzed. Patients were subdivided into adult and pediatric cohorts.ResultsVarious neurosurgical procedures were performed; resection of tumors and epileptic foci, endoscopic skull base procedures including pituitary lesions, deep brain stimulation (DBS) and laser interstitial thermal therapy (LITT). In total, 41 patients were pediatric. An iMRI scan was carried out in 96% of cases and led to continuation of surgery in 50% of cases, mainly due to visualized remaining pathological tissue (95.2%). Median time to iMRI from intubation was 280 min and median total duration of surgery was 445 min. The majority of patients experienced no postoperative complications (70%), 13 patients suffered permanent postoperative deficits, predominantly visual.ConclusionHerein, we demonstrate the first 100 patients undergoing neurosurgery aided by iMRI at our facility since introduction. Indications for surgery differed between pediatric and adult patients. The iMRI was utilized for tumor surgeries, particularly adult low-grade gliomas and pediatric tumors, as well as for epilepsy surgery and DBS. In this heterogenous population, iMRI led to continuation of surgery in 50%. To establish the benefit in maximizing the extent of resection in these brain pathologies future studies are recommended.Clinical trial numberNot applicable.

Trends, outcomes, and complications of surgery for lesional epilepsy in infants and toddlers: A multicenter study.

To assess seizure and developmental outcomes, their predictors, and complications in 160 children who, between 1998 and 2022, underwent surgery for lesional epilepsy with curative intent before the age of 3 years. To compare trends in epilepsy surgery in this age group before and after the year 2014. Retrospective multicenter study. Descriptive and univariate analyses, and multivariable models for all outcomes. These 160 patients (76 F; 47.5%) underwent 169 surgeries (age at surgery 20.4 ± 9.4 months). At the last follow-up (77 ± 57.4 months), 121 patients (75.6%) were in Engel class I, 106 (66.2%) of whom were in Engel class Ia. Antiseizure medications were stopped in 84 patients (52.5%). Complications requiring reoperations were observed in 16 patients (10%; 9.5% of surgeries) and unexpected permanent deficits in 12 (7.5%; 7.1% of surgeries). Postoperative cognitive functions remained unchanged in 56 patients (44.4%), improved in 51 (40.5%), and worsened in 19 (15.1%). Multivariable analyses showed that the probability of achieving Engel class Ia was lower when the duration of epilepsy was longer, patients underwent preoperative video-EEG, and unexpected postoperative permanent deficits occurred. Cognitive improvement after surgery was associated with lower preoperative seizure frequency, better preoperative developmental level, and a longer postoperative follow-up. FCDII and tumors were the histopathologies carrying a higher probability of achieving seizure freedom, while polymicrogyria was associated with a lower probability of cognitive improvement. The number of patients operated on after 2014 was higher than before (61.3% vs. 38.7%), with stable outcomes. Epilepsy surgery is effective and safe in infants and toddlers, although the complication rate is higher than seen in older patients. Shorter duration of epilepsy, lower seizure frequency, no need for video-EEG, tumors, and some malformations of cortical development are robust predictors of seizure and cognitive outcome that may be exploited to increase earlier referral. This study analyzed the results of epilepsy surgery in 160 children who had been operated on before the age of 3 years at four Italian centers between 1998 and 2022. At the last follow-up (77 ± 57.4 months), 121 patients (75.6%) were free from disabling seizures, of which 106 (66.2%) were completely seizure-free since surgery. Major surgical complications occurred in 28 patients (17.5%), which is higher than observed with epilepsy surgery in general, but similar to hemispheric/multilobar surgery. Postoperative cognitive function remained unchanged in 56 patients (44.4%), improved in 51 (40.5%), and worsened in 19 (15.1%). Epilepsy surgery is effective and safe in infants and toddlers.

Resection of meningiomas located in motor eloquent areas – comparative analysis of navigated transcranial magnetic stimulation and conventional neuronavigation

ABSTRACT Background Navigated transcranial magnetic stimulation (nTMS) has been established as a preoperative diagnostic procedure in glioma surgery, increasing the extent of resection and preserving functional outcome. nTMS motor mapping for the resection of motor eloquent meningiomas has not been evaluated in a comparative analysis, yet. Methods We conducted a retrospective matched-pair analysis for tumor location and size in meningioma patients with tumors located over or close to the primary motor cortex. Half of the study population received nTMS motor mapping preoperatively (nTMS-group). The primary endpoint were permanent surgery-related motor deficits. Additional factors associated with new motor deficits were evaluated apart from nTMS. Results 62 patients (mean age 62 ± 15.8 years) were evaluated. 31 patients received preoperative nTMS motor mapping. In this group, motor thresholds (rMT) corresponded with tumor location and preoperative motor status, but could not predict motor outcome. No patient with preoperative intact motor function had a surgery-related permanent deficit in the nTMS group whereas four patients in the non-TMS group with preoperative intact motor status harbored from permanent deficits. 13 patients (21.3%) had a permanent motor deficit postoperatively with no difference between the nTMS and the non-TMS-group. Worsening in motor function was associated with higher patient age (p = 0.01) and contact to the superior sagittal sinus (p = 0.027). Conclusion nTMSmotor mapping did not lead to postoperative preservation in motorfunction. nTMS data corresponded well with the preoperative motorstatus and were associated with postoperative permanent deficits if tumors were located over the motor hotspot according to nTMS.

A novel radiological classification of midbrain pilocytic astrocytomas and its implication for surgical management: a single-institution experience of 57 cases.

Surgery for midbrain pilocytic astrocytoma (PA) remains a formidable challenge. To facilitate decision-making and achieve a better outcome in the management of patients with midbrain PA, the authors have proposed a novel radiological classification of midbrain PAs with long-term follow-up. Fifty-seven midbrain PA patients who underwent surgery at Beijing Tiantan Hospital, Capital Medical University, from January 2008 to June 2021, were reviewed. Based on tumor location and the topological anatomical change identified on MRI, midbrain PAs were categorized into four types: crural (12/57, 21.1%), tegmental (25/57, 43.9%), aqueductal (5/57, 8.8%), and tectal (15/57, 26.3%) PAs. The relevant clinical, radiological, and pathological data; surgical procedures and results; and long-term outcomes were collected and analyzed. The 1-, 3-, and 5-year survival rates reached 98%, 96%, and 96%, respectively, with gross-total resection achieved in 66.7% of cases, followed by near-total resection in 17.5% cases. The clinical and radiological features, selection of surgical approaches, and long-term postoperative deficits were distinct among each type. Crural PAs were associated with younger age (median 9 years, IQR 5.0-12.8 years); the largest tumor volume (median 31.9 cm3, IQR 17.2-42.6 cm3); the lowest preoperative Karnofsky Performance Scale (KPS) score (median 65, IQR 50-70); the most frequent preoperative motor deficit (91.7%); a mixed solid-cystic component (75%); occupation of the crural cistern; elevation and rotation of the thalamus (medial and/or lateral); displacement of the anterior third ventricle, uncus, and anterior commissure; the most diverse surgical approaches; more frequent use of multimodality image-guided surgery (58.3%); and the most remarkable improvement in KPS score at long-term follow-up. Tegmental PAs were associated with adolescents and young adults (median age 21 years, IQR 8-33 years); tumor volume (median 13.9 cm3, IQR 9.5-20.5 cm3); a good preoperative KPS score (median 80, IQR 70-80); a mixed solid-cystic component (72%); occupation of the ambient cistern and cerebellomesencephalic fissure; a close relationship with the dorsal pons, superior cerebellar peduncle, and posterior inferior third ventricle; and a higher probability of permanent postoperative sensory deficits (40%). Aqueductal and tectal PAs were associated with small tumor volume (median 9.14 cm3, IQR 5.1-17.4 cm3 and median 11.84 cm3, IQR 5.7-18.3 cm3, respectively), a higher percentage of hydrocephalus (80% and 86.7%, respectively), and a straightforward selection of limited surgical approaches. A novel and comprehensive radiological classification of midbrain PAs was established, which will serve as a valuable tool in patient management and promote uniform communication and comparison across different studies and publications.

P07.14.A OBSERVATIONS FROM THE FIRST 100 CASES OF INTRAOPERATIVE MRI - EXPERIENCES, TRENDS AND SHORT-TERM OUTCOMES IN PEDIATRIC VERSUS ADULT NEUROSURGICAL POPULATION

Abstract BACKGROUND The intraoperative MRI (iMRI) at Sahlgrenska University Hospital installed in 2017 was the first introduced in Sweden. Herein, we present a single center study with our observations from the first 100 patients undergoing neurosurgery in the dedicated iMRI surgical theater. METHODS Patients undergoing surgery in the 3T iMRI hybrid surgical theatre at our neurosurgical department between December 2017 to May 2021 were included after informed consent. Demographic, clinical, surgical, histological, radiological and outcome parameters, as well as variables related to iMRI, were retrospectively collected and analyzed. Patients were subdivided into adult and pediatric cohorts. RESULTS A variety of neurosurgical procedures were performed; resection of tumors and epileptic foci, endoscopic skull base procedures including pituitary lesions, deep brain stimulation (DBS), laser interstitial thermal therapy (LITT) and biopsies. Mean age was 32 years (range 0-81 years), 41 patients were pediatric and 42% were female. An iMRI scan was carried out in 96% of cases and led to continuation of surgery in 50 percent of cases, mainly due to visualized remaining pathological tissue. Median time to iMRI from intubation was 280 minutes and median total duration of surgery was 445 minutes. The majority of patients experienced no postoperative complications (70%), 13 patients suffered permanent postoperative deficits, predominantly visual. CONCLUSION We demonstrate demographics, clinical, surgical and radiological variables from the first 100 patients planned for surgery in the iMRI surgical theatre after INTRODUCTION in 2017. We found that iMRI was performed in almost all cases. In the pediatric cohort, tumors and epileptic focus were main indications for surgery. In adults, indications were intrinsic brain tumors, transsphenoidal pituitary tumor and DBS. Utilization from a resource and patients perspective appears to be most beneficial in tumor surgeries (specially pediatric), epileptic surgery and DBS.

Comparative study of preoperative functional imaging combined with tractography for prediction of iatrogenic motor deficits.

Robust preoperative imaging can improve the extent of resection in patients with brain tumors while minimizing postoperative neurological morbidity. Both structural and functional imaging techniques can provide helpful preoperative information. A recent study found that transcranial magnetic stimulation (TMS) tractography has significant predictive value for permanent deficits. The present study directly compares the predictive value of TMS tractography and task-based functional MRI (fMRI) tractography in the same cohort of glioma patients. Clinical outcome data were collected from charts of patients with motor eloquent glioma and preoperative fMRI and TMS studies. The primary outcome was a new or worsened motor deficit present at the 3-month postoperative follow-up, which was termed a "permanent deficit." Postoperative MR images were overlaid onto preoperative plans to determine which imaging features were resected. Multiple fractional anisotropic thresholds (FATs) were screened for both TMS and fMRI tractography. The predictive value of the various thresholds was modeled using receiver operating characteristic curve analysis. Forty patients were included in this study. Six patients (15%) sustained permanent postoperative motor deficits. A significantly greater predictive value was found for TMS tractography than for fMRI tractography regardless of the FAT. Despite 35% of patients showing clinically relevant neuroplasticity captured by TMS, only 2.5% of patients showed a blood oxygen level-dependent signal displaced from the precentral gyrus. Comparing the best-performing FAT for both modalities, TMS seeded tractography showed superior predictive value across all metrics: sensitivity, specificity, positive predictive value, and negative predictive value. The results from this study indicate that the prediction of permanent deficits with TMS tractography is superior to that with fMRI tractography, possibly because TMS tractography captures clinically relevant neuroplasticity. However, future large-scale prospective studies are needed to fully illuminate the proper role of each modality in comprehensive presurgical workups for patients with motor-eloquent tumors.

Adjustable, Dynamic Subcortical Stimulation Technique for Brain Tumor Resection: A Case-Series.

Subcortical stimulation (SCS) is the gold standard neuromonitoring technique for intraoperative identification of descending white matter tracts. Dynamic SCS confers several advantages over more commonly used static devices; however, current commercially available devices for dynamic SCS have not been widely adopted. We fashioned a dynamic SCS device using a stainless-steel suction and commonly available materials and assessed its efficacy in a series of 14 patients with brain tumors. The device was used to provide continuous SCS during tumor resection. Preoperative and postoperative motor function were characterized, and preoperative and postoperative imaging were analyzed to determine extent of tumor resection and proximity to motor-eloquent structures. Inferential statistics were used to correlate study parameters. Fourteen patients (12 male and 2 female, median age 52.5 years) were analyzed. The lowest intraoperative SCS intensities were 10 to 15 mA (3 surgeries), 5 to 10 mA (4 surgeries), and <5 mA (2 surgeries). SCS with this device did not elicit motor evoked potentials in 5 surgeries because of distance from the corticospinal tract (CST) and served as negative controls. Three patients (21.4%) experienced new postoperative motor deficits immediately after surgery that resolved by discharge. We observed no instances of mechanical CST injury resulting in permanent postoperative motor deficits using this technique and no correlation between lower SCS intensity and the presence of new motor impairments after surgery. No patient experienced an intraoperative seizure. The novel dynamic SCS device is easily adoptable and allows accurate intraoperative identification of the CST, facilitating safe resection of tumors near motor-eloquent structures.

A comparison of three- and two-rod constructs in the correction of severe pediatric scoliosis.

Managing severe scoliosis is challenging and risky with a significant complication rate regardless of treatment strategy. In this retrospective comparative study, we report our results using a three-rod compared to two-rod construct in the surgical treatment of severe spine deformities to investigate which technique is safer, and which provides superior radiological outcomes. Forty-six consecutive patients undergoing posterior spine fusion for scoliosis between 2006 and 2017 were identified in our institutional records. Inclusion criteria were minimum coronal deformity of 90°, age < 18 years at the time of surgery and a minimum 2 years of follow-up. Radiographic and clinical parameters, as well as post-operative complications were compared between the two groups. There were 21 patients in the three-rod group and 25 in the two-rod group. The mean preoperative major coronal deformity was 100°± 9 and 102°± 10 in the three-rod and two-rod, respectively (p = 0.6). The average major curve correction was 51% and 59% in three-rod and two-rod groups, respectively (p = 0.03). The post-operative thoracic kyphosis was 30°± 11 and 21°± 12 in the three-rod and the two-rod groups, respectively (p = 0.01). The surgical time was 476 ± 52 and 387 ± 84 min in three-rod and two-rod, respectively (p < 0.01). One patient in the two-rod cohort showed permanent post-operative sensory deficit. There were three unplanned returns to operating theater in the two-rod group. Coronal correction was better with two-rod, whereas sagittal balance was superior with three-rod. Both techniques achieved balanced spine treating severe scoliosis. The two-rod technique was associated with a higher likelihood of requiring revision surgery. level 3.

Intraoperative cortical and subcortical stimulation for lesions related to eloquent motor cortex and corticospinal tract in a developing country

ObjectiveSurgery for lesions related to the eloquent motor cortex and the corticospinal tract is challenging. Intraoperative cortical and subcortical stimulation are reliable techniques for motor cortex and corticospinal tract (CST) mapping. Pre-operative functional magnetic resonance imaging (fMRI) and diffusion tensor imaging (DTI) are able to provide helpful data for safe surgical planning with both cortical and subcortical lesion resection. The authors combine these imaging techniques with intraoperative stimulation to identify and preserve cortical and subcortical motor tissue. MethodsThis is a prospective analysis of 56 patients between May 2020 and June 2021, who underwent lesion resection. Thirty-one patients underwent preoperative DTI, thirteen patients underwent preoperative fMRI and their data were used for a tractography-based neuronavigation system. All patients were operated under general anesthesia. Intraoperative mapping data were collected from operative protocol and neurophysiologist’s notes. The assessment of paresis was done by an independent neurosurgeon and was carried out using the motor strength scale of 0–5 according to the Medical Research Council scale. All patients with new or worsened postoperative motor deficits were followed for 6 months. ResultsNone of the patients exhibited a seizure during the operation. There were eight cases that experienced immediate motor deficits after surgery. At six months after surgery, only two patients (3.6%) had permanent motor deficits (motor strength scale rating 3 in one case and 4 in the other). The average distance between the lesions and CSTs in the positive subcortical stimulation response group was 3.39 ± 2.19 mm and 8.59 ± 3.27 mm in the negative group. Using a 5 mA stimulation threshold value resulted in a sensitivity of 12.5% and a specificity of 92.7%, corresponding to a negative predictive value of 84.4% and a positive predictive value of 25% for motor function. ConclusionsIntraoperative cortical and subcortical motor mapping in lesion resection resulted in a low ratio of permanent postoperative deficits. Subcortical alert threshold ≤ 5 mA is supposed to be a safe threshold in lesion resection with a high specificity of 92.7% and a negative predictive value of 84.4%.

Balancing the Extent of Resection and Ischemic Complications in Insular Glioma Surgery: Technical Nuances and Proposal of a Novel Composite Postoperative Outcome Index.

Maximal safe resection remains the most desired goal of insular glioma surgery. Intraoperative surgical adjuncts provide better tumor visualization and real-time "safety" data but remain limited due to a high cost and limited availability. To highlight the importance of anatomical landmarks in insular glioma resection and avoidance of vascular complications. We also propose to objectify the onco-functional balance in insular glioma surgery. Forty-six insular gliomas operated upon by a single surgeon between January 2015 and February 2020 were reviewed, focusing on the operative technique and clinical outcomes. A novel composite postoperative outcome index (CPOI) was designed, comprising the extent of resection and permanent postoperative deficits, and utilized to assess the surgical outcomes. Gross-total, near-total, and subtotal resections were achieved in 10.9%, 52.1% (n = 24), and 36.9% (n = 17) patients, respectively. The median overall survival (OS) was 20 months (95% CI = 9.56-30.43). CPOI was optimal in 38 patients (82.6%). A well-defined tumor margin (P = 0.01) and surgeon's experience (P = 0.04) were significantly associated with an optimal CPOI. Out of seven (15.2%) patients who developed permanent neurological deficits, three (6.5%) patients had severe disability. Favorable prognostic factors of survival included younger age (<40 years) (P = 0.002), tumors with only frontal lobe extension (P = 0.011), tumors with caudate head involvement (P = 0.04), and non-glioblastoma histology (P = 0.006). Tumor margin and increasing surgeon experience are critical to an optimal postoperative outcome. Respecting the basi-sulcal plane is key to lenticulostriate artery preservation. Caudate head involvement is a new favorable prognostic factor in insular gliomas.

Eloquent Lower Grade Gliomas, a Highly Vulnerable Cohort: Assessment of Patients' Functional Outcome After Surgery Based on the LoG-Glio Registry.

Majority of lower grade glioma (LGG) are located eloquently rendering surgical resection challenging. Aim of our study was to assess rate of permanent deficits and its predisposing risk factors. We retrieved 83 patients harboring an eloquently located LGGs from the prospective LoG-Glio Database. Patients without surgery or incomplete postoperative data were excluded. Sign rank test, explorative correlations by Spearman ρ and multivariable regression for new postoperative deficits were calculated. Eloquent region involved predominantly motor (45%) and language (40%). At first follow up after 3 months permanent neuro-logical deficits (NDs) were noted in 39%. Mild deficits remained in 29% and severe deficits in 10%. Complete tumor removal (CTR) was successfully in 62% of intended cases. Postoperative and 3-month follow up National Institute of Health Stroke Score (NIHSS) showed significantly lower values than preoperatively (p<0.001). 38% cases showed a decreased NIHSS at 3-month, while occurrence was only 14% at 9-12-month follow up. 6/7 patients with mild aphasia recovered after 9-12 months, while motor deficits present at 3-month follow up were persistent in majority of patients. Eastern oncology group functional status (ECOG) significantly decreased by surgery (p < 0.001) in 31% of cases. Between 3-month and 9-12-months follow up no significant improvement was seen. In the multivariable model CTR (p=0.019, OR 31.9), and ECOG>0 (p=0.021, OR 8.5) were independent predictors for permanent postoperative deficit according to NIHSS at 3-month according to multivariable regression model. Patients harboring eloquently located LGG are highly vulnerable for permanent deficits. Almost one third of patients have a permanent reduction of their functional status based on ECOG. Risk of an extended resection has to be balanced with the respective oncological benefit. Especially, patients with impaired pre-operative status are at risk for new permanent deficits. There is a relevant improvement of neurological symptoms in the first year after surgery, especially for patients with slight aphasia.

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.

Culprit vascular patterns and surgical outcomes of hemifacial spasm caused by an AICA segment passing between cranial nerve VII and VIII: A series of 25 cases

ObjectiveTo report the vascular anatomic characteristics and surgical outcomes of hemifacial spasm (HFS) caused by an anterior inferior cerebellar artery (AICA) segment passing between cranial nerve VII (CN VII) and cranial nerve VIII (CN VIII). Patients and methodsThis case series study retrospectively reviewed records of 1040 consecutive patients treated with MVD for HFS in our hospital in 10 years. 25 patients had the culprit vessel recorded as an AICA segment passing between CN VII and CN VIII. Vascular anatomic characteristics were reviewed from intraoperative microscopic videos. The clinical outcomes were followed up at 3-month and 1-year time points. ResultsThe culprit AICA segments feature 3 discrete anatomic patterns. The patterns denoted as pattern A, B, and C were identified in 19(76%), 3(12%), and 3 (12%) of the 25 patients respectively. Postoperative spasm relief were achieved in 19(76%), 22(88%), and 23 (92%) of the patients at immediately after surgery, 3-month, and 1-year follow-up respectively. 3(12%) of them have permanent postoperative cranial nerve deficits, including one patient with hearing loss and 2 patients with vocal cord palsy. ConclusionsThough an AICA segment passing between CN VII and CN VIII is common, very rarely it was deemed the culprit for HFS in our patients. We used fREZ centered definition and operation. We found the culprit AICA segments feature 3 discrete anatomic patterns. We observed good spasm relief outcome and relatively fewer complications with CN VII and CN VIII. Identifying the 3 anatomic patterns may help with a smooth decision-making when vascular compression by an AICA segment passing between CN VII and CN VIII is suspected.

Awake Epilepsy Surgery in Patients with Focal Cortical Dysplasia

Awake craniotomy (AC) and direct electric stimulation emerged together with epilepsy surgery >80 years ago. The goal of our study was to evaluate the benefits of awake surgery in patients with drug-resistant epilepsy caused by focal cortical dysplasia (FCD) affecting eloquent areas. Our material included 95 patients with drug-resistant epilepsy and FCD, who were operated on between January 2009 and December 2018. These 95 patients were assigned into 3 groups: AC; general anesthesia (GA) with intraoperative neuromonitoring; and GA without intraoperative neuromonitoring. We investigated the following variables: age at surgery, lesion side, eloquent cortex involvement, brain mapping success rate, epilepsy surgery success rate, intraoperative complications, postoperative complications, and intraoperative changes of the preoperative resection plan according to results of the brain mapping by direct electric stimulation. We found statistically significant differences between the AC and GA groups in the mean age at operation, lesion side, eloquent localization, and postoperative transient neurologic deficit. Seizure outcome in the AC was satisfactory (71% complete seizure control) and comparable to the seizure outcome in the GA groups. Our preoperative plan was changed because of functional constraints in 6 patients (43%) operated on during AC. AC during epilepsy surgery for FCD in eloquent areas may change the preoperative plan. The good rate of postoperative seizure control and the absence of permanent postoperative neurologic deficit in our series is the main proof that AC is a useful tool in patients with FCD involving the eloquent cortex.

The impact and causes of negative cortical mapping in primary motor area tumours

Introduction: Intraoperative neurophysiological monitoring is the golden standard for lesions located in eloquent areas of the brain. On the one hand, positive mapping offers a view of the relationship between the anatomo-functional cortical organisation of the patient and the lesion, facilitating the choice of the cerebrotomy entry point and the resection until the functional borders are found. On the other hand, negative mapping does not offer certainty that the absence of the motor response, from the operative field, is the real feedback or is the result of the false-negative response. In such a situation, a differentiation between those two must be done.&#x0D; Materials and methods: We evaluated the results of direct cortical stimulation of lesion located in or near the primary motor area, which were diagnosticated with contrast-enhancement head MRI and admitted to the Third Department of Neurosurgery, "Prof. Dr N. Oblu” Emergency Clinical Hospital, Iasi, Romania, between January 2014 and July 2018. Special attention was given especially to the negative mapping cases, regarding the histological type, imagistic localisation, symptoms and neurological outcome immediate postoperative, at 6 months and one-year follow-up.&#x0D; Results: From all 66 patients meeting the inclusion and exclusion criteria in 9,09% (6 cases) we did not obtain any motor response after direct cortical stimulation. The imagistic localisations of those cases were: 3 – Rolandic, 2 – pre-Rolandic and one retro-Rolandic. Tumors histological types were: glioblastoma, anaplastic astrocytoma, oligoastrocytoma and oligodendroglioma each one case and two cases of fibrillary astrocytoma. The intensity range was between 6 – 18mA, the mode – 12mA and the median – 10mA. Postoperatively the neurological condition of 3 patients worsened (4,54% from all the cases), while 3 had a favourable evolution with symptom remission. At 6monts and one-year follow-up in one case (1,51%), we observed no improvement in contrast with the other two, where dysfunction remission was highlighted.&#x0D; Conclusion: The possible technical, surgical and anesthesiologic causes of false-negative motor response must be eliminated to be able to differentiate from the real absence of the functional area from the operative field. In the first scenario, the resection may be associated with permanent postoperative neurologic deficit and major life quality alteration while in the second one the patient presents no motor dysfunction after surgery and the resection may be extensive with multiple oncological benefits.

Analysis of the effect of intraoperative neuromonitoring during resection of benign nerve sheath tumors on gross-total resection and neurological complications.

The aim of this study was to examine the role of intraoperative neuromonitoring (IONM) during resection of benign peripheral nerve sheath tumors in achieving gross-total resection (GTR) and in reducing postoperative neurological complications. Data from consecutive adult patients who underwent resection of a benign peripheral nerve sheath tumor at 7 participating institutions were combined. Propensity score matching was used to balance covariates. The primary outcomes of interest were the association between IONM and GTR and the association of IONM and the development of a permanent postoperative neurological complication. The secondary outcomes of interest were the association between IONM and GTR and the association between IONM and the development of a permanent postoperative neurological complication in the subgroup of patients with tumors involving a motor or mixed nerve. Univariate and multivariate logistic regression were then performed on the propensity score-matched samples to assess the ability of the independent variables to predict the outcomes of interest. A total of 337 patients who underwent resection of benign nerve sheath tumors were included. In multivariate analysis, the use of IONM (OR 0.460, 95% CI 0.199-0.978; p = 0.047) was a significant negative predictor of GTR, whereas none of the variables, including IONM, were associated with the occurrence of a permanent postoperative neurological complication. Within the subgroup of motor/mixed nerve tumors, in the multivariate analysis, IONM (OR 0.263, 95% CI 0.096-0.723; p = 0.010) was a significant negative predictor of a GTR, whereas IONM (OR 3.800, 95% CI 1.925-7.502; p < 0.001) was a significant positive predictor of a permanent postoperative motor deficit. Overall, 12% of the cohort had a permanent neurological complication, with new or worsened paresthesias most common, followed by pain and then weakness. The authors found that formal IONM was associated with a reduced likelihood of GTR and had no association with neurological complications. The authors believe that these data argue against IONM being considered standard of care but do not believe that these data should be used to universally argue against IONM during resection of benign nerve sheath tumors.

SURG-36. THE EVALUATION OF POSTOPERATIVE MOTOR FUNCTION DEFICITS AFTER SUPRATENTORIAL BRAIN TUMOR SURGERY THROUGH THE ANALYSIS OF INTRAOPERATIVE MEP AND ISCHEMIC LESION ON POSTOPERATIVE DWI

Abstract BACKGROUND The authors investigated the incidence of ischemic lesions on immediate postoperative diffusion-weighted imaging (DWI) according to the findings of intraoperative motor evoked potential (MEP) and the correlation with postoperative motor function deficits. METHODS From January 2016 to June 2018, total 127 supratentorial brain tumor patients were enrolled in this study. The intraoperative MEP results were analyzed in the following three groups: no decline below 50 % of baseline (A), transient decline below 50 % of baseline (B), no recovery until end stage of surgery (C). Postoperative magnetic resonance imaging was performed within 48 hours after surgery. RESULTS Of the total 127 patients, MEP changes (group B&amp;C) were observed in 25 patients (25/127, 19.7%), DWI positive findings were identified in 31 patients (31/127, 24.4%) and motor function deficits were observed in 19 patients (19/127, 15%), respectively. DWI positive finding rate was higher in gliomas (14/43, 32.6%) than meningiomas (8/51, 15.7%) or other tumors including metastasis (6/32, 18.8%), however, there was no statistical significance. In MEP changes, group B&amp;C (16/25, 64%) showed higher DWI positive rate than group A (13/102, 12.7%). In DWI findings, the DWI positive cases (16/31, 51.6%) showed a higher motor function deficit rates than the DWI negative cases (3/96, 3%). These two results were all statistically significant (P&amp;lt;0.01). In group A, motor function deficits were presented in 3 of 13 DWI positive case, all of which were transient. In group B, motor function deficits were presented in 9 out of 13 DWI positive cases with permanent 4 and transient 5. In group C, motor function deficits were presented in 4 out of 5 DWI positive cases with permanent 3 and transient 1. CONCLUSIONS Both intraoperative MEP changes and postoperative DWI positive findings in supratentorial brain tumor surgery were significant related with postoperative motor function deficits. Even if intraoperative MEP changes occur during supratentorial brain tumor surgery, active and appropriate efforts to prevent irreversible MEP changes may reduce the occurrence of permanent postoperative motor function deficits.

The Effects of Postoperative Neurological Deficits on Survival in Patients With Single Brain Metastasis.

The prognosis for brain metastasis is poor, and surgical resection is part of the standard of care for these patients as it has been shown to improve median overall survival. Development of neurological deficits after surgical resection has been associated with worsened outcomes in patients with glioblastoma. The effect of postoperative neurological deficits on survival in patients with single brain metastasis has not been studied to date. To evaluate the association between postoperative neurological deficits and median overall survival. A single-institution retrospective cohort study was performed on all patients with single brain metastasis undergoing surgical resection by a single neurosurgeon. A total of 121 patients met the inclusion criteria for this study. Among them 61% of patients presented with a preoperative deficit, and 26% of patients had a new postoperative deficit. However, most postoperative deficits resolved and only 3.3% of patients developed a new permanent postoperative deficit. Median overall survival in patients with a new postoperative deficit was 2.4 mo, whereas mOS in patients without a postoperative deficit was 12.6 mo (P<.0001). This study suggests that a new neurological deficit is associated with worsened outcomes after surgical resection of a single brain metastasis. This finding has potential implications for patient selection and counseling as the patients most likely to benefit from surgical resection are the patients who are most likely to have resolution of a preoperative deficit.