Diagnosis and Treatment of Periimplant Mucositis and Periimplantitis: An Overview and Related Controversial Issues

Periimplant mucositis and periimplantitis are common complications of dental implant. This article provides a comprehensive overview of the 2017 World Workshop's new definition, clinical and radiographic presentation, pathogenesis, risk factors, and classification of periimplant diseases. Also, the authors discuss various types of instruments, materials, and techniques commonly used for treatment of nonsurgical and surgical periimplantitis. Lastly, the authors include some controversial topics surrounding this subject.

Network coupling and surgical treatment response in temporal lobe epilepsy: A proof-of-concept study

OBJECTIVE

This proof-of-concept study aimed to examine the overlap between structural and functional activity (coupling) related to surgical response.

METHODS

We studied intracranial rest and ictal stereoelectroencephalography (sEEG) recordings from 77 seizures in thirteen participants with temporal lobe epilepsy (TLE) who subsequently underwent resective/laser ablation surgery. We used the stereotactic coordinates of electrodes to construct functional (sEEG electrodes) and structural connectomes (diffusion tensor imaging). A Jaccard index was used to assess the similarity (coupling) between structural and functional connectivity at rest and at various intraictal timepoints.

RESULTS

We observed that patients who did not become seizure free after surgery had higher connectome coupling recruitment than responders at rest and during early and mid seizure (and visa versa).

SIGNIFICANCE

Structural networks provide a backbone for functional activity in TLE. The association between lack of seizure control after surgery and the strength of synchrony between these networks suggests that surgical intervention aimed to disrupt these networks may be ineffective in those that display strong synchrony. Our results, combined with findings of other groups, suggest a potential mechanism that explains why certain patients benefit from epilepsy surgery and why others do not. This insight has the potential to guide surgical planning (e.g., removal of high coupling nodes) following future research.

Efficiency of surgery on posttraumatic epilepsy: a systematic review and meta-analysis

Posttraumatic epilepsy (PTE) accounts for approximately 20% of structural epilepsy, and surgical intervention may be a potential treatment option for these patients. Therefore, the purpose of this meta-analysis is to evaluate the effectiveness of surgical interventions for the management of PTE. Four electronic databases (Pubmed, Embase, Scopus and Cochrane library) were searched to identify studies on surgical management of PTE. Seizures reduction rate were analyzed quantitatively in a meta-analysis. Fourteen studies involving 430 PTE patients were selected for analysis, out of which 12 reported on resective surgery (RS), 2 on vagus nerve stimulation (VNS), and 2 of the 12 RS studies reported that 14 patients underwent VNS. The seizure reduction rate for surgical interventions (both RS and VNS) was 77.1% (95% confidence interval [CI]: 69.8%-83.7%) with moderate heterogeneity (I² = 58.59%, P_hetero = 0.003). Subgroup analysis based on different follow-up times revealed that the seizure reduction rate was 79.4% (95% CI: 69.1%-88.2%) within 5 years and 71.9% (95% CI: 64.5%-78.8%) beyond 5 years. The seizure reduction rate for RS alone was 79.9% (95% CI: 70.3%-88.2%) with high heterogeneity (I² = 69.85%, P_hetero = 0.001). Subgroup analysis showed that the seizure reduction rate was 77.9% (95% CI: 66%-88.1%) within 5 years and 85.6% (95% CI: 62.4%-99.2%) beyond 5 years, with 89.9% (95% CI: 79.2%-97.5%) for temporal lobectomy and 84% (95% CI: 68.2%-95.9%) for extratemporal lobectomy. The seizure reduction rate for VNS alone was 54.5% (95% CI: 31.6%-77.4%). Surgical interventions appeared to be effective for PTE patients without severe complications, RS seemed more beneficial than VNS, while temporal lobectomy is more favorable than extratemporal resection. However, further studies with long-term follow-up data are needed to better understand the relationship between VNS and PTE.

Chronic aphasias after left-hemisphere resective surgery

Surgical resection of brain tumours is associated with an increased risk of aphasia. However, relatively little is known about outcomes in the chronic phase (i.e., >6 months). Using voxel-based lesion symptom mapping (VLSM) in 46 patients, we investigated whether chronic language impairments are related to the location of surgical resection, residual tumour characteristics (e.g., peri-resection treatment effects, progressive infiltration, oedema) or both. Approximately 72% of patients scored below the cut-off for aphasia. Action naming and spoken sentence comprehension deficits were associated with lesions in the left anterior temporal and inferior parietal lobes, respectively. Voxel-wise analyses revealed significant associations between ventral language pathways and action naming deficits. Reading impairments were also associated with increasing disconnection of cerebellar pathways. The results indicate chronic post-surgical aphasias reflect a combination of resected tissue and tumour infiltration of language-related white matter tracts, implicating progressive disconnection as the critical mechanism of impairment.

Longitudinal changes in emotional functioning following pediatric resective epilepsy surgery: 2-Year follow-up

OBJECTIVE

To examine longitudinal changes and predictors of depression and anxiety 2 years following resective epilepsy surgery, compared to no surgery, in children with drug-resistant epilepsy (DRE).

METHOD

This multicenter cohort study involved 128 children and adolescents with DRE (48 surgical, 80 nonsurgical; 8-18 years) who completed self-report measures of depression and anxiety at baseline and follow-up (6-month, 1-year, 2-year). Child demographic (age, sex, IQ) and seizure (age at onset, duration, frequency, site and side) variables were collected.

RESULTS

Linear mixed-effects models controlling for age at enrolment found a time by treatment by seizure outcome interaction for depression. A negative linear trend across time (reduction in symptoms) was found for surgical patients, irrespective of seizure outcome. In contrast, the linear trend differed depending on seizure outcome in nonsurgical patients; a negative trend was found for those with continued seizures, whereas a positive trend (increase in symptoms) was found for those who achieved seizure freedom. Only a main effect of time was found for anxiety indicating a reduction in symptoms across patient groups. Multivariate regressions failed to find baseline predictors of depression or anxiety at 2-year follow-up in surgical patients. Older age, not baseline anxiety or depression, predicted greater symptoms of anxiety and depression at 2-year follow-up in nonsurgical patients.

CONCLUSION

Children with DRE reported improvement in anxiety and depression, irrespective of whether they achieve seizure control, across the 2 years following surgery. In contrast, children with DRE who did not undergo surgery, but achieved seizure freedom, reported worsening of depressive symptoms, which may indicate difficulty adjusting to life without seizures and highlight the potential need for ongoing medical and psychosocial follow-up and support.

Aphasic status epilepticus of frontal origin treated by resective surgery

Aphasic status epilepticus (SE) is a clinical entity of SE, but it has not been well recognized. We report a 43-year-old female with a chronic drug-resistant epilepsy with aphasic SE, treated by resective surgery. The patient showed long-lasting weekly episodes of hypokinesia, slow verbal response, and dysphasia, which were diagnosed as symptoms of aphasic SE. Magnetic resonance imaging showed encephalomalacia in the left frontal lobe with a hemosiderin rim. Intracranial electroencephalography revealed continuous spikes, predominantly on the left superior frontal gyrus with hemosiderin deposit. The aphasic symptoms were seen when ictal discharges gradually spread to the wide area of the left anterior frontal lobe, including the language area. The episodes of recurrent aphasic SE had disappeared by one year after the left anterior frontal resection. We should consider aphasic SE when language impairment is episodic, and consider surgical intervention in cases where it repeatedly occurs despite appropriate medical therapy.

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Long-lasting slow verbal response and dysphasia could be manifestations of aphasic status epilepticus of frontal origin

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Epilepsy surgery should be considered for repeat aphasic SE under appropriate medical treatment after definite diagnosis

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Precise time correlations between aphasic symptoms and ictal discharges could be unclear even by intracranial electroencephalography.

Practice of stereoelectroencephalography (sEEG) in drug-resistant epilepsy: Retrospective series with surgery and thermocoagulation outcomes

OBJECTIVE

The aim of this study was to determine the success rate of sEEG in locating the epileptogenic zone (EZ) in patients with pharmaco-resistant epilepsy. Secondary objectives were to analyze sEEG-related morbidity and outcomes for post-sEEG thermocoagulation and cortical resection.

METHODS

Data were collected on 49 sEEGs from 46 consecutive patients between 2010 and 2018. Following sEEG, either resective or palliative surgery with vagus nerve stimulation was performed. In 8 patients, EZ thermocoagulation was performed before EEG leads were withdrawn. Outcomes were collected based on the Engel and ILAE outcome scales.

RESULTS

sEEG was contributive in 45 of 49 recordings, with a success rate of 92% in locating the EZ. Minor complications, such as transient neurologic deficit and electrode implantation failures, occurred in 6%. One major complication occurred, with death due to atypical late hematoma. Thermocoagulation was performed in 8 patients and stopped or significantly reduced seizure frequency in 7 (88%). Outcome of surgical resection (n=33) was good, with 20 (61%) seizure-free patients and 32 (97%) with definite improvement.

CONCLUSIONS

Our findings suggest that sEEG is an effective technique for EZ location in patients with drug-resistant epilepsy. sEEG was contributive in up to 92% of patients, allowing thermocoagulation and/or surgical resection that resulted in seizure-freedom in two-thirds and seizure-reduction in one-third of cases. This study highlights the need for strict selection of implantation candidates, with strong initial hypothesis as to EZ location.

Impact of resective surgery for pediatric drug-resistant epilepsy on emotional functioning

OBJECTIVE

The objective of the study was to evaluate emotional functioning following surgical and medical treatment in children with drug-resistant epilepsy (DRE; i.e., uncontrolled seizures despite treatment with ≥2 antiepileptic drugs [AED]).

METHOD

This prospective, longitudinal, multicenter study involved 128 children and adolescents (8-18 years) with DRE who were assessed for surgical candidacy; 48 went on to have surgery and 80 continued medical treatment. Participants completed child-validated self-report measures of anxiety and depression at baseline, 6, and 12 month follow-up. Standardized z-scores were calculated with higher scores indicative of greater symptoms.

RESULTS

At baseline, 16% and 22% of all patients reported elevated symptoms of depression and anxiety, respectively (i.e., z ≥ 1.00). Seizure freedom was higher in the surgical, compared with the medical, group at 6 (64 vs. 11%) and 12 month (77 vs. 24%) follow-up. Linear mixed effects models controlling for age found a main effect of time for both depression and anxiety; scores decreased over time for all patients. A main effect of seizure outcome was found for depression, but not anxiety; seizure freedom was associated with lower scores overall. There were no main effects of treatment or significant interactions. Multiple regression analyses found baseline mood predicted outcomes at 6 and 12 month follow-up; higher anxiety and depression scores at baseline were associated with higher scores at follow-up. Older age and greater number of AEDs at baseline was associated with higher depression scores at 12 month follow-up.

CONCLUSION

Overall, patients reported a reduction in anxiety and depressive symptoms over the first 12 months, irrespective of treatment, and baseline level of functioning was the best predictor of outcome. Despite more children achieving seizure freedom with surgery compared with medical treatment, surgery was not associated with better outcomes over time. It may be that changes in anxiety and depression require a longer time to emerge postsurgery; however, being seizure-free is associated with fewer depressive symptoms, irrespective of treatment type.

Resective epilepsy surgery involving eloquent cortex in the age of responsive neurostimulation: A value-based decision-making framework

Resective epilepsy surgery has endured as the most effective way to render patients with seizure-free intractable localization-related epilepsy. Under conditions where the seizure focus is in close proximity to eloquent cortex, a postoperative deficit may be expected. Patients often accept the risk or certainty of these deficits for the possibility of seizure freedom. Recently, responsive neurostimulation (RNS) has emerged as an alterative to resective epilepsy surgery. This cranially implanted closed-loop neurostimulation system records brain activity and interrupts seizure propagation, thereby decreasing seizure frequency. The introduction of RNS to clinical practice raises several challenges to clinicians and patients alike. Despite a dearth of long-term data, should this be considered as a safer and potentially reversible option for patients who would otherwise be candidates for resective surgery in eloquent cortex? In the current report, we analyze the complex bioethical implications of presenting a new, "safer" technology, alongside a well-established, "more effective" treatment. We present an adapted value-based decision-making model to guide patients and help clinicians navigate the tradition of resective epilepsy surgery in eloquent cortex in the nascent age of RNS.

Intradural Ganglioneuroma Mimicking Lumbar Disc Herniation: Case Report

BACKGROUND

Ganglioneuroma (GN) is a slow-growing tumor originating from the neural crest-derived cells, which form the sympathetic nervous system. These tumors can affect anywhere along the peripheral autonomic ganglion sites and are most commonly found in the mediastinum and retroperitoneum. Spinal GNs are extremely rare and, so far, only 1 case arising from a lumbar nerve root has been reported in the English literature. GNs are often asymptomatic, and the majority of them are found incidentally in healthy subjects. Because of their slow growth, symptoms may result from the compressive effect of the tumor.

CASE DESCRIPTION

A 40-year-old man presented with a right sciatica episode accompanied by global muscle weakness and tingling pain. Findings of the neurologic examination displayed positive Lasegue test and sensory deficit over L5-S1 dermatomes. Magnetic resonance imaging of the lumbar spine without contrast showed a well-circumscribed longitudinal lesion arising from L5-S1 disc space, moving us toward a diagnosis of lumbar disc herniation. During surgery, we observed a mass well-encapsulated and oval-shaped inside S1 right root. The patient underwent subtotal resection. Histopathologic examination showed clusters of ganglion mature cells with neuromatous stroma, consistent with a ganglioneuroma.

CONCLUSIONS

We report a case that illustrates the clinical, radiologic, and histopathologic features of a ganglioneuroma mimicking a lumbosciatica syndrome and review related literature and similar cases.

Leading up to saying "yes": A qualitative study on the experience of patients with refractory epilepsy regarding presurgical investigation for resective surgery

OBJECTIVES

Adult patients with refractory epilepsy who are potential candidates for resective surgery undergo a period of presurgical investigation in tertiary epilepsy centers (TECs), where they engage extensively with healthcare professionals and receive a range of treatment-related information. This qualitative study aimed to examine the experiences of adult patients with refractory epilepsy leading up to and during presurgical investigation and how their perceptions of resective surgery are shaped.

METHODS

In-depth interviews with 12 patients and six epilepsy specialist clinicians and 12 observations of routine patient-clinician consultations took place at two TECs in Sydney, Australia. Data were thematically analyzed via group work.

RESULTS

Patients reflected on prior experiences of poor seizure control and inadequate antiepileptic drug management and a lack of clarity about their condition before referral to tertiary care. Poor continuity of care and disrupted care transitions affected patients from regional locations. Tertiary referral increased engagement with personalized information about refractory epilepsy, which intensified during presurgical assessments with additional hospital visits and consultations. Experiential information, such as testimonials of other patients, influenced perceptions of surgery and fostered more trust and confidence towards healthcare professionals.

CONCLUSION

Qualitative inquiry detailed multifaceted effects of information on patients' overall treatment trajectory and experience of healthcare. Earlier patient identification for surgical assessments should be accompanied by access to good quality information at primary and community care levels and strengthened referral processes.

Evaluating resective surgery targets in epilepsy patients: A comparison of quantitative EEG methods

BACKGROUND

Quantitative analysis of intracranial EEG is a promising tool to assist clinicians in the planning of resective brain surgery in patients suffering from pharmacoresistant epilepsies. Quantifying the accuracy of such tools, however, is nontrivial as a ground truth to verify predictions about hypothetical resections is missing.

NEW METHOD

As one possibility to address this, we use customized hypotheses tests to examine the agreement of the methods on a common set of patients. One method uses machine learning techniques to enable the predictive modeling of EEG time series. The other estimates nonlinear interrelation between EEG channels. Both methods were independently shown to distinguish patients with excellent post-surgical outcome (Engel class I) from those without improvement (Engel class IV) when assessing the electrodes associated with the tissue that was actually resected during brain surgery. Using the AND and OR conjunction of both methods we evaluate the performance gain that can be expected when combining them.

RESULTS

Both methods' assessments correlate strongly positively with the similarity between a hypothetical resection and the corresponding actual resection in class I patients. Moreover, the Spearman rank correlation between the methods' patient rankings is significantly positive.

COMPARISON WITH EXISTING METHOD(S)

To our best knowledge, this is the first study comparing surgery target assessments from fundamentally differing techniques.

CONCLUSIONS

Although conceptually completely independent, there is a relation between the predictions obtained from both methods. Their broad consensus supports their application in clinical practice to provide physicians additional information in the process of presurgical evaluation.

Positive interictal epileptiform discharges in adults: A case series of a rare phenomenon

OBJECTIVE

Positive interictal epileptiform discharges (IEDs) are rarely recorded from surface EEG, due to the orientation of the cortex and its neurons. Their frequency and significance in adults is unknown, and has only been studied as a phenomenon of the neonatal period and childhood. We aimed to evaluate the frequency and characteristics of positive epileptiform discharges in a large cohort of patients.

METHODS

We retrospectively reviewed 24,178 reports from 18,060 patients of non-invasively recorded EEGs for various indications.

RESULTS

Positive IEDs were recorded in six patients (eight EEGs - 0.033%), all of which had epileptic seizures. Brain surgery was the most common reason for recording positive and not negative IEDs. Cortical malformation was the most probable etiology in the remaining patients.

CONCLUSIONS

Positive IEDs seem to be of lower frequency in adults than in children and are highly associated with epilepsy. They appear more often, but not exclusively, in adult patients with skull defects.

SIGNIFICANCE

This is the first adult series reported. Positive IEDs must be identified for the correct diagnosis and clearly differentiated from normal variants.

Spectral characteristics of intracranial electroencephalographic activity in patients with Lennox-Gastaut syndrome

OBJECTIVE

The purpose of the current study was to characterize the frequency profiles of epileptogenic regions, independent of visible epileptiform discharges, in intracranial EEG (iEEG) recordings of Lennox-Gastaut syndrome (LGS) patients.

METHODS

We selected eight LGS patients who underwent resective surgery in the absence of definite neuroimaging findings. We calculated the absolute and relative band powers of continuous spike-free iEEG data and compared the characteristics of the resected and remaining regions.

RESULTS

For absolute band powers, there was a trend for higher absolute gamma band power in the remaining brain section. We also found that the absolute delta power in the resected area was higher than that in the remaining area. However, this trend was not statistically different in all patients. For relative band powers, we found decreased relative band power in the beta and gamma band ranges within the areas defined by the surgical margins. Delta, theta, and alpha relative band power differences between the resected and remaining areas were inconsistent between the subjects.

CONCLUSIONS

Our results showed systematic relative beta and gamma band power variation in the resected areas of LGS patients.

Resective surgery combined with corpus callosotomy for children with non-focal lesional Lennox-Gastaut syndrome

BACKGROUND

The first prospective trial for resective surgery combined with corpus callosotomy (CCT) was performed to investigate the outcomes of the combined surgery in children with Lennox-Gastaut syndrome (LGS) without focal lesion on brain MRI.

METHODS

This study enrolled 68 children with LGS and without focal lesion on brain MRI, of which 25 received medicine (medicine group) and 43 underwent surgery (surgery group), including 20 with exclusively resective surgery (exclusively resection subgroup) and 23 with resective surgery combined with CCT (combined CCT subgroup). All patients were followed for 3-5 years.

RESULTS

Significant differences in seizure control were observed between the medicine group and the exclusively resection subgroup and combined CCT subgroup at the 1-year, 3-year, and 5-year follow-ups. There was a trend that the children with resection combined with CCT had better seizure control than those with exclusively resection at the three follow-ups, but this could not be verified by the statistical method used. Furthermore, significant differences were not observed in seizure control between children with different MRI findings, age at surgery, or pathology in the surgery group. The percentage of long-term seizure-free did not remain as high as the percentage of early stage seizure-free at 1-year follow-up. However, the children with combined CCT surgery demonstrated more postoperative improvement than the children with resective surgery alone based on the mean QOL score (10.78 vs. 5.75, p = 0.0152) and full-scale IQ (7.91 vs. 4.55, p = 0.0446).

CONCLUSIONS

Resective surgery combined with CCT can provide favorable seizure control and obvious improvements in QOL and IQ in children with LGS. This combined approach can be performed in carefully selected LGS children without focal lesions and can localize the epileptogenic zone following a comprehensive preoperative evaluation.

Cost-utility analysis of competing treatment strategies for drug-resistant epilepsy in children with Tuberous Sclerosis Complex

BACKGROUND

The management of drug-resistant epilepsy in children with Tuberous Sclerosis Complex (TSC) is challenging because of the multitude of treatment options, wide range of associated costs, and uncertainty of seizure outcomes. The most cost-effective approach for children whose epilepsy has failed to improve with first-line medical therapy is uncertain.

METHODS

A review of MEDLINE from 1990 to 2015 was conducted. A cost-utility analysis, from a third-party payer perspective, was performed for children with drug-resistant epilepsy that had failed to improve with 2 antiseizure drugs (ASDs) and that was amenable to resective epilepsy surgery, across a time-horizon of 5years. Four strategies were included: (1) resective epilepsy surgery, (2) vagus nerve stimulator (VNS) implantation, (3) ketogenic diet, and (4) addition of a third ASD (specifically, carbamazepine). The incremental cost per quality-adjusted life year (QALY) gained was analyzed.

RESULTS

Given a willingness-to-pay (WTP) of $100,000 per QALY, the addition of a third ASD ($6600 for a gain of 4.14 QALYs) was the most cost-effective treatment strategy. In a secondary analysis, if the child whose epilepsy had failed to improve with 3 ASDs, ketogenic diet, addition of a fourth ASD, and resective epilepsy surgery were incrementally cost-effective treatment strategies. Vagus nerve stimulator implantation was more expensive yet less effective than alternative strategies and should not be prioritized.

CONCLUSIONS

The addition of a third ASD is a universally cost-effective treatment option in the management of children with drug-resistant epilepsy that has failed to improve with 2 ASDs. For children whose epilepsy has failed to improve with 3 ASDs, the most cost-effective treatment depends on the health-care resources available reflected by the WTP.

Long-term seizure and psychosocial outcomes after resective surgery for intractable epilepsy

Resective surgery is considered an effective treatment for refractory localization-related epilepsy. Most studies have reported seizure and psychosocial outcomes of 2-5 years postsurgery and a few up to 10 years. Our study aimed to assess long-term (up to 15 years) postsurgical seizure and psychosocial outcomes at our epilepsy center. The Henry Ford Health System Corporate Data Store was accessed to identify patients who had undergone surgical resection for localization-related epilepsy from 1993 to 2011. Demographics including age at epilepsy onset and surgery, seizure frequency before surgery, and pathology were gathered from electronic medical records. Phone surveys were conducted from May 2012 to January 2013 to determine patients' current seizure frequency and psychosocial metrics including driving and employment status and use of antidepressants. Surgical outcomes were based on Engel's classification (classes I and II=favorable outcomes). McNemar's tests, chi-square tests, two sample t-tests, and Wilcoxon two sample tests were used to analyze the relationships of psychosocial and surgical outcomes with demographic and surgical characteristics. A total of 470 patients had resective epilepsy surgery, and of those, 50 (11%) had died since surgery. Of the remaining, 253 (60%) were contacted with mean follow-up of 10.6±5.0years (27% of patients had follow-up of 15 years or longer). Of the patients surveyed, 32% were seizure-free and 75% had a favorable outcome (classes I and II). Favorable outcomes had significant associations with temporal resection (78% temporal vs 58% extratemporal, p=0.01) and when surgery was performed after scalp EEG only (85% vs 65%, p<0.001). Most importantly, favorable and seizure-free outcome rates remained stable after surgery over long-term follow-up [i.e., <5 years (77%, 41%), 5-10 years (67%, 29%), 10-15 years (78%, 38%), and >15 years (78%, 26%)]. Compared to before surgery, patients at the time of the survey were more likely to be driving (51% vs 35%, p<0.001) and using antidepressants (30% vs 22%, p=0.013) but less likely to be working full-time (23% vs 42%, p<0.001). A large majority of patients (92%) considered epilepsy surgery worthwhile regardless of the resection site, and this was associated with favorable outcomes (favorable=98% vs unfavorable=74%, p<0.001). The findings suggest that resective epilepsy surgery yields favorable long-term postoperative seizure and psychosocial outcomes.

Connectivity in MEG resting-state networks increases after resective surgery for low-grade glioma and correlates with improved cognitive performance

Purpose

Low-grade glioma (LGG) patients often have cognitive deficits. Several disease- and treatment related factors affect cognitive processing. Cognitive outcome of resective surgery is unpredictable, both for improvement and deterioration, especially for complex domains such as attention and executive functioning. MEG analysis of resting-state networks (RSNs) is a good candidate for presurgical prediction of cognitive outcome. In this study, we explore the relation between alterations in connectivity of RSNs and changes in cognitive processing after resective surgery, as a stepping stone to ultimately predict postsurgical cognitive outcome.

Methods

Ten patients with LGG were included, who had no adjuvant therapy. MEG recording and neuropsychological assessment were obtained before and after resective surgery. MEG data were recorded during a no-task eyes-closed condition, and projected to the anatomical space of the AAL atlas. Alterations in functional connectivity, as characterized by the phase lag index (PLI), within the default mode network (DMN), executive control network (ECN), and left- and right-sided frontoparietal networks (FPN) were compared to cognitive changes.

Results

Lower alpha band DMN connectivity was increased after surgery, and this increase was related to improved verbal memory functioning. Similarly, right FPN connectivity was increased after resection in the upper alpha band, which correlated with improved attention, working memory and executive functioning.

Discussion

Increased alpha band RSN functional connectivity in MEG recordings correlates with improved cognitive outcome after resective surgery. The mechanisms resulting in functional connectivity alterations after resection remain to be elucidated. Importantly, our findings indicate that connectivity of MEG RSNs may be used for presurgical prediction of cognitive outcome in future studies.