Intraoperative electrocorticography in epilepsy surgery: useful or not?

Intraoperative electrocorticography (ECoG) has been traditionally used in the surgical management of medically refractory partial epilepsies to identify the location and limits of the epileptogenic area, to guide the extent of resection, and to assess its completeness. Although in clinical use for many years, the basic questions regarding indications and limitations of this method has remained unanswered. ECoG plays a major role in tailored temporal lobectomies, whereas, it serves no practical purpose in standard resection of medial temporal lobe epilepsy (TLE) with magnetic resonance imaging (MRI) evidence of mesial temporal sclerosis (MTS). Residual hippocampal spikes, unaltered by resection, correlate with a greater proportion of seizure recurrence. Intraoperative hippocampal ECoG can allow sparing of functionally important hippocampus, thus minimising postoperative memory decline. ECoG eminently aids removal of developmental malformations of brain, and most importantly, the excision of highly epileptogenic cortical dysplasias (CDs) for deciding the extent of resection for best seizure control. The ECoG can be a valuable tool during multiple subpial transections (MST).     

皮层脑电图监测在颅脑病变伴发癫(癎)手术中的应用

目的 探讨皮层脑电图监测在颅脑病变伴发癫(癎)手术中的应用价值.方法 回顾分析58 例皮层脑电监测下手术切除病变及致(癎)灶患者临床资料.结果 所有患者在切除病变后复查皮层脑电图仍有(癎)样放电,其中37 例行扩大皮层切除,18 例加行皮层热灼术,3 例加行MST.术后1 /2 ～6 年随访发现癫(癎)控制达到EngelⅠ级32 例,EngelⅡ12 例,Engel Ⅲ级3 例,Engel Ⅳ 11 例,术后癫(癎)控制有效率为84.48%.结论 对于颅脑病变伴发癫(癎)的患者,应在皮层脑电图监测下进行手术,且在切除病变的同时一并将致(癎)灶切除.     

Intraoperative ElectroCorticoGraphy (ECog): indications,techniques, and utility in epilepsy surgery

Aims. To describe the technique, indications, and utility of intraoperative ECoG monitoring during various surgeries for medically intractable epilepsy. Methods. Literature was reviewed to obtain published results on using intraoperative ECoG techniques for the surgical treatment of medically intractable epilepsy of various underlying aetiologies. Results. General intraoperative ECoG techniques were described, including effects of anaesthetic agents on intraoperative ECoG signals. Use of intraoperative ECoG in temporal lobe epilepsy with mesial temporal sclerosis (MTS) is generally considered not necessary, whereas intraoperative ECoG in temporal lobe epilepsy without mesial temporal sclerosis may provide useful information. Intraoperative ECoG in extra‐temporal epilepsy with structural lesions may facilitate resection, whereas the use of intraoperative ECoG in extra‐temporal epilepsy without a structural lesion is more controversial. Conclusions. Intraoperative ECoG is a useful technique to be employed in surgical treatment of medically intractable epilepsy. However, its effectiveness may vary depending on the underlying pathological causes of the seizures.     

癫痫手术的麻醉

随着麻醉技术和脑电图术中监测的发展，目前大多数癫痫手术都在全身麻醉下进行，但是因为麻醉医生不但要处理患的各种生理和心理问题，还要选择合适的麻醉药以减少对术中脑电监测的影响，所以癫痫手术的麻醉是对麻醉医生的一个挑战。本综述了癫痫手术的麻醉原则，围术期处理和麻醉药的选择，主要讨论了各种常用的全身麻醉药、阿片类镇痛药和肌肉松弛药对癫痫病人的影响。     

Impact of epilepsy surgery on quality of life: Systematic review and meta-analysis

Improved quality of life (QoL) is an important outcome goal following epilepsy surgery. This study aims to quantify change in QoL for adults with drug-resistant epilepsy (DRE) who undergo epilepsy surgery, and to explore clinicodemographic factors associated with these changes. We conducted a systematic review and meta-analysis using Medline, Embase, and Cochrane Central Register of Controlled Trials. All studies reporting pre- and post-epilepsy surgery QoL scores in adults with DRE via validated instruments were included. Meta-analysis assessed the postsurgery change in QoL. Meta-regression assessed the effect of postoperative seizure outcomes on postoperative QoL as well as change in pre- and postoperative QoL scores. A total of 3774 titles and abstracts were reviewed, and ultimately 16 studies, comprising 1182 unique patients, were included. Quality of Life in Epilepsy Inventory–31 item (QOLIE-31) meta-analysis included six studies, and QOLIE-89 meta-analysis included four studies. Postoperative change in raw score was 20.5 for QOLIE-31 (95% confidence interval [CI] = 10.9–30.1, I² = 95.5) and 12.1 for QOLIE-89 (95% CI = 8.0–16.1, I² = 55.0%). This corresponds to clinically meaningful QOL improvements. Meta-regression demonstrated a higher postoperative QOLIE-31 score as well as change in pre- and postoperative QOLIE-31 score among studies of cohorts with higher proportions of patients with favorable seizure outcomes. At an individual study level, preoperative absence of mood disorders, better preoperative cognition, fewer trials of antiseizure medications before surgery, high levels of conscientiousness and openness to experience at the baseline, engagement in paid employment before and after surgery, and not being on antidepressants following surgery were associated with improved postoperative QoL. This study demonstrates the potential for epilepsy surgery to provide clinically meaningful improvements in QoL, as well as identifies clinicodemographic factors associated with this outcome. Limitations include substantial heterogeneity between individual studies and high risk of bias.     

颞叶癫痫手术时的皮质脑电描记

报告1980年10月至1992年6月间,在皮质脑电描记下手术治疗颞叶癫痫55例,前颞叶切除50例.杏仁核海马切除5例。皮质脑电描记结果说明颞叶癫痫的痫灶绝大多数来源于颞叶外侧皮质和颞叶内侧结构。术中皮质脑电描记可提供痫灶的精确部位和范围。     

Intraoperative magnetic resonance imaging in epilepsy surgery: A systematic review and meta-analysis

This systematic review investigated the added value of intraoperative magnetic resonance imaging (iMRI)-guidance in epilepsy surgery, compared to conventional non-iMRI surgery, with respect to the rate of gross total resection (GTR), postoperative seizure freedom, neurological deficits, non-neurological complications and reoperations. A comprehensive literature search was conducted using Medline, Embase, PubMed, and Cochrane Reviews databases. Randomized control trials, case control or cohort studies, and surgical case series published from January 1993 to February 2021 that reported on iMRI-guided epilepsy surgery outcomes for either adults or children were eligible for inclusion. Studies comparing iMRI-guided epilepsy surgery to non-iMRI surgery controls were selected for meta-analysis using random-effects models. Forty-two studies matched the selection criteria and were used for qualitative synthesis and ten of these were suitable for meta-analysis. Overall, studies included various 0.2–3.0 Tesla iMRI systems, contained small numbers with heterogenous clinical characteristics, utilized subjective GTR reporting, and had variable follow-up durations. Meta-analysis demonstrated that the use of iMRI-guidance led to statistically significant higher rates of GTR (RR = 1.31 [95% CI = 1.10–1.57]) and seizure freedom (RR = 1.44 [95% CI = 1.12–1.84]), but this was undermined by moderate to significant statistical heterogeneity between studies (I² = 55% and I² = 71% respectively). Currently, there is only level III-2 evidence supporting the use of iMRI-guidance over conventional non-iMRI epilepsy surgery, with respect to the studied outcomes.     

皮质脑电图联合深部电极监测在症状性癫痫手术中的应用及疗效影响因素分析

目的 探讨皮质脑电图(ECoG)联合深部电极监测在症状性癫痫手术中的应用及疗效影响因素分析.方法 回顾性分析2017年1月-2020年6月该院收治的24例行症状性癫痫手术患者的临床资料.术中采用ECoG联合深部电极监测并定位致痫灶,确定手术切除病灶深度、范围及周围致痫灶.术后随访12个月,采用Engel分级评估疗效,并根据疗效分为有效组(18例)、无效组(6例).采用单因素分析、多因素Logistic回归分析症状性癫痫手术疗效的影响因素.结果 所有患者均顺利完成手术,术中ECoG、深部电极均监测到病变处阵发性或持续性棘慢复合波、棘波、尖波;此外,深部电极还在病变周围正常脑组织内监测到明显棘慢复合波、尖波,但放电程度及频率均较病变部位低.术后出现暂时性单侧肢体轻度偏瘫、语言障碍、情感淡漠各2例,术后2个月恢复正常,术后无严重感染及颅内出血等发生.多因素Logistic回归分析结果显示,病程＞2年[OR:6.500,95％CI:1.741～24.274]、部分切除致痫灶[ORe:14.583,95％CI:1.545～137.661]为症状性癫痫手术疗效的危险因素,而术后无早期发作[OR:0.066,95％CI:0.012～0.368]为症状性癫痫手术疗效的保护因素.结论 症状性癫痫手术中采用ECoG联合深部电极监测可精准定位致痫灶深度及范围.患者病程、致痫灶切除程度、术后早期癫痫发作情况等为症状性癫痫手术疗效影响因素.     

Long-term intellectual and developmental outcomes after pediatric epilepsy surgery: A systematic review and meta-analysis

In addition to the primary aim of seizure freedom, a key secondary aim of pediatric epilepsy surgery is to stabilize and, potentially, optimize cognitive development. Although the efficacy of surgical treatment for seizure control has been established, the long-term intellectual and developmental trajectories are yet to be delineated. We conducted a systematic review and meta-analysis of studies reporting pre- and postsurgical intelligence or developmental quotients (IQ/DQ) of children with focal lesional epilepsy aged ≤18 years at epilepsy surgery and assessed at >2 years after surgery. We determined the IQ/DQ change and conducted a random-effects meta-analysis and meta-regression to assess its determinants. We included 15 studies reporting on 341 patients. The weighted mean age at surgery was 7.1 years (range = .3–13.8). The weighted mean postsurgical follow-up duration was 5.6 years (range = 2.7–12.8). The overall estimate of the mean presurgical IQ/DQ was 60 (95% confidence interval [CI] = 47–73), the postsurgical IQ/DQ was 61 (95% CI = 48–73), and the change was +.94 IQ/DQ (95% CI = −1.70 to 3.58, p = .486). Children with presurgical IQ/DQ ≥ 70 showed a tendency for higher gains than those with presurgical IQ/DQ < 70 (p = .059). Higher gains were determined by cessation of antiseizure medication (ASM; p = .041), not just seizure freedom. Our findings indicate, on average, stabilization of intellectual and developmental functioning at long-term follow-up after epilepsy surgery. Once seizure freedom has been achieved, ASM cessation enables the optimization of intellectual and developmental trajectories in affected children.     

High frequency oscillations in intra-operative electrocorticography before and after epilepsy surgery

ObjectiveRemoval of brain tissue showing high frequency oscillations (HFOs; ripples: 80–250 Hz and fast ripples: 250–500 Hz) in preresection electrocorticography (preECoG) in epilepsy patients seems a predictor of good surgical outcome. We analyzed occurrence and localization of HFOs in intra-operative preECoG and postresection electrocorticography (postECoG).MethodsHFOs were automatically detected in one-minute epochs of intra-operative ECoG sampled at 2048 Hz of fourteen patients. Ripple, fast ripple, spike, ripples on a spike (RoS) and not on a spike (RnoS) rates were analyzed in pre- and postECoG for resected and nonresected electrodes.ResultsRipple, spike and fast ripple rates decreased after resection. RnoS decreased less than RoS (74% vs. 83%; p = 0.01). Most fast ripples in preECoG were located in resected tissue. PostECoG fast ripples occurred in one patient with poor outcome. Patients with good outcome had relatively high postECoG RnoS rates, specifically in the sensorimotor cortex.ConclusionsOur observations show that fast ripples in intra-operative ECoG, compared to ripples, may be a better biomarker for epileptogenicity. Further studies have to determine the relation between resection of epileptogenic tissue and physiological ripples generated by the sensorimotor cortex.SignificanceFast ripples in intra-operative ECoG can help identify the epileptogenic zone, while ripples might also be physiological.     

Epilepsy surgery for patients with genetic refractory epilepsy: a systematic review

Aims. In recent years, many different DNA mutations underlying the development of refractory epilepsy have been discovered. However, genetic diagnostics are still not routinely performed during presurgical evaluation and reports on epilepsy surgery outcome for patients with genetic refractory epilepsy are limited. We aimed to create an overview of the literature on seizure outcome following epilepsy surgery in patients with different genetic causes of refractory epilepsy. Methods. We systematically searched PubMed and Embase prior to January 2017 and included studies describing treatment outcome following epilepsy surgery in patients with genetic causes of epilepsy. We excluded studies in which patients were described with epilepsy due to Tuberous Sclerosis Complex or Sturge‐Weber syndrome (since this extensive body of research has recently been described elsewhere) and articles in which surgery was aimed to be palliative. Results. We identified 24 eligible articles, comprising a total of 82 patients who had undergone surgery for (mainly childhood‐onset) refractory epilepsy due to 15 different underlying genetic causes. The success rate of surgery varied widely across these different genetic causes. Surgery was almost never effective in patients with epilepsy due to mutations in genes involved in channel function and synaptic transmission, whereas surgery was significantly more successful regarding seizure control in patients with epilepsy due to mutations in the mTOR pathway. Patients with a lesion on MRI tended to have higher seizure freedom rates than those who were MRI‐negative. Conclusion. Although the evidence is still scarce, this systematic review suggests that studying genetic variations in patients with refractory epilepsy could help guide the selection of surgical candidates.     

Monitoring cognition during awake brain surgery in adults: A systematic review

Introduction: Historically, most studies about awake brain surgery have focused on language or motor functions. More recently, other cognitive functions have also been assessed. However, a clear overview of the neuropsychological tests or test paradigms that are used during such procedures is missing. The primary research question of this review is: What neuropsychological tests or paradigms are used during awake brain surgery? This review aims to give an extensive overview about the assessment of cognition during awake brain surgery.

Method: A systematic search was performed in PubMed and Embase. Studies about awake surgery that mentioned a specific test or test paradigm for assessing cognition were included in this review.

Results: The search yielded 4,052 articles. A manual selection for cognition in title and abstract resulted in 360 studies. Those were evaluated in full text; 212 articles described a cognitive task or paradigm. Further reference-list search yielded 20 more studies. In 207 of 232 studies, a test for assessment of language is reported. Tests for the visuospatial domain and motor and sensory functions are described in, respectively, only 23 and 20 studies. Tests for memory, calculation, emotions, or other cognitive functions are reported only in a minority of the included studies.

Conclusions: Tests for assessment of language functions during awake brain surgery are widely reported. Other cognitive functions are underexposed. There is a need for development of tests or paradigms for assessment of other cognitive functions so that the broad spectrum of cognition can be monitored during awake brain surgery.     

Transforming epilepsy research: A systematic review on natural language processing applications

Despite improved ancillary investigations in epilepsy care, patients' narratives remain indispensable for diagnosing and treatment monitoring. This wealth of information is typically stored in electronic health records and accumulated in medical journals in an unstructured manner, thereby restricting complete utilization in clinical decision-making. To this end, clinical researchers increasing apply natural language processing (NLP)—a branch of artificial intelligence—as it removes ambiguity, derives context, and imbues standardized meaning from free-narrative clinical texts. This systematic review presents an overview of the current NLP applications in epilepsy and discusses the opportunities and drawbacks of NLP alongside its future implications. We searched the PubMed and Embase databases with a “natural language processing” and “epilepsy” query (March 4, 2022) and included original research articles describing the application of NLP techniques for textual analysis in epilepsy. Twenty-six studies were included. Fifty-eight percent of these studies used NLP to classify clinical records into predefined categories, improving patient identification and treatment decisions. Other applications of NLP had structured clinical information retrieval from electronic health records, scientific papers, and online posts of patients. Challenges and opportunities of NLP applications for enhancing epilepsy care and research are discussed. The field could further benefit from NLP by replicating successes in other health care domains, such as NLP-aided quality evaluation for clinical decision-making, outcome prediction, and clinical record summarization.     

Cortical resection with electrocorticography for intractable porencephaly-related partial epilepsy

PURPOSE: We evaluated the results of cortical resection of epileptogenic tissue for treatment of intractable porencephaly-related epilepsy. METHODS: We examined clinical features, electrophysiological data, surgical findings, and seizure outcomes after cortical resection in eight patients with intractable epilepsy related to porencephalic cysts. RESULTS: All eight patients had hemiparesis. Five retained motor function in the hemiparetic extremities; six retained visual fields. All had partial seizures, six with secondary generalization. Seven patients had simple and three had complex partial seizures (CPSs); two also had drop attacks. Four patients had multiple seizure types. Long-term scalp video-EEG (LVEEG) localized interictal epileptic abnormalities that anatomically corresponded to the cyst location in three patients. LVEEG recorded ictal-onset zones in five; these anatomically corresponded to the cyst location in three of the five. EEG recorded generalized seizures in two patients, hemispheric in one, and multifocal in two. Intraoperative electrocorticography (ECoG) revealed interictal epileptic areas extending beyond the margins of the cyst in seven patients. We resected ECoG-localized interictal epileptic areas completely in five patients and partially in two. Cortical resection was based on seizure semiology and LVEEG in one patient whose ECoG showed no epileptiform discharges. After a minimum follow-up of 1 year, six patients had excellent seizure outcome (Engel class I), and two had a >90% seizure reduction (Engel class III) without complications. CONCLUSIONS: Cortical resection guided by ECoG allows preservation of motor function and visual field and provides an effective surgical procedure for treatment of intractable epilepsy secondary to porencephaly.     

Outcome of resective surgery for intractable partial epilepsy guided by subdural electrode arrays

The aim of this paper was to evaluate the outcome and the factors predictive for a good prognosis of resective surgery for intractable partial epilepsy guided by subdural electrode arrays (SEA's) and operative electrocorticography. Sixty-four patients, aged 8–52 years, were evaluated with chronic SEAs in order to record interictal and ictal activity and delineate speech and motor areas by functionally mapping. Resection were individualized to each patient's SEA recorded electrocorticogram and operative electrocorticogram and functional mapping results (tailored resection). The follow-up time was a minimum of one year. Good seizure outcome was defined as seizure free from complex partial and secondary generalized seizures. After one year 70% of the patients with a temporal ictal focus was seizure free compared to 55% of the patients with an extratemporal focus. Complete resection of interictal or ictal fields as mapped with SEAs, gave better prognosis than partial resection. Patients with no postresection spikes had a better prognosis than patients with residual postresection spikes evaluated with operative electrocorticography. Sex, age, duration of epilepsy prior to surgery, extent of temporal lobe resection and structural abnormalities determined by MRI were not associated with a favorable seizure outcome after surgery. We conclude that complete resection of the interictal and ictal field mapped with SEA's and absence of postresection spikes on operative electrocorticography are associated with an excellent seizure outcome.