Precuneal epilepsy: Clinical features and surgical outcome

ObjectiveThe precuneus is a complex and highly connected structure located in the medial portion of the superior parietal lobule. The clinical presentation of precuneal epilepsy is poorly characterized, mostly because these patients have seldom been distinguished from those with other types of parietal lobe epilepsy. The present study aims to improve the understanding of precuneal epilepsy by detailing its clinical features and surgical outcomes.MethodsSix previously unreported cases of drug-resistant precuneal epilepsy investigated between 2002 and 2014 were retrospectively studied. Seizure focus was confirmed by presence of a lesion, intracranial monitoring, or post-operative seizure control when applicable.ResultsSeizures arising from the precuneus have heterogeneous presentations, including body movement sensation, visual auras, eye movements, vestibular manifestations, and complex motor behaviors. Two patients with an anterior precuneus lesion described body movement sensations whereas two others with a posterior precuneus lesion experienced visual symptoms. Two of the five patients who underwent epilepsy surgery achieved good seizure control (Engel IA). One patient underwent gamma knife surgery with an Engel IV outcome. Surgical complications included contralateral visual field impairment, limb hypoesthesia and hemispatial neglect. One patient developed late-onset epilepsia partialis continua from a Rolandic subdural grid-related contusion.SignificanceIn absence of a clear precuneal epileptogenic lesion, recognition of a precuneal focus is challenging. Magnetoencephalography may sometimes localize the generator but invasive EEG remains in well-selected cases necessary to identify the seizure focus. Surgical failures may be explained by the widespread connectivity of the precuneus with distant and adjacent structures. Different ictal manifestations of precuneal epilepsy in this series provide a clinical correlate to the described functional subdivisions of the precuneus.     

Temporal lobe developmental malformations and hippocampal sclerosis: epilepsy surgical outcome

BACKGROUND: Temporal lobe developmental malformations coexist with mesial temporal sclerosis in the form of dual pathology with a high frequency of bilateral amygdala or hippocampal abnormalities. OBJECTIVE: The aim of this study was to correlate and compare the MRI findings and the surgical outcome in patients with temporal lobe developmental malformations (n = 20) and isolated mesial temporal sclerosis (n = 36). METHODS: MRI-based normalized volumetry of the amygdala and hippocampal formation in patients with unilateral temporal lobe developmental malformations and isolated mesial temporal sclerosis who underwent temporal lobe resections was performed. Seizure outcome was compared between groups at follow-up. RESULTS: The frequency of bilateral hippocampal or amygdala atrophy (p < 0.04) and combined hippocampal-amygdala atrophy (p < 0.02) was higher in patients with temporal lobe developmental malformations. Although no significant difference in postsurgical seizure-free status was found between the temporal lobe developmental malformations and isolated mesial temporal sclerosis groups (70% versus 91%), patients with temporal lobe developmental malformations and bilateral amygdala or hippocampal-amygdala atrophy had a significantly worse outcome (p < 0.02). CONCLUSION: Bilateral hippocampal atrophy is frequent in patients with temporal lobe developmental malformations. However, it is the presence of bilateral amygdala or amygdalo-hippocampal atrophy that is associated with a higher risk of seizure recurrence.     

枕叶癫痫外科治疗的特点与疗效(附13例报道)

目的 探讨枕叶癫痫外科治疗的特点与手术疗效.方法 回顾分析13例枕叶癫痫患者完整的临床资料,总结其发作症状学、影像学、EEG、神经病理学及手术治疗等方面的特征与手术疗效.结果 局灶性皮质发育不良为最常见病理表现(6例).术后2周时6例患者原有视觉障碍加重或新出现视觉障碍.术后随访2～5年,Engel's I级7例(53.8%),II级1例,III级2例,IV级3例.结论 定位明确的枕叶癫痫可以通过适当的手术治疗获得较满意疗效,但常常加重视觉功能障碍.     

Presurgical evaluation and surgical outcome of temporal lobe epilepsy

The authors analyzed 22 patients younger than 18 years of age with temporal lobe epilepsy (TLE) treated surgically. Patients underwent a comprehensive presurgical evaluation, including video-electroencephalogram. Fifty-five percent had a history of febrile seizures. Eighty-two percent had auraes and most exhibited oroalimentary and gestural automatisms. Contralateral dystonic posturing was present in 36% and postictal dysphasia in 54% of patients with left-sided resections. Cranial magnetic resonance imaging (MRI) was abnormal in 59% of patients. MRI revealed changes consistent with mesial temporal sclerosis in 8 (47%) of 17 patients without lesions. Fluorodeoxyglucose-positron emission tomography (PET) scans revealed ipsilateral temporal hypometabolism (PET-TH) in 12 (85.7%) of 14 patients. The intracarotid amobarbital procedure revealed impaired memory of the epileptogenic side in 59% of patients. Seventeen patients underwent en-bloc resections and five lesionectomies and resection of the epileptogenic area. There was no surgical morbidity or mortality. Forty-three percent had hippocampal sclerosis, 28.5% gliosis, 14% low-grade tumors, 9.5% cavernous angiomas, and 5% had no pathologic findings. Follow-up (6 months to 12 years) was available for 21 patients; 76% became seizure free, 19% had rare seizures, and 5% had a worthwhile improvement. TLE can be safely treated surgically in younger patients with excellent results. The clinical manifestations were similar to adult patients. PET-TH was present even at a younger age, suggesting that the focal functional deficits appear early in patients with medically refractory TLE, which may help in the early identification of these patients.     

Neocortical temporal lobe epilepsy: intracranial EEG features and surgical outcome.

Patients with neocortical temporal lobe epilepsy (NTLE) may have less favorable outcome with anterior temporal lobectomy than those with mesial temporal foci. The authors analyzed ictal intracranial electroencephalograms (EEGs) in patients with NTLE to identify features that predict surgical outcome. The following intracranial ictal EEG features in 31 consecutive medically intractable NTLE patients were studied: Frequency (i.e., low-voltage fast [>20 Hz], recruiting ictal-onset spikes, ictal-onset rhythms less than 5 Hz, ictal-onset rhythms with repetitive sharp waves between 5 and 20 Hz); extent of ictal onset (focal, sublobar, and lobar); localization within the temporal lobe (anterior, posterior, or regional); and the time to seizure spread outside the temporal lobe (rapid, intermediate, and slow). The average follow-up period was 36.7 months (range, 18 to 60 months). Findings between two outcome groups were compared: class I group (seizure-free) and class II to IV group (persistent seizures). Twenty-one (66.7%) of 31 patients with NTLE were seizure-free. Intracranial EEG features which were significantly associated with seizure-free outcome were focal or sublobar onset, anterior temporal onset, and slow propagation time (P < 0.05). There was a trend for patients with ictal onset morphologies of slow ictal-onset rhythm and repetitive sharp waves to be seizure-free (P = 0.07). Intracranial EEG is helpful in predicting surgical outcome in NTLE patients.     

Betweenness centrality of intracranial electroencephalography networks and surgical epilepsy outcome

Objective

We sought to determine whether the presence or surgical removal of certain nodes in a connectivity network constructed from intracranial electroencephalography recordings determines postoperative seizure freedom in surgical epilepsy patients.

症状性枕叶癫(癎)术前致(癎)灶评估及疗效分析

目的:探讨36例症状性枕叶癫(癎)的术前评估和3年以上的随访结果.方法:采用长程视频脑电图(V-EEG)监测结合皮层脑电图(EEG)定位的方法,对症状性枕叶癫(癎)患者行术前评估方法,结合病理结果和手术疗效进行回顾性分析.结果:在36例症状性枕叶癫(癎)患者中,29例(81％)依据长程V-EEG和MRI等无创检查不能精确定位致(痫)灶,需应用颅内电极记录定位.对所有术后患者随访3年以上,Engel分级:Ⅰ级21例(58％);Ⅱ级8例(22％);Ⅲ级4例(11％);Ⅳ级:3例(9％).结论:症状性枕叶癫(癎)的临床特点包括:具有视觉先兆、枕叶区域异常EEG及影像学改变的症状性枕叶癫(癎)患者,结合V-EEG和皮层EEG监测,手术切除致(痫)灶能获得良好手术效果,特别是致(痫)灶病理为神经节胶质细胞瘤和胚胎发育不良性神经上皮肿瘤预后良好.     

Extent of neocortical resection and surgical outcome of epilepsy: Intracranial EEG analysis

Purpose: Intracranial electroencephalography (EEG) monitoring is an important process in the presurgical evaluation for epilepsy surgery. The objective of this study was to identify the ideal resection margin in neocortical epilepsy guided by subdural electrodes. For this purpose, we investigated the relationship between the extent of resection guided by subdural electrodes and the outcome of epilepsy surgery. Methods: Intracranial EEG studies were analyzed in 177 consecutive patients who had undergone resective epilepsy surgery. We reviewed various intracranial EEG findings and resection extent. We analyzed the relationships between the surgical outcomes and intracranial EEG factors: the frequency, morphology, and distribution of ictal‐onset discharges, the propagation speed, and the time lag between clinical and intracranial ictal onset. We also investigated whether the extent of resection, including the area showing ictal rhythm and various interictal abnormalities—such as frequent interictal spikes, pathologic delta waves, and paroxysmal fast activity—influenced the surgical outcome. Results: Seventy‐five patients (42%) were seizure free. A seizure‐free outcome was significantly associated with a resection that included the area showing ictal spreading rhythm during the first 3 s or included all the electrodes showing pathologic delta waves or frequent interictal spikes. However, subgroup analysis revealed that the extent of resection did not affect the surgical outcome in lateral temporal lobe epilepsy. Conclusions: The extent of resection is closely associated with surgical outcome, especially in extratemporal lobe epilepsy. Resection that includes the area with total pathologic delta waves and frequent interictal spikes predicts a good surgical outcome.     

癫痫患儿脑FDG-PET显像与发作类型、脑电图异常及手术效果的相关性

目的 探讨小儿癫痫发作类型、脑电图异常、手术效果等与癫痫患儿脑FDG-PET显像的相关性.方法 方法回顾经临床、脑电图、影像学检查确诊的并行手术治疗的71例癫痫患儿脑18F-FDG-PET显像检测结果,以了解癫痫灶脑细胞葡萄糖代谢情况.根据脑FDG-PET显像结果,将71例患儿分为3个代谢减低组.33例患儿脑代谢减低位于单个脑叶,28例位于两个脑叶,10例多个脑叶均见代谢减低.收集71例患儿病程、性别、年龄、发作类型、脑电图资料、手术效果等临床资料,采用卡方检验,统计分析3个代谢减低组之间临床资料的总构成比差别.结果 癫痫发作类型、癫痫放电异常程度和术后效果在脑代谢减低3组间均有明显的区别,差异有统计学意义(P＜0.05).结论 脑FDG-PET显像与手术效果、发作类型和脑电图异常均明显相关.     

Intractable epilepsy associated with brain tumors in children: surgical modality and outcome

OBJECTS: The aim of this study was to evaluate the role of surgical modality in children with brain tumors and intractable epilepsy. METHODS: Twenty-three patients who were treated for brain tumors and intractable epilepsy between January 1985 and March 1998 were retrospectively reviewed. The most common tumors were dysembryoplastic neuroepithelial tumors (n=9), oligodendrogliomas (n=6), and gangliogliomas (n=5). Six patients exhibited cortical dysplasia. The mean duration of follow-up was 43.4 months (range 12 to 125 months). Seizure outcome was more favorable (Engel's classes I and II) in patients with a complete resection of tumor (14/14 vs 6/9 for incomplete resection; P<0.05). There was no significant difference in seizure outcome between lesionectomy (n=13) and epilepsy surgery (n=10). The likelihood of requiring postoperative antiepileptic drugs was not influenced by the extent of resection or type of surgery. CONCLUSIONS: On the basis of this study, we conclude that the complete resection of these tumors can be an appropriate initial treatment for children with brain tumors who experience intractable epilepsy.     

EEG predicts surgical outcome in lesional frontal lobe epilepsy

BACKGROUND: Because of the relatively poor results of frontal lobe epilepsy (FLE) surgery, identification of prognostic factors for surgical outcome is of great importance. METHODS: To identify predictive factors for FLE surgery, we analyzed the data of 61 patients (mean age at surgery 19.2) who had undergone presurgical evaluation and resective surgery in the frontal lobe. Postoperative follow-up ranged from 0.5 to 5 years (mean 1.78). Fifty-nine patients had MRI-detectable lesions. Histopathologic examination showed dysplasia (57.4%), tumor (16.4%), or other lesions (26.2%). Thirty postoperatively seizure-free patients were compared with 31 non-seizure-free patients with respect to clinical history, seizure semiology, EEG and neuroimaging data, resected area, and postoperative data including histopathology. RESULTS: Three preoperative and two postoperative variables were related to poor outcome: generalized epileptiform discharges, generalized slowing, use of intracranial electrodes, incomplete resection detected by MRI, and postoperative epileptiform discharges. The only preoperative factor associated with seizure-free outcome was the absence of generalized EEG signs. Multivariate analysis showed that only the absence of generalized EEG signs predicts the outcome independently. Moreover, the occurrence of a somatosensory aura, secondarily generalized seizures, and negative MRI was identified as additional independent risk factors for poor surgical results. CONCLUSIONS: The absence of generalized EEG signs is the most predictive variable for a seizure-free outcome in FLE surgery. Furthermore, nonlesional MRI, somatosensory aura, and secondarily generalized seizures are risk factors for poor surgical results.     

Subdural strip electrode monitoring and surgical decision making in refractory epilepsy: validity and prognostic value of noninvasive localizing data

We analyzed the rationale for invasive monitoring in refractory epilepsy. In 54 selected patients, video/scalp-EEG was insufficient for seizure focus localization. Therefore, bilateral subdural electrodes were implanted for ictal recording. In 40 (74.1%) of 54 patients, ictal electrocorticography (ECoG) localized a seizure focus amenable to resection. Fourteen (25.9%) of 54 patients, had multiple foci or primary generalized seizures. Among 36 patients who had focal resection with at least 1-year follow-up, 32 (88.9%) are either seizure-free or significantly improved. Magnetic resonance imaging (MRI) and interictal single photon emission computed tomography (SPECT) had the highest sensitivity and specificity (80.0 and 81.8%, respectively) and the greatest diagnostic value (64.0 and 77.8%, respectively) for seizure focus localization. Independent of electrophysiologic data, MRI determination of focal abnormality was prognostic for seizure-free outcome. Concordance of one or more noninvasive techniques with ictal ECoG seizure focus localization was statistically significant in predicting seizure-free outcome. Although interest in noninvasive selection of candidates for focal resection is increasing, there remains a role for invasive monitoring of epileptogenic foci that are difficult to localize. Our study should improve selection of patients with refractory epilepsy for focal resection when ictal ECoG is used in conjunction with noninvasive data for surgical decision making.     

Magnetoencephalography source localization and surgical outcome in temporal lobe epilepsy.

OBJECTIVE: We prospectively investigated the role of magnetoencephalography (MEG) in localizing the seizure focus and in predicting outcome to surgical resections for intractable temporal lobe epilepsy (TLE). METHODS: We performed simultaneous interictal EEG and MEG recording (two 37-channel system) in 26 TLE patients followed by MEG source localization. We correlated early modeling dipoles with intracranial EEG, temporal surgical resection and surgical outcome. RESULTS: There were 12 patients who had anterior temporal horizontal or tangential dipoles to the anterior infero-lateral temporal tip cortex. Two patients underwent selective amygdalo-hippocampectomy (SAH) and nine patients had antero-medial temporal lobectomy (AMTL). All patients had successful outcome except for one patient who initially failed SAH, but became seizure-free after AMTL. There were 11 patients who demonstrated anterior temporal vertical or tangential oblique dipoles. Five patients had AMTL and three had SAH; all became seizure free. Five of above 23 patients had invasive EEG and demonstrated mesial seizure onset. Three TLE patients had lateral vertical dipoles that were concordant with intracranial EEG and these became seizure free after temporal neocortical resections. CONCLUSIONS: MEG source analysis produces distinct source patterns that provide useful localizing information, predict surgical outcome, and may aid in planning limited surgical resection in TLE.     

Relationship between preoperative hypometabolism and surgical outcome in neocortical epilepsy surgery

Purpose: Fluorine‐18‐fluorodeoxyglucose–positron emission tomography (FDG‐PET) hypometabolism has been used to localize the epileptogenic zone. However, glucose hypometabolism remote to the ictal focus is common and its relationship to surgical outcome has not been considered in many studies. We investigated the relationship between surgical outcome and FDG‐PET hypometabolism topography in a large cohort of patients with neocortical epilepsy. Methods: We identified all patients (n = 68) who had interictal FDG‐PET between 1994 and 2004 and who underwent resective epilepsy surgery with follow up for more than 2 years. The volumes of significant FDG‐PET hypometabolism involving the resected epileptic focus and its surrounding regions (perifocal hypometabolism) and those distant to and not contiguous with the perifocal hypometabolism (remote hypometabolism) were determined statistically using Statistical Parametric Mapping (voxel threshold p = 0.01, extent threshold ≥250 voxels, uncorrected cluster‐level significance p < 0.05) and were compared with magnetic resonance imaging (MRI) and clinical and demographic variables using a multiple logistic regression model to identify independent predictors of seizure outcome. Key Findings: Remote hypometabolism was present in 39 patients. Seizure freedom was 49% (19 of 39 patients) in patients with glucose hypometabolism remote from the epileptogenic zone compared to 90% (26 of 29 patients) in patients without remote hypometabolism. In 43 patients with an MRI‐identified lesion, seizure freedom was 79% (34 of 43 patients). In patients with normal MRI, cortical dysplasia was the predominant pathologic substrate. Multiple logistic regression analysis identified a larger volume of significant remote hypometabolism (p < 0.005) and absence of a MRI‐localized lesion (p = 0.006) as independent predictors of continued seizures after surgery. Significance: In patients with widespread glucose hypometabolism that is statistically significant when compared to controls, epilepsy surgery may not result in complete seizure freedom despite complete removal of the MRI‐identified lesion. The volume of significant glucose hypometabolism remote to the ictal‐onset zone may be an independent predictor of the success of epilepsy surgery.