Seizure outcome after temporal lobectomy in temporal lobe cortical dysplasia

PURPOSE: To identify the temporal lobe cortical dysplasia (CD) histopathology classification subtype and determine the seizure outcome of patients who underwent temporal lobectomy with coincident CD. METHODS: We reviewed the data of 28 patients with temporal lobe epilepsy who underwent surgery with pathologically verified CD at our institution from 1990 to 2000. The seizure outcome was assessed at a minimum of 1 year after surgery according to Engel's classification. RESULTS: Of 28 patients who underwent surgery, nine (32.1%) had isolated CD, and 19 (67.9%) had CD and hippocampal sclerosis (CD&HS). Twenty-six (92.9%) patients had histopathology subtype Ia (architectural abnormalities). Twenty (71.4%) patients were seizure free (Engel class I). Favorable seizure outcome (Engel class I, II) was achieved in 26 (92.9%) patients. No difference in seizure outcome was noted between patients with CD and CD&HS. CONCLUSIONS: The most common histopathologic subtype in patients with temporal lobe CD is type Ia (architectural abnormalities). Temporal lobectomy in temporal lobe epilepsy patients with CD can achieve favorable seizure outcome.     

Clinical characteristics of 92 patients with temporal lobe focal cortical dysplasia identified by pathological examination

Focal cortical dysplasia (FCD) is frequently associated with focal epilepsy, and a broad spectrum of histopathology is included in the diagnosis of FCD. In 2011, an International League Against Epilepsy (ILAE) task force proposed an international consensus for a classification system to better characterise specific clinicopathological FCD entities. The clinical characteristics of patients with FCD should be confirmed according to the new ILAE classification. We retrospectively analysed 92 patients who had undergone surgical treatment for temporal lobe epilepsy and received a pathological diagnosis of FCD. The pathological sections were re-examined and diagnosed according to the 2011 ILAE classification. The clinical data from patients with different FCD subtypes were evaluated, including a detailed history regarding spontaneous abortions, trauma, ischaemic injury, encephalitis, and febrile seizures at an early age. The age of epilepsy onset, duration of epilepsy, age at surgery, seizure frequency, history of febrile seizures, and seizure type, particularly whether the seizures were secondarily generalised tonic-clonic seizures, were recorded. Clinical differences were found in the patients with temporal lobe FCD. The associated FCD subtypes have unique clinical characteristics, including a later age of epilepsy onset and a shorter duration of epilepsy, especially in FCD Type IIIc; and a high susceptibility to febrile seizures was observed in FCD Type IIIa.     

Electrocorticographic discharge patterns in glioneuronal tumors and focal cortical dysplasia

Summary:  Purpose: To determine whether highly epileptiform electrocorticographical discharge patterns occur in patients with glioneuronal tumors (GNTs) and focal cortical dysplasia (FCD) and whether specific histopathological features are related to such patterns.
Methods: The series consists of operated patients with pharmacoresistant epilepsy because of FCD or GNT between 1992 and 2003. Electrocorticography was reviewed for presence of continuous spiking, bursts, recruiting discharges, or sporadic spikes. Surgical specimens were reviewed for the presence of balloon cells, (coexisting) cortical dysplasia, and relative frequencies of neurons, glia, and microglia.
Results: Continuous spiking was seen in 55% versus 12% of patients with FCD and GNT, respectively (p = 0.005). Bursts and recruiting discharges were seen in a similar proportion of patients with FCD or GNT. Ninety-one percent of patients with continuous spiking showed (coexisting) cortical dysplasia in contrast to 42% of patients without this pattern (p = 0.004). The presence of balloon cells and glia or microglia content were not associated with discharge patterns.
Conclusion: Continuous spiking, bursts, and recruiting discharges occur in patients with FCD and GNT. Continuous spiking was seen significantly more often in patients with FCD. When continuous spiking is found with GNT, it is likely to be associated with dysplastic regions with a high neuronal density.     

Surgical outcome and predictive factors in adult patients with intractable epilepsy and focal cortical dysplasia

OBJECTIVES: To determine the surgical outcome and prognostic factors in adult patients with intractable epilepsy and focal cortical dysplasia (FCD). MATERIALS AND METHODS: We retrospectively studied the operative outcome in 21 consecutive adult patients with FCD who underwent surgical treatment for intractable partial epilepsy. RESULTS: The mean age at surgery was 32.7 years (range, 18-58 years). The median post-operative follow-up was 2.5 years. The FCD was extratemporal in 11 patients, involved the temporal lobe in 10 patients, and was multilobar in eight patients. Eleven patients (52%) were rendered seizure-free, four patients (19%) had >95% reduction in seizures, and two patients (10%) had an 80-94% reduction in seizures. A seizure-free outcome was associated with shorter duration of epilepsy (P = 0.02). CONCLUSION: Adult patients with FCD may be candidates for surgical treatment of intractable partial epilepsy. Most individuals have neocortical, extrahippocampal seizures and approximately 50% of patients are rendered seizure-free.     

Architectural (Type IA) focal cortical dysplasia and parvalbumin immunostaining in temporal lobe epilepsy

PURPOSE: We analyzed 26 surgically treated patients operated on for intractable epilepsy associated with type IA (architectural) cortical dysplasia, to investigate neuropathologic and immunocytochemical features, particularly of the gamma-aminobutyric acid (GABA)ergic system, and to compare the findings with those observed in normal cortex. METHODS: Routinely stained slides and serial sections immunostained for neurofilaments (SMI 311), microtubule-associated protein-2 (MAP-2), neuron-specific nuclear protein (NeuN), glial fibrillary acidic protein (GFAP), parvalbumin (PV), calbindin (CB), and calretinin (CR) were processed. Some sections were processed by using single-immunoperoxidase procedures; others were processed for double immunofluorescence labelling and observed by confocal microscopy. The density of inhibitory PV-immunoreactive interneurons was quantitatively assessed in all patients and control cases by using a two-dimensional cell-counting technique on PV immunostained sections. RESULTS: The density of PV-immunoreactive interneurons was significantly reduced in this group of patients, whereas CB- and CR- positivity appeared similar to those in normal cortex. In five cases, architectural abnormalities, in addition to those that defined type 1A dysplasia, were present and characterized by abnormal clusters of neurons and laminar cellular loss in superficial cortical laminate. CONCLUSIONS: The reduction of PV expression in type IA cortical dysplasia suggests an impairment of the GABAergic system as a possible mechanism for the epileptogenicity; in addition, PV immunoreactivity can be helpful in the neuropathologic characterization of this form of cortical dysplasia.     

术中皮层脑电图在颞叶癫痫手术中的应用

目的 探讨术中皮层脑电图(ECoG)在颢叶癫痫手术中的应用价值.方法 回顾性分析105例前颞叶切除手术患者的临床资料与ECoG的监测结果,统计对ECoG的影响因素及其对手术疗效的影响.结果 术前ECoG平均监测时间为72 min,结果显示:无异常11例、颢叶或前颞叶局限性放电73例、广泛痫性放电21例;术后ECoG平均监测时间为38 min,结果显示:无异常91例、颞叶后部痫性放电9例、广泛痫性放电5例.年龄与术前EcoG结果无明显相关性;而病程＜5年者术前EcoG痫性放电局限于前颞叶的比率较高,达到83.3%,且与另外两组差异有统计学意义.有6例(5.7%)根据术后ECoG结果行颞叶皮层后部扩大切除.术前ECoG显示痫性放电局限于前颞叶和术后ECoG正常与其他同期结果间的手术疗效差异有统计学意义,提示术后无癫痫发作.结论 颞叶癫痫患者ECoG监测可发现70%的痫波局限于前颞区,术前和术后ECoG监测结果可用于初步判断手术疗效,ECoG监测对颞叶癫痫手术具有一定的应用价值.     

Temporal lobe focal cortical dysplasia: MRI imaging using FLAIR shows lesions consistent with neoplasia

Focal cortical dysplasia (FCD), a form of neuronal migration disorder, is a malformative lesion of the neocortex that occurs during development of the brain. It can cause partial and generalized epilepsy. Seizures occur at an early age and are often resistant to medication. Surgical resection has been found to be beneficial in these patients. Dual pathology, in the form of mesial temporal sclerosis, has been associated with FCD. At the Children’s Hospital of Eastern Ontario, four patients with temporal lobe FCD have re-cently, been identified. This paper discusses how these children presented and how they were managed, with particular emphasis on their MRI findings and differential diagnoses. In three of the four patients neuroimaging studies showed lesions consistent with a neoplastic process because of the large volume and mass effect. Radiologically, FCD may mimic the MRI appearance of tumors, such as dysembryoplastic neuroepithelial tumors, primitive neuroectodermal tumors, gangliogliomas, oligodendrogliomas, and astrocytomas. These lesions are best visualized on fluid-attenuated inversion recovery (FLAIR) imaging, a technique that has recently become applicable in the clinical setting, as we help demonstrate in this series. With better MRI capability, milder forms of FCD and microdysplasia may be distinguished. Received: 7 September 1999     

Efficacy of temporal lobe surgery for epilepsy in patients with negative MRI for mesial temporal lobe sclerosis

Epilepsy surgery is a successful treatment for refractory temporal lobe epilepsy (TLE). Reports suggest fewer seizure-free outcomes for patients with TLE and who have a negative brain MRI (nMRI) for mesial temporal sclerosis. Data were collected prospectively from patients with nMRI who underwent temporal lobe surgery for TLE characterized by unilateral ictal temporal lobe seizure onset based on a scalp video electroencephalogram or invasive subdural electrode recordings. A total of 86 patients were followed for at least 24 months after surgery. Outcome was evaluated using the Engel classification. Seizure control was obtained by 55% (47/86) of patients (Class [CL]-I), 27% (23/86) showed significant improvement (CL-II) and 19% (16/86) were deemed surgical failures. Shorter duration of epilepsy, later onset of seizures, and ictal theta rhythm (5-7 Hz) were the most significant predictors of postoperative seizure control. Although hypometabolism on positron emission tomography scan and significant memory disparity (>2.5/8) were not significant prognosticators independently, cumulatively they were predictors for favorable outcome.     

Temporo-mesial extraventricular neurocytoma and cortical dysplasia in focal temporal lobe epilepsy

We describe a 17-year-old boy with a left extraventricular temporo-mesial neurocytoma associated with cortical dysplasia causing focal pharmacoresistant temporal lobe epilepsy. He presented with a long history of medically refractory, temporal complex partial seizures. MRI showed a left temporo-mesial lesion suspect to be a low-grade tumor. Based on the pre-operative non-invasive neurophysiological studies, the patient underwent a left tailored temporal antero-mesial resection. Histopathological examination showed an extraventricular neurocytoma associated with architectural dysplasia (Type 1a) of the temporal pole. The patient was seizure-free at 2 years follow-up. Extraventricular neurocytomas must be considered in the differential diagnosis of the plethora of low-grade tumors associated with focal epilepsy that typically involve the temporal lobe, and are frequently associated with focal cortical dysplasia.     

Depression in temporal lobe epilepsy surgery patients: an FDG-PET study

PURPOSE: Depression is common in temporal lobe epilepsy (TLE) and after temporal lobectomy, and its etiology is obscure. In nonepileptic depression (including depression associated with other neurologic disorders), a consistent PET imaging finding is frontal lobe hypometabolism. Many TLE patients have hypometabolism involving frontal regions. Thus in data available from routine clinical assessments in an epilepsy surgery unit, we tested the hypothesis that the pattern of hypometabolism, particularly in the frontal lobe, may be associated with the depression seen in patients with TLE and TLE surgery. METHODS: We studied 23 medically refractory TLE patients who underwent anterior temporal lobectomy and who had preoperative FDG-PET scanning. All patients had pre- and postoperative psychiatric assessment. By using statistical parametric mapping (SPM-99), patterns of hypometabolism were compared between patients who had a preoperative history of depression (n=9) versus those who did not (n=14) and between those in whom postoperative depression developed (n=13) versus those in whom it did not (n=10). A significant region of hypometabolism was set at p<0.001 for a cluster of >or=20 contiguous voxels. RESULTS: Patients with a history of depression at any time preoperatively showed focal hypometabolism in ipsilateral orbitofrontal cortex compared with those who did not (t=4.64; p<0.001). Patients in whom depression developed postoperatively also showed hypometabolism in the ipsilateral orbitofrontal region (t=5.10; p<0.001). CONCLUSIONS: Although this study is methodologically limited, and other explanations merit consideration, orbitofrontal cortex dysfunction, already implicated in the pathophysiology of nonepileptic depression, may also be relevant to the depression of TLE and temporal lobectomy.     

胚胎发育不良性神经上皮瘤与颞叶癫

目的探讨胚胎发育不良性神经上皮瘤（dysembryoplastic neuroepithelial tumor,DNT）相关颞叶癫的临床特点及外科治疗方法。方法回顾性分析21例颞叶癫DNT病人的临床资料,均以部分性癫起病,平均起病年龄轻。MRI上有典型的＂倒三角征＂和瘤内分隔表现。PET检查表现为病灶及周边脑皮质葡萄糖摄取减低。均行标准前颞叶切除术。结果术后随访1~6年,癫控制良好,无肿瘤复发病例。术后病理提示：单纯型DNT 6例,复杂型DNT 15例,伴局灶性脑皮质发育不良13例。结论应用标准前颞叶切除治疗癫相关的颞叶DNT,手术预后较好。     

Altered layer-specific gene expression in cortical samples from patients with temporal lobe epilepsy

Purpose: Neuropathologic investigations frequently reveal the presence of architectural cortical dysplasia in patients with temporal lobe epilepsy (TLE), sometimes as an isolated finding but more commonly associated with hippocampal sclerosis (HS) and white matter abnormalities. The histologic pattern and the developmental origin of these alterations are not clear, and their diagnostic criteria are poorly defined. The aim of this study was to investigate the expression patterns of layer‐specific genes in cortical specimens from patients with TLE presenting different subtypes of cortical malformations in order to elucidate the disorganization of the laminar architecture of such epileptogenic abnormalities and provide evidence to enable a more objective neuropathologic diagnosis. Methods: We analyzed the expression patterns of CUX2, RORBETA, ER81, NURR1, and CTGF genes, respectively specific markers of layers II–III, IV, V, VI, and VIb, in surgical samples by means of in situ hybridization and compared them with those observed in control cortices. The pathologic samples included typical architectural dysplasia (group 1); temporal lobe sclerosis, a variant of architectural dysplasia (group 2); and white matter heterotopic neuronal aggregates, namely small lentiform nodules (group 3). These abnormalities may have been associated or not with HS. Key Findings: All of the genes had a laminar expression pattern in normal cortices, whereas groups 1 and 2 showed alterations mainly involving layers V and VI, and highlighted by the altered distribution of ER81‐ and NURR1‐positive cells. The expression of ER81 and NURR1 genes was different among the groups, and atypical coexpression of NURR1 and CUX2 mRNA was detected in the neurons making up the small lentiform nodules. Significance: These findings indicate that defects in cortical organization involving the deeper cortical neurons may be a common etiopathogenic mechanism in group 1 and 2 cortical dysplasia, whether isolated or associated with HS, and that developmental disorders may also be present in the white matter (group 3). They also provide evidence that the layer‐specific genes can be usefully used to investigate the neuropathology of human cortical dysplasia.     

Relevance of Residual Histologic and Electrocorticographic Abnormalities for Surgical Outcome in Frontal Lobe Epilepsy

PURPOSE: To estimate the significance of residual electrocorticographic and neuropathologic abnormalities on seizure control after surgery for frontal lobe epilepsy with the purpose of determining their relevance in deciding the extent of the surgical procedure. METHODS: The presence of epileptiform discharges in intraoperative electrocorticograms (ECoGs) and the nature and extent of neuropathologic abnormalities were reviewed for 35 patients who underwent frontal lobe resections for the treatment of epilepsy at our institution. The relations between surgical outcome and presence of the following features were studied: (a) presence of abnormal tissue at the limits of the resection; (b) presence of sporadic spikes and seizure patterns in the preresection ECoG; (c) their abolition in the postresection ECoG; and (d) the topography of residual discharges with respect to the margins of the resection. RESULTS: On neuropathologic examination, 18 patients showed focal cortical dysplasia (CD), and 17 showed other abnormalities (non-CD). Ten CD patients and 11 non-CD patients experienced a favourable outcome. Seizure patterns were significantly more common in patients with focal cortical dysplasia than in those without, with a sensitivity of 94% and a specificity of 75%. Abolition of seizure patterns was associated with a favourable surgical outcome (p = 0.031). Abolition of sporadic spikes or their presence in the postresection ECoG did not influence outcome. There was no clear relation between outcome and location of residual sporadic discharges. Seizure patterns persisted in the postresection ECoG in three CD patients, were located at the margins of the resection in all three, and these patients had a poor outcome. Incomplete removal of abnormal tissue was not associated with a poorer outcome in either patient group or in the complete sample. CONCLUSIONS: Seizure patterns were significantly more common in patients with cortical dysplasia, and their abolition on postresection ECoG recordings was associated with a favourable surgical outcome. Persistence of sporadic ECoG spikes and incomplete removal of histologic abnormalities did not affect outcome significantly.     

Sleep related epilepsy in focal cortical dysplasia type 2: Insights from sleep recordings in presurgical evaluation

ObjectiveTo determine the relationship between seizure onset, sleep stage and focal cortical dysplasia type 2 (FCD2) location in sleep related epilepsy (SRE).MethodsWe reviewed scalp video-EEG data of 77 patients with SRE among 130 surgically treated patients with histologically confirmed FCD2. Seizure onset was classified as occurring during NREM, REM and after arousal.ResultsSleep recordings were available for 65 patients (37 males, 7–49 years old). FCD2 was located in frontal lobe in 46 (71%) and in extra-frontal regions in 19, including the temporal lobe in 6. MRI was negative/doubtful in 35 cases. Interictal rhythmic/pseudorhythmic spike rate increased from 31% during waking to 65% during sleep. Seizure onset occurred from NREM in 46 cases (71%), mostly from stage 2, and after arousal in 14 (22%). Seizures occurring from NREM/REM sleep were significantly more frequent in frontal (89%) compared to extra-frontal location (42%), whilst arousal preceded seizure onset more often in extra-frontal (58%) compared to frontal location (7%).ConclusionsNREM seizure onset is the most common ictal pattern in SRE due to frontal FCD2 whereas preceding arousal points to extra-frontal regions.SignificanceSleep recordings may help for FCD2 localisation and suggest topography dependent impact on sleep related epileptic networks.     

Hyperkinetic seizures in patients with temporal lobe epilepsy: clinical features and outcome after temporal lobe resection

Purpose: Temporal lobe epilepsy (TLE) is usually associated with automatisms. Hyperkinetic seizures are supposed to be unusual. Because we witnessed several patients with TLE and ictal hyperkinetic symptoms, we retrospectively assessed the number, clinical findings, and seizure outcome in such patients who had undergone temporal lobe resection. Methods: We reviewed medical history, video–electroencephalography (EEG) recording and neuroimaging of adult patients who underwent epilepsy surgery for TLE at the Kork Epilepsy Center over the last 20 years with a minimum postoperative follow‐up of 12 months. Key Findings: Among 294 patients who were resected exclusively in the temporal region, we identified 17 (6%) who presented with hyperkinetic semiology such as violent vocalization, complex movements of the proximal segments of the limbs, rotation of the trunk, pelvic thrusting, or early tonic or dystonic posturing. Most of the patients had a preceding aura. Ictal EEG activity was located in the corresponding temporal region, usually with a wide distribution over temporal electrodes with fast spread to unilateral frontal electrodes and to the contralateral side. Neuroimaging revealed extended lesions in the temporal lobe involving mesial and neocortical structures. Most of the patients underwent classical anterior temporal lobe resection including amygdalo‐hippocampectomy. Fourteen patients (82%) became completely seizure‐free (Engel class Ia). Histopathology showed mainly focal cortical dysplasia plus hippocampal sclerosis. Significance: Hyperkinetic seizure semiology may occasionally occur in patients with TLE and is, therefore, no contradiction to the hypothesis of TLE if scalp EEG patterns and neuroimaging findings correspond. The postoperative seizure outcome is favorable in such patients and not different from outcome data in classical TLE.     

Widespread frontal lobe cortical dysplasia or partial hemimegalencephaly: a continuum of the spectrum

Focal cortical dysplasia (FCD) type II and hemimegalencephaly (HME) are currently considered as a continuum of pathology, the most important distinction being the extent or the size/volume of the lesion. While partial HME involving the posterior cortex has been well described, we present an unusual case with a dysplastic lesion of the whole frontal lobe. A 17‐year‐old boy had focal seizures from the age of nine years. Apart from diminished right‐hand dexterity, his neurological and cognitive status were unremarkable. The course of his epilepsy exhibited a relapsing‐remitting pattern, with prolonged periods of remission. Imaging showed dysplastic left frontal lobe (including paracentral lobule) thickened cortex with an abnormal gyration pattern resembling polymicrogyria, as well as dystrophic calcifications and hypodensity scattered throughout the white matter. This patient represents an intermediate case within the FCD type II/HME spectrum. Localization of the lesion in the frontal lobe as well as clinical characteristics (childhood onset, relapsing‐remitting epilepsy, without hemiparesis and overt cognitive impairment) are more consistent with FCD type II, while a range of MRI features is shared between HME and FCD type II.