Focal Cortical Dysplasia Subtypes Research Articles

Multimodal MRI profiling of focal cortical dysplasia type II.

To characterize in vivo MRI signatures of focal cortical dysplasia (FCD) type IIA and type IIB through combined analysis of morphology, intensity, microstructure, and function. We carried out a multimodal 3T MRI profiling of 33 histologically proven FCD type IIA (9) and IIB (24) lesions. A multisurface approach operating on manual consensus labels systematically sampled intracortical and subcortical lesional features. Geodesic distance mapping quantified the same features in the lesion perimeter. Logistic regression assessed the relationship between MRI and histology, while supervised pattern learning was used for individualized subtype prediction. FCD type IIB was characterized by abnormal morphology, intensity, diffusivity, and function across all surfaces, while type IIA lesions presented only with increased fluid-attenuated inversion recovery signal and reduced diffusion anisotropy close to the gray-white matter interface. Similar to lesional patterns, perilesional anomalies were more marked in type IIB extending up to 16 mm. Structural MRI markers correlated with categorical histologic characteristics. A profile-based classifier predicted FCD subtypes with equal sensitivity of 85%, while maintaining a high specificity of 94% against healthy and disease controls. Image processing applied to widely available MRI contrasts has the ability to dissociate FCD subtypes at a mesoscopic level. Integrating in vivo staging of pathologic traits with automated lesion detection is likely to provide an objective definition of lesional boundary and assist emerging approaches, such as minimally invasive thermal ablation, which do not supply tissue specimen.

Focal Cortical Dysplasia: Gene Mutations, Cell Signaling, and Therapeutic Implications.

Focal cortical dysplasias (FCDs) are malformations of cortical development (MCDs) that are highly associated with medication-resistant epilepsy and are the most common cause of neocortical epilepsy in children. FCDs are a heterogeneous group of developmental disorders caused by germline or somatic mutations that occur in genes regulating the PI3K/Akt/mTOR pathway-a key pathway in neuronal growth and migration. Accordingly, FCDs are characterized by abnormal cortical lamination, cell morphology (e.g., cytomegaly), and cellular polarity. In some FCD subtypes, balloon cells express proteins typically seen in neuroglial progenitor cells. Because recurrent intractable seizures are a common feature of FCDs, epileptogenic electrophysiological properties are also observed in addition to local inflammation. Here, we will summarize the current literature regarding FCDs, addressing the current classification system, histopathology, molecular genetics, electrophysiology, and transcriptome and cell signaling changes.

Temporal lobe epilepsy and focal cortical dysplasia in children: A tip to find the abnormality.

To demonstrate an association between magnetic resonance imaging (MRI) findings and pathologic characteristics in children who had surgery for medically refractory epilepsy due to focal cortical dysplasia (FCD). We retrospectively studied 110 children who had epilepsy surgery. Twenty-seven patients with FCD were included. Thirteen had temporal lobe epilepsy (TLE) and 14 had extra-temporal lobe epilepsy (ETLE). Three patients had associated mesial temporal sclerosis. Preoperative 3T MRIs interleaved with nine controls were blindly re-reviewed and categorized according to signal alteration. Pathologic specimens were classified according to the 2011 International League Against Epilepsy (ILAE) classification and compared to MRI studies. Rates of pathology subtypes differed between TLE and ETLE (χ2 (3) = 8.57, p = 0.04). FCD type I was more frequent in TLE, whereas FCD type II was more frequent in ETLE. In the TLE group, nine patients had temporal tip abnormalities. They all exhibited gray-white matter blurring with decreased myelination and white matter hyperintense signal. Blurring involved the whole temporal tip, not just the area of dysplasia. These patients were less likely to demonstrate cortical thickening compared to those without temporal tip findings (χ2 (1) = 9.55, p = 0.002). Three of them had FCD Ib, three had FCD IIa, two had FCD IIIa, and one had FCD IIb; MRI features could not entirely distinguish between FCD subtypes. TLE patients showed more pronounced findings than ETLE on MRI (χ2 (1) = 11.95, p = 0.003, odds ratio [OR] 18.00). In all cases of FCD, isolated blurring was more likely to be associated with FCD II, whereas blurring with decreased myelination was seen with FCD I (χ2 (6) = 13.07, p = 0.042). Our study described associations between MRI characteristics and pathology in children with FCD and offered a detailed analysis of temporal lobe tip abnormalities and FCD subtypes in children with TLE. These findings may contribute to the presurgical evaluation of patients with refractory epilepsy.

Focal cortical dysplasia: Molecular disturbances and clinicopathological classification (Review)

Focal cortical dysplasia(FCD) is one of the most important causes of drug-resistant epilepsy in paediatric patients, particularly in those below the age of3. Even though over 40years have passed since the first description of the entity by Taylor, the exact mechanisms causing these cortical abnormalities remain unelucidated. In this review, we summarise the current knowledge on clinical and histopathological aspects, taking into account the new classification system proposed by the International League Against Epilepsy. We focus on the clinicopathological associations and differences in post-surgical outcome among FCD subtypes, in particular isolated FCD vs.FCD associated with principal lesions, which have not been summarised to date. We also recapitulate genetic studies, pointing to the possible mechanisms of the cortical dysregulation and drug resistance, and summarise novel factors which may contribute to epileptogenesis in FCD. Furthermore, we compare FCD typeIIB(FCDIIB) with brain tumours found in a neurocutaneous disorder, tuberous sclerosis, as we evaluate the hypothesis that FCDIIB may be a local form of this disease.

Whole-brain MRI phenotyping in dysplasia-related frontal lobe epilepsy.

To perform whole-brain morphometry in patients with frontal lobe epilepsy and evaluate the utility of group-level patterns for individualized diagnosis and prognosis. We compared MRI-based cortical thickness and folding complexity between 2 frontal lobe epilepsy cohorts with histologically verified focal cortical dysplasia (FCD) (13 type I; 28 type II) and 41 closely matched controls. Pattern learning algorithms evaluated the utility of group-level findings to predict histologic FCD subtype, the side of the seizure focus, and postsurgical seizure outcome in single individuals. Relative to controls, FCD type I displayed multilobar cortical thinning that was most marked in ipsilateral frontal cortices. Conversely, type II showed thickening in temporal and postcentral cortices. Cortical folding also diverged, with increased complexity in prefrontal cortices in type I and decreases in type II. Group-level findings successfully guided automated FCD subtype classification (type I: 100%; type II: 96%), seizure focus lateralization (type I: 92%; type II: 86%), and outcome prediction (type I: 92%; type II: 82%). FCD subtypes relate to diverse whole-brain structural phenotypes. While cortical thickening in type II may indicate delayed pruning, a thin cortex in type I likely results from combined effects of seizure excitotoxicity and the primary malformation. Group-level patterns have a high translational value in guiding individualized diagnostics.

Clinical characteristics and post-surgical outcomes of focal cortical dysplasia subtypes

We retrospectively studied 105 patients with a focal cortical dysplasia (FCD) diagnosed on pathological examination, and investigated the long term postoperative seizure outcomes, different clinical characteristics of the three FCD subtypes, particularly type I and II, and surgical outcomes for each group. FCD is a common cause of drug-resistant epilepsy, which is divided into three different subtypes according to its involvement at different stages of brain development. Each of these groups may have different characteristics and may even have different surgical outcomes. After treatment, 55% of patients were completely seizure-free, with two significant predictive variables for poorer outcomes: focal MRI findings and electrode implantation. FCD type I had relatively poor surgical outcomes compared to FCD type II and type IIIa. Compared with FCD type I, type II, particularly IIb, had a higher frequency of seizure attacks, predominantly located in the extratemporal lobes, and was more readily detected and diagnosed via focal lesions on MRI and localized electroencephalogram abnormalities. FCD type II patients seem to show better surgical outcomes than FCD type I, but the difference was not significant. Larger cohort studies are needed for further evaluation of the seizure outcomes of different FCD subtypes.

Post-surgical outcome for epilepsy associated with type I focal cortical dysplasia subtypes

Focal cortical dysplasias are a well-recognized cause of medically intractable seizures. The clinical relevance of certain subgroups of the International League Against Epilepsy (ILAE) classification scheme remains to be determined. The aim of the present work is to assess the effect of the focal cortical dysplasia type Ib and Ic histologic subtypes on surgical outcome with respect to seizure frequency. This study also provides an opportunity to compare the predictive value of the ILAE and Palmini et al classification schemes with regard to the type I focal cortical dysplasias. We retrospectively reviewed 91 focal cortical dysplasia patients (55% female; median age: 19 years (interquartile range 8–34); median seizure duration: 108 months (interquartile range 36–204)) with chronic epilepsy who underwent surgery. We compared the pathological subtypes, evaluating the patients' post-surgical outcome with respect to seizure frequency according to the Engel's classification and the ILAE outcome classification. Both the ILAE classification scheme and Palmini et al classification scheme were utilized to classify the histologic subtype. Using χ2 and Fisher's exact tests, we compared the post-surgical outcomes among these groups. Of the 91 patients, there were 50 patients with ILAE focal cortical dysplasia type Ib, 41 with ILAE focal cortical dysplasia type Ic, 63 with Palmini et al focal cortical dysplasia type IA, and 28 with Palmini et al focal cortical dysplasia type IB. After surgery, 44 patients (48%) were seizure-free. Crude analysis revealed no significant difference between patients with subtypes of ILAE focal cortical dysplasia type I or Palmini et al focal cortical dysplasia type I concerning postoperative outcome according to the Engel and ILAE scoring systems on seizure frequency. Our findings revealed no significant difference concerning surgical outcome with respect to seizure frequency for the histologic subtypes of ILAE focal cortical dysplasia type I (Ib vs Ic) or Palmini et al focal cortical dysplasia type I (IA vs IB). In isolation, the histologic subtype of focal cortical dysplasia type I does not appear predictive of postoperative 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.

Epilepsies associated with focal cortical dysplasias (FCDs).

Focal cortical dysplasias (FCDs) are increasingly recognized as one of the most common causes of pharmaco-resistant epilepsies. FCDs were recently divided into various clinico-pathological subtypes due to distinct imaging, electrophysiological, and outcome characteristics. In this review, we will overview the international consensus classification of FCDs in light of more recently reported clinical, electrical, imaging and functional observations, and will also address areas of ongoing debate. In addition, we will summarize our current knowledge on pathobiology and epileptogenicity of FCDs as well as its underlying molecular and cellular mechanisms. The clinical (electroencephalographic, imaging, and functional) characteristics of major FCD subtypes and their implications on the presurgical evaluation and surgical management will be discussed in light of studies describing these characteristics and postoperative seizure outcomes in patients with medically intractable focal epilepsy due to histopathologically confirmed FCDs.

Seizure outcome in surgically treated drug-resistant mesial temporal lobe epilepsy based on the recent histopathological classifications

The study was performed to investigate the relation between seizure outcome after surgical treatment of mesial temporal lobe epilepsy (MTLE) and pathological findings, classified according to the recently proposed classifications of mesial temporal sclerosis (MTS), granule cell pathology (GCP), focal cortical dysplasia (FCD) and epilepsy-associated low-grade tumors (ELGT). The authors analyzed data obtained in 120 consecutive cases involving patients presenting with drug-resistant MTLE, who underwent tailored anteromesial temporal lobe resection, and correlated seizure outcome with pathological findings. They identified 5 histopathological groups: Group 1-ELGT, alone or associated with other lesions (30 cases); Group 2-isolated FCD (17 cases); Group 3-MTS, with or without GCP (28 cases); Group 4-MTS associated with FCD, with or without GCP (37 cases); Group 5-other lesions (8 cases). Engel Class I outcome was observed in 83% of patients with ELGT (Class IA in 63%); in 59% of patients with isolated FCD, with FCD Type II showing a better prognosis than FCD Type I; in 82% of patients with isolated MTS (Class IA in 50%), with MTS Type 1a and MTS Type 1b showing a better prognosis than MTS Type 2 and patients with MTS and GCP having better postsurgical results than those with MTS without GCP. Engel Class I outcome was also achieved in 84% of patients with FCD associated with MTS (Engel Class IA in 62%); also in this group MTS 1a and MTS 1b associated with FCD showed a better prognosis than FCD associated with MTS 2. Finally, Engel Class I was also achieved in 2 patients with vascular malformation and in 1 with a temporal pole encephalocele. Patients with MTLE and ELGT, MTS, or MTS associated with FCD showed the best postsurgical seizure outcome (Engel Class I in more than 80% of cases), whereas only 63% of patients with isolated FCD achieved the same type of outcome. Interestingly, the analysis of seizure outcome in histopathological subtypes of FCD and of MTS showed different prognoses in the different pathological subgroups, with worse outcomes for atypical MTS, absence of GCP, and isolated FCD Type I.

Comparison of MRI features and surgical outcome among the subtypes of focal cortical dysplasia

PurposeFocal cortical dysplasia (FCD) is the most common pathological diagnosis in patients who have undergone surgical treatment for intractable neocortical epilepsy. However, presurgical identification of MRI abnormalities in FCD patients remains difficult, and there are no highly sensitive imaging parameters available that can reliably differentiate among FCD subtypes. The purpose of our study was to investigate the surgical outcome in FCD patients with identifiable MRI abnormalities and to evaluate the prognostic role of the various MRI features and the characteristics of FCD pathology. MethodsWe retrospectively recruited epilepsy patients who had undergone surgical treatment for refractory epilepsy with focal MRI abnormalities and the pathological diagnosis of FCD. We evaluated the surgical outcome according to the pathological subtypes, and studied the prognostic roles of various MRI features. We used recently proposed three-tiered FCD classification system which included FCD type III when FCD occurs in association with other potentially epileptogenic pathologies. ResultsA total of 69 patients were included, and 68.1% of patients became seizure free. Patients with FCD type III had a lower chance for achieving seizure freedom (7/15) than in patients with isolated FCD (FCD types I and II) (40/54, p=0.044). Cortical thickness and blurring of gray–white matter junction were more common in isolated FCD than in FCD type III, but most MRI features failed to differentiate between FCD types I and II, and only the transmantle sign was specific for FCD type II. We failed to find a prognostic value of specific MRI abnormalities of prognostic value in terms of post-epilepsy surgery outcome in FCD patients. ConclusionsOur study showed that patients with FCD III have poor surgical outcome. Typical MRI features of isolated FCD such as cortical thickness and blurring of gray–white matter junction were less common in FCD type III and only transmantle sign was helpful in differentiating between FCD types I and II.

Long‐term seizure outcome and risk factors for recurrence after extratemporal epilepsy surgery

We aimed to assess long-term seizure outcome and risk factors for seizure recurrence in a cohort of patients who have undergone extratemporal resection for management of refractory seizures. Eighty-one patients underwent extratemporal resection at Austin Health, Melbourne, Australia (1991-2004). Seizure recurrence was any postoperative disabling seizure (complex partial seizure [CPS] ± secondary generalization). Multivariate Cox proportional hazards regression models examined potential preoperative and perioperative risk factors and the risk associated with early postoperative seizures (≤ 28 days postsurgery). The change between preoperative and postoperative seizure frequency was also measured. Median follow-up was 10.3 years (range 1-17.7). The probabilities of freedom from disabling seizures (on or off antiepileptic medication) were 40.7% (95% confidence interval [CI] 30-51) at 1 month, 23.5% (95% CI 15-33) at 1 year, and 14.7% (95% CI 8-23) at 5 years postoperative. Reduction of disabling seizures to at least 20% of preoperative frequency was attained by 57% of patients at 5 postoperative years. Of the preoperative/perioperative factors, focal cortical dysplasia (FCD) type 1 (hazard ratio [HR] 1.90, 95% CI 1.08-3.34, p = 0.025) and incomplete resection (HR 1.71, 95% CI 1.06-2.76, p = 0.028) were independent recurrence risks. After surgery, an early postoperative seizure was the only factor associated with higher risk (HR 4.28 [2.42-7.57], p = 0.00). Distinction between subtypes of focal cortical dysplasia, which can be made using magnetic resonance imaging (MRI) criteria, may be useful for preoperative prognostication. Early seizures after surgery are not benign and may be markers of factors that contribute to seizure recurrence. Most patients achieve substantial reduction in seizure frequency. Further study of the significance of this reduction in terms of surgical "success" or otherwise is required.

Neuropathologic measurements in focal cortical dysplasias: validation of the ILAE 2011 classification system and diagnostic implications for MRI

Focal cortical dysplasias (FCD) which represent a composite group of cortical malformations are increasingly recognized as morphological substrate for severe therapy-refractory epilepsy in children and young adults. However, presurgical evaluation remains challenging as not all FCD variants can be reliably detected by high-resolution magnetic resonance imaging (MRI). Here, we studied a cohort of 52 epilepsy patients with neuropathological evidence for FCD using the 2011 classification of the International League against Epilepsy (ILAE) and systematically analysed those histopathologic features applicable also for MRI diagnostics. Histopathologic parameters included quantitative measurements of cellular profiles, cortical thickness, heterotopic neurons in white matter, and myelination that were compared between FCD subtypes and age-/localization-matched controls (n = 36) using multivariate analysis. Dysmorphic neurons in both FCD Type II variants showed significantly increased diameter of their cell bodies and nuclei. Cortical thickness was also increased with a distinct loss of myelin content specifying FCD Type IIb from IIa. The data further suggested that myelination deficits in FCD Type IIb result from compromised oligodendroglial lineage differentiation and we concluded that the "transmantle sign" is a unique finding in FCD Type IIb. In contrast, FCD Type Ia was characterized by a smaller cortical ribbon and higher neuronal densities, but these parameters failed to reach statistical significance (considering age- and location-dependent variability in controls). All FCD variants showed abnormal grey-white matter boundaries with increased numbers of heterotopic neurons. Similar results were obtained also at deep white matter location. Thus, many FCD variants may indeed escape visual MRI inspection, but suspicious areas with increased or decreased cortical thickness as well as grey-white matter blurring may be uncovered using post-processing protocols of neuroimaging data. The systematic analysis of well-specified histopathological features could be helpful to improve sensitivity and specificity in MRI detection during pre-surgical work-up of patients with drug-resistant focal epilepsies.

An international consensus classification for focal cortical dysplasias

The term focal cortical dysplasia (FCD) was introduced for localised malformative brain lesions in patients with epilepsy who have drug-resistant seizures. Such lesions are increasingly recognised using high-resolution MRI. Tailored surgical resections provide favourable seizure control in many patients; however, presurgical identification of clinicopathological FCD variants remains difficult. The International League Against Epilepsy (ILAE) therefore initiated an ad-hoc task force to review published work and to redefine clinicopathological FCD subtypes. 1 Blümcke I Thom M Aronica E et al. The clinicopathologic spectrum of focal cortical dysplasias: a consensus classification proposed by an ad hoc Task Force of the ILAE Diagnostic Methods Commission. Epilepsia. 2010; (published online Nov 10.)https://doi.org/10.1111/j.1528-1167.2010.02777.x Crossref PubMed Scopus (1253) Google Scholar An international consensus classification will help to advance available diagnostic standards and to improve presurgical patient counselling regarding seizure control and therapy management.

MRI characteristics of various pathological subtypes of focal cortical dysplasia

Objective To summarize MRI findings of focal cortical dysplasia (FCD), analyze MRI characteristics of various pathological subtypes of focal cortical dysplasia. Methods Forty-four patients with FCD were collected. Their MRI findings were analyzed retrospectively. According to pathologic findings, these patients were divided into FCD type Ⅰ group and FCD type Ⅱ group. The following MR signs were observed in the two types of FCD: ( 1 ) Focal thickening of the cortex. ( 2 ) Blurring of the gray matter-white matter junction. ( 3 ) Tapering of white matter signal intensity alteration toward the ventricle on FLAIR and on T2WI. (4)Focal brain hypoplasia. (5)Increased signal intensity of gray matter on FLAIR. (6)Increased signal intensity of gray matter on T2 WI. ( 7 ) Increased signal intensity of subcortical white matter on FLAIR.(8) Increased signal intensity of subeortical white matter on T2WI. (9) Decreased signal intensity of subcortical white matter on T1 WI. The χ2 tests and corrected χ2 tests were used for comparison between the two groups. Results In the 44 cases, there were 30 cases with FCD type Ⅰ and 14 cases with FCD type Ⅱ. FCD was identified by MRI in 32 cases. Blurring of the gray-white matter junction is the most common sign of FCD (23 cases). There were 21 cases identified by MRI in FCD type Ⅰ group. Focal brain hypoplasia is a typical sign of FCD type Ⅰ , which was found in 11 cases in FCD type Ⅰ group but none in FCD type Ⅱ group. There was statistically significant difference between the two groups (continuity corrected χ2 =5. 0286,P =0. 0249) . In FCD type Ⅱ group, 11 cases were identified by MRI. Increased cortical thickness was found in 10 eases in FCD type Ⅱ group and 11 cases in FCD type Ⅰ group ( χ2 =4. 6234 ,P =0. 0315). Increased signal intensity of subcortical white matter on FLAIR was found in 9 cases in FCD type Ⅱ group and 7 cases in FCD type Ⅰ group (χ2 =6.9180,P =0.0085). Tapering of white matter signal intensity alteration toward the ventricle was found in 4 cases in FCD type Ⅱ group and none in FCD type Ⅰ group ( continuity corrected χ2 = 6. 2883, P = 0. 0122). The above-mentioned three MRI findings showed statistically significant difference between the two groups and were features of FCD type Ⅱ.All of the other MRI findings showed no statistically significant difference between the two groups. Conclusions Different pathological subtypes of FCD have different MRI characteristics. It is helpful to make preoperative diagnosis and planning. Key words: Cerebral cortex; Nervous system abnormalities; Magnetic resonance imaging

Clinicopathological features and surgical outcomes of intractable epilepsy due to focal cortical dysplasia

Objective To study the correlation with subtypes of focal cortical dysplasia(FCD) and surgical outcomes in patients with intractable epilepsy due to FCD.Method According to Palmini's FCD classification,the clinical,radioiogical and pathological features of 42 intractable epilepsy patients of FCD received surgical treatment were reviewed retrospectively.Results Among 42 epilepsy patients,the FCD lesions were located in 24 temporal lobes,14 frontal lobes,6 parietal lobes,3 occipital lobes,5 multilple lesions.The positive rate of preoperative MRI examination was 62%.The subtypes of FCD were identified as following:FCD type Ⅰ A in 9,FCD type Ⅰ B in 21,FCD type Ⅱ A in 5 and FCD type Ⅱ B in 7,respectively.FCD type Ⅰ B was the predominant pathological subtype and almost located in temporal lobe associated hippocampal sclerosis.The curative rate of FCD surgery in temporal lobe epilepsy group was 67% and that in extratemporal group was 43% (Engle Ⅰ a)during follow -up period (at leastⅠ year).Conclusions FCD is a common cause of intractable epilepsy.The different intrinsic neuropathological characteristics,particularly the potential epileptogenic feature,have significant correlations with clinical findings.Further study should be made between each category with its surgical outcome. Key words: Focal cortical dysplasia; Intractable epilepsy; Pathology; Surgical procedures,operative

Microscopic mild focal cortical dysplasia in temporal lobe dual pathology: An electrocorticography study

Background Associations between electrophysiological and histological findings might provide an insight into the epileptogenicity of mild focal cortical dysplasia (FCD) in patients with temporal lobe epilepsy (TLE) and a dual pathology. Subjects and methods A total of 22 patients with pharmacoresistant TLE were included in the study, 16 of them with histologically confirmed hippocampal sclerosis (HS) associated with neocortical temporal mild Palmini Type-I FCD subtypes and 6 with HS. Intraoperative electrocorticography (ECoG) recordings were analysed for epileptiform discharge frequency and morphology. Associations between histological, and electrocorticography pattern findings in these patients were analysed. Electroclinical outcomes in these patients were also evaluated. Results Neocortical areas with mild Palmini Type-I FCD showed a significantly higher spike frequency (SF) recorded in the inferior temporal gyrus than those neocortical areas in patients with HS. There was a tendency to higher spike frequency and lower amplitude in neocortical areas with histopathologic subtype IB FCD in relation with IA during intraoperative ECoG. Post-SF excision and amplitude were significantly lower during neocortical post-excision intraoperative ECoG than during neocortical pre-excision recording. There was no difference found in the clinical outcome between patients with and without FCD. Conclusions Intraoperative electrocorticographic interictal spike frequency recorded in the neocortical inferior temporal gyrus may help to characterize the histopathologic subtypes of mild Palmini Type-I FCD in patients with temporal lobe epilepsy (TLE) and a dual pathology. Our data support the epileptogenicity of neocortical mild FCD in TLE and assessments of ECoG patterns are relevant to determine the extent of the resection in these patients which can influence the electroclinical outcome.

This week in Neurology

### Predictors of surgical outcome and pathologic considerations in focal cortical dysplasia Although surgical resection has been an important alternative treatment for patients with intractable epilepsy related to focal cortical dysplasia (FCD), the prognostic relevance of the degree of pathologic severity is controversial. This study assesses whether the pathologic subtypes of FCD affect surgical outcomes in patients with drug-resistant epilepsy. The authors also studied the prognostic roles of clinical factors and various diagnostic modalities in the surgical treatment. See p. 211; Editorial, p. 206; see also p. 217 ### Incomplete resection of focal cortical dysplasia is the main predictor of poor postsurgical outcome Focal cortical dysplasia is the most …

MRI Findings and Seizure Outcomes Compared in Focal Cortical Dysplasias Types I and II

Preoperative clinical, neuropsychological, EEG, and imaging features and surgical outcomes of focal cortical dysplasias (FCD) types I and II were compared in 40 children with refractory epilepsy and histopathologically confirmed FCD subtypes, in a study at Charles University, Prague, Czech Republic and centers in Germany.

Predictors of surgical outcome and pathologic considerations in focal cortical dysplasia

Although surgical resection has been an important alternative treatment for patients with intractable epilepsy related to focal cortical dysplasia (FCD), the prognostic relevance of the degree of pathologic severity is controversial and there has been only limited information regarding the prognostic factors involved in the surgical treatment of refractory epilepsy in patients with FCD. We undertook the present study to assess whether the pathologic subtypes of FCD affect surgical outcomes in patients with drug-resistant epilepsy. We also studied the prognostic roles of clinical factors and various diagnostic modalities in the surgical treatment. A total of 166 consecutive patients were included. By univariate analysis, incomplete resection of epileptogenic area (p < 0.001), mild pathologic features (p = 0.01), and the presence of secondary tonic clonic seizures (2GTCS) (p = 0.05) were associated with poor surgical outcomes. There was a strong tendency for patients with severe pathologic features to have MRI abnormalities (p < 0.001). Incomplete resection of epileptogenic area (p < 0.001) and mild pathologic features (p = 0.02) were poor independent outcome predictors on multivariate analysis. The results of MRI, scalp EEG, fluorodeoxyglucose-PET, and ictal SPECT were not associated with surgical outcomes. Our study shows that there is a strong tendency for patients with severe pathologic features to have MRI abnormalities, and patients with incomplete resection, mild pathologic features, or the presence of secondary tonic clonic seizures have a high chance of a poorer surgical outcome.