Evaluation of spatial precision and accuracy of cone-beam CT using an in vitro phantom model.

OBJECTIVE: High accuracy and precision are essential in stereotactic neurosurgery, as targeting errors can significantly affect clinical outcomes. Image registration is a vital step in stereotaxis, and understanding the error associated with different image registration methods is important to inform the choice of equipment and techniques in stereotactic neurosurgery. The authors aimed to quantify the test-retest reliability and stereotactic accuracy of cone-beam CT (CBCT) compared with the current clinical gold-standard technique (i.e., CT). METHODS: Two anthropomorphic phantom models with 40 independent unique steel spheres were developed to compare CBCT frame and stereotactic space registration with the clinical gold standard (CT). The cartesian coordinates of each sphere were compared between the imaging modalities for test-retest reliability and overall accuracy. RESULTS: Both imaging modalities showed similar levels of fiducial deviation from the expected geometry. The equivalence test demonstrated mean differences between CT and CBCT registration of -0.082 mm (90% CI -0.27 to 0.11), -0.045 mm (90% CI -0.43 to 0.34), and -0.041 mm (90% CI -0.064 to 0.018) for coordinates in the x-, y-, and z-axes, respectively. The mean euclidean distance difference between the two modalities was 0.28 mm (90% CI 0.27-0.29). CONCLUSIONS: Accuracy and precision were comparable between CBCT and CT image registrations. These findings suggest that CBCT registration can be used as a clinically equivalent substitute to gold-standard CT acquisition.

Temporopolar blurring in temporal lobe epilepsy with hippocampal sclerosis and long-term prognosis after epilepsy surgery.

PURPOSE: We conducted a retrospective study in order to investigate the clinical significance of temporopolar grey/white matter abnormalities (GWMA) in patients with temporal lobe epilepsy (TLE) and unilateral hippocampal sclerosis (HS) with a long post-surgical follow-up. METHODS: The study comprised 122 consecutive patients with medically refractory TLE and unilateral HS who underwent epilepsy surgery and had a minimum postoperative follow-up of 5 years. Patients were divided into two groups, based on findings of pre-surgical MRI: group 1 with GWMA and 2 with normal signal and grey/white matter definition in temporal pole. Demographic and clinical data were reviewed and compared between groups. RESULTS: GWMA were found in 52.5% of patients, always ipsilateral to HS. Compared with group 2, group 1 patients had earlier epilepsy onset (mean, 9.3 vs 14.4 years, P=0.001), a higher occurrence of first seizure ≤2 years of age (25.8% vs 10.5%, P=0.036; OR=2.96 [95% CI=1.07-8.19]), and greater prevalence of left HS (76.6% vs 43.1%, P<0.001; OR=4.31 [95% CI=1.98-9.38]). No differences were found in gender, presence or type of initial precipitating injury, history of secondary generalized seizures, duration of epilepsy, seizure frequency before surgery, neuropsychological evaluation and presence or lateralization of pre-surgical interictal epileptiform discharges. Postoperative follow-up varied from 5 to 11.5 years (mean 7.4) and was similar in both groups (P=0.155). The proportion of patients classified as seizure-free (Engel class I) at last follow-up in groups 1 and 2 were 73.4% and 69%, respectively (P=0.689). Similarly, the percentages of seizure-free patients with no antiepileptic drugs at last evaluation were not different between groups (P=0.817). In logistic regression analysis, left HS (P=0.001; OR=4.166 [95% CI=1.86-9.34]) and age at epilepsy onset ≤2 years (P=0.047; OR=3.885 [95% CI=1.86-17.50]) were independently associated with risk of having GWMA. CONCLUSION: GWMA are frequent findings in patients with TLE and HS, and may help lateralize the epileptogenic zone. Our data support the hypothesis that GWMA are caused by seizure-related insults during the critical period of cerebral myelination. GWMA did not influence the postoperative seizure outcome of patients with TLE and HS, even after an extended duration of post-surgical follow-up.

[Post-operative progress of patients with Rasmussen's encephalitis who have undergone hemispherotomy surgery]. / Evolucion posquirurgica en pacientes con encefalitis de Rasmussen operados por hemisferotomia.

INTRODUCTION: Rasmussen's encephalitis (RE) is a progressive pathology affecting the brain that causes unilateral hemispheric atrophy, neurological dysfunction and refractory epilepsy. Hemispherotomy is considered the most effective treatment today, but some cases present certain peculiarities that can seriously affect the decision to go ahead with this procedure. AIMS: To evaluate the post-operative progress made by children with RE who have undergone hemispherotomy surgery, and who, in the pre-operative assessment, presented certain characteristics that complicated the decision to perform surgery. PATIENTS AND METHODS: The sample selected for study consisted of the cases of RE attended in the Hospital Sao Paulo between 2003 and 2012 who, in the pre-surgery evaluation, presented clinical, electroencephalographic or neuroimaging evidence of involvement of both brain hemispheres, compromise of the dominant brain hemisphere, absence of severe neurological deficit and absence of criteria for refractory epilepsy and atypical crises. The post-operative assessment of the epileptic seizures was evaluated using the Engel scale; motor function was analysed with the Gross Motor Function Classification System and Manual Ability Classification System scales, and language was evaluated clinically. RESULTS: Six cases were selected (four girls), with a mean age at clinical onset of 3.3 ± 1.2 years (range: 2-7 years) and a mean age at hemispherotomy of 6.7 years (range: 2.3-16.5 years). The mean post-surgery follow-up time was three years (range: 0.5-7.2 years). In the post-surgery evaluation of the epileptic seizures, four cases were classified as Engel class I (66%); there was some improvement in motor functioning in five of them, and language improved in all cases. CONCLUSIONS: Hemispherotomy must be considered an efficient option for treatment in children with RE.

Evolución posquirúrgica en pacientes con encefalitis de Rasmussen operados por hemisferotomía / Post-operative progress of patients with Rasmussen’s encephalitis who have undergone hemispherotomy surgery

Introducción. La encefalitis de Rasmussen (ER) es una afección cerebral progresiva que provoca una atrofia hemisférica unilateral, disfunción neurológica y epilepsia refractaria. La hemisferotomía se considera actualmente el tratamiento más efectivo, pero algunos casos presentan particularidades que dificultan la decisión de realizarla. Objetivo. Evaluar la evolución posquirúrgica de niños con ER operados por hemisferotomía, que en la evaluación prequirúrgica presentaron algunas características que dificultaron la decisión quirúrgica. Pacientes y métodos. Se seleccionaron los casos con ER, atendidos en el Hospital São Paulo entre 2003 y 2012, que en la evaluación prequirúrgica presentaran evidencias clínicas, electroencefalográficas o en la neuroimagen de participación de ambos hemisferios cerebrales, afectación del hemisferio cerebral dominante, ausencia de déficit neurológico grave y ausencia de criterios de epilepsia refractaria y crisis atípicas. Para la evaluación posquirúrgica de las crisis epilépticas se utilizó la escala de Engel; para analizar la función motora, las escalas Gross Motor Function Classification System y Manual Ability Classification System, y el lenguaje se evaluó clínicamente. Resultados. Se seleccionaron seis casos (cuatro niñas), con edad media de inicio clínico de 3,3 ± 1,2 años (rango: 2-7 años) y edad media de hemisferotomía de 6,7 años (rango: 2,3-16,5 años). El tiempo medio de seguimiento posquirúrgico fue de tres años (rango: 0,5-7,2 años). En la evaluación posquirúrgica de las crisis epilépticas, cuatro casos se clasificaron como Engel clase I (66%); hubo mejoría en la función motora en cinco, y mejoría en el lenguaje, en todos. Conclusión. La hemisferotomía debe considerarse una opción eficiente de tratamiento en niños con ER (AU)

Introduction. Rasmussen’s encephalitis (RE) is a progressive pathology affecting the brain that causes unilateral hemispheric atrophy, neurological dysfunction and refractory epilepsy. Hemispherotomy is considered the most effective treatment today, but some cases present certain peculiarities that can seriously affect the decision to go ahead with this procedure. Aims. To evaluate the post-operative progress made by children with RE who have undergone hemispherotomy surgery, and who, in the pre-operative assessment, presented certain characteristics that complicated the decision to perform surgery. Patients and methods. The sample selected for study consisted of the cases of RE attended in the Hospital São Paulo between 2003 and 2012 who, in the pre-surgery evaluation, presented clinical, electroencephalographic or neuroimaging evidence of involvement of both brain hemispheres, compromise of the dominant brain hemisphere, absence of severe neurological deficit and absence of criteria for refractory epilepsy and atypical crises. The post-operative assessment of the epileptic seizures was evaluated using the Engel scale; motor function was analysed with the Gross Motor Function Classification System and Manual Ability Classification System scales, and language was evaluated clinically. Results. Six cases were selected (four girls), with a mean age at clinical onset of 3.3 ± 1.2 years (range: 2-7 years) and a mean age at hemispherotomy of 6.7 years (range: 2.3-16.5 years). The mean post-surgery follow-up time was three years (range: 0.5-7.2 years). In the post-surgery evaluation of the epileptic seizures, four cases were classified as Engel class I (66%); there was some improvement in motor functioning in five of them, and language improved in all cases. Conclusions. Hemispherotomy must be considered an efficient option for treatment in children with RE (AU)

Auras in temporal lobe epilepsy with hippocampal sclerosis: relation to seizure focus laterality and post surgical outcome.

We examined the relationship between presence and frequency of different types of auras and side of lesion and post surgical outcomes in 205 patients with medically intractable mesial temporal lobe epilepsy (MTLE) with unilateral hippocampal sclerosis (HS). With respect to the number of auras, multiple auras were not associated with side of lesion (p=0.551). The side of HS was not associated with the type of auras reported. One hundred fifty-seven patients were operated. The occurrence of multiple auras was not associated with post-surgical outcome (p=0.740). The presence of extratemporal auras was significantly higher in patients with poor outcome. In conclusion, this study suggests that the presence of extratemporal auras in patients with MTLE-HS possibly reflects extratemporal epileptogenicity in these patients, who otherwise showed features suggestive of TLE. Therefore, TLE-HS patients undergoing pre-surgical evaluation and presenting clinical symptoms suggestive of extratemporal involvement should be more extensively evaluated to avoid incomplete resection of the epileptogenic zone.

Atypical presentation in Rasmussen encephalitis: delayed late-onset periodic epileptic spasms.

A five-and-a-half-year-old girl started experiencing progressive left hemiparesis at age two and a half years. At age five years and four months she started presenting clusters of asymmetric periodic epileptic spasms with no hypsarrhythmia. The ictal EEG showed periodic, constant and stereotyped complexes. Serial brain imaging revealed progressive atrophy of the right hemisphere with increased T2 signal on MRI. She underwent a right hemispherotomy, and histological examination showed signs of inflammation and features of focal cortical dysplasia (FCD). She has been seizure-free for 16 months. This case is unique in the following aspects: the presence of typical Rasmussen encephalitis features of progressive unilateral brain involvement without seizures, a delay of almost three years prior to seizure onset; an atypical seizure type presentation with periodic epileptic spasms and the presence of FCD associated with inflammatory changes. [Published with video sequences].

Sign of the Cross (Signum Crucis): observation of an uncommon ictal manifestation of mesial temporal lobe epilepsy.

The objective of the study was to describe the clinical characteristics and determine the lateralizing value of ictal Sign of the Cross (SC) as a complex hand automatism (CHA) in patients evaluated by video/EEG monitoring in a comprehensive epilepsy unit. We reviewed video/EEG data of 530 patients with epilepsy recorded in a tertiary epilepsy center from 2002 to 2008. Four patients were found to have manifested a CHA similar to the SC at least once during their complex partial seizures. All patients had unilateral right mesial temporal lobe epilepsy (TLE) refractory to medical treatment. The limbic system is often suggested as the critical site of religious experience. Moreover, it may be localized predominantly to the temporal regions of the right hemisphere. However, this rare and peculiar ictal manifestation may be related not only to the neural substrate and personality characteristics of TLE, but also to the general religious convictions of Brazilians.

Clinical features and surgical outcome of patients with indolent brain tumors and epilepsy

INTRODUCTION: In this study the authors review the outcomes of 22 patients with medically refractory epilepsy and slow growth brain tumors. OBJECTIVES: Evaluate the clinical, electrophysiological, operative, and histopathological features. PATIENTS AND RESULTS: The majority of the tumors were located in the temporal lobe (n = 20) and involved the cortical gray matter. The most frequent tumors were gangliogliomas (n = 9), astrocytomas grade I and II (n = 6), dysembryoplastic neuroepithelial tumors (n = 5) and ganglioneuroma (n = 2). The biological behavior of the tumors was strikingly indolent, as indicated by a long preoperative history of chronic seizures (mean, 14 years). Mean follow-up time after resection was 27 months, and according to EngelÆs classification, 85 percent were seizure-free, 10 percent showed a reduction of seizure frequency of at least 90 percent, and 5 percent had reduction in seizure frequency at least 75 percent. CONCLUSION: The data indicate that neoplasms associated with pharmacoresistent epilepsy constitute a distinct clinicopathological group of tumors that arise in young patients, involve the cortex, and exhibit indolent biological behavior for many years. Complete surgical removal of these tumors, including the epileptogenic area, can achieve excellent seizure control.

INTRODUÇÃO: Neste estudo os autores avaliaram retrospectivamente 22 pacientes tratados cirurgicamente com diagnóstico de epilepsia refratária e tumor cerebral de crescimento lento. OBJETIVOS: Avaliar os aspectos clínicos, eletrofisiológicos, cirúrgicos e histopatológicos. PACIENTES E RESULTADOS: A maioria dos tumores estava localizada no lobo temporal (n = 20) com envolvimento da substância cinzenta. Ganglioglioma foi o tumor mais frequente (n = 9), seguido do astrocitoma grau I e II OMS (n = 6), tumor neuroepitelial disembrioplástico (DNET) (n = 5) e ganglioneuroma (n = 2). O comportamento biológico dos tumores foi estritamente indolente como indicado pela longa história pré-operatória de (média, 14 anos). O tempo de acompanhamento pós-operatório médio foi de 27 meses e de acordo com a Classificacão de Engel, 85 por cento ficaram sem crises (Classe I), 10 por cento obtiveram redução maior de 90 por cento das crises (Classe II), e 5 por cento tiveram redução menor que 75 por cento (Classe III). CONCLUSÃO: Os dados indicam que neoplasias associadas à epilepsia crônica refratária constituem um grupo de tumores com características clinico-patológicas distintas que se iniciam em pacientes jovens, envolvem o córtex e apresentam comportamento biológico indolente. A ressecção cirúrgica completa destes tumores, incluindo a zona epileptogênica, levou ao controle total das crises na maior parte dos casos estudados.

Correlation between temporal pole MRI abnormalities and surface ictal EEG patterns in patients with unilateral mesial temporal lobe epilepsy.

OBJECTIVE: The objective of this retrospective study is to analyze ictal patterns observed during continuous Video-EEG monitoring in patients with temporal lobe epilepsy (TLE) due to unilateral hippocampal sclerosis (HS), and to correlate these EEG patterns to temporal pole abnormalities observed on magnetic resonance imaging exams. METHODS: We analyzed 147 seizures from 35 patients with TLE and unilateral HS. Ictal patterns were classified and correlated to signal abnormalities and volumetric measures of the temporal poles. Volume differences over 10% were considered abnormal. RESULTS: The most frequent type of ictal pattern was rhythmic theta activity (RTA), encountered in 65.5% of the seizures. Rhythmic beta activity (RBA) was observed in 11% of the seizures, localized attenuation in 8%, interruption of epileptiform discharges in 6%, repetitive discharges in 5.5%, and rhythmic delta activity (RDA) in 4%. Sixty-six percent of the patients presented signal abnormalities in the temporal pole that were always ipsilateral to the HS. Sixty percent presented significant asymmetry of the temporal poles consisting of reduced volume that was also always ipsilateral to HS. Although patients with RTA as the predominant ictal pattern tended to present asymmetry of temporal poles (p=0.305), the ictal EEG pattern did not correlate with temporal pole asymmetry or signal abnormalities. CONCLUSIONS: RTA is the most frequent initial ictal pattern in patients with TLE due to unilateral HS. Temporal pole signal changes and volumetric reduction were commonly found in this group of patients, both abnormalities appearing always ipsilateral to the HS. However, neither temporal pole volume reduction nor signal abnormalities correlated with the predominant ictal pattern, suggesting that the temporal poles are not crucially involved in the process of epileptogenesis.

Can intraoperative electrocorticography patterns predict surgical outcome in patients with temporal lobe epilepsy secondary to unilateral mesial temporal sclerosis?

INTRODUCTION: Intraoperative electrocorticography (ECoG) can be performed in cases of temporal lobe epilepsy due to hippocampal sclerosis (TLE-HS). However, its significance and correlation with surgical outcome are still controversial. OBJECTIVES: To analyze the electrophysiological characteristics of temporal lobe structures during ECoG of patients with TLE-HS, with emphasis on the comparison between pre- and post-resection recordings and surgical outcome. PATIENTS AND METHODS: Seventeen patients with refractory TLE-HS submitted to corticoamigdalohipocampectomy were included in the study. Clinical variables included age at the onset, duration of epilepsy and seizure outcome. The post-operative follow-up ranged from 24 to 36 months. According to outcome subjects were divided in two subgroups: (A) individuals free of seizures (Engel 1A), and (B) individuals not-free of seizures (Engel 1B-IV). Four patterns of ECoG findings were identified: isolated discharges; high frequency spikes (HFS); continuous discharges; combination of isolated discharges and HFS. According to predominant topography ECoG was classified as mediobasal, lateral (or neocortical), mediobasal and lateral. RESULTS: The progressive removal of the temporal pole and the hippocampus was associated with significant decrease of neocortical spikes. No correlation between clinical variables and seizure outcome was observed. Patients who only had isolated spikes on intraoperative ECoG presented a statistical trend for excellent surgical control. Patients who presented temporal pole blurring on MRI also had better post-surgical seizure outcome. CONCLUSIONS: This study showed that out of diverse clinical and laboratory variables, only isolated discharges on intraoperative ECoG and temporal pole blurring on MRI predicted excellent post-surgical seizure outcome. However, other studies with larger number of patients are still necessary to confirm these findings.