Frontal lobe epilepsy

About one-quarter of patients with refractory focal epilepsies have frontal lobe epilepsy (FLE). The typical seizure semiology for FLE includes unilateral clonic, tonic asymmetric or hypermotor seizures. Interictal electroencephalograms (EEG) usually reveal interictal epileptiform discharges and rhythmical midline theta, which has localizing value. The usefulness of ictal EEG recordings is limited by frequent muscle artifacts in motor seizures and because a large portion of the frontal lobe cortex is “hidden” to scalp electrodes. Ictal single photon emission CT and positron emission tomography are able to localize FLE in about one-third of patients only. A pre-surgical evaluation should include, whenever possible, a subclassification of FLE as dorsolateral frontal, mesial frontal or basal frontal lobe epilepsy to allow a minimal cortical resection. A review of the typical findings of seizure semiology, interictal and ictal EEG regarding the different FLE subtypes is given. Etiology, medical treatment and surgery are also discussed.     

额叶癫痫

额叶癫痫作为一种特定的癫痫类型,早已为人们所认识。近年国内外相继有关于额叶癫痫的病例报道。在临床工作实践中,额叶癫痫虽不少见,但由于额叶结构及功能的复杂性以及额叶癫痫发作形式的多样性,使其极易被漏诊或误诊。至今人们对该病认识的深度和广度仍嫌不足。本文就额叶癫痫的临床及脑电图表现加以综述。一、额叶癫痫的解剖定位及分型额叶位于大脑前部,包括中央沟以前的全部皮质区。额叶是仅次于颞叶易产生癫痫的第二脑区。目前认为造成额叶癫痫的病因以颅脑创伤、颅内肿瘤、感染、缺氧、脑动-静脉畸形以及皮质发育异常为多见。1989年国…     

Frontal lobe epilepsy.

Frontal lobe epilepsy accounts for only 10-20% of the patients in surgical series, but the incidence in non-surgical patient cohorts seems to be much higher. The typical clinical presentation of the seizures includes contralateral clonic movements, uni- or bilateral tonic motor activity as well as complex automatism. The yield of surface EEG may be limited due to the difficulty in detection of mesial or basal foci, and the patient may be misdiagnosed as having non-epileptic events. In addition, in patients with mesial frontal foci the epileptiform discharges may be mislateralized ("paradoxical lateralization"). Therefore, epilepsy surgery has been commonly considered as less promising in patients with frontal lobe epilepsy. However, the advent of sophisticated neuroimaging techniques, particularly MRI with epilepsy-specific sequences, has made it possible to delineate the epileptogenic lesion and detect a specific etiology, in an increasing number of patients. Thus, the success rate of epilepsy surgery in frontal lobe epilepsy is currently comparable to temporal lobe epilepsy, if the candidates are carefully selected. Patients with frontal lobe epilepsy who do not respond to anticonvulsive medication, and who are not eligible for epilepsy surgery may benefit from alternative approaches such as electrical brain stimulation.     

Frontal lobe function in temporal lobe epilepsy

Temporal lobe epilepsy (TLE) is typically associated with long-term memory dysfunction. The frontal lobes support high-level cognition comprising executive skills and working memory that is vital for daily life functioning. Deficits in these functions have been increasingly reported in TLE. Evidence from both the neuropsychological and neuroimaging literature suggests both executive function and working memory are compromised in the presence of TLE. In relation to executive impairment, particular focus has been paid to set shifting as measured by the Wisconsin Card Sorting Task. Other discrete executive functions such as decision-making and theory of mind also appear vulnerable but have received little attention. With regard to working memory, the medial temporal lobe structures appear have a more critical role, but with emerging evidence of hippocampal dependent and independent processes. The relative role of underlying pathology and seizure spread is likely to have considerable bearing upon the cognitive phenotype and trajectory in TLE. The identification of the nature of frontal lobe dysfunction in TLE thus has important clinical implications for prognosis and surgical management. Longitudinal neuropsychological and neuroimaging studies assessing frontal lobe function in TLE patients pre- and postoperatively will improve our understanding further.     

Frontal lobe epilepsy in childhood

Frontal lobe epilepsy is poorly understood and often unrecognized by health care workers caring for children. We sought to better characterize frontal lobe epilepsy in childhood and help delineate this condition from other nonepileptic events. We reviewed pediatric patients admitted to the Comprehensive Epilepsy Program at the University of Alberta Hospitals with a proven diagnosis of frontal lobe epilepsy. Twenty-two patients, 13 males and 9 females, were studied. Age of onset was variable from 10 months to 16 years (mean 7.5 years). Seizures were brief (30 seconds to 2 minutes), stereotypic, nocturnal (17/21), and frequent (3-22/night). Clinical features included explosive onset, screaming, agitation, stiffening, kicking or bicycling of the legs, and incontinence. The diagnosis of frontal lobe epilepsy was not made in any child before referral. The referring diagnosis was sleep disturbance (10), psychiatric problems (6), or other seizure types (6). Interictal electroencephalogram was usually normal (18/21). Long-term video electroencephalographic monitoring demonstrated frontal (9) or bifrontal (13) epileptic discharges. Magnetic resonance imaging was normal in most patients (18/21). Seizure control was difficult, with only half (11/21) the patients being controlled on medication. Three intractable patients went on to epilepsy surgery and became seizure-free. Frontal lobe epilepsy in childhood is a distinct epilepsy syndrome with characteristic features. The seizures are brief, stereotypic, nocturnal, and frequent. Electroencephalogram and magnetic resonance imaging are usually normal. The condition is often misdiagnosed as a sleep disorder or psychiatric problem. Seizures are difficult to control but may respond to carbamazepine, valproic acid, or epilepsy surgery.     

Frontal lobe dysfunction in children with temporal lobe epilepsy

There is evidence that adults with temporal lobe epilepsy present executive impairments. However, there is limited information in children, especially when using a comprehensive neuropsychologic battery. We aimed to: 1) investigate the presence and severity of executive dysfunctions in children with temporal lobe epilepsy, and 2) determine the implications of clinical variables (including etiology) in the occurrence and severity of executive dysfunction, using eight paradigms. Thirty-one children with temporal lobe epilepsy were evaluated and compared with 21 age-matched controls. Patients with temporal lobe epilepsy had significantly worse performance than controls. Intragroup analysis indicated that patients with symptomatic epilepsy were more impaired than those with cryptogenic epilepsy. In the former group, patients with mesial lesions performed worse than those with lateral lesions. Regarding the severity of executive dysfunction, 83.87% manifested severe to moderate executive impairment. Early age of onset, longer duration of epilepsy, and use of polytherapy were correlated with worse executive dysfunction. These findings indicated the presence of frontal lobe dysfunction in children with temporal lobe epilepsy, with worse performance in those with mesial temporal lobe epilepsy, early onset, longer duration of disease, and use of polytherapy. Our study corroborates the hypothesis that temporal lobe epileptogenic activity affects the extratemporal regions that mediate attentional and executive functions.     

Frontal lobe epilepsy presented as ictal aggression

Abstract Aggressive behaviour is rarely observed as an ictal semiology. Ictal aggression can occur in lesions of frontal and limbic structures. In limbic structure lesions, the main mechanism of aggressive behaviour is hyperactivity; whereas frontal lesions may cause aggressive behaviour with an indirect mechanism in which the suppression on limbic system is lost. Here we present a patient with ictal aggression. In this case a right frontoparietal epileptiform focus was detected during the postictal period. Magnetic resonance imaging showed cortical dysplasia on the right inferior frontal gyrus. The seizures disappeared completely after pharmacological treatment.     

Frontal lobe connectivity and cognitive impairment in pediatric frontal lobe epilepsy

Purpose: Cognitive impairment is frequent in children with frontal lobe epilepsy (FLE), but its etiology is unknown. With functional magnetic resonance imaging (fMRI), we have explored the relationship between brain activation, functional connectivity, and cognitive functioning in a cohort of pediatric patients with FLE and healthy controls. Methods: Thirty‐two children aged 8–13 years with FLE of unknown cause and 41 healthy age‐matched controls underwent neuropsychological assessment and structural and functional brain MRI. We investigated to which extent brain regions activated in response to a working memory task and assessed functional connectivity between distant brain regions. Data of patients were compared to controls, and patients were grouped as cognitively impaired or unimpaired. Key Findings: Children with FLE showed a global decrease in functional brain connectivity compared to healthy controls, whereas brain activation patterns in children with FLE remained relatively intact. Children with FLE complicated by cognitive impairment typically showed a decrease in frontal lobe connectivity. This decreased frontal lobe connectivity comprised both connections within the frontal lobe as well as connections from the frontal lobe to the parietal lobe, temporal lobe, cerebellum, and basal ganglia. Significance: Decreased functional frontal lobe connectivity is associated with cognitive impairment in pediatric FLE. The importance of impairment of functional integrity within the frontal lobe network, as well as its connections to distant areas, provides new insights in the etiology of the broad‐range cognitive impairments in children with FLE.     

额叶离断术治疗无影像学异常的难治性额叶癫痫

目的 探讨额叶离断术治疗无影像学异常的难治性额叶癫痫的可行性、有效性、并发症及适应证.方法 2006年6月至2012年1月解放军第153医院全军神经外科中心对12例无影像学异常的难治性额叶癫痫患者,采用额叶离断术治疗,对手术适应证的选择、手术方法、离断范围、额叶功能区的保护方法、手术效果以及并发症进行总结分析.12例患者中,10例行单纯额叶离断,2例一侧额叶离断后皮质脑电图(ECoG)监测发现离断部位后缘仍有癫痫波,加行胼胝体前部切开术.结果 5例术后出现短暂精神、记忆及性格改变,2例出现一侧肢体轻度偏瘫,均于1个月内恢复正常.无颅内出血、感染及严重并发症.随访1.0～5.5年,Engel Ⅰ级9例,Ⅱ级3例.结论 在术中直接皮层电刺激技术及ECoG监测下,采用额叶离断术治疗无影像学异常的难治性额叶癫痫,是一种安全有效的手术方法.     

Frontal lobe epilepsy may present as myoclonic seizures

We describe a patient with seizures arising from right anterior–inferior frontal lobe presenting as myoclonic epilepsy. A 19-year-old man had experienced frequent paroxysmal bilateral myoclonic jerks involving his upper arms, shoulders, neck, and upper trunk since the age of 10. His baseline EEG showed intermittent right frontal spikes, and his ictal EEG showed rhythmic sharp theta discharges in the same area. MRI revealed cortical dysplasia in the right inferior frontal gyrus, and ictal–interictal SPECT analysis by SPM showed increased signal abnormality in this region. Diffusion tensor imaging (DTI) showed defects in fasciculi in the same area. These findings suggest that frontal lobe epilepsy should be considered in some patients with myoclonic seizures.     

Frontal lobe epilepsy manifesting with seizures consisting of isolated vocalization.

Vocalizations may occur in focal epileptic seizures, which typically arise from frontal and temporal regions. They are commonly associated with other motor phenomena such as automatisms, tonic posturing, or head version. We report on a patient whose seizures were documented by video-EEG monitoring, but in whom the observable ictal semiology consisted solely of a brief, monotonous vocalization. Ictal EEGs showed left frontal seizure patterns. Isolated vocalizations can constitute an ictal epileptic event and may be the only observable clinical manifestation of a left frontal lobe epilepsy. [Published with video sequences].     

Intellectual functioning in children with epilepsy: Frontal lobe epilepsy,childhood absence epilepsy and benign epilepsy with centro-temporal spikes

PurposeThe purpose of our study is to describe intellectual functioning in three common childhood epilepsy syndromes – frontal lobe epilepsy (FLE), childhood absence epilepsy (CAE) and benign epilepsy with centro-temporal spikes (BECTS). And also to determine the influence of epilepsy related variables, type of epilepsy, age at epilepsy onset, duration and frequency of epilepsy, and treatment on the scores.MethodsIntellectual functioning was examined in a group of 90 children with epilepsy (30 FLE, 30 CAE, 30 BECTS), aged 6–15 years, and compared with a control group (30). All subjects obtained a Full Scale IQ ≥ 70 and they were receiving no more than two antiepileptic medications. Participants completed the Wechsler Intelligence Scale for Children – Third Edition. The impact of epilepsy related variables (type of epilepsy, age at epilepsy onset, duration of epilepsy, seizure frequency and anti-epileptic drugs) on intellectual functioning was examined.ResultsChildren with FLE scored significantly worse than controls on WISC-III Verbal IQ, Full Scale IQ and Processing Speed Index. There was a trend for children with FLE to have lower intelligence scores than CAE and BECTS groups. Linear regression analysis showed no effect for age at onset, frequency of seizures and treatment. Type of epilepsy and duration of epilepsy were the best indicators of intellectual functioning.ConclusionIt is crucial that children with FLE and those with a longer active duration of epilepsy are closely monitored to allow the early identification and evaluation of cognitive problems, in order to establish adequate and timely school intervention plans.     

Frontal lobe epilepsy: Clinical characteristics, surgical outcomes and diagnostic modalities.

OBJECTIVE: To identify surgical prognostic factors and to characterize clinical features according to the location of the intracranial ictal onset zone of frontal lobe epilepsy (FLE) in order to assess the role of various diagnostic modalities, including concordances with presurgical evaluations. METHODS: We studied 71 FLE patients who underwent epilepsy surgery and whose outcomes were followed for more than 2 years. Diagnoses were established by standard presurgical evaluation. RESULTS: Clinical manifestations could be categorized into six types: initial focal motor (9 patients), initial versive seizure (15), frontal lobe complex partial seizure (14), complex partial seizure mimicking temporal lobe epilepsy (18), initial tonic elevation of arms (11), and sudden secondary generalized tonic-clonic seizure (4). Thirty-seven patients became seizure-free after surgery. Five patients were deleted in the analysis because of incomplete resection of ictal onset zones. The positive predictive value of interictal EEG, ictal EEG, MRI, PET, and ictal SPECT, respectively were 62.5%, 56.4%, 73.9%, 63.2%, and 63.6%, and the negative predictive value were 46.0%, 44.4%, 53.5%, 44.7%, and 51.7%. No significant relationship was found between the diagnostic accuracy of these modalities and surgical outcome, with the exception of MRI (p=0.029). Significant concordance of two or more modalities was observed in patients who became seizure-free (p=0.011). We could not find any clinical characteristic related to surgical outcome besides seizure frequency. No definite relationship was found between the location of intracranial ictal onset zone and clinical semiology. CONCLUSION: Although various diagnostic methods can be useful in the diagnosis of FLE, only MRI can predict surgical outcome. Concordance between presurgical evaluations indicates a better surgical outcome.     

Frontal lobe tumoral epilepsy: clinical,neurophysiologic features and predictors of surgical outcome

PURPOSE: To review the clinical, neurophysiologic features and surgical outcomes in patients with frontal lobe tumors and chronic intractable seizures. METHODS: Medical records of patients with intractable epilepsy who underwent resection or stereotactic biopsy of frontal lobe tumor (confirmed by surgical pathology) seen between 1985 and 1999 at Yale University School of Medicine Epilepsy Center were reviewed for age at diagnosis, age at onset of seizures, delay between seizure onset and tumor diagnosis, types and frequencies of seizures, EEG results, use of anticonvulsants, extent of surgery, pathological diagnosis, and tumor recurrence. RESULTS: Thirty-seven patients were included. Mean age at seizure onset was 31.6 years, and at tumor diagnosis was 36.2 years. Mean duration between onset of seizures and tumor diagnosis was 6.1 years. Seventeen patients had auras. Seizure frequency averaged 7.6 seizures per week, with 58% of patients having more than one seizure type. All patients used anticonvulsants, with 90% eventually using polytherapy. All patients eventually underwent at least one surgical procedure. Only 13 (35.1%) patients were class I. Twelve (32.4%) patients were class II, seven (18.9%) class III, and five (13.5%) class IV. No statistically significant differences were seen between good and poor long-term seizure outcome in relation to specific tumor pathology, seizure types, or type of resection. CONCLUSIONS: Long-term surgical outcomes in tumoral frontal lobe epilepsy are more favorable than those in nontumoral intractable frontal lobe epilepsy (65% class I or II) and less favorable than those in other tumoral epilepsy (overall, 70% class I). Frontal location of intracranial neoplasm may predict a less favorable long-term epilepsy prognosis than tumoral epilepsy in general, an observation for which several explanations are proposed.     

Serotonergic stimulation of corticotropin-releasing hormone and pro-opiomelanocortin gene expression

The neurotransmitter serotonin (5-HT) stimulates adrenocorticotropic hormone (ACTH) secretion from the anterior pituitary gland via activation of central 5-HT1 and 5-HT2 receptors. The effect of 5-HT is predominantly indirect and may be mediated via release of hypothalamic corticotropin-releasing hormone (CRH). We therefore investigated the possible involvement of CRH in the serotonergic stimulation of ACTH secretion in male rats. Increased neuronal 5-HT content induced by systemic administration of the precursor 5-hydroxytryptophan (5-HTP) in combination with the 5-HT reuptake inhibitor fluoxetine raised CRH mRNA expression in the paraventricular nucleus (PVN) by 64%, increased pro-opiomelanocortin (POMC) mRNA in the anterior pituitary lobe by 17% and stimulated ACTH secretion five-fold. Central administration of 5-HT agonists specific to 5-HT1A, 5-HT1B, 5-HT2A or 5-HT2C receptors increased CRH mRNA in the PVN by 15-50%, POMC mRNA in the anterior pituitary by 15-27% and ACTH secretion three- to five-fold, whereas a specific 5-HT3 agonist had no effect. Systemic administration of a specific anti-CRH antiserum inhibited the ACTH response to 5-HTP and fluoxetine and prevented the 5-HTP and fluoxetine-induced POMC mRNA response in the anterior pituitary lobe. Central or systemic infusion of 5-HT increased ACTH secretion seven- and eight-fold, respectively. Systemic pretreatment with the anti-CRH antiserum reduced the ACTH responses to 5-HT by 80% and 64%, respectively. It is concluded that 5-HT via activation of 5-HT1A, 5-HT2A, 5-HT2C and possibly also 5-HT1B receptors increases the synthesis of CRH in the PVN and POMC in the anterior pituitary lobe, which results in increased ACTH secretion. Furthermore, the results indicate that CRH is an important mediator of the ACTH response to 5-HT.