Epilepsy Functional Neuroanatomy

Modern neuroscience agrees that neurological processing emerges from the multimodal interaction among multiple cortical and subcortical neuronal hubs, connected at short and long distance by white matter, to form a largely integrated and dynamic network, called the brain "connectome." The final architecture of these circuits results from a complex, continuous, and highly protracted development process of several axonal pathways that constitute the anatomical substrate of neuronal interactions. Awareness of the network organization of the central nervous system is crucial not only to understand the basis of children's neurological development, but also it may be of special interest to improve the quality of neurosurgical treatments of many pediatric diseases...

The corpus callosum is the largest axonal tract in the human brain, connecting the left and right cortical hemipheres. This structure is affected in myriad human neurodevelopmental disorders, and can be entirely absent as a result of congenital or surgical causes. The age when callosal loss occurs, for example via surgical section in cases of refractory epilepsy, correlates with resulting brain morphology and neuropsychological outcomes, whereby an earlier loss generally produces relatively improved interhemispheric connectivity compared to a loss in adulthood (known as the "Sperry's paradox")...

The classic brain criticality hypothesis postulates that the brain benefits from operating near a continuous second-order phase transition. Slow feedback regulation of neuronal activity could, however, lead to a discontinuous first-order transition and thereby bistable activity. Observations of bistability in awake brain activity have nonetheless remained scarce and its functional significance unclear. Moreover, there is no empirical evidence to support the hypothesis that the human brain could flexibly operate near either a first- or second-order phase transition despite such a continuum being common in models...

BACKGROUND AND OBJECTIVE: Epilepsy is a common chronic brain disease. Despite the availability of various anti-seizure drugs, approximately 30% of patients do not respond to treatment. Recent research suggests that Kalirin plays a role in regulating neurological function. However, the pathogenesis of Kalirin in epileptic seizures remains unclear. This study aims to investigate the role and mechanism of Kalirin in epileptogenesis. MATERIALS AND METHODS: An epileptic model was induced by intraperitoneal injection of pentylenetetrazole (PTZ)...

OBJECTIVE: People with epilepsy are at an increased risk of experiencing executive dysfunction, particularly those with frontal lobe epilepsy (FLE). The literature has also demonstrated alterations in executive functioning (EF) in patients with temporal lobe epilepsy (TLE). However, few studies have examined the neuropsychological profile of posterior cortex epilepsy (PCE), and little attention has been given to cognitive impairments in the pediatric population with PCE. This study aims to investigate EF performance in children with drug-resistant PCE compared to patients with FLE and TLE...

The human brain is the most complex structure generated during development. Unveiling the ontogenesis and the intrinsic organization of specific neural networks may represent a key to understanding the physio-pathological aspects of different brain areas. The cortico-thalamic and thalamo-cortical (CT-TC) circuits process and modulate essential tasks such as wakefulness, sleep and memory, and their alterations may result in neurodevelopmental and psychiatric disorders. These pathologies are reported to affect specific neural populations but may also broadly alter physiological connections and thus dysregulate brain network generation, communication, and function...

Refractory subhemispheric epilepsy has been traditionally treated by resection. The last few decades have seen the emergence of disconnective techniques, for both hemispheric and subhemispheric disease. The aim of this study was to describe the technique for a disconnective surgery for large epileptogenic lesions involving the central (perirolandic cortices), parietal, and occipital lobes. This junctional cortex within the hemisphere (in contrast to anterior and posterior quadrantotomies) presents unique challenges when contemplating a complete disconnection of the region...

Electrical stimulation of the cervical vagus nerve using implanted electrodes (VNS) is FDA-approved for the treatment of drug-resistant epilepsy, treatment-resistant depression, and most recently, chronic ischemic stroke rehabilitation. However, VNS is critically limited by the unwanted stimulation of nearby neck muscles - a result of non-specific stimulation activating motor nerve fibers within the vagus. Prior studies suggested that precise placement of small epineural electrodes can modify VNS therapeutic effects, such as cardiac responses...

Vagus nerve stimulation (VNS) often results in off-target effects due to the unknown fascicular organisation of the cervical vagus nerve and thus nonspecific nature of stimulation. This currently limits its therapeutic efficacy in treating epilepsy and depression and restricts its extension to treating numerous other conditions, such as heart failure and lung injury, for which it could be a promising treatment. The purpose of this work was to determine the fascicular anatomical representation of the recurrent laryngeal, cardiac and pulmonary branches of the vagus nerve at the mid-cervical level of VNS cuff placement in the vagus nerve in pigs using micro-computed tomography (microCT) to trace anatomical connections to end-organs with the intention of extension to humans...

OBJECTIVE: This study was undertaken to determine whether undiagnosed illness duration (time between functional seizures [FS] onset and diagnosis) is linked to differences in neural response and functional connectivity during processing of stressful experiences. METHODS: Forty-nine participants with traumatic brain injury preceding the onset of FS confirmed by video-electroencephalography were recruited prospectively. Participants completed psychiatric symptom assessments before undergoing functional magnetic resonance imaging (fMRI) with an acute psychosocial stress task...

Alzheimer's disease (AD) is the most common neurodegenerative disease which affects more than 40 million people worldwide with progressive loss of memory and cognitive functions. It is reported, persistent AD is also one of the main causes of epilepsy in elders and comorbidity of both these will contribute to worsening the health status of AD patients. Recently, herbal plants with potent neuroprotective and antioxidant properties were used for increasing the quality of life in neurodegenerative disease patients...

Epilepsy is a chronic seizure disorder that affects about 1% of the global population.1 When seizure freedom cannot be obtained solely through antiseizure medicines (ASMs), the condition is termed medically refractory epilepsy (MRE).2,3 Though posterior quadrant disconnection (PQD) is underutilized in our experience, it is a highly effective surgical procedure for MRE restricted to the temporal, parietal, and/or occipital lobes.4-12 In this operative video, we demonstrate a right-sided completion PQD following failed temporal lobectomy in an 8-yr-old female with focal MRE...

Genetic generalized epilepsy is a network disorder typically involving distributed areas identified by classical neuroanatomy. However, the finer topological relationships in terms of continuous spatial arrangement between these systems are still ambiguous. Connectome gradients provide the topological representations of human macroscale hierarchy in an abstract low-dimensional space by embedding the functional connectome into a set of axes. Leveraging connectome gradients, we systematically scrutinized abnormalities of functional connectome gradient in patients with genetic generalized epilepsy with tonic-clonic seizure (GGE-GTCS, n = 78) compared to healthy controls (HC, n = 85), and further examined the reproducibility across multiple processing configurations and in an independent validation sample (patients with GGE-GTCS, n = 28; HC, n = 31)...

The amygdaloid body is a limbic nuclear complex characterized by connections with the thalamus, the brainstem and the neocortex. The recent advances in functional neurosurgery regarding the treatment of refractory epilepsy and several neuropsychiatric disorders renewed the interest in the study of its functional Neuroanatomy. In this scenario, we felt that a morphological study focused on the amygdaloid body and its connections could improve the understanding of the possible  implications in functional neurosurgery...

Despite technological and interpretative advances, the non-invasive modalities used for pre-surgical evaluation of patients with drug-resistant epilepsy (DRE), fail to generate a concordant anatomo-electroclinical hypothesis for the location of the seizure onset zone in many patients. This requires chronic monitoring with intracranial electroencephalography (EEG), which facilitates better localization of the seizure onset zone, and allows evaluation of the functional significance of cortical regions-of-interest by electrical stimulation mapping (ESM)...

The most common approaches in the treatment of epilepsy, the trans-sylvian selective amygdalohippocampectomy (SAH) and the anterior temporal lobe resection (ATLR) reach the medial temporal lobe through different surgical routes. Our aim was to delineate the white matter (WM) fiber tracts at risk in relation to trans-sylvian SAH and ATLR by defining each fascicle en route to medial temporal lobe during each approach. ATLR and trans-sylvian SAH were performedand related WM tracts en route to medial temporal region were presented in relation to the relevant approaches and surrounding neurovascular structures...

OBJECTIVE. Functional MRI (fMRI) is clinically used for localization of eloquent cortex before surgical intervention, most commonly motor and language function in patients with tumors or epilepsy. In the pediatric population, special considerations for fMRI relate to limited examination tolerance, small head size, developing anatomy and physiology, and diverse potential abnormalities. In this article, we will highlight pearls and pitfalls of clinical pediatric fMRI including blood oxygenation level-dependent imaging principles, patient preparation, study acquisition, data postprocessing, and examination interpretation...

Intra-cranial electroencephalographic brain recordings (iEEG) provide a powerful tool for investigating the neural processes supporting episodic memory encoding and form the basis of experimental therapies aimed at improving memory dysfunction. However, given the invasiveness of iEEG, investigations are constrained to patients with drug-resistant epilepsy for whom such recordings are clinically indicated. Particularly in the case of temporal lobe epilepsy (TLE), neuropathology and the possibility of functional reorganization are potential constraints on the generalizability of intra-cerebral findings and pose challenges to the development of therapies for memory disorders stemming from other etiologies...

Careful study of the clinical outcomes of temporal lobe epilepsy (TLE) surgery has greatly advanced our knowledge of the neuroanatomy of human memory. After early cases resulted in profound amnesia, the critical role of the hippocampus and associated medial temporal lobe (MTL) structures to declarative memory became evident. Surgical approaches quickly changed to become unilateral and later, to be more precise, potentially reducing cognitive morbidity. Neuropsychological studies following unilateral temporal lobe resection (TLR) have challenged early models, which simplified the lateralization of verbal and visual memory function...

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