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Query: UMLS:C0036572 (seizures)
 80,221 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Intravascular lymphomatosis is a rare extra-nodal form of diffuse, large B-cell non-Hodgkin's lymphoma that causes a myriad of neurological symptoms, including focal neurological deficits, cognitive decline, and seizure. Intravascular lymphomatosis is difficult to make ante-mortem diagnosis because of its variable clinical presentation and non-specific laboratory findings. Neuroimaging findings also vary widely in patients of intravascular lymphomatosis. We present, herein, a patient with rapidly deteriorating neurological deficit whose brain MRI revealed rapidly progressing white matter diseases. This patient was diagnosed and treated as having a cerebral demyelinating disorder. Intravascular lymphomatosis involving multiple organs was finally diagnosed after autopsy.
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PMID:Intravascular lymphomatosis mimicks a cerebral demyelinating disorder. 1721 91

The autonomic consequences of seizures can be severe. Death can follow from autonomic overactivity that causes a parasympathetically mediated bradyarrhythmia. We studied the cardiovascular consequences of unilateral and bilateral stimulation of the distal segments of transected vagus nerve in rats anesthetized with urethane. The range of stimulation rates tested is comparable to the firing rates observed in vagus nerve during seizures. There was a consistent inverse relation between stimulus rate and heart rate with nodal block appearing at 5-10 Hz and minimum HR levels (cardiac standstill) occurring at 50 Hz. Cardiac standstill could last many seconds. Blood pressure during VNS was maintained during lower frequency VNS, but collapsed at frequencies > or =20 Hz to dramatically impair ventricular filling. Recovery of heart rate and blood pressure after VNS was rapid. In the presence of sympathetic co-activation (pharmacological or hypercapnia and/or hypoxia), mean arterial pressure was better maintained and there was much better ventricular filling, but cardiac performance was worse (e.g. ejection fraction derived from echocardiography). The combination of sympathetic and parasympathetic overactivity was sometimes associated with prolonged (> or =20 s) apneic periods during VNS. We conclude that an abrupt increase in parasympathetic activity on the order of 5 times the background of parasympathetic tone can produce transient bradyarrhythmias, and increases on the order of 20 times can produce cardiac standstill, sometimes accompanied by apnea. Our findings suggest that parasympathetically mediated bradyarrhythmia must be accompanied by airway obstruction to sustain parasympathetic overactivity and produce hypoxia to ultimately cause death.
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PMID:Vagus nerve stimulation-induced bradyarrhythmias in rats. 1965 41

The human brain is a large-scale integrated network in the functional and structural domain. Graph theoretical analysis provides a novel framework for analysing such complex networks. While previous neuroimaging studies have uncovered abnormalities in several specific brain networks in patients with idiopathic generalized epilepsy characterized by tonic-clonic seizures, little is known about changes in whole-brain functional and structural connectivity networks. Regarding functional and structural connectivity, networks are intimately related and share common small-world topological features. We predict that patients with idiopathic generalized epilepsy would exhibit a decoupling between functional and structural networks. In this study, 26 patients with idiopathic generalized epilepsy characterized by tonic-clonic seizures and 26 age- and sex-matched healthy controls were recruited. Resting-state functional magnetic resonance imaging signal correlations and diffusion tensor image tractography were used to generate functional and structural connectivity networks. Graph theoretical analysis revealed that the patients lost optimal topological organization in both functional and structural connectivity networks. Moreover, the patients showed significant increases in nodal topological characteristics in several cortical and subcortical regions, including mesial frontal cortex, putamen, thalamus and amygdala relative to controls, supporting the hypothesis that regions playing important roles in the pathogenesis of epilepsy may display abnormal hub properties in network analysis. Relative to controls, patients showed further decreases in nodal topological characteristics in areas of the default mode network, such as the posterior cingulate gyrus and inferior temporal gyrus. Most importantly, the degree of coupling between functional and structural connectivity networks was decreased, and exhibited a negative correlation with epilepsy duration in patients. Our findings suggest that the decoupling of functional and structural connectivity may reflect the progress of long-term impairment in idiopathic generalized epilepsy, and may be used as a potential biomarker to detect subtle brain abnormalities in epilepsy. Overall, our results demonstrate for the first time that idiopathic generalized epilepsy is reflected in a disrupted topological organization in large-scale brain functional and structural networks, thus providing valuable information for better understanding the pathophysiological mechanisms of generalized tonic-clonic seizures.
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PMID:Altered functional-structural coupling of large-scale brain networks in idiopathic generalized epilepsy. 2197 88

Benign familial neonatal epilepsy is a neuronal channelopathy most commonly caused by mutations in KCNQ2, which encodes the K(v)7.2 subunit of the slow K(+) channel. K(v)7.2 is expressed in both central and peripheral nervous systems. Seizures occur in the neonatal period, often in clusters within the first few days of life, and usually remit by 12 months of age. The mechanism of involvement of K(v)7.2 mutations in the process of seizure generation has not been established in vivo. In peripheral axons, K(v)7.2 contributes to the nodal slow K(+) current. The present study aimed to determine whether axonal excitability studies could detect changes in peripheral nerve function related to dysfunction or loss of slow potassium channel activity. Nerve excitability studies were performed on eight adults with KCNQ2 mutations and a history of benign familial neonatal epilepsy, now in remission. Studies detected distinctive changes in peripheral nerve, indicating a reduction in slow K(+) current. Specifically, accommodation to long-lasting depolarizing currents was reduced in mutation carriers by 24% compared with normal controls, and the threshold undershoot after 100 ms depolarizing currents was reduced by 22%. Additional changes in excitability included a reduction in the relative refractory period, an increase in superexcitability and a tendency towards reduced sub-excitability. Modelling of the nerve excitability changes suggested that peripheral nerve hyperexcitability may have been ameliorated by upregulation of other potassium channels. We conclude that subclinical dysfunction of K(v)7.2 in peripheral axons can be reliably detected non-invasively in adulthood. Related alterations in neuronal excitability may contribute to epilepsy associated with KCNQ2 mutations.
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PMID:In vivo loss of slow potassium channel activity in individuals with benign familial neonatal epilepsy in remission. 2306 94

The human brain can be modeled as a network, whose structure can be revealed by either anatomical or functional connectivity analyses. Little is known, so far, about the topological features of the large-scale interregional functional covariance network (FCN) in the brain. Further, the relationship between the FCN and the structural covariance network (SCN) has not been characterized yet, in the intact as well as in the diseased brain. Here, we studied 59 patients with idiopathic generalized epilepsy characterized by tonic-clonic seizures and 59 healthy controls. We estimated the FCN and the SCN by measuring amplitude of low-frequency fluctuations (ALFF) and gray matter volume (GMV), respectively, and then we conducted graph theoretical analyses. Our ALFF-based FCN and GMV-based results revealed that the normal human brain is characterized by specific topological properties such as small worldness and highly-connected hub regions. The patients had an altered overall topology compared to the controls, suggesting that epilepsy is primarily a disorder of the cerebral network organization. Further, the patients had altered nodal characteristics in the subcortical and medial temporal regions and default-mode regions, for both the FCN and SCN. Importantly, the correspondence between the FCN and SCN was significantly larger in patients than in the controls. These results support the hypothesis that the SCN reflects shared long-term trophic mechanisms within functionally synchronous systems. They can also provide crucial information for understanding the interactions between the whole-brain network organization and pathology in generalized tonic-clonic seizures.
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PMID:Relationship between large-scale functional and structural covariance networks in idiopathic generalized epilepsy. 2351 Feb 72

Psychogenic non-epileptic seizures (PNES) are paroxysmal behaviors that resemble epileptic seizures but lack abnormal electrical activity. Recent studies suggest aberrant functional connectivity involving specific brain regions in PNES. Little is known, however, about alterations of topological organization of whole-brain functional and structural connectivity networks in PNES. We constructed functional connectivity networks from resting-state functional MRI signal correlations and structural connectivity networks from diffusion tensor imaging tractography in 17 PNES patients and 20 healthy controls. Graph theoretical analysis was employed to compute network properties. Moreover, we investigated the relationship between functional and structural connectivity networks. We found that PNES patients exhibited altered small-worldness in both functional and structural networks and shifted towards a more regular (lattice-like) organization, which could serve as a potential imaging biomarker for PNES. In addition, many regional characteristics were altered in structural connectivity network, involving attention, sensorimotor, subcortical and default-mode networks. These regions with altered nodal characteristics likely reflect disease-specific pathophysiology in PNES. Importantly, the coupling strength of functional-structural connectivity was decreased and exhibited high sensitivity and specificity to differentiate PNES patients from healthy controls, suggesting that the decoupling strength of functional-structural connectivity might be an important characteristic reflecting the mechanisms of PNES. This is the first study to explore the altered topological organization in PNES combining functional and structural connectivity networks, providing a new way to understand the pathophysiological mechanisms of PNES.
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PMID:Altered functional and structural connectivity networks in psychogenic non-epileptic seizures. 2371 98

A 60-year-old male presented with an unexplained seizure whose aetiology could not be demonstrated. After 8 weeks, patient on evaluation for abdominal pain was detected to have primary midgut carcinoid with nodal and hepatic metastasis. Patient underwent cytoreductive surgery and metastatectomy with successful outcome. The case is being presented for its rarity and the need to recognize the paraneoplastic neurological manifestations of these rare neuroendocrine tumors.
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PMID:Primary midgut carcinoid, a rare cause of paraneoplastic limbic encephalitis: a case report. 2470 16

Syncope is a transient loss of consciousness as a result of global cerebral hypoperfusion. It is generally benign but may be a sign of pathology. The purpose of this study was to analyze the frequency of syncope due to cardiac, neurocardiogenic, neurologic, situational, psychiatric, and other causes and make a differential diagnosis of syncope types according to detailed medical history and further investigations. We examined prospectively 268 children presented to pediatric polyclinics as well as cardiology and neurology departments (age range, 1-18 years) with a primary complaint of syncope for the study. Cardiac syncope was diagnosed in 12 patients, neurocardiogenic syncope in 232, neurologic syncope in 9, psychiatric syncope in 9, situational in 4, and benign paroxysmal positional vertigo in 2. The neurologic syncope group consists of patients diagnosed with epilepsy after evaluation. Eight patients in the cardiac syncope group were found to have diseases such as long QT syndrome, and the remaining patients had hypertrophic cardiomyopathy, atrioventricular nodal reentry tachycardia, ventricular tachycardia, and a second-degree heart block that can cause sudden death. In conclusion, syncope is a common problem in childhood that requires hospitalization. Because it may be the first finding of an underlying malignant cardiac or neurologic disease, clinicians must be very careful during medical evaluation. An electrocardiogram and a medical history including the details of the event, chronic diseases, and familial diseases are among the most important steps for the right diagnosis and prognosis. Instead of a routine procedure, further diagnostic workup should be directed according to medical history for high yield. Convulsive movements may be defined in all types of syncope related with cerebral hypoxia, and this may lead to a misdiagnosis of seizure by the clinician.
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PMID:Pediatric syncope: is detailed medical history the key point for differential diagnosis? 2475 88

The seizure focus is the site in the brain from which the seizure originated and is most likely equivalent to the epileptogenic zone, defined as the area of cerebral cortex indispensable for the generation of clinical seizures. The boundaries of this region cannot be defined at present by any diagnostic test. Imaging and EEG recording can define regions of functional deficit during the interictal period, regions that generate interictal spikes, regions responsible for the ictal symptoms, regions from which the seizure is triggered, and regions of structural damage. However, these regions define the epileptogenic zone only when they are spatially concordant. The frequent discrepancies suggest the essential involvement of synaptically connected regions, that is a distributive focus, in the origination of most seizures. Here we review supporting evidence from animal studies and studies of persons undergoing surgical resection for medically-intractable epilepsy. We conclude that very few of the common seizures are truly local, but rather depend on nodal interactions that permit spontaneous network excitability and behavioral expression. Recognition of the distributive focus underlying most seizures has motivated many surgical programs to upgrade their intracranial studies to capture activity in as much of the network as possible.
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PMID:What is a seizure focus? 2501 66

Intravascular lymphoma (IVL) is a rare extra nodal variant of non Hodgkin's lymphoma characterised by neoplastic lymphoid cells growing inside the lumina of medium and small vessels. IVL limited to the central nervous system (CNS) is an extremely rare condition as IVL is usually found with systemic lesions. Most cases of IVL are not diagnosed until post mortem because of variable clinical presentation and non-specific laboratory findings. Even if diagnosed early the disease is clinically aggressive and usually fatal, even with early detection and treatment. We present a case of a 37-year-old woman with a short history of behavioural abnormality, rapidly progressive cognitive decline and seizures. There were no cutaneous manifestations. Diagnosis was established only after the brain biopsy. The case is presented for the rarity of its presentation and role of brain biopsy in diagnosis.
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PMID:Intravascular lymphoma: an unusual cause of rapid cognitive decline and the role of brain biopsy. 2514 97


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