Painful generalised clonic and tonic-clonic seizures with retained consciousness

Bihemispheric Seizure Without Generalization

A 70-year-old male without prior psychiatric history presented with recurrent episodes (<60 seconds each, every 5-10 minutes) of left hemibody and right lower extremity jerking movements concerning for seizure with preserved awareness (Video). Examination showed left hemiparesis (leg > arm) in addition to right lower extremity weakness. Computed tomography showed a right parafalcine acute subdural hematoma (SDH). Clinical events did not recur after intravenous lorazepam (4 mg) and levetiracetam load (3500 mg), and his weakness improved. He was continued on levetiracetam and has since remained seizure free for 16 months. A 60-minute awake/sleep electroencephalogram (EEG) obtained 12 hours after administration of antiseizure medications showed low amplitude theta slowing (posterior predominant) in the range of 5-7 Hz. There was no apparent epileptiform activity or other abnormalities during the awake and sleep recording or photic stimulation. Focal seizures originate from pathologic disruption of neuronal activity within an isolated brain region, almost exclusively from a single hemisphere. Focal seizures may generalize bilaterally with associated impaired awareness. This is the first visual report demonstrating focal, bihemispheric clinical seizures, without generalization or impaired awareness. Rarely patients with generalized motor involvement from seizures have had retained consciousness and memory. The parafalcine SDH likely promoted epileptogenicity of the bilateral hemispheres. Acute and chronic SDH commonly present with seizures. Although there were no supportive electrographic findings, parasagittal epileptogenic lesions may be difficult for both clinical and electrographic localization. Post-event paresis with clinical improvement in the hours after event cessation supports clinical seizure.

Seizure semiology: ILAE glossary of terms and their significance

This educational topical review and Task Force report aims to address learning objectives of the International League Against Epilepsy (ILAE) curriculum. We sought to extract detailed features involving semiology from video recordings and interpret semiological signs and symptoms that reflect the likely localization for focal seizures in patients with epilepsy. This glossary was developed by a working group of the ILAE Commission on Diagnostic Methods incorporating the EEG Task Force. This paper identifies commonly used terms to describe seizure semiology, provides definitions, signs and symptoms, and summarizes their clinical value in localizing and lateralizing focal seizures based on consensus in the published literature. Video-EEG examples are included to illustrate important features of semiology in patients with epilepsy.

Epilepsia Partialis Continua as an Early Sign of Anti-Myelin Oligodendrocyte Glycoprotein Antibody-positive Encephalitis

Anti-myelin oligodendrocyte glycoprotein (MOG) antibodies have been associated with steroid-responsive cortical encephalitis and comorbid generalized epilepsy. A 44-year-old woman developed repeated epilepsia partialis continua (EPC) without generalized seizures and was anti-MOG antibody-positive. Radiological abnormalities were detected in the bilateral medial frontoparietal cortices, but there were no cerebrospinal fluid abnormalities. She achieved remission with anti-epileptic drugs alone. However, encephalitis recurred four months later when pleocytosis appeared, and steroid therapy was effective. Altogether, EPC without typical cerebrospinal fluid features can be an early sign of anti-MOG antibody-positive encephalitis. Thus, patients with EPC of unknown etiology need to be screened for anti-MOG antibodies.

Absence of an Autonomic Sign Assists in the Diagnosis of Extratemporal Lobe Epilepsy Manifesting Generalized Convulsion with Retained Awareness

We herein report two epilepsy patients with the seizure focus in the non-dominant hemisphere manifesting secondarily generalized convulsion (sGC) with retained awareness characterized by a lack of autonomic signs although GC was complicated by respiratory arrest. Given the semiology and electrophysiological findings, the seizure activity was considered to propagate to the supplementary-motor area and the bilateral primary-motor area, with a clinical manifestation of sGC. The absence of autonomic signs during GC can be a key indicator that the seizure remains in the bilateral suprasylvian area and thus does not involve the region necessary for awareness preservation, which may assist in the diagnosis of this atypical epileptic seizure.

Disrupted Coupling Between the Spontaneous Fluctuation and Functional Connectivity in Idiopathic Generalized Epilepsy

Purpose: The purpose of this study was to comprehensively evaluate alterations of resting-state spontaneous brain activity in patients with idiopathic generalized epilepsy (IGE) and its subgroups [juvenile myoclonic epilepsy (JME) and generalized tonic-clonic seizures (GTCS)]. Methods: Resting state functional magnetic resonance imaging (fMRI) data were acquired from 60 patients with IGE and 60 healthy controls (HCs). Amplitude of low frequency fluctuation (ALFF), global functional connectivity density (gFCD), local FCD (lFCD), and long range FCD (lrFCD) were used to evaluate spontaneous brain activity in the whole brain. Moreover, the coupling between ALFF and FCDs (gFCD, lFCD, and lrFCD) was analyzed on both voxel-wise and subject-wise levels. Two-sample t-tests were used to analyze the difference in ALFF, FCDs and coupling on a subject-wise level between the two groups. Nonparametric permutation tests were used to evaluate differences in coupling on a voxel-wise level. Key findings: Patients with IGE and its subgroups showed reduced ALFF, gFCD and lrFCD in posterior regions of the default mode network (DMN). In addition, decreased ALFF and increased coupling with FCD were found in the cerebellum, while decreased coupling was observed in the bilateral pre- and postcentral gyrus in IGE compared with the coupling in HCs. Similar findings were found in the analysis between each of the two subgroups of IGE (JME and GTCS) and HCs, and JME patients had increased coupling in the cerebellum and bilateral middle occipital gyrus compared with coupling in the GTCS patients. Significance: This study demonstrated a multifactor abnormality of the DMN in IGE and emphasized that the abnormality in the cerebellum was associated with dysfunctional motor symptoms during seizures and might participate in the regulation of GSWDs in IGE.

Influence of calcium channel blockers on anticonvulsant and antinociceptive activities of valproic acid in pentylenetetrazole-kindled mice

BACKGROUND

Comorbidities of epilepsy comprise some pain disorders, including acute nociceptive pain, therefore, antiepileptic drugs can prove efficacy in the management of this kind of pain albeit with several adverse reactions. The current study aimed to evaluate the modulatory effects of calcium channel blockers on the anticonvulsant and antinociceptive effects of valproic acid (VPA) in pentylenetetrazole (PTZ)-kindled mice.

METHODS

Kindled mice were treated with 20 mg/kg (ip) of diltiazem, nifedipine, or verapamil, then VPA(200 mg/kg, ip) at 30 min intervals before PTZ administration (35 mg/kg, ip).

RESULTS

Our data demonstrated that the three calcium channel blockers afforded a protection against sub-convulsive doses of PTZ. Their protective effects were comparable to that exerted by the standard antiepileptic drug, VPA. The anticonvulsant activity of VPA was further enhanced by its combination with diltiazem. Also, PTZ-kindling reduced pain-threshold as evaluated by hot plate analgesimeter and acetic acid-induced writhing test. Although the repeated administration of VPA significantly increased pain-threshold in kindled mice, it was not able to normalize it. Similar results were obtained with diltiazem and nifedipine. Interestingly, combination of diltiazem or nifedipine with VPA elicited the most profound antinociceptive effect in kindled mice.

CONCLUSIONS

These results demonstrate for the first time the beneficial role of some calcium channel blockers in combination with VPA in the management of acute nociceptive pain. Therapeutically, this enhancing profile for calcium channel blockers fosters a safer and more effective drug-combination regimen than valproic acid alone.

Impaired consciousness in epilepsy

Consciousness is essential to normal human life. In epileptic seizures consciousness is often transiently lost, which makes it impossible for the individual to experience or respond. These effects have huge consequences for safety, productivity, emotional health, and quality of life. To prevent impaired consciousness in epilepsy, it is necessary to understand the mechanisms that lead to brain dysfunction during seizures. Normally the consciousness system-a specialised set of cortical-subcortical structures-maintains alertness, attention, and awareness. Advances in neuroimaging, electrophysiology, and prospective behavioural testing have shed light on how epileptic seizures disrupt the consciousness system. Diverse seizure types, including absence, generalised tonic-clonic, and complex partial seizures, converge on the same set of anatomical structures through different mechanisms to disrupt consciousness. Understanding of these mechanisms could lead to improved treatment strategies to prevent impairment of consciousness and improve the quality of life of people with epilepsy.

Epilepsy and the consciousness system: transient vegetative state?

Recent advances have shown much in common between epilepsy and other disorders of consciousness. Behavior in epileptic seizures often resembles a transient vegetative or minimally conscious state. These disorders all converge on the "consciousness system" -the bilateral medial and lateral fronto-parietal association cortex and subcortical arousal systems. Epileptic unconsciousness has enormous clinical significance leading to accidental injuries, decreased work and school productivity, and social stigmatization. Ongoing research to better understand the mechanisms of impaired consciousness in epilepsy, including neuroimaging studies and fundamental animal models, will hopefully soon enable treatment trails to reduce epileptic unconsciousness and improve patient quality of life.

Semiology of epileptic seizures: a critical review

Epileptic seizures are characterized by a variety of symptoms. Their typical semiology served for a long time as the major tool to classify epilepsy syndromes. The signs and symptoms of epileptic seizures include the following spheres: sensorial sphere, consciousness, motor and autonomic spheres. Most seizures involve more than one sphere, however, some like for instance aura (sensorial sphere) or dialeptic seizures (consciousness) involve only one sphere. The predominant clinical features of a seizure determines the seizure classification. The following review gives an introduction into the semiological seizure classification. This approach enables us to better identify the epileptogenic zone of our patients and to choose the most effective medical or surgical treatment.

Cortical and subcortical networks in human secondarily generalized tonic-clonic seizures

Generalized tonic-clonic seizures are among the most dramatic physiological events in the nervous system. The brain regions involved during partial seizures with secondary generalization have not been thoroughly investigated in humans. We used single photon emission computed tomography (SPECT) to image cerebral blood flow (CBF) changes in 59 secondarily generalized seizures from 53 patients. Images were analysed using statistical parametric mapping to detect cortical and subcortical regions most commonly affected in three different time periods: (i) during the partial seizure phase prior to generalization; (ii) during the generalization period; and (iii) post-ictally. We found that in the pre-generalization period, there were focal CBF increases in the temporal lobe on group analysis, reflecting the most common region of partial seizure onset. During generalization, individual patients had focal CBF increases in variable regions of the cerebral cortex. Group analysis during generalization revealed that the most consistent increase occurred in the superior medial cerebellum, thalamus and basal ganglia. Post-ictally, there was a marked progressive CBF increase in the cerebellum which spread to involve the bilateral lateral cerebellar hemispheres, as well as CBF increases in the midbrain and basal ganglia. CBF decreases were seen in the fronto-parietal association cortex, precuneus and cingulate gyrus during and following seizures, similar to the 'default mode' regions reported previously to show decreased activity in seizures and in normal behavioural tasks. Analysis of patient behaviour during and following seizures showed impaired consciousness at the time of SPECT tracer injections. Correlation analysis across patients demonstrated that cerebellar CBF increases were related to increases in the upper brainstem and thalamus, and to decreases in the fronto-parietal association cortex. These results reveal a network of cortical and subcortical structures that are most consistently involved in secondarily generalized tonic-clonic seizures. Abnormal increased activity in subcortical structures (cerebellum, basal ganglia, brainstem and thalamus), along with decreased activity in the association cortex may be crucial for motor manifestations and for impaired consciousness in tonic-clonic seizures. Understanding the networks involved in generalized tonic-clonic seizures can provide insights into mechanisms of behavioural changes, and may elucidate targets for improved therapies.

Theories of impaired consciousness in epilepsy

Although the precise mechanisms for control of consciousness are not fully understood, emerging data show that conscious information processing depends on the activation of certain networks in the brain and that the impairment of consciousness is related to abnormal activity in these systems. Epilepsy can lead to transient impairment of consciousness, providing a window into the mechanisms necessary for normal consciousness. Thus, despite differences in behavioral manifestations, cause, and electrophysiology, generalized tonic-clonic, absence, and partial seizures engage similar anatomical structures and pathways. We review prior concepts of impaired consciousness in epilepsy, focusing especially on temporal lobe complex partial seizures, which are a common and debilitating form of epileptic unconsciousness. We discuss a "network inhibition hypothesis" in which focal temporal lobe seizure activity disrupts normal cortical-subcortical interactions, leading to depressed neocortical function and impaired consciousness. This review of the major prior theories of impaired consciousness in epilepsy allows us to put more recent data into context and to reach a better understanding of the mechanisms important for normal consciousness.

Consciousness and epilepsy: why are patients with absence seizures absent?

Epileptic seizures cause dynamic, reversible changes in brain function and are often associated with loss of consciousness. Of all seizure types, absence seizures lead to the most selective deficits in consciousness, with relatively little motor or other manifestations. Impaired consciousness in absence seizures is not monolithic, but varies in severity between patients and even between episodes in the same patient. In addition, some aspects of consciousness may be more severely involved than other aspects. The mechanisms for this variability are not known. Here we review the literature on human absence seizures and discuss a hypothesis for why effects on consciousness may be variable. Based on behavioral studies, electrophysiology, and recent neuroimaging and molecular investigations, we propose absence seizures impair focal, not generalized brain functions. Impaired consciousness in absence seizures may be caused by focal disruption of information processing in specific corticothalamic networks, while other networks are spared. Deficits in selective and varying cognitive functions may lead to impairment in different aspects of consciousness. Further investigations of the relationship between behavior and altered network function in absence seizures may improve our understanding of both normal and impaired consciousness.

Focal network involvement in generalized seizures: new insights from electroconvulsive therapy

Generalized seizures are commonly thought to involve the entire brain homogeneously. However, recent evidence suggests that selective cortical-subcortical networks may be crucial for the initiation, propagation, and behavioral manifestations of generalized seizures, while other brain regions are relatively spared. Here we review previous studies, and describe a new human model system for the investigation of generalized seizures: single-photon emission computed tomography, ictal-interictal difference imaging of generalized tonic-clonic seizures induced by electroconvulsive therapy (ECT). Bitemporal ECT activates focal bilateral frontotemporal and parietal association cortex, sparing other regions; bifrontal ECT activates mainly prefrontal cortex; while in right unilateral ECT the left frontotemporal region is relatively spared. Associated midline subcortical networks are also involved. Focal verbal memory deficits parallel the focal regions involved in these neuroimaging studies. Further studies of this kind may elucidate specific networks in generalized tonic-clonic seizures, providing targets for new therapeutic interventions in epilepsy.

Why do seizures cause loss of consciousness?

Model systems are needed for the scientific investigation of consciousness. A good model system should include variable states of consciousness, allowing the relationship between brain activity and consciousness to be investigated. Examples include sleep, anesthesia, focal brain lesions, development, evolution, and epilepsy. One advantage of epilepsy is that changes are dynamic and rapidly reversible. The authors review previous investigations of impaired consciousness in epilepsy and describe new findings that may shed light on both normal and abnormal mechanisms of consciousness. Abnormal increased activity in fronto-parietal association cortex and related subcortical structures is associated with loss of consciousness in generalized seizures. Abnormal decreased activity in these same networks may cause loss of consciousness in complex partial seizures. Thus, abnormally increased or decreased activity in the same networks can cause loss of consciousness. Information flow during normal conscious processing may require a dynamic balance between these two extremes of excitation and inhibition.