Plasma concentrations of prolactin, noradrenaline, vasopressin and oxytocin during and after a prolonged epileptic seizure

Therapeutic potential of vasopressin in the treatment of neurological disorders

Vasopressin (VP) is a nonapeptide made of nine amino acids synthesized by the hypothalamus and released by the pituitary gland. VP acts as a neurohormone, neuropeptide and neuromodulator and plays an important role in the regulation of water balance, osmolarity, blood pressure, body temperature, stress response, emotional challenges, etc. Traditionally VP is known to regulate the osmolarity and tonicity. VP and its receptors are widely expressed in the various region of the brain including cortex, hippocampus, basal forebrain, amygdala, etc. VP has been shown to modulate the behavior, stress response, circadian rhythm, cerebral blood flow, learning and memory, etc. The potential role of VP in the regulation of these neurological functions have suggested the therapeutic importance of VP and its analogues in the management of neurological disorders. Further, different VP analogues have been developed across the world with different pharmacotherapeutic potential. In the present work authors highlighted the therapeutic potential of VP and its analogues in the treatment and management of various neurological disorders.

Hiding in plain sight? A review of post-convulsive leukocyte elevations

During physiological stress responses such as vigorous exercise, emotional states of fear and rage, and asphyxia, the nervous system induces a massive release of systemic catecholamines that prepares the body for survival by increasing cardiac output and redirecting blood flow from non-essential organs into the cardiopulmonary circulation. A curious byproduct of this vital response is a sudden, transient, and redistributive leukocytosis provoked mostly by the resultant shear forces exerted by rapid blood flow on marginated leukocytes. Generalized convulsive seizures, too, result in catecholamine surges accompanied by similar leukocytoses, the magnitude of which appears to be rooted in semiological factors such as convulsive duration and intensity. This manuscript reviews the history, kinetics, physiology, and clinical significance of post-convulsive leukocyte elevations and discusses their clinical utility, including a proposed role in the scientific investigation of sudden unexpected death in epilepsy (SUDEP).

Differentiation of psychogenic nonepileptic attacks from status epilepticus among patients intubated for convulsive activity

BACKGROUND AND OBJECTIVE

Patients with psychogenic nonepileptic attacks (PNEA) sometimes receive aggressive treatment leading to intubation. This study aimed to identify patient characteristics that can help differentiate PNEA from status epilepticus (SE).

METHODS

We retrospectively identified patients with a final diagnosis of PNEA or SE, who were intubated for emergent convulsive symptoms and underwent continuous electroencephalography (cEEG) between 2012 and 2017. Patients who had acute brain injury or progressive brain disease as the cause of SE were excluded. We compared clinical features and laboratory values between the two groups, and identified risk factors for PNEA-related convulsive activity.

RESULTS

Over a six-year period, 24 of 148 consecutive patients (16%) intubated for convulsive activity had a final diagnosis of PNEA rather than SE. Compared to patients intubated for SE, intubated PNEA patients more likely were <50 years of age, female, white, had a history of a psychiatric disorder, had no history of an intracranial abnormality, and had a maximum systolic blood pressure <140 mm Hg (all P < 0.001). Patients with 0-2 of these six risk factors had a 0% (0/88) likelihood of having PNEA, those with 3-4 had a 15% (6/39) chance of having PNEA, and those with 5-6 had an 86% (18/21) chance of having PNEA. Sensitivity for PNEA among those with 5-6 risk factors was 75% (95% CI: 53-89%) and specificity was 98% (95% CI: 93-99%).

CONCLUSIONS

In the absence of a clear precipitating brain injury, approximately one in six patients intubated for emergent convulsive symptoms had PNEA rather than SE. Although PNEA cannot be diagnosed only by the presence of these risk factors, these simple characteristics could raise clinical suspicion for PNEA in the appropriate setting. Urgent neurological consultation may prevent unnecessary intubation of this at-risk patient population.

Takotsubo Syndrome: Clinical Manifestations, Etiology and Pathogenesis

The purpose of the review is the analysis of clinical and experimental data on the etiology and pathogenesis of takotsubo syndrome (TS). TS is characterized by contractile dysfunction, which usually affects the apical region of the heart without obstruction of coronary artery, moderate increase in myocardial necrosis markers, prolonged QTc interval (in 50% of patients), sometimes elevation of ST segment (in 19% of patients), increase N-Terminal Pro-B-Type Natriuretic Peptide level, microvascular dysfunction, sometimes spasm of the epicardial coronary arteries (in 10% of patients), myocardial edema, and life-threatening ventricular arrhythmias (in 11% of patients). Stress cardiomyopathy is a rare disease, it is observed in 0.6 - 2.5% of patients with acute coronary syndrome. The occurrence of takotsubo syndrome is 9 times higher in women, who are aged 60-70 years old, than in men. The hospital mortality among patients with TS corresponds to 3.5% - 12%. Physical or emotional stress do not precede disease in all patients with TS. Most of patients with TS have neurological or mental illnesses. The level of catecholamines is increased in patients with TS, therefore, the occurrence of TS is associated with excessive activation of the adrenergic system. The negative inotropic effect of catecholamines is associated with the activation of β2 adrenergic receptors. An important role of the adrenergic system in the pathogenesis of TS is confirmed by studies which were performed using 125I-metaiodobenzylguanidine (125I -MIBG). TS causes edema and inflammation of the myocardium. The inflammatory response in TS is systemic. TS causes impaired coronary microcirculation and reduces coronary reserve. There is a reason to believe that an increase in blood viscosity may play an important role in the pathogenesis of microcirculatory dysfunction in patients with TS. Epicardial coronary artery spasm is not obligatory for the occurrence of TS. Cortisol, endothelin-1 and microRNAs are challengers for the role of TS triggers. A decrease in estrogen levels is a factor contributing to the onset of TS. The central nervous system appears to play an important role in the pathogenesis of TS.

[Clinical Manifestation of Stressful Cardiomyopathy (Takotsubo Syndrome) and the Problem of Differential Diagnosis with Acute Myocardial Infarction]

The presented data show that tacotsubo syndrome (TS) is characterized by the absence of coronary artery obstruction, cardiac contractile dysfunction, apical ballooning, and heart failure, and in some patients, ST-segment elevation and prolongation of the QTc interval. Every tenth patient with TS develops ventricular arrhythmias. Most of TS patients have elevated markers of necrosis (troponin I, troponin Т, and creatine kinase МВ (CK-МВ), which are considerably lower than in patients with acute myocardial infarction (AMI) with ST-segment elevation. The level of N-terminal pro-B-type natriuretic peptide (NT-proBNP), in contrast, is considerably higher in patients with TS than with AMI. Differential diagnosis of TS and AMI should be based on a multifaceted approach using coronary angiography, echocardiography, analysis of ECG, magnetic resonance imaging, single-photon emission computed tomography, and measurement of troponins, CK-MB, and NT-proBNP.

How does ECT work? A new explanatory model and suggestions for non-convulsive applications

In this article a new hypothesis is presented concerning the causal mechanism underlying electroconvulsive therapy (ECT). According to this model the antidepressant effect is caused by a change in sleep architecture triggered by the ictal events induced by ECT. This change in sleep architecture - a profound change in the neurophysiological and neurochemical state of the organism - is what causes the therapeutic effects of ECT and not any simple change in the release of neurotransmitters, neurotrophic factors and/or hormones. This realization also means that a comparable antidepressant effect could be achieved without the need of inducing seizures, but with the help of behavioral interventions that explicitly take aim at changing sleep architecture. The article presents and discusses evidence in favor of this thesis and also puts forth two simple, non-convulsive, applications of the theory.

Audiogenic kindling activates expression of vasopressin in the hypothalamus of Krushinsky-Molodkina rats genetically prone to reflex epilepsy

The present study analysed the effects of audiogenic kindling on the functional state of the vasopressinergic system of Krushinsky-Molodkina (KM) rats. KM rats represent a genetic model of audiogenic reflex epilepsy. Multiple audiogenic seizures in KM rats lead to the involvement of the limbic structures and neocortex in the epileptic network. The phenomenon of epileptic activity that overspreads from the brain stem to the forebrain is called audiogenic kindling and represents a model of limbic epilepsy. In the present study, audiogenic kindling was induced by 25 repetitive audiogenic seizures (AGS) with 1 AGS per day. A proportion of KM rats did not express AGS to sound stimuli, and these rats were characterised as the AGS-resistant group. The data demonstrated that audiogenic kindling did not change activity of extracellular signal-regulated kinase 1/2 or cAMP response element-binding protein, although it led to an increase in vasopressin (VP) expression in the supraoptic nucleus (SON) and in the magnocellular division of the paraventricular nucleus (PVN). Additionally, we observed a decrease in GABAergic innervation of the hypothalamic neuroendocrine neurones after audiogenic kindling, whereas glutamatergic innervation of the SON and PVN was not altered. By contrast, analysis of AGS-resistant KM rats did not reveal any changes in the activity of the VP-ergic system, confirming that the activation of VP expression was caused by repetitive AGS expression, rather than by repetitive acoustic stress. Thus, we suggest that overspread of epileptiform activity in the brain is the main factor that affects VP expression in the hypothalamic magnocellular neurones.

The Magnitude of Postconvulsive Leukocytosis Mirrors the Severity of Periconvulsive Respiratory Compromise: A Single Center Retrospective Study

Background: Generalized epileptic convulsions frequently exhibit transient respiratory symptoms and non-infectious leukocytosis. While these peri-ictal effects appear to arise independently from one another, the possibility that they stem from a common ictal pathophysiological response has yet to be explored. We aimed to investigate whether peri-ictal respiratory symptoms and postictal leukocytosis coexist.

Methods: We performed a single center retrospective chart review of 446 patients brought to our emergency department between January 1, 2017 and August 23, 2018 for the care of generalized epileptic convulsions with or without status epilepticus. We included 152 patients who were stratified based on the presence (PeCRC+) or absence (PeCRC–) of overt periconvulsive respiratory compromise (PeCRC). In addition, patients were stratified based on the presence or absence of postconvulsive leukocytosis (PoCL), defined as an initial postconvulsive white blood cell (WBC) count ≥ 11,000 cells/mm³. Triage vital signs, and chest x ray (CXR) abnormalities were also examined.

Results: Overt PeCRC was observed in 31.6% of patients, 43% of whom required emergent endotracheal intubations. PoCL was observed in 37.5% of patients, and was more likely to occur in PeCRC+ than in PeCRC– patients (79.2 vs. 18.2%; OR = 17.0; 95% CI = 7.2–40.9; p < 0.001). Notably, the magnitude of PoCL was proportional to the severity of PeCRC, as the postconvulsive WBC count demonstrated a negative correlation with triage hemoglobin oxygen saturation (R = −0.22; p < 0.01; CI = −0.48 to −0.07). Moreover, a receiver operating characteristic analysis of the WBC count's performance as predictor of endotracheal intubation reached a significant area under the curve value of 0.81 (95% CI = 0.71–0.90; p < 0.001). Finally, PeCRC+ patients demonstrated frequent CXR abnormalities, and their postconvulsive WBC counts correlated directly with triage heart rate (R = 0.53; p < 0.001).

Conclusion: Our data support the existence of an ictal pathophysiological response, which induces proportional degrees of PoCL and PeCRC. We suggest this response is at least partially propelled by systemic catecholamines.

Artificial intelligence as an emerging technology in the current care of neurological disorders

BACKGROUND

Artificial intelligence (AI) has influenced all aspects of human life and neurology is no exception to this growing trend. The aim of this paper is to guide medical practitioners on the relevant aspects of artificial intelligence, i.e., machine learning, and deep learning, to review the development of technological advancement equipped with AI, and to elucidate how machine learning can revolutionize the management of neurological diseases. This review focuses on unsupervised aspects of machine learning, and how these aspects could be applied to precision neurology to improve patient outcomes. We have mentioned various forms of available AI, prior research, outcomes, benefits and limitations of AI, effective accessibility and future of AI, keeping the current burden of neurological disorders in mind.

DISCUSSION

The smart device system to monitor tremors and to recognize its phenotypes for better outcomes of deep brain stimulation, applications evaluating fine motor functions, AI integrated electroencephalogram learning to diagnose epilepsy and psychological non-epileptic seizure, predict outcome of seizure surgeries, recognize patterns of autonomic instability to prevent sudden unexpected death in epilepsy (SUDEP), identify the pattern of complex algorithm in neuroimaging classifying cognitive impairment, differentiating and classifying concussion phenotypes, smartwatches monitoring atrial fibrillation to prevent strokes, and prediction of prognosis in dementia are unique examples of experimental utilizations of AI in the field of neurology. Though there are obvious limitations of AI, the general consensus among several nationwide studies is that this new technology has the ability to improve the prognosis of neurological disorders and as a result should become a staple in the medical community.

CONCLUSION

AI not only helps to analyze medical data in disease prevention, diagnosis, patient monitoring, and development of new protocols, but can also assist clinicians in dealing with voluminous data in a more accurate and efficient manner.

Effect of monoamine reuptake inhibition and α1 blockade on respiratory arrest and death following electroshock-induced seizures in mice

OBJECTIVE

Sudden unexpected death in epilepsy (SUDEP) is the leading cause of death in patients with refractory epilepsy. Although the mechanisms for SUDEP are incompletely understood, seizure-induced respiratory arrest (S-IRA) has been strongly and consistently implicated. A body of evidence indicates that serotonin (5-HT), a modulator of breathing, plays a critical role in SUDEP. Because the 5-HT and norepinephrine (NE) systems interact in many biologic processes and NE is known to modulate breathing and seizures, we hypothesized that NE may play a role in S-IRA and SUDEP.

METHODS

We examined the effects of pharmacologic manipulation of 5-HT and NE on S-IRA and death following maximal electroshock (MES)-induced seizures in adult wild-type (WT) mice, genetically 5-HT neuron-deficient (Lmx1bf/f/p ) mice, and chemically NE neuron-deficient mice. Mice were treated with pharmacologic agents targeting the serotonergic and noradrenergic systems and subjected to seizure induction via MES while breathing was measured via whole-body plethysmography.

RESULTS

S-IRA and death was reduced in WT mice with NE reuptake inhibitors (NRIs), reboxetine and atomoxetine, selective serotonin reuptake inhibitors (SSRIs), fluoxetine and citalopram, and the dual 5-HT/NE reuptake inhibitor (SNRI), duloxetine. S-IRA and death was also reduced in Lmx1bf/f/p mice with reboxetine and fluoxetine. The protective effects of the reuptake inhibitors were prevented by the α1 antagonist, prazosin. Citalopram did not reduce S-IRA and death in NE neuron-deficient mice.

SIGNIFICANCE

These data suggest that 5-HT and NE critically interact in the modulation of breathing following a seizure and potentially inform preventive strategies for SUDEP.

Closed-loop Neuropharmacology for Epilepsy: Distant Dream or Future Reality?

Epilepsy is considered the most frequent severe neurological condition but most patients treated with medication become seizure free. The management of treatment, however, is highly empirical, mainly relying on observation. A closed-loop therapy for epilepsy would be very valuable for more efficient treatment regimens. Here we discuss monitoring treatment (therapeutic drug monitoring) and the potential developments in this field, as well as providing a review of potential biomarkers that could be used to monitor the disease activity. Finally, we consider the pharmacogenetic input in epilepsy treatment.

Immediate versus delayed detection of Takotsubo syndrome after epileptic seizures

Takotsubo syndrome(TTS) is often preceded by emotional or physical stress. Epileptic seizures are described in >100 cases. It is unknown whether patients with immediate and delayed detection of seizure-induced TTS differ. We screened the literature and compared clinical and electrocardiographic (ECG) findings. In 48 cases with seizure-associated TTS, the time between seizure and TTS-detection was reported. Troponin levels were elevated in 37/40. ECG abnormalities were negative T-waves(40%), ST-elevations(33%) and ventricular fibrillation/flutter(10%). Immediate detection was reported in 23 patients, in the remaining 25 patients, TTS was detected 5-288 h postictally. Patients did not differ in gender, age or symptoms. Negative T-waves were more frequent in patients with delayed detection(64 vs. 13%, p = .0009), whereas ECG-abnormalities suggesting acute myocardial infarction tended to be more prevalent in patients with immediate detection. Due to lack of typical symptoms, seizure-induced TTS can be overlooked. Postictally, an ECG should be recorded and troponin levels measured. New T-wave inversions might indicate seizure-induced TTS.

Epilepsy is associated with ventricular alterations following convulsive status epilepticus in children

Objective

Convulsive status epilepticus can exert profound cardiovascular effects in adults, including ventricular depolarization–repolarization abnormalities. Whether status epilepticus adversely affects ventricular electrical properties in children is less understood. Therefore, we sought to characterize ventricular alterations and the associated clinical factors in children following convulsive status epilepticus.

Methods

We conducted a 2‐year retrospective case–control study. Children between 1 month and 21 years of age were included if they were admitted to the pediatric intensive care unit with primary diagnosis of convulsive status epilepticus and had 12‐lead electrocardiogram (ECG) within 24 h of admission. Children with heart disease or ion channelopathy, or who were on vasoactive medications were excluded. Age‐matched control subjects had no history of seizures or epilepsy. The primary outcome was ventricular abnormalities represented by ST segment changes, abnormal T wave, QRS axis deviation, and corrected QT (QTc) interval prolongation. The secondary outcomes included QT/RR relationship, beat‐to‐beat QTc interval variability, ECG interval measurement between groups, and clinical factors associated with ECG abnormalities.

Results

Of 317 eligible children, 59 met the inclusion criteria. History of epilepsy was present in 31 children (epileptic) and absent in 28 children (nonepileptic). Compared with the control subjects (n = 31), the status epilepticus groups were more likely to have an abnormal ECG, with overall odds ratios of 3.8 and 7.0 for the nonepileptic and the epileptic groups, respectively. Simple linear regression analysis demonstrated that children with epilepsy exhibited impaired dependence and adaptation of the QT interval on heart rate. Beat‐to‐beat QTc interval variability, a marker of ventricular repolarization instability, was increased in children with epilepsy.

Significance

Convulsive status epilepticus can adversely affect ventricular electrical properties and stability in children, especially those with epilepsy. These findings suggest that children with epilepsy may be particularly vulnerable to seizure‐induced arrhythmias. Therefore, postictal cardiac surveillance may be warranted in this population.

Seizure Associated Takotsubo Syndrome: A Rare Combination

Takotsubo cardiomyopathy (TC) is increasingly recognized in neurocritical care population especially in postmenopausal females. We are presenting a 61-year-old African American female with past medical history of epilepsy, bipolar disorder, and hypertension who presented with multiple episodes of seizures due to noncompliance with antiepileptic medications. She was on telemetry which showed ST alarm. Electrocardiogram (ECG) was ordered and showed ST elevation in anterolateral leads and troponins were positive. Subsequently Takotsubo cardiomyopathy was diagnosed by left ventriculography findings and absence of angiographic evidence of obstructive coronary artery disease. Echocardiogram showed apical hypokinesia, ejection fraction of 40%, and systolic anterior motion of mitral valve with hyperdynamic left ventricle, in the absence of intracoronary thrombus formation in the angiogram. Electroencephalography showed evidence of generalized tonic-clonic seizure. She was treated with supportive therapy. This case illustrates importance of ECG in all patients with seizure irrespective of cardiac symptoms as TC could be the cause of Sudden Unexpected Death in Epilepsy (SUDEP) and may be underdiagnosed and so undertreated.

Changes in vagus nerve activity associated with ictal tachycardia in pigs

OBJECTIVE

Ictal tachycardia (IT) is common and may pave the way towards cardiac conditions with high risk potential. However, the mechanisms of IT remain obscure and therefore difficult to control. For example, whereas IT is associated with a sympathetic surge, it is unclear why the IT effects are not opposed by baroreflex cardiac inhibition during seizures. As the vagus nerves (VN) are main mediators for such baroreflexes, this study was performed to investigate the VN activity in IT.

METHODS

The present experiments were performed in ten pigs where IT seizures were induced by controlled infusion of pentylenetetrazole. The electrocorticogram was recorded using a cranial electrode, the electrocardiogram (ECG) using surface electrodes and the blood pressure (BP) using a catheter inserted in the right carotid artery. The VN activity was recorded from both nerves using cuff electrodes and further analyzed in correlation with the cortical seizures and the associated heart rate (HR), BP and HR variability (HRV) changes.

RESULTS

The cortical seizures progressed from spike-and-wave (SW) to tonic-clonic (TC) discharges associated with ECG, HR and BP changes proportional with this progression and comparable to the IT effects reported in humans. Those IT effects were accompanied by parasympathetic HRV changes, a 20% VN activation (p=0.004) before the onset of TC seizures, a suppression of this VN activation during the TC episode and a rebound VN activation by 79% (left VN, p=0.02) and 57% (right VN, p=0.03) after the TC offset. Further analysis of an afferent BP-related VN component and a mixed VN component showed normal BP-related afferent input and a suppressed efferent output through both nerves during the TC episode.

CONCLUSIONS

This study indicates a suppressed ictal VN activation and a rebound postictal VN activation, which may account for the absence of baroreflexes during seizures and the postictal cardiac inhibition, respectively.

Biventricular Takotsubo Cardiomyopathy Associated with Epilepsy

We describe a case of Takotsubo cardiomyopathy in an elderly woman after status epilepticus. In an emergency echocardiography, not only left ventricular apical ballooning but also right ventricular apical hypokinesia was observed. After a medical management, the patient's condition was improved and a follow-up echocardiography showed substantial recovery of left and right ventricular apical ballooning.

Cardiac Dysfunction After Neurologic Injury: What Do We Know and Where Are We Going?

Recent literature has implicated severe neurologic injuries, such as aneurysmal subarachnoid hemorrhage, as a cause of cardiac dysfunction, impaired hemodynamic function, and poor outcomes. Mechanistic links between the brain and the heart have been explored in detail over the past several decades, and catecholamine excess, neuroendocrine dysfunction, and unchecked inflammation all likely contribute to the pathophysiologic process. Although cardiac dysfunction has also been described in other disease paradigms, including septic shock and thermal injury, there is likely a common underlying pathophysiology. In this review, we will examine the pathophysiology of cardiac dysfunction after neurologic injury, discuss the evidence surrounding cardiac dysfunction after different neurologic injuries, and suggest future research goals to gain knowledge and improve outcomes in this patient population.

Prevalence and Risk Factors of Stress Cardiomyopathy After Convulsive Status Epilepticus in ICU Patients

OBJECTIVE

Although stress cardiomyopathy has been described in association with epilepsy, its frequency in patients with convulsive status epilepticus remains unknown. Accordingly, we sought to determine the prevalence and risk factors of stress cardiomyopathy in patients admitted to the ICU for convulsive status epilepticus.

DESIGN

Prospective, descriptive, single-center study.

SETTING

Medical-surgical ICU of a teaching hospital.

PATIENTS

Thirty-two consecutive ventilated patients (21 men; age, 50 ± 18 yr; Simplified Acute Physiology Score II, 53 ± 15; Sequential Organ Failure Assessment, 6 ± 2) hospitalized in the ICU for convulsive status epilepticus.

INTERVENTIONS

None.

MEASUREMENTS AND MAIN RESULTS

Hemodynamic parameters, transthoracic echocardiography, biological data, and electrocardiogram were obtained serially on ICU admission (H0), and after 6, 12, 24, and 48 hours of hospitalization (H6, H12, H24, and H48). Stress cardiomyopathy was defined as a 20% decrease in left ventricular ejection fraction between H0 or H6 and H48. Stress cardiomyopathy was diagnosed in 18 patients (56%; 95% CI, 38-74%). Mean left ventricular ejection fraction, left ventricular stroke index and cardiac index were initially (at H0 or H6 according to lowest individual values) significantly reduced in stress cardiomyopathy patients (45 ± 14% vs 61 ± 6%, p < 0.001; 24 ± 8 vs 28 ± 8 mL/m(2), p < 0.05; 2.3 ± 0.7 vs 3.0 ± 0.8 L/min/m(2), p < 0.05, respectively) and increased secondarily to reach similar mean values than those observed in patients without transient left ventricular dysfunction at H24. Dobutamine was more frequently used in patients with stress cardiomyopathy. Mean lactate level was increased and significantly higher in stress cardiomyopathy patients at H0 and H6, whereas mean central venous oxygen saturation was preserved but significantly lower in this group. Only three patients with stress cardiomyopathy had left ventricular regional wall motion abnormalities but normal coronary angiography. Risk factors of stress cardiomyopathy were age and Simplified Acute Physiology Score II.

CONCLUSIONS

These results suggest that stress cardiomyopathy is common in patients admitted to the ICU for convulsive status epilepticus. Accordingly, these patients should be screened for stress cardiomyopathy and monitored if they present with hemodynamic compromise.

Systemic complications of status epilepticus--An update

Systemic complications occur at every stage of status epilepticus, involve every organ system, and may worsen outcome. Initially, there is a massive catecholamine release and hyperadrenergic state that may result in neurocardiogenic, pulmonary, and, sometimes, musculoskeletal or renal injury. Further medical complications accompany the various treatments used to abort the seizures including the use of nonanesthetic antiseizure drugs and high-dose anesthetic infusions. Later, sequelae of prolonged immobility and critical illness occur and add to the cumulative morbidity of these patients. Clinicians should follow a protocol to guide screening for early markers of systemic injury, complications of specific pharmacologic and adjunctive treatments, and periodic surveillance for complications related to prolonged immobility. This article is part of a Special Issue entitled "Status Epilepticus".

CNS disease triggering Takotsubo stress cardiomyopathy

There are a number of hereditary and non-hereditary central nervous system (CNS) disorders, which directly or indirectly affect the heart (brain-heart disorders). The most well-known of these CNS disorders are epilepsy, stroke, infectious or immunological encephalitis/meningitis, migraine, and traumatic brain injury. In addition, a number of hereditary and non-hereditary neurodegenerative disorders may impair cardiac functions. Affection of the heart may manifest not only as arrhythmias, myocardial infarction, autonomic impairment, systolic dysfunction/heart failure, arterial hypertension, or pulmonary hypertension, but also as stress cardiomyopathy (Takotsubo syndrome, TTS). CNS disease triggering TTS includes subarachnoid bleeding, epilepsy, ischemic stroke, intracerebral bleeding, migraine, encephalitis, traumatic brain injury, PRES syndrome, or ALS. Usually, TTS is acutely precipitated by stress triggered by various different events. TTS is one of the cardiac abnormalities most frequently induced by CNS disorders. Appropriate management of TTS from CNS disorders is essential to improve the outcome of affected patients.

[New aspects in the field of epilepsy]

Regarding epilepsy several new developments can be reported. The International League Against Epilepsy (ILAE) has suggested a new definition of epilepsy, for the first time including a definition of epilepsy resolution. Progress in the diagnosis relates to new genetic findings, improvements in magnetic resonance imaging (MRI) and the increasing use of stereo electroencephalograms (sEEG). Regarding treatment there are new clinically relevant data on the pathophysiology and prevention of sudden unexpected death in epilepsy (SUDEP). Zonisamide has been approved by the European Medicines Agency (EMA) for monotherapy in adults with focal seizures and combination therapy in children aged ≥ 6 years. Retigabin and perampanel have been approved but are currently taken off the market in Germany (only) because the Gemeinsamer Bundesausschuss (GBA, Joint Federal Committee) did not find any additional therapeutic value as compared to lamotrigine due to a lack of data. A decision regarding a new application for perampanel is pending. Regarding surgical treatment novel ablation techniques (e.g. stereotactic radiofrequency and laser ablation as well as focussed ultrasound ablation) and brain stimulation paradigms are under investigation. Experimental studies, generously supported by the European Union (EU) and the Deutsche Forschungsgemeinschaft (DFG, German Research Foundation) are focusing on (opto-)genetic (e.g. using lentoviral transfection), epigenetic (e.g. micro-RNA-related) approaches and on the investigation of neuronal micronetworks.

Neuropeptides as targets for the development of anticonvulsant drugs

Epilepsy is a common neurological disorder characterized by recurrent seizures. These seizures are due to abnormal excessive and synchronous neuronal activity in the brain caused by a disruption of the delicate balance between excitation and inhibition. Neuropeptides can contribute to such misbalance by modulating the effect of classical excitatory and inhibitory neurotransmitters. In this review, we discuss 21 different neuropeptides that have been linked to seizure disorders. These neuropeptides show an aberrant expression and/or release in animal seizure models and/or epilepsy patients. Many of these endogenous peptides, like adrenocorticotropic hormone, angiotensin, cholecystokinin, cortistatin, dynorphin, galanin, ghrelin, neuropeptide Y, neurotensin, somatostatin, and thyrotropin-releasing hormone, are able to suppress seizures in the brain. Other neuropeptides, such as arginine-vasopressine peptide, corticotropin-releasing hormone, enkephalin, β-endorphin, pituitary adenylate cyclase-activating polypeptide, and tachykinins have proconvulsive properties. For oxytocin and melanin-concentrating hormone both pro- and anticonvulsive effects have been reported, and this seems to be dose or time dependent. All these neuropeptides and their receptors are interesting targets for the development of new antiepileptic drugs. Other neuropeptides such as nesfatin-1 and vasoactive intestinal peptide have been less studied in this field; however, as nesfatin-1 levels change over the course of epilepsy, this can be considered as an interesting marker to diagnose patients who have suffered a recent epileptic seizure.

A case of water intoxication with prolonged hyponatremia caused by excessive water drinking and secondary SIADH

Water intoxication is a life-threatening disorder accompanied by brain function impairment due to severe dilutional hyponatremia. We treated a 22-year-old man without psychotic illness who had been put in a detention facility. He drank 6 liters of water over a 3-hour period at the facility as a game's penalty, and he showed progressive psychiatric and neurological signs including restlessness, peculiar behavior and convulsions. On his admission, 15 h after the discontinuation of the water drinking, he was in a coma, showing intermittent convulsions and remarkable hyponatremia (120 mmol/l). Because his laboratory tests showed hypertonic urine and normal sodium excretion, the diagnosis of secondary development of syndrome of inappropriate secretion of antidiuretic hormone (SIADH) was strongly suggested and later confirmed by the suppression of the renin-aldosterone system and the inappropriately elevated secretion of ADH. Saline infusion and an initial administration of furosemide in addition to dexamethasone as treatments for the patient's brain edema successfully improved his laboratory data and clinical signs by the 3rd hospital day, and he was returned to the facility without physical or psychiatric abnormalities on the 6th day. The secondary SIADH might have been due to the prolonged emesis, recurrent convulsions and rapid elevation of intracranial pressure.

Oxytocin inhibits pentylentetrazol-induced seizures in the rat

We aimed to reveal the anti-convulsant effects of oxytocin (OT) in pentylenetetrazol (PTZ)-induced seizures in rats. Thirty rats were randomly divided into 5 equal groups. Using stereotaxy, we implanted electroencephologram (EEG) electrodes in the left nucleus of the posterior thalamus. After 2 days, the first and second groups were used as the control and PTZ (35 mg/kg) groups, respectively. We administered 40, 80 and 160 nmol/kg OT+35 mg/kg PTZ to the rats, constituting the third, fourth, and fifth groups, respectively, for 5 days. At the end of 5 days, we recorded EEGs via bipolar EEG electrodes. After 12h, all groups except the first received 70 mg/kg PTZ and we determined the dose-response ratio. Racine's Convulsion Scale was used to evaluate seizures. The spike-wave complex percentage in the EEG was determined as 0% for the first group, 38.6%±7.2 for the second group, 36.4%±5.6 for the third group, 4.3%±1.8 for the fifth group and 4.1%±1.1 for the fifth group. The fourth and fifth groups had significantly decreased spike-wave complex percentages compared to the second group (p<0.0001). OT may prevent PTZ-induced epilepsy on an EEG. OT may also be considered for use in the treatment of epilepsy in the future.

Ictal electrocardiographic changes in children presenting with seizures

BACKGROUND

The aim of this study was to determine electrocardiographic changes in children during seizures.

METHODS

We assessed heart rate changes, RR intervals and QT changes during 47 seizures in children. Consecutive QT and RR intervals were measured for 60 s before the seizures, during the seizures and 60 s after the seizures during video electroencephalography monitoring.

RESULTS

There were 47 seizures in 18 patients. Five patients had generalized seizures and 13 patients had focal seizures. Twelve patients were male. The mean age during monitoring was 10.1 years (range 4 months-19 years). Ictal tachycardia was seen in every seizure. No ictal bradycardia was noted. There was only one dropped beat in a patient. The mean ictal heart-rate-corrected QT (QTc) interval was significantly higher than the postictal measurements (P= 0.005). Mean ictal QTc variation tended to increase during seizures and then decreased below the pre-ictal measurements in the postictal period. However these changes were statistically insignificant (P > 0.05). RR variance was significantly decreased during seizures compared to the postictal period and the standard deviation of the RR intervals was significantly decreased in the ictal period compared to the pre-ictal period (P= 0.014 and P= 0.001, respectively).

CONCLUSION

Tachycardia is the main finding in seizures in children. Ictal bradycardia and cardiac arrhythmias are very rare despite being more frequent in adults with seizures.

Upregulation of arginine vasopressin synthesis in the rat hypothalamus after kainic acid-induced seizures

We examined the effects of kainic acid (KA)-induced seizures on arginine vasopressin (AVP) gene expression in the paraventricular (PVN) and the supraoptic nuclei (SON) of normal rats using in situ hybridization histochemistry. We also investigated the expression of the AVP-enhanced green fluorescent protein (eGFP) fusion gene after KA-induced seizures in transgenic rats. AVP heteronuclear (hn) RNA levels in the PVN and the SON were significantly increased at 3h and 24h after subcutaneous (s.c.) administration of KA in normal rats. AVP mRNA levels in the PVN and the SON did not change significantly at 3h, 24h and 1 week after s.c. administration of KA in normal rats. In KA-administered transgenic rats, AVP-eGFP fluorescence in the magnocellular and parvocellular divisions of the PVN and the SON were significantly stronger compared to vehicle-administered transgenic rats. By pretreatment with MK-801 (nonselective N-methyl-D-aspartate, NMDA, receptor antagonist), AVP-eGFP transgenic rats after administration of KA did not show preconvulsive symptoms or convulsions and AVP-eGFP fluorescence in the magnocellular and parvocellular divisions of the PVN and the SON of these rats was significantly reduced. These results suggested that KA-induced increases in AVP transcripts and AVP were prevented by MK801 because seizure activity was prevented or reduced.

Cardiovascular and neuroendocrine features of Panayiotopoulos syndrome in three siblings

OBJECTIVE

Panayiotopoulos syndrome is a benign idiopathic childhood epilepsy characterized by altered autonomic activity at seizure onset.

METHODS

Three siblings with Panayiotopoulos syndrome underwent 24-hour EEG recording and head-up tilt testing with continuous blood pressure and RR interval monitoring. Plasma catecholamines and vasopressin were measured while supine, upright, and during a typical seizure.

RESULTS

Patient 1, a 12-year-old girl, had a history of involuntary lacrimation, abdominal pain, and recurrent episodes of loss of muscle tone and unresponsiveness followed by somnolence. Her EEG revealed bilateral frontotemporal spikes. Patient 2, a 10-year-old boy, had episodic headaches with pinpoint pupils, skin flushing of the face, trunk, and extremities, purple discoloration of hands and feet, diaphoresis, nausea, and vomiting. Tilt testing triggered a typical seizure after 9 minutes; there was a small increase in blood pressure (+5/4 mm Hg, systolic/diastolic) and pronounced increases in heart rate (+59 bpm) and norepinephrine (+242 pg/mL), epinephrine (+175 pg/mL), and vasopressin (+22.1 pg/mL) plasma concentrations. Serum glucose was elevated (206 mg/dL). His EEG revealed right temporal and parietal spikes. Patient 3, an 8-year-old boy, had a history of restless legs at night, enuresis, night terrors, visual hallucinations, cyclic abdominal pain, and nausea. His EEG showed bitemporal spikes.

CONCLUSION

Hypertension, tachycardia, and the release of vasopressin suggest activation of the central autonomic network during seizures in familial Panayiotopoulos syndrome. These autonomic and neuroendocrine features may be useful in the diagnosis and may have therapeutic implications.

Continuous monitoring of electrodermal activity during epileptic seizures using a wearable sensor

We present a novel method for monitoring sympathetic nervous system activity during epileptic seizures using a wearable sensor measuring electrodermal activity (EDA). The wearable sensor enables long-term, continuous EDA recordings from patients. Preliminary results from our pilot study suggest that epileptic seizures induce a surge in EDA. These changes are greater in generalized tonic-clonic seizures and reflect a massive sympathetic discharge. This paper offers a new approach for investigating the relationship between epileptic seizures and autonomic alterations.

Alteration in chromogranin A, obestatin and total ghrelin levels of saliva and serum in epilepsy cases

This study was designed to measure the levels of chromogranin A (CgA), ghrelin and obestatin in serum and saliva (including CgA expression in healthy tissue) in epileptic patients to determine any significant differences between these patients and healthy controls. Samples were obtained from a total of 91 subjects: 10 newly-diagnosed primary generalized epilepsy (PGE) patients who had started treatment with valproic acid and phenytoin for seizure control; 18 PGE patients who were previously and currently receiving treatment with valproic acid and phenytoin for seizure control; 37 patients with partial epilepsy (PE) (simple, n=17 or complex, n=20) who had been and were still being treated with carbazebime for seizures; and 26 healthy controls. CgA immunoreactivity in healthy salivary gland was analyzed by immunohistochemistry and ELISA. The levels of CgA, total ghrelin and obestatin in serum and saliva were measured by ELISA. The results revealed that normal salivary gland produces its own CgA. Before treatment, CgA levels in saliva and serum were significantly greater in patients newly-diagnosed with PGE than controls. Ghrelin and CgA concentrations were also greater in PGE patients previously or currently treated with drugs, and in patients with simple or complex partial epilepsy (PE) previously or currently treated with drugs, than in healthy normal controls. In conclusion, salivary concentrations of CgA, ghrelin and obestatin were similar to their serum levels, so saliva might be a desirable alternative to serum for measuring these hormones because it is easy and painless to collect.

Autonomic alterations and cardiac changes in epilepsy

Studies with heart rate variability have revealed interictal autonomic alterations in patients with epilepsy. In addition, epilepsy is frequently associated with ictal tachycardia or bradycardia, which sometimes precedes the onset of seizures. Ictal tachycardia is sometimes associated with electrocardiography (ECG) morphologic changes and ictal bradycardia often progresses to asystole. Such cardiac manifestations of seizures have been hypothesized as possible causes for sudden unexplained death in epilepsy (SUPEP). The present review relates to interictal and ictal cardiac manifestations of epilepsy with focus on heart rate, heart rate variability, and ECG changes. Aspects of the supporting mechanisms are discussed and attention is drawn to the interaction between central and peripheral effects, interictal autonomic conditions, ictal autonomic discharges, and administration of antiepileptic drugs in shaping the ictal cardiac changes. Because these interactions are complex and not totally understood, closer surveillance of patients and more experimental work is necessary to elucidate the mechanistic support of autonomic and cardiac changes in epilepsy, and to design better strategies to avoid their undesirable effects. It is also suggested that some of these changes could be used as predictors or markers for the onset of seizures.

Sudden unexpected death in epilepsy: risk factors and potential pathomechanisms

Sudden unexpected death in epilepsy (SUDEP) is the most common cause of death directly related to epilepsy, and most frequently occurs in people with chronic epilepsy. The main risk factors for SUDEP are associated with poorly controlled seizures, suggesting that most cases of SUDEP are seizure-related events. Dysregulation in cardiac and respiratory physiology, dysfunction in systemic and cerebral circulation physiology, and seizure-induced hormonal and metabolic changes might all contribute to SUDEP. Cardiac factors include bradyarrhythmias and asystole, as well as tachyarrhythmias and alterations to cardiac repolarization. Altered electrolytes and blood pH, as well as the release of catecholamines, modulate cardiac excitability and might facilitate arrhythmias. Respiratory symptoms are not uncommon during seizures and comprise central apnea or bradypnea, and, less frequently, obstruction of the airways and neurogenic pulmonary edema. Alterations to autonomic function, such as a reduction in heart rate variability or disturbed baroreflex sensitivity, can impair the body's capacity to cope with challenging situations of elevated stress, such as seizures. Here, we summarize data on the incidence of and risk factors for SUDEP, and consider the pathophysiological aspects of chronic epilepsy that might lead to sudden death. We suggest that SUDEP is caused by the fatal coexistence of several predisposing and triggering factors.

A single generalized seizure alters the amplitude, but not phase, of the circadian activity rhythm of the hamster

People with epilepsy exhibit high rates of sleep disturbances. In many cases, these sleep disruptions appear to be related to the occurrence of the seizures themselves. Changes in sleep structure may reflect underlying changes in the circadian clock, as circadian rhythms of locomotor activity, body temperature, and hormone release are disrupted following a seizure. The present study was designed to determine if a single generalized seizure could alter the phase and waveform of the circadian rhythm of wheel-running behavior in the Syrian hamster. Animals were housed in constant darkness, and were administered either a sham treatment or a maximal electroconvulsive shock at one of three time-points: 6 h before activity onset, 1 h after activity onset, or 6 h after activity onset. Seizures at all of these phases did not significantly affect the phase of the circadian activity rhythm. The circadian locomotor activity levels were significantly attenuated following seizures at all three phases. This attenuation was prominent over the 24 h following the seizure, and was also evident over the three post-seizure days. These data suggest that while seizures do not affect phase, they may alter the amplitude of the circadian clock. Because the amplitude of the circadian clock affects sleep quality, these findings suggest one mechanism by which persistent seizures may decrease the quality of sleep in patients with epilepsy.

Neurogenic stunned myocardium associated with status epileptics and postictal catecholamine surge

A 75-year-old woman developed left ventricular apical ballooning, shortly after recovering from status epileptics. Plasma noradrenaline and adrenaline levels were 2.05 ng/ml and 0.48 ng/ml, respectively. Endomyocardial biopsy disclosed patchy areas of interstitial myocardial fibrosis, atrophy and vacuolization of cardiac myocytes, and some disappearance of myocyte nuclei. Follow-up echocardiography showed that the left ventricular apical ballooning was restored to normal within 25 days. These findings are compatible with neurogenic stunned myocardium. It is important to recognize that patients suffering from intractable seizures may harbor a risk of postictal catecholamine surge and catecholamine-induced myocardial dysfunction.

Serum ghrelin levels are enhanced in patients with epilepsy

PURPOSE

In patients with epilepsy, although many changes in the physiology of hormones in the neuroendocrine system can occur (especially in the sex hormones, for example), the causes of these changes have not been fully elucidated. There are also relations between seizure activity and stages of sleep. Ghrelin is the peptide hormone, which has been shown to affect both endocrine function and sleep. The purpose of this study was to evaluate serum levels of ghrelin in epilepsy patients.

METHODS

A total of 35 patients currently receiving antiepileptic drug therapy (of these patients, 20 had primary generalized seizure and 15 had partial seizure) were studied. The control group consisted of 30 healthy volunteers matched for age and gender. In all participants, serum levels of ghrelin, cholesterol and triglycerides were measured and body mass index (BMI) was determined. Patients with endocrine, immune or any other chronic diseases were excluded.

RESULTS

In the epilepsy patients, the mean serum ghrelin level was 158.81+/-55.97 pg/ml, and this was significantly higher than the control group's level of 93.43+/-21.33 pg/ml (p<0.001). In terms of serum cholesterol, triglycerides and BMI, no significant differences were found between the epilepsy patients and the control group (p>0.05).

CONCLUSIONS

The origin of higher serum ghrelin levels in epilepsy and their relation to seizures are not completely known. However, this elevation of serum ghrelin could contribute to the lengthening of NREM sleep in epilepsy patients, thereby playing a role in seizure occurrence. From another direction, high serum ghrelin levels could cause changes and/or dysfunction in hormone secretion and physiology via its effects on growth hormone, and thereby play a facilitating role in seizure occurrence.

Arginine vasopressin does not contribute to seizures induced by intracerebroventricularly-injected pilocarpine

Arginine vasopressin (AVP) has been shown to contribute to the production of seizures. Here, we aimed to investigate the effects of AVP on seizures induced by intracerebroventricular (i.c.v.) injection of pilocarpine. Rats were treated with 0.2-2.4 mg/5 microl pilocarpine intracerebroventricularly, to obtain the dose-response relationship for behavioural seizures. 2.4 mg/5 microl pilocarpine induced status epilepticus in all rats and 0. 2 mg/5 microl pilocarpine did not produce any sign of seizure in any of the rats. In the second step, AVP (0.01-1000 ng/2 microl; i.c.v.) was injected 5 min before i.c.v. injection of a low dose pilocarpine (0.4 mg/5 microl) and rats were observed for percentage of status epilepticus, status epilepticus latency and behavioural seizure scores. None of the applied doses of AVP had any significant effect on seizures induced by 0.4 mg/5 microl i.c.v. pilocarpine. Subcutaneous injection of 1000 ng AVP 1h before 0.4 mg i.c.v. pilocarpine also did not produce significant difference with respect to the 0.4 mg pilocarpine group. Finally, pretreatment with neither an AVP V(1) receptor antagonist (25, 125, 250 ng/5 microl; i.c.v.) nor an AVP V(2) receptor antagonist (25, 125, 250 ng/5 microl; i.c.v.) prevented status epilepticus, induced by 2.4 mg/5 microl i.c.v. pilocarpine. We conclude that AVP does not act as a convulsant agent in centrally-induced pilocarpine seizures.

Early post-convulsive prolongation of QT time in children

AIM

An important differential diagnosis of seizures in childhood is the long QT syndrome. Childhood epilepsy occurs about 400 times more often than long QT syndrome. We had observed children with slight post-convulsive prolongation of QT time more often than the reported incidence of long QT syndrome. We therefore conducted a prospective study to define the characteristics of post-convulsive prolongation of QT time in children.

METHODS

We investigated 30 consecutive infants and children (3 mo to 14 y) within 2 h after seizures. A follow-up ECG was obtained 1-9 d later. We also obtained ECGs from 30 healthy age- and gender-matched controls. We calculated the QT interval corrected for heart rate (QTc) by Bazett's formula in leads II, V5, V6, QT dispersion and the number of notched T waves.

RESULTS

We found a QTc interval of more than 440 ms in one or more leads in the first ECG in seven of 30 infants and children compared to 1 of 30 in the follow-up ECG (p=0.0003) and two of 30 in the healthy controls (p=0.14). Average QTc was higher for all leads in the first ECG. This was statistically significant in leads II (414 vs 402 ms, p=0.008), V5 (416 vs 404 ms, p=0.002) and V6 (415 vs 399 ms, p=0.001). Compared to healthy controls, QT dispersion was slightly larger in the early post-convulsive ECG (36 vs 31 ms, p=0.03). Notched T waves occurred more frequently in the early compared to the late post-convulsive ECGs (p=0.009).

CONCLUSION

Slight to moderate post-convulsive prolongation of the QT interval is not rare but transient in paediatric patients.

Hippocampal melatonin receptors modulate seizure threshold

PURPOSE

The pineal hormone melatonin has been shown to enhance hippocampal excitability. We therefore investigated whether inactivation of hippocampal melatonin receptors affects behavioral seizures.

METHODS

Intrahippocampal infusions were performed in rats to study the effect of different melatonin receptor antagonists on behavioral activity, EEG, and seizure susceptibility. Experiments were conducted at 2 times of the day that coincided with the peak and trough of the daily melatonin rhythm.

RESULTS

Local infusion of the Mel(1b) receptor antagonist 4-phenyl-2-propionamidotetralin (4-P-PDOT) into the hippocampus, but not the overlying neocortex, significantly increased seizure latency and in some cases provided complete protection against seizure development. In addition, 4-P-PDOT suppressed open field activity and hippocampal EEG amplitude. The mixed Mel(1a)/Mel(1b) receptor antagonist luzindole also increased seizure latency but to a lesser degree than 4-P-PDOT. The behavioral effects of Mel(1b) receptor inhibition were comparable to those of the gamma-aminobutyric acid (GABA)(A) receptor agonist muscimol and were observed during the dark phase (2400-0200 h) but not the light phase (1200-1400 h) of the daily photocycle. The anticonvulsant effect of intrahippocampal infusion of 4P-P-DOT was blocked by coadministration of the GABA(A) antagonist bicuculline.

CONCLUSIONS

Our results suggest that nocturnal activation of hippocampal Mel(1b) receptors depresses GABA(A) receptor function in the hippocampus and enhances seizure susceptibility.

Vasopressinergic hypothalamic neurons are recruited during the audiogenic seizure of WARs

The Wistar Audiogenic Rat (WAR) is a genetic model of reflex epilepsy with seizures induced by high-intensity sound stimulation (120 dB SPL). In spite of the known neural substrates involved in WAR seizure phenotype, neuroendocrine hypothalamic neurons were never investigated. In this work, AVP immunohistochemistry in the hypothalamus and radioimmunoassay (RIA) in plasma and in hypothalamic and hypophysial tissues were performed on both controls and WARs in order to evaluate the dynamics of AVP release due to seizure induction. Susceptible animals (WARs) displayed at least tonic-clonic convulsions followed by clonic spasms, while resistant Wistar rats (R) had no convulsive behavior. Animals were sacrificed at 3 instances: basal condition (without stimulus) and at 3 and 10 min after sound stimulation. For the immunohistochemistry AVP study, brains were harvested and processed by the avidin-biotin-peroxidase detection method. Optic densitometry was used for quantifying AVP labeling in supraoptic (SON) and paraventricular (PVN) hypothalamic nuclei. SON presented higher densitometry levels (%D--relative to background) for both WARs and R when compared to PVN. Nevertheless, both nuclei presented a marked decrease, referenced to basal levels, in %D for WARs at 3 min (approximately 35%) against a discrete change for R (approximately 90%). RIA results were significantly higher in the hypophysis of WARs when compared to R rats, at 3 min. Also, at 3 min, plasma AVP in WARs (89.32 +/- 24.81 pg/mL) were higher than in R (12.01 +/- 2.39 pg/mL). We conclude, based on the AVP releasing profiles, that vasopressinergic hypothalamic neurons are recruited during the audiogenic seizure of WARs.

α2-Adrenergic inhibition prevents the accompanied anticonvulsant effect of swim stress on behavioral convulsions induced by lithium and pilocarpine

There has been much debate regarding the potential influence of stress on epilepsy. Many studies have reported that stress can affect seizure susceptibility through eliciting either proconvulsant or anticonvulsant effects within the nervous system. In this study, we investigated the potential anticonvulsant effect of a 10-min swim stress on convulsions induced by a single systemic injection of lithium chloride followed 4 h later with pilocarpine. Rats pretreated with lithium chloride and exposed to a 10-min swim stressor prior to pilocarpine injection displayed a significant delay to seizure onset compared to unstressed rats or rats exposed to swim stress 10 min after lithium chloride, 2 h after lithium chloride, or immediately after pilocarpine injection. We then determined whether administration of a glucocorticoid antagonist (mifepristone; 10 or 50 mg/kg), an alpha(2)-adrenergic antagonist (yohimbine; 2 or 5 mg/kg), or a nonspecific opioid blocker (naloxone; 0.2 or 1 mg/kg) could prevent the anticonvulsant effect of swim stress. Only the high dose of yohimbine was capable of inhibiting the anticonvulsant effect of swim stress on lithium-pilocarpine seizures. Our findings highlight the importance of an endogenous noradrenergic-dependent anticonvulsant system in mediating the effects of swim stress on seizures. Further studies exploring the benefits of treatments with noradrenergic acting drugs in epilepsy is well warranted.

Involvement of prolactin, vasopressin and opioids in post-ictal antinociception induced by electroshock in rats

The neurochemical mechanisms involved in post-ictal antinociception remain to be elucidated. Application of electroconvulsive shock (ECS) to rats results in post-ictal antinociception. The objective of this study was to identify endogenous substances that could participate in antinociception during post-ictal depression induced by ECS (70 mA, 60 Hz, 1 s). Antinociception was measured by the rat paw-pressure test, in which increased sensitivity is induced by intraplantar injection of carrageenan. This test proved to be efficient in detecting the electroshock-induced antinociception. Intense post-ictal antinociception was observed over a period of 30 min after the end of the seizure. It was used nonspecific opioid and specific vasopressin antagonists and the prolactin (PRL) release inhibitor to test the reversal of antinociception. Administration of naloxone (5, 7.5 and 10 mg/kg) blocked the post-ictal antinociception. The V(1) (125 microg/kg) and V(2) (250 microg/kg) vasopressin receptor antagonists ([beta-mercapto-beta,beta-cyclopentamethylenepropionyl(1),O-Et-Tyr(2),Val(4),Arg(8)]-vasopressin and [adamantaneacetyl(1),O-Et-d-Tyr(2),Val(4),Abu(6),Arg(8,9)]-vasopressin) also inhibited the nociceptive response. The antinociception blockade was more intense after administration of the V(1) receptor antagonist. Bromocriptine (4, 8 and 12 mg/kg) was able to reverse antinociception behavior during the post-ictal period. Morphine (1, 2 and 4 mg/kg), vasopressin (12.5, 100 and 400 microg/kg) and prolactin (100, 200 and 400 microg/kg) administration promoted a higher nociceptive threshold. It was administered the three substances with their respective antagonists to verify the opioidergic pathway and vasopressin and prolactin release interactions, and as a positive control. We observed that the tested mediators were released in an independent manner, indicating no interference in which other.

Seizures induce phase shifts of rat circadian rhythms

RATIONALE

Epileptic seizures may alter neuroendocrinological cycles. Light pulses induce phase shifts in circadian rhythms. Using hippocampal-kindled rats to ensure maximal clinical expression, we determined if seizures likewise induce phase shifts.

METHODS

We monitored the circadian rhythm of temperature (CRT) with intraperitoneal radiotelemetry in rats (n=21) isolated from time cues and light for 3-week trials. Seizures were triggered with hippocampal electrical stimulation at different circadian phases. Optimized, least-error phase shifts were calculated from preictal and postictal CRTs. Induced seizures were referenced to CRT (t(max)=00:00, 24-h circadian cycle).

RESULTS

Phase shifts (individual responses=57) differed across the circadian cycle. Rather than forming a clear phase-response curve, phase shifts were especially variable between 00:00 and 06:00 h.

CONCLUSIONS

This study demonstrates that electrically-induced seizures induce advances and delays in CRT in a phase-dependent fashion but in a pattern different from typical light-induced phase shifts. Disorders of circadian regulation may contribute to some of the altered endogenous cycles associated with epilepsy.

Prenatal morphine exposure induces age- and sex-dependent changes in seizure susceptibility

1. Prenatal exposure to morphine induces long-term alterations in seizure susceptibility, which are age-, sex-, and seizure model-specific. 2. Adult male and female rats exposed prenatally to morphine show decreased susceptibility to GABA-regulated seizures. 3. Prenatally morphine-exposed, adult male rats are more sensitive to excitatory amino acid receptor-mediated seizures than control males, control females, or morphine-exposed females.

Circadian rhythms: interactions with seizures and epilepsy

Circadian rhythms are endogenously-mediated 24 h cycles of behavioral or physiological activity. The interactions among the mammalian circadian clock, acute seizures, and chronic epilepsy are not well-characterized. Evidence suggests that seizures are susceptible to circadian modulation, and that this modulation varies with epilepsy syndrome and location of seizure foci. The circadian timing system and secondary circadian cycles of hormone secretion, sleep and wakefulness, and recurrent environmental factors are discussed as potential systems that effect spontaneous seizure recurrence. Experimental designs should take into account time-of-day effects on seizure threshold and occurrence. Further work is required to determine what mechanisms account for daily variation in seizure susceptibility.