The effect of electrical stimulation of medial temporal lobe structures in epileptic patients upon ACTH, prolactin, and growth hormone

Hypothalamic-pituitary-adrenal axis targets for the treatment of epilepsy

Stress is a common seizure trigger in persons with epilepsy. The body's physiological response to stress is mediated by the hypothalamic-pituitary-adrenal (HPA) axis and involves a hormonal cascade that includes corticotropin releasing hormone (CRH), adrenocorticotropin releasing hormone (ACTH) and the release of cortisol (in humans and primates) or corticosterone (in rodents). The prolonged exposure to stress hormones may not only exacerbate pre-existing medical conditions including epilepsy, but may also increase the predisposition to psychiatric comorbidities. Hyperactivity of the HPA axis negatively impacts the structure and function of the temporal lobe of the brain, a region that is heavily involved in epilepsy and mood disorders like anxiety and depression. Seizures themselves damage temporal lobe structures, further disinhibiting the HPA axis, setting off a vicious cycle of neuronal damage and increasing susceptibility for subsequent seizures and psychiatric comorbidity. Treatments targeting the HPA axis may be beneficial both for epilepsy and for associated stress-related comorbidities such as anxiety or depression. This paper will highlight the evidence demonstrating dysfunction in the HPA axis associated with epilepsy which may contribute to the comorbidity of psychiatric disorders and epilepsy, and propose treatment strategies that may dually improve seizure control as well as alleviate stress related psychiatric comorbidities.

Prolactin levels as a criterion to differentiate between psychogenic non-epileptic seizures and epileptic seizures: A systematic review

OBJECTIVE

Psychogenic non-epileptic seizures (PNES) are conversion disorders with functional neurological symptoms that can resemble epileptic seizures (ES). We conducted a systematic review to obtain an overview of the value of prolactin (PRL) levels in the differential diagnosis between PNES and ES.

METHODS

We searched PubMed, EMBASE, and Cochrane Library databases for studies published up to June 4th, 2020. Published studies were included if they fulfilled the following criteria: original research on PRL changes after ES and PNES. By applying Bayes' theorem, we calculated the predicted values of PRL with pretest probabilities of 90 % and 75 % in ES.

RESULTS

Sixteen studies were included in this review. All the studies showed that PRL levels increase after ES, especially 10-20 min after ES, when the elevation was most obvious. In studies where capillary PRL level measurements were included, the median sensitivity in the diagnosis of ES (all epileptic seizure types), generalized tonic clonic seizures (GTCS), focal impaired awareness seizures (FIAS), and focal aware seizures (FAS) was 67.3 %, 66.7 %, 33.9 %, and 11.1 %, respectively. The median specificity in the diagnosis of ES was 99.1 %. By using Bayes' theorem, when we used the median specificity and sensitivity for predictive value calculation, assuming a pretest probability of 90 %, a positive PRL measure was highly predictive (99 %) of all types of ES, and negative predictive values were all below 30 %. When we used the lowest specificity and sensitivity for predictive value calculation, assuming a pretest probability of 75 %, ES and GTCS had positive predictive values of 77.2 % and 81.0 %, respectively; the negative predictive values of PRL in ES and GTCS were 26.2 % and 29.6 %, respectively.

CONCLUSIONS

The use of PRL could be a useful adjunct to differentiate GTCS from PNES. However, PRL levels are of limited use for differentiating FIAS or FAS from PNES, and a negative PRL measure is not predictive of PNES.

Increased protein and mRNA expression of corticotropin-releasing factor (CRF), decreased CRF receptors and CRF binding protein in specific postmortem brain areas of teenage suicide subjects

Overactivity of hypothalamic-pituitary-adrenal (HPA) axis function has been implicated in depression and suicidal behavior. This is based on the observation of an abnormal dexamethasone (DEX) and DEX-adrenocorticotropic hormone (ACTH) test in patients with depression and suicidal behavior. Recently, some studies have also found abnormalities of glucocorticoid receptors (GR), mineralocorticoid receptors (MR), corticotropin releasing factor (CRF), CRF receptors (CRF-R) and CRF binding protein (CRF-BP) in depressed and suicidal patients. Some investigators have also observed increased levels of CRF in the cerebrospinal fluid (CSF) and altered levels of MR, GR and CRF in the postmortem brain of depressed and suicidal subjects. We have earlier reported decreased protein and mRNA expression of GR and GILZ, a chaperone protein, in the postmortem brain of teenage suicide subjects. We have further studied CRF and its receptors in different areas of the postmortem brain of suicide subjects, i.e., the prefrontal cortex (PFC), hippocampus (HIPPO), subiculum and amygdala (AMY) from teenage suicide subjects. The CRF and its receptors were determined in the PFC (Brodmann area 9), HIPPO, subiculum and different amygdaloid nuclei from 24 normal control subjects and 24 teenage suicide subjects. Protein expression of CRF, its receptors and CRF-BP was determined by immunolabeling using the Western blot technique and mRNA expression was determined by real-time PCR (qPCR) technique. We found that the mRNA levels of CRF were significantly increased in the PFC, in the central amygdaloid nucleus (CeAMY) and in the subiculum. mRNA levels of CRF-R1 and CRF-BP were significantly decreased in the PFC. We did not find any changes in the HIPPO of any of the CRF components we studied. When we compared the protein expression of CRF components we found that CRF was significantly increased and CRF-R1, CRF-R2 and CRF-BP significantly decreased in the PFC. On the other hand, there were no changes in the protein expression of CRF components in the HIPPO. Our results in the postmortem brain suggest that, as found by clinical studies in the CSF, there are significant alterations of CRF and its receptors in the postmortem brain of teenage suicide subjects. These alterations of CRF and its components were region-specific, as changes were not generally observed in the HIPPO.

Neural oscillations in the infralimbic cortex after electrical stimulation of the amygdala. Relevance to acute stress processing

The stress system coordinates the adaptive reactions of the organism to stressors. Therefore, dysfunctions in this circuit may correlate to anxiety-related disorders, including depression. Comprehending the dynamics of this network may lead to a better understanding of the mechanisms that underlie these diseases. The central nucleus of the amygdala (CeA) activates the hypothalamic-pituitary-adrenal axis and brainstem nodes by triggering endocrine, autonomic and behavioral stress responses. The medial prefrontal cortex plays a significant role in regulating reactions to stressors, and is specifically important for limiting fear responses. Brain oscillations reflect neural systems activity. Synchronous neuronal assemblies facilitate communication and synaptic plasticity, mechanisms that cooperatively support the temporal representation and long-term consolidation of information. The purpose of this article was to delve into the interactions between these structures in stress contexts by evaluating changes in oscillatory activity. We particularly analyzed the local field potential in the infralimbic region of the medial prefrontal cortex (IL) in urethane-anesthetized rats after the electrical activation of the central nucleus of the amygdala by mimicking firing rates induced by acute stress. Electrical CeA activation induced a delayed, but significant, change in the IL, with prominent slow waves accompanied by an increase in the theta and gamma activities, and spindles. The phase-amplitude coupling of both slow waves and theta oscillations significantly increased with faster oscillations, including theta-gamma coupling and the nesting of spindles, theta and gamma oscillations in the slow wave cycle. These results are further discussed in neural processing terms of the stress response and memory formation.

Cortisol levels and seizures in adults with epilepsy: A systematic review

Stress has been suggested as a trigger factor for seizures in epilepsy patients, but little is known about cortisol levels, as indicators of stress, in adults with epilepsy. This systematic review summarizes the evidence on this topic. Following PRISMA guidelines, 38 articles were selected: 14 analyzing basal cortisol levels, eight examining antiepileptic drugs (AEDs) effects, 13 focused on seizure effects, and three examining stress. Higher basal cortisol levels were found in patients than in healthy people in studies with the most homogeneous samples (45% of 38 total studies). Despite heterogeneous results associated with AEDs, seizures were related to increases in cortisol levels in 77% of 38 total studies. The only study with acute stress administration found higher cortisol reactivity in epilepsy than in healthy controls. In studies using self-reported stress, high seizure frequency was related to increased cortisol levels and lower functional brain connectivity. Findings suggest that epilepsy could be considered a chronic stress model. The potential sensitizing role of accumulative seizures and issues for future research are discussed.

Causes of CNS inflammation and potential targets for anticonvulsants

Inflammation is one of the most important endogenous defence mechanisms in an organism. It has been suggested that inflammation plays an important role in the pathophysiology of a number of human epilepsies and convulsive disorders, and there is clinical and experimental evidence to suggest that inflammatory processes within the CNS may either contribute to or be a consequence of epileptogenesis. This review discusses evidence from human studies on the role of inflammation in epilepsy and highlights potential new targets in the inflammatory cascade for antiepileptic drugs. A number of mechanisms have been shown to be involved in CNS inflammatory reactions. These include an inflammatory response at the level of the blood-brain barrier (BBB), immune-mediated damage to the CNS, stress-induced release of inflammatory mediators and direct neuronal dysfunction or damage as a result of inflammatory reactions. Mediators of inflammation in the CNS include interleukin (IL)-1β, tumour necrosis factor-α, nuclear factor-κB and toll-like receptor-4 (TLR4). IL-1β, BBB and high-mobility group box-1-TLR4 signalling appear to be the most promising targets for anticonvulsant agents directed at inflammation. Such agents may provide effective therapy for drug-resistant epilepsies in the future.

Interaction of the serotonin transporter-linked polymorphic region and environmental adversity: increased amygdala-hypothalamus connectivity as a potential mechanism linking neural and endocrine hyperreactivity

BACKGROUND

Gene by environment (G×E) interaction between genetic variation in the promoter region of the serotonin transporter gene (serotonin transporter-linked polymorphic region [5-HTTLPR]) and stressful life events (SLEs) has been extensively studied in the context of depression. Recent findings suggest increased neural and endocrine stress sensitivity as a possible mechanism conveying elevated vulnerability to psychopathology. Furthermore, these G×E mediated alterations very likely reflect interrelated biological processes.

METHODS

In the present functional magnetic resonance imaging study, amygdala reactivity to fearful stimuli was assessed in healthy male adults (n = 44), who were previously found to differ with regard to endocrine stress reactivity as a function of 5-HTTLPR × SLEs. Furthermore, functional connectivity between the amygdala and the hypothalamus was measured as a potential mechanism linking elevated neural and endocrine responses during stressful/threatening situations. The study sample was carefully preselected regarding 5-HTTLPR genotype and SLEs.

RESULTS

We report significant G×E interaction on neural response patterns and functional amygdala-hypothalamus connectivity. Specifically, homozygous carriers of the 5-HTTLPR S' allele with a history of SLEs (S'S'/high SLEs group) displayed elevated bilateral amygdala activation in response to fearful faces. Within the same sample, a comparable G×E interaction effect has previously been demonstrated regarding increased cortisol reactivity, indicating a cross-validation of heightened biological stress sensitivity. Furthermore, S'S'/high SLEs subjects were characterized by an increased functional coupling between the right amygdala and the hypothalamus, thus indicating a potential link between neural and endocrine hyperreactivity.

CONCLUSIONS

The present findings contribute to the ongoing debate on 5-HTTLPR × SLEs interaction and are discussed with respect to clinical implications.

Association of amygdala volumes with cortisol secretion in unipolar depressed patients

Major depressive disorder (MDD) is accompanied by morphological changes of brain structures which are of great importance in the neural circuitry mediating depression like the hippocampus and the amygdala. Hyperactivity of the hypothalamic-pituitary-adrenocortical (HPA) system resulting in enhanced glucocorticoid secretion can often be observed during depression and has been thought to play an important role in inducing these morphological changes. We used magnetic resonance imaging to investigate alterations of amygdala and hippocampal volumes in 86 in-patients with unipolar depression and 87 healthy controls, and we then correlated amygdala and hippocampal volumes of 76 in-patients with the area under the curve of cortisol secretion in the dexamethasone/corticotropin releasing hormone (Dex/CRH) test at baseline and during short-term antidepressant therapy. In line with recently published studies both left and right amygdala volumes of patients in a first depressive episode were smaller than those of healthy controls. Patients with recurrent depressive episodes showed a reduction of hippocampal volumes, while amygdala volumes were normal. Larger left and right amygdala volumes correlated with a more pronounced reduction of HPA activity, measured by the cortisol secretion in the combined DEX/CRH test, during antidepressant therapy in patients with recurrent depressive episodes.

Limbic regulation of hypothalamo-pituitary-adrenocortical function during acute and chronic stress

The hypothalamo-pituitary-adrenocortical (HPA) axis is responsible for initiation of glucocorticoid stress responses in all vertebrate animals. Activation of the axis is regulated by diverse afferent input to the hypothalamic paraventricular nucleus (PVN). This review discusses brain mechanisms subserving generation and inhibition of stress responses focusing on the contribution of the limbic system and highlighting recent conceptual advances regarding organization of stress response pathways in the brain. First, control of HPA axis responses to psychogenic stimuli is exerted by a complex neurocircuitry that involves oligosynaptic networks between limbic forebrain structures and the PVN. Second, individual stress-modulatory structures can have a heterogeneous impact on HPA axis responses, based on anatomical micro-organization and/or stimulus properties. Finally, HPA axis hyperactivity pursuant to chronic stress involves a substantial functional and perhaps anatomical reorganization of central stress-integrative circuits. Overall, the data suggest that individual brain regions do not merely function as monolithic activators or inhibitors of the HPA axis and that network approaches need be taken to fully understand the nature of the neuroendocrine stress response.

How to assess circadian rhythm in humans: a review of literature

It is well known that seizures of some types of epilepsy tend to occur in patterns. The circadian rhythm may play a significant role in this phenomenon. In animal studies it has been found that seizures in experimental partial epilepsy are probably under the influence of the biological clock. In this review an introduction to the influence of the human circadian rhythm in epilepsy is given. Furthermore, the methodology of measuring the circadian rhythm in humans is explored. An overview of widely used methods includes protocols used to desynchronize circadian rhythm, and sleep-wake and biological markers such as the dim light melatonin onset, core body temperature, and cortisol that are employed to determine the phase of the circadian rhythm. Finally, the use of sleep parameters, actigraphy, and questionnaires is discussed. These are also important in assessment of the circadian rhythm.

Behavioral and hormonal reactivity to threat: effects of selective amygdala, hippocampal or orbital frontal lesions in monkeys

We compared the effects of bilateral amygdala, hippocampal or orbital frontal cortex lesions on emotional and hormonal reactivity in rhesus monkeys (Macaca mulatta). Experiment 1 measured behavioral reactivity to an unfamiliar human intruder before and after surgery. Animals with amygdala lesions demonstrated decreases in one passive defensive behavior (freezing), whereas animals with hippocampal lesions showed decreases in a more stimulus-directed defensive behavior (tooth grinding). Orbital frontal cortex lesions also reduced these two defensive behaviors, as well as decreased cage-shaking dominance displays. Animals with amygdala, hippocampal or sham lesions also demonstrated increased tension-related behaviors after surgery, but those with orbital frontal lesions did not. Finally, all three lesions diminished the operated animals' ability to modulate tension-related behaviors depending on the magnitude of threat posed by the human intruder. Experiment 2 measured circulating levels of cortisol and testosterone when a subset of these same animals was at rest and following physical restraint, temporary isolation, exposure to threatening objects and social interactions with an unfamiliar conspecific. None of the lesions impacted on testosterone levels in any condition. Amygdala or orbital frontal lesions blunted cortisol reactivity during isolation from peers, but not during any other condition. Hippocampal lesions did not alter circulating levels of cortisol under any condition. These results indicate that the amygdala, hippocampus and orbital frontal cortex play distinct, yet complimentary roles in coordinating emotional and hormonal reactivity to threat.

Brain inflammation in epilepsy: experimental and clinical evidence

Inflammatory reactions occur in the brain in various CNS diseases, including autoimmune, neurodegenerative, and epileptic disorders. Proinflammatory and antiinflammatory cytokines and related molecules have been described in CNS and plasma, in experimental models of seizures and in clinical cases of epilepsy. Inflammation involves both the innate and the adaptive immune systems and shares molecules and pathways also activated by systemic infection. Experimental studies in rodents show that inflammatory reactions in the brain can enhance neuronal excitability, impair cell survival, and increase the permeability of the blood-brain barrier to blood-borne molecules and cells. Moreover, some antiinflammatory treatments reduce seizures in experimental models and, in some instances, in clinical cases of epilepsy. However, inflammatory reactions in brain also can be beneficial, depending on the tissue microenvironment, the inflammatory mediators produced in injured tissue, the functional status of the target cells, and the length of time the tissue is exposed to inflammation. We provide an overview of the current knowledge in this field and attempt to bridge experimental and clinical evidence to discuss critically the possibility that inflammation may be a common factor contributing, or predisposing, to the occurrence of seizures and cell death, in various forms of epilepsy of different etiologies. The elucidation of this aspect may open new perspectives for the pharmacologic treatment of seizures.

Seizure Frequency and Cortisol and Dehydroepiandrosterone Sulfate (DHEAS) Levels in Women with Epilepsy Receiving Antiepileptic Drug Treatment

PURPOSE

Hormonal changes occur in epilepsy because of seizures themselves and of antiepileptic drug (AED) effects on steroid production, binding, and metabolism. Conversely, steroids may influence neuron activity and excitability by acting as neuroactive steroids. This cross-sectional observational study aimed to evaluating cortisol and dehydroepiandrosterone sulfate (DHEAS) levels in female epilepsy patients with different disease severity, as assessed by a seizure frequency score (SFS).

METHODS

Morning serum levels of cortisol and DHEAS were assayed in 113 consecutive women, aged 16 to 47 years, with varied epilepsy syndromes, receiving mono- or polytherapy with enzyme-inducing and/or noninducing antiepileptic drugs (AEDs). Hormonal data were correlated with clinical parameters (age, body mass index, epilepsy syndrome, disease onset and duration, SFS, AED therapy, and AED serum levels) and compared with those of 30 age-matched healthy women.

RESULTS

In epilepsy patients, cortisol levels and cortisol-to-DHEAS ratios (C/Dr) were significantly higher, whereas DHEAS levels were significantly lower than those in controls. Patients with more frequent seizures showed higher cortisol and C/Dr values and lower DHEAS levels than did those with rarer or absent seizures during the previous 6 months. SFS mainly explained the increase of cortisol levels and C/Dr in patients with more active disease. Changes in DHEAS levels correlated with SFS and epilepsy syndrome, as well as with AED treatments and ages.

CONCLUSIONS

Women with more frequent seizures had alterations of their adrenal steroids characterized by an increase of cortisol and a decrease of DHEAS levels. Such hormonal changes might be relevant in seizure control and in patient health.

Central mechanisms of stress integration: hierarchical circuitry controlling hypothalamo-pituitary-adrenocortical responsiveness

Appropriate regulatory control of the hypothalamo-pituitary-adrenocortical stress axis is essential to health and survival. The following review documents the principle extrinsic and intrinsic mechanisms responsible for regulating stress-responsive CRH neurons of the hypothalamic paraventricular nucleus, which summate excitatory and inhibitory inputs into a net secretory signal at the pituitary gland. Regions that directly innervate these neurons are primed to relay sensory information, including visceral afferents, nociceptors and circumventricular organs, thereby promoting 'reactive' corticosteroid responses to emergent homeostatic challenges. Indirect inputs from the limbic-associated structures are capable of activating these same cells in the absence of frank physiological challenges; such 'anticipatory' signals regulate glucocorticoid release under conditions in which physical challenges may be predicted, either by innate programs or conditioned stimuli. Importantly, 'anticipatory' circuits are integrated with neural pathways subserving 'reactive' responses at multiple levels. The resultant hierarchical organization of stress-responsive neurocircuitries is capable of comparing information from multiple limbic sources with internally generated and peripherally sensed information, thereby tuning the relative activity of the adrenal cortex. Imbalances among these limbic pathways and homeostatic sensors are likely to underlie hypothalamo-pituitary-adrenocortical dysfunction associated with numerous disease processes.

CNS inputs to the suprachiasmatic nucleus of the rat

The neural circuits that modulate the suprachiasmatic nucleus (SCN) of the rat were studied with the retrograde transneuronal tracer--pseudorabies virus. First-order afferents were also identified using cholera toxin beta subunit. Olfactory processing regions (viz., main olfactory bulb, anterior olfactory nucleus, taenia tecta, endopiriform nucleus, medial amygdaloid nucleus, piriform cortex, and posteriomedial cortical amygdaloid nucleus) were virally labeled. The subfornical organ directly innervates SCN; two other circumventricular organs: organum vasculosum of the lamina terminalis and area postrema provide multisynaptic inputs. Direct limbic afferents arise from lateral septum, bed nucleus of the stria terminalis, amygdalohippocampal zone, and ventral subiculum; multineuronal connections come from the basolateral and basomedial amygdaloid nuclei, ventral hippocampus, amygdalopiriform area, as well as lateral entorhinal, perirhinal, and ectorhinal cortices. Most preoptic regions project directly to SCN. Multisynaptic inputs come from the lateral preoptic region. Hypothalamic inputs originate from the anterior, arcuate, dorsal, dorsomedial, lateral, paraventricular, posterior, periventricular posterior, retrochiasmatic, subparaventricular, ventromedial and tuberomammillary nuclei. Paraventricular thalamic nucleus, intergeniculate leaflet and zona incerta directly innervate SCN. Polyneuronal inputs arise from the subparafascicular parvicellular thalamic nucleus. Brainstem afferents originate from the pretectum, superior colliculus, periaqueductal gray matter, parabrachial nucleus, pedunculopontine nucleus, raphe system, locus coeruleus, nucleus incertus and reticular formation. Nucleus tractus solitarius, C3 catecholamine region, rostral ventrolateral medulla and spinal trigeminal nucleus provide indirect inputs. We propose that the SCN receives feedback primarily from interoceptive systems such as the circumventricular, autonomic, and neuroendocrine systems that are important in the central regulation of glucose metabolism (e.g., insulin and glucocorticoids).

The effect of seizures and kindling on reproductive hormones in the rat

Reproductive dysfunction and endocrine disorders are common among both women and men with epilepsy, and, in particular, with temporal lobe epilepsy. In clinical studies, it is hard to separate the effects of seizures from the effects of medication and life style. Studies in rodents, however, suggest that seizures per se can contribute to reproductive dysfunction. In female rats, generalized seizures disrupt normal ovarian cyclicity in adults, and repeated electroshock seizures delay the onset of puberty in juveniles. Right amygdala kindling in adult female rats causes acyclicity, the development of polycystic ovaries and premature aging of the hypothalamic-pituitary neuroendocrine axis, leading to chronic anovulation and continuous estrogen exposure. In adult male rats, repeated electroshock seizures result in transient hypogonadism, characterized by decreased serum testosterone levels and lowered gonadal tissue weight. In contrast, right amygdala kindling increases serum testosterone, estradiol levels and gonadal weight. These findings suggest that reproductive dysfunction in women and men with epilepsy may result from recurrent seizure activity, due to seizure-related interference with the normal functions of the hypothalamic-pituitary-gonadal axis.

Autonomic and hormonal ictal changes in gelastic seizures from hypothalamic hamartomas

OBJECTIVES

We describe two patients with hypothalamic hamartoma and gelastic seizures.

METHODS

We performed ictal neurophysiological studies with polygraphic recordings of autonomic parameters and hormonal ictal plasma concentration measurements.

RESULTS

Ictal recordings showed a stereotyped modification of autonomic parameters: increase in blood pressure and heart rate, peripheral vasoconstriction and modification of respiratory activity. At seizure onset, the norepinephrine plasma level was high and epinephrine unchanged, whereas prolactin and adrenocorticotropic hormone were increased in both cases. Growth hormone and cortisol plasma concentrations in each patient showed a different response to seizures.

CONCLUSIONS

These data provide evidence that gelastic seizures are accompanied by an abrupt sympathetic system activation, probably due to the direct paroxysmal activation of limbic and paralimbic structures or other autonomic centres of the hypothalamus and medulla.

Magnetic brain stimulation: safety studies

We describe short-term and long-term safety studies after low repetition rate magnetic brain stimulation in 10 normal subjects. We obtained quantitative EEG data, psychometric test results, serum prolactin and cortisol levels before and after brain stimulation. EEG and psychometric data were also obtained in 5 of these subjects 16-24 months after the initial experiment. Short- and long-term studies did not show any deleterious effects. Randt delayed recalls, however, showed a transient reduction in the score immediately after stimulation which resolved on retesting in 2 weeks. To address the question of fatigue we repeated Randt tests in 4 subjects before and after magnetic brain stimulation but without the other extensive psychometric, EEG and blood tests. Pre- and post-stimulation scores on this occasion showed no significant difference in these 4 subjects suggesting that the transient changes in the previous Randt score were related to fatigue. We conclude that single-pulse magnetic brain stimulation has no deleterious effects after magnetic brain stimulation.

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

The time course and extent of changes in plasma prolactin, noradrenaline, vasopressin and oxytocin levels is reported following serial observations of a prolonged epileptic seizure arising in the temporal lobe, recorded by video-EEG-telemetry, in which the epileptic activity evolved from a simple partial to complex partial to secondarily generalised attack. The prolactin levels were markedly elevated during the phase of the simple partial seizure, at a time when consciousness was preserved, when motor activity was minimal and when EEG activity was highly localised. The hormonal levels continued to rise during the subsequent seizure evolution, suggesting that the duration (or intensity) of the seizure is an important, perhaps the most important, factor determining the degree of prolactin release during limbic seizures. Indeed, the prolactin elevation in this case (26 times the baseline level) is higher than any previously recorded, reflecting the unusual duration and intensity of this seizure. We did not observe the phenomenon of "exhaustion" of prolactin release and levels peaked after 49 min, and were high for over 2 h after the onset of the seizure, and after the convulsion had ceased. The concentrations of vasopressin, oxytocin and noradrenaline remained low during the aura, but rapidly increased during the phase of generalisation. The oxytocin and noradrenaline levels peaked during the phase of generalised convulsion, but the vasopressin levels peaked well into the post ictal phase, and remained high for several hours.(ABSTRACT TRUNCATED AT 250 WORDS)

Transcranial magnetic stimulation. Its role in the evaluation of patients with partial epilepsy

Transcranial magnetic stimulation (TMS) is a relative new method in the evaluation of patients with various neurological diseases. With the introduction of repetitive (rapid rate) transcranial magnetic stimulators (RTMS), it has been possible to apply cortical stimuli with a stimulus rate up to 100 Hz. The preliminary results with TRMS suggest that it may be used in the study of speech lateralization. Seizures have been reported in patients with partial epilepsy during TMS. In these cases it remains uncertain whether the seizures were induced by the TMS or coincidentally with it. Minor changes in paroxysmal activity have been reported in some patients. These data suggest, that TMS is neither sensitive nor specific as an activation procedure of the epileptic focus in patients with partial epilepsy. Seizures have been provoked using RTMS, but its use as a seizure-inducing method is not yet evaluated.

Growth hormone and prolactin in temporal lobe epilepsy

Growth hormone and prolactin levels were measured sequentially during wakefulness and sleep, in seven patients with unilateral temporal lobe epilepsy who underwent telemetric EEG monitoring (10-24 h), and in three additional patients studied while temporal structures were stimulated with implanted electrodes during pre-surgical evaluation. The results indicated that growth hormone/prolactin release patterns were not significantly affected by selective unilateral stimulation of deep temporal structures, or, when sleep patterns were normal, by epileptic activity confined to one temporal lobe.

Serum thyroid hormones and pituitary response to thyrotropin-releasing hormone in epileptic children receiving anti-epileptic medication

Thyroid hormones and pituitary function were assessed in 49 children with epilepsy who were receiving either a single medication of carbamazepine, phenobarbital and valproate or a combination of carbamazepine with phenobarbital or valproate. All therapeutic regimens except valproate monotherapy were associated with low levels of circulating thyroxine, free tri-iodothyronine and free thyroxine. Carbamazepine with valproate was associated with the lowest serum concentration of thyroid hormones. It seems probable that accelerated hormone metabolism is responsible for these hormonal changes. However, all drug regimens also had effects on the function of the hypothalamic pituitary axis. Because of these findings, thyroid hormones should be checked frequently during anti-epileptic drug treatment, although clinical hypothyroidism was not seen in our patients.

Nocturnal prolactin and growth hormone levels in children with complex partial and generalized tonic-clonic seizures

This study measures whether there is a rise in the secretion of nocturnal prolactin and growth hormone (GH), during the delta phase of the first sleep cycle in children who are suffering from either complex partial or generalized tonic-clonic seizures. The findings are compared with those obtained in the control group of patients which is made up who suffer from pseudoseizures. There is a moderate but significant rise in the nocturnal prolactin plasma level in both types of infantile seizures. No significant difference was found in the GH.

Serum prolactin concentrations and epilepsy. A study which compares healthy subjects with a group of patients in presurgical evaluation and circadian variations with those related to seizures

In 20 healthy subjects (10 female and 10 male) and 17 patients undergoing presurgical epilepsy evaluation with intracranial EEG electrodes, circadian variations of serum prolactin (PRL) were measured. A comparison between the peak values found in normals with the postictal rises in patients, led us to consider 700 microU/ml to be the threshold of diagnostic value and the observed rises above this level to be all induced by seizures. In order to assess the clinical value of this threshold, PRL was measured postictally in a further 30 patients with epilepsy and in 11 patients with psychogenic seizures. In none of the latter group did PRL rises exceed 700 microU/ml, while they did so in 39% of the complex partial seizures and in 80% of the tonic-clonic seizures. There was no significant difference with respect to sex (a rise over 700 microU/ml in 42% in male and in 55% in female patients). Based on the findings in 17 patients investigated by means of intracranial electrodes, we were not able to establish different criteria for different focus localisations: in 66% of both temporal as well as frontal lobe seizures the 700 microU/ml level was exceeded. As a trend, in the period preceding an epileptic seizure we found a slightly decreasing PRL level, whereas in healthy persons the PRL concentrations gradually increased in the 40 minutes before the maximum spontaneous peak was reached.

Effect of non-sex hormones on neuronal excitability, seizures, and the electroencephalogram

Several of the non-sex hormones have been found to be useful in the treatment of seizures. These hormones have an effect on seizures, and seizures have an effect on these hormones. Adrenocorticotropic hormone (ACTH) and corticosteroid drugs have been found to be useful in the treatment of infantile spasms and other seizure disorders. Unfortunately, there is no clear consensus regarding superiority of ACTH versus prednisone in regard to efficacy and long-term benefits, dosage, or duration of treatment. There is also considerable debate regarding reasons why ACTH and prednisone are useful in infantile spasms, their mechanism of action, and their long-term effects on brain development. Thyrotropin-releasing hormone also has been used in the treatment of infantile spasms and other seizure types in children, with modest success. As with ACTH and prednisone, the mechanisms of action remain unclear.

The effect of seizures on hormones

Serum prolactin (HPR) levels are influenced by waking and sleep states, as reflected by surges in serum concentrations during daytime naps and nocturnal sleep. Other physiological causes of hyperprolactinemia include sexual activity, pregnancy, and lactation. Drugs may stimulate or inhibit HPR secretion. Pathological causes for HPR secretion include destructive lesions of the hypothalamus, prolactin-secreting neoplasms of the pituitary gland, lesions of the spinal cord, and occasionally Parkinson's disease. The most predictable postictal changes are increased serum cortisol levels and hyperprolactinemia. Serum HPR rises after virtually all generalized tonic-clonic seizures, most complex partial seizures, and some simple partial seizures. Absence and myoclonic seizures do not affect serum HPR levels. Repeated epileptic seizures and electroconvulsive therapy treatments produce successively less marked rises in serum HPR. The postictal elevation of serum cortisol has a longer latency than for HPR and follows an earlier rise in serum ACTH. Other postictal hormonal changes are much more variable. Because of the normal diurnal variation in serum cortisol levels and the relative delay in the postictal elevation of serum cortisol, HPR is more useful as a diagnostic measure of epileptic seizures. This application of HPR requires an understanding of other factors that influence serum HPR and the use of baseline serum HPR levels for comparison. HPR data must be correlated with behavioral and electroencephalographic events.

Electrical stimulation of the human hippocampus produces verbal intrusions during memory testing

Verbal memory testing was conducted during electrical stimulation of the human hippocampus in 12 epilepsy surgery candidates with unilateral temporal lobe seizure onset. Performance was assessed during baseline, left hippocampal stimulation and right hippocampal stimulation. Verbal intrusion errors were greater during electrical stimulation of the hippocampus contralateral to the seizure focus. These findings suggest that verbal intrusions are related to memory deficits, and that patients with cerebral disease who intrude words from an earlier portion of a learning test are likely to have bilateral cerebral dysfunction.