Lateral asymmetry in activation of hypothalamic neurons with unilateral amygdaloid seizures

Female sex steroids and epilepsy: Part 1. A review of reciprocal changes in reproductive systems, cycles, and seizures

Seizures, antiseizure medications, and the reproductive systems are reciprocally entwined. In Section 2 of this review, we outline how seizures may affect the hypothalamic-pituitary-gonadal axis, thereby altering sex steroids, and changes in sex steroids across the menstrual cycle and changes in pharmacokinetics during pregnancy may alter seizure susceptibility. The literature indicates that females with epilepsy experience increased rates of menstrual disturbances and reproductive endocrine disorders. The latter include polycystic ovary syndrome, especially for females on valproate. Studies of fertility have yielded mixed results. We aim to summarize and attempt to detangle the existing knowledge on these reciprocal interactions. The menstrual cycle causes changes in seizure intensity and frequency for many females. When this occurs perimenstrually, during ovulation, or in association with an inadequate luteal phase, it is termed catamenial epilepsy. There is a clear biophysiological rationale for how the key female reproductive neurosteroids interact with the brain to alter the seizure threshold, and Section 3 outlines this important relationship. Critically, what remains unknown is the specific pathophysiology of catamenial epilepsy that describes why not all females are affected. There is a need for mechanism-focused investigations in humans to uncover the complexity of the relationship between reproductive hormones, menstrual cycles, and the brain.

Mechanisms linking neurological disorders with reproductive endocrine dysfunction: Insights from epilepsy research

Gonadal hormone actions in the brain can both worsen and alleviate symptoms of neurological disorders. Although neurological conditions and reproductive endocrine function are seemingly disparate, compelling evidence indicates that reciprocal interactions exist between certain disorders and hypothalamic-pituitary-gonadal (HPG) axis irregularities. Epilepsy is a neurological disorder that shows significant reproductive endocrine dysfunction (RED) in clinical populations. Seizures, particularly those arising from temporal lobe structures, can drive HPG axis alterations, and hormones produced in the HPG axis can reciprocally modulate seizure activity. Despite this relationship, mechanistic links between seizures and RED, and vice versa, are still largely unknown. Here, we review clinical evidence alongside recent investigations in preclinical animal models into the contributions of seizures to HPG axis malfunction, describe the effects of HPG axis hormonal feedback on seizure activity, and discuss how epilepsy research can offer insight into mechanisms linking neurological disorders to HPG axis dysfunction, an understudied area of neuroendocrinology.

Psychometric Properties of the Persian Version of Adult Eating Behavior Questionnaire in Patients with Epilepsy

Background

Adult eating behavior questionnaire (AEBQ) is an age upward extension tool that measures appetite traits in individuals. This instrument was developed by Hunot in 2016. The present study aimed to determine the psychometric properties of the Persian version of AEBQ in adults with epilepsy.

Methods

The current research is a cross-sectional study conducted in 2019 in Iran. 700 adults with epilepsy completed the 35-item AEBQ. Qualitative face validity, qualitative content and structure validity (exploratory factor analysis [EFA], N=400, and confirmatory factor analysis [CFA], N=300) appetitive traits were evaluated. Reliability was also measured using Cronbach's alpha, Construct reliability (CR), and Intra-Class Correlation (ICC). The SPSS 26-AMOS24 software was employed to analyze the data with a significance level of 0.05.

Results

The EFA and CFA results comprised eight factors, namely enjoyment of food, emotional over-eating, food responsiveness, hunger, satiety responsiveness, emotional under-eating, food fussiness, and eating slowly. Indices of root mean square error of approximation=0.068, parsimonious normed fit index=0.644, parsimonious comparative fit index=0.671, adjusted goodness of fit index=0.618, goodness of fit index=0.911, and Chi square degree-of-freedom ratio (normalized Chi square CMIN/DF=2.842) confirmed the fitness of the final model. Convergent and divergent validity was acceptable for all the factors. The results revealed that the internal stability>0.8 and CR>0.7 of the eight extracted AEBQ structures are confirmed. The ICC was 0.899 (95% CI: 0.878-0.917; P<0.001). The results also showed that AEBQ has acceptable convergent and divergent validity.

Conclusion

The eight-factor structure of AEBQ can measure eating behavior traits and is of good validity and reliability for assessing the eating behavior of Iranian adults with epilepsy.

The interactions between reproductive hormones and epilepsy

There are complex interactions between hormones, epilepsy, and antiepileptic drugs (AEDs). While there is ample evidence that hormones influence epilepsy, it is also apparent that epileptic activity influences hormones in both women and men. In addition, AEDs may disturb endocrine function. The clinical importance of these interactions is primarily related to the effects on reproductive hormones, which is the focus of this article. Reproductive endocrine dysfunction is common among women and men with epilepsy. Menstrual disorders, polycystic ovaries, and infertility have been described among women with epilepsy, while reduced potency and sperm abnormalities have been found in men. Sexual problems and endocrine changes have been frequently described in both sexes. Epilepsy and AEDs can target a number of substrates to impact hormone levels. These include the limbic system, hypothalamus, pituitary, peripheral endocrine glands, liver, and adipose tissue. AEDs may also alter the synthesis of steroids and binding proteins, as well as hormone metabolism, and produce direct gonadal effects.

Rasmussen's encephalitis and central precocious puberty. Neuroendocrinological characterization of three cases

PURPOSE

Rasmussen's encephalitis (RE) is a chronic neurological disorder characterized by inflammation of the cerebral cortex, mainly unilateral, that leads to drug-resistant epilepsy and progressive neurological impairment. Central Precocious Puberty (CPP) is uncommon, albeit increased in frequency in patients with neurological conditions and the physiopathological bases of these associations remains unclear in most cases. Epilepsy has been proposed to play a role, as well as the accumulation of substances produced as a result of metabolism or tissue degeneration in some neurodegenerative diseases. However, CPP has not been previously described in patients with RE.

METHODS

From a series of patients affected by RE followed-up at a referral center, an in-depth review of the characteristics of those who developed CCP was carried out.

RESULTS

Three cases were identified, representing a relative frequency of 21.4 % for CPP. They were girls, of Caucasian ethnicity, without family history of CPP or any image-identified abnormalities in the hypothalamic area. In two cases CPP manifested immediately before the onset of the epilepsy (prior to the diagnosis of RE) and in the other, after epilepsy onset but coinciding with a worsening of the seizures. A GnRH test with pubertal response confirmed CPP in the three cases.

CONCLUSION

The high proportion of CPP in patients affected by RE suggested a plausible relationship between these two entities. Various factors involved, including neuroinflammation, are hypothesized in the present study. However, further studies are needed to elucidate the pathophysiological bases, which could provide insight in the understanding of both entities.

Anhedonia Following Early-Life Adversity Involves Aberrant Interaction of Reward and Anxiety Circuits and Is Reversed by Partial Silencing of Amygdala Corticotropin-Releasing Hormone Gene

BACKGROUND

Anhedonia, the diminished ability to experience pleasure, is an important dimensional entity linked to depression, schizophrenia, and other emotional disorders, but its origins and mechanisms are poorly understood. We have previously identified anhedonia, manifest as decreased sucrose preference and social play, in adolescent male rats that experienced chronic early-life adversity/stress (CES). Here we probed the molecular, cellular, and circuit processes underlying CES-induced anhedonia and tested them mechanistically.

METHODS

We examined functional brain circuits and neuronal populations activated by social play in adolescent CES and control rats. Structural connectivity between stress- and reward-related networks was probed using high-resolution diffusion tensor imaging, and cellular/regional activation was probed using c-Fos. We employed viral-genetic approaches to reduce corticotropin-releasing hormone (Crh) expression in the central nucleus of the amygdala in anhedonic rats, and tested for anhedonia reversal in the same animals.

RESULTS

Sucrose preference was reduced in adolescent CES rats. Social play, generally considered an independent measure of pleasure, activated brain regions involved in reward circuitry in both control and CES groups. In CES rats, social play activated Crh-expressing neurons in the central nucleus of the amygdala, typically involved in anxiety/fear, indicating aberrant functional connectivity of pleasure/reward and fear circuits. Diffusion tensor imaging tractography revealed increased structural connectivity of the amygdala to the medial prefrontal cortex in CES rats. Crh-short hairpin RNA, but not control short hairpin RNA, given into the central nucleus of the amygdala reversed CES-induced anhedonia without influencing other emotional measures.

CONCLUSIONS

These findings robustly demonstrate aberrant interactions of stress and reward networks after early-life adversity and suggest mechanistic roles for Crh-expressing amygdala neurons in emotional deficits portending major neuropsychiatric disorders.

Interactions between hormones and epilepsy

There is a complex, bidirectional interdependence between sex steroid hormones and epilepsy; hormones affect seizures, while seizures affect hormones thereby disturbing reproductive endocrine function. Both female and male sex steroid hormones influence brain excitability. For the female sex steroid hormones, progesterone and its metabolites are anticonvulsant, while estrogens are mainly proconvulsant. The monthly fluctuations in hormone levels of estrogen and progesterone are the basis for catamenial epilepsy described elsewhere in this issue. Androgens are mainly anticonvulsant, but the effects are more varied, probably because of its metabolism to, among others, estradiol. The mechanisms for the effects of sex steroid hormones on brain excitability are related to both classical, intracellularly mediated effects, and non-classical membrane effects due to binding to membrane receptors. The latter are considered the most important in relation to epilepsy. The different sex steroids can also be further metabolized within the brain to different neurosteroids, which are even more potent with regard to their effect on excitability. Estrogens potentiate glutamate responses, primarily by potentiating NMDA receptor activity, but also by affecting GABA-ergic mechanisms and altering brain morphology by increasing dendritic spine density. Progesterone and its main metabolite 5α-pregnan-3α-ol-20-one (3α-5α-THP) act mainly to enhance postsynaptic GABA-ergic activity, while androgens enhance GABA-activated currents. Seizures and epileptic discharges also affect sex steroid hormones. There are close anatomical connections between the temporolimbic system and the hypothalamus controlling the endocrine system. Several studies have shown that epileptic activity, especially mediated through the amygdala, alters reproductive function, including reduced ovarian cyclicity in females and altered sex steroid hormone levels in both genders. Furthermore, there is an asymmetric activation of the hypothalamus with unilateral amygdala seizures. This may, again, be the basis for the occurrence of different reproductive endocrine disorders described for patients with left-sided or right-sided temporal lobe epilepsy.

Sex dimorphism in seizure-controlling networks

Males and females show a different predisposition to certain types of seizures in clinical studies. Animal studies have provided growing evidence for sexual dimorphism of certain brain regions, including those that control seizures. Seizures are modulated by networks involving subcortical structures, including thalamus, reticular formation nuclei, and structures belonging to the basal ganglia. In animal models, the substantia nigra pars reticulata (SNR) is the best studied of these areas, given its relevant role in the expression and control of seizures throughout development in the rat. Studies with bilateral infusions of the GABA(A) receptor agonist muscimol have identified distinct roles of the anterior or posterior rat SNR in flurothyl seizure control, that follow sex-specific maturational patterns during development. These studies indicate that (a) the regional functional compartmentalization of the SNR appears only after the third week of life, (b) only the male SNR exhibits muscimol-sensitive proconvulsant effects which, in older animals, is confined to the posterior SNR, and (c) the expression of the muscimol-sensitive anticonvulsant effects become apparent earlier in females than in males. The first three postnatal days are crucial in determining the expression of the muscimol-sensitive proconvulsant effects of the immature male SNR, depending on the gonadal hormone setting. Activation of the androgen receptors during this early period seems to be important for the formation of this proconvulsant SNR region. We describe molecular/anatomical candidates underlying these age- and sex-related differences, as derived from in vitro and in vivo experiments, as well as by [(14)C]2-deoxyglucose autoradiography. These involve sex-specific patterns in the developmental changes in the structure or physiology or GABA(A) receptors or of other subcortical structures (e.g., locus coeruleus, hippocampus) that may affect the function of seizure-controlling networks.

Obesity in adults with epilepsy

Sixty-eight percent of the US adult population is overweight, and 35% is obese. The rate of obesity in patients with epilepsy is unknown. Its determination was the goal of the present study. Weight and height were measured, and body mass index (BMI) was calculated in all newly evaluated patients with epilepsy at a single epilepsy center between 2003 and 2009. Five hundred fifty-four patients aged ≥16-87years were included (62.7% were women, 12.6% with primary generalized epilepsy, and 86.4% with localization-related epilepsy). Three hundred six (55.2%) patients were overweight or obese (BMI>25kg/m(2)) (95% confidence interval [CI]: 51.1%-59.3%), 173 (31.2%) were obese (BMI>30kg/m(2)) (95% CI: 27.5%-35.2%), and 24 (4.3%) were morbidly obese (BMI>40kg/m(2)). Overweight/obesity combined was more common in men (65.4% [95% CI: 58.8%-71.5%]) than in women (49% women [95% CI: 43.3%-54.3%]) (p≤0.001). The rate of overweight/obesity combined trended to be greater in blacks (67.9%) than in whites (51.9%). Obesity alone was more common in blacks (46.4%) than in whites (29.4%), with too few Hispanics and Asians to allow a comparison. Overweight/obesity and obesity rates were higher in patients with refractory than nonrefractory epilepsy (60.4% vs. 49.2% overweight, 36.9% vs.24.6% obesity). Obesity was more common in patients treated with polytherapy than those treated with monotherapy (37.7% vs. 25%). There were no associations between obesity and other disease characteristics such as epilepsy type, duration, or etiology. Obesity is common in patients with epilepsy, similar to the general population.

Neuroendocrine considerations in the treatment of men and women with epilepsy

Complex, multidirectional interactions between hormones, seizures, and the medications used to control them can present a challenge for clinicians treating patients with epilepsy. Many hormones act as neurosteroids, modulating brain excitability via direct binding sites. Thus, changes in endogenous or exogenous hormone levels can affect the occurrence of seizures directly as well as indirectly through pharmacokinetic effects that alter the concentrations of antiepileptic drugs. The underlying structural and physiological brain abnormalities of epilepsy and the metabolic activity of antiepileptic drugs can adversely affect hypothalamic and gonadal functioning. Knowledge of these complex interactions has increased and can now be incorporated in meaningful treatment approaches for men and women with epilepsy.

Hormonal consequences of epilepsy and its treatment in men

PURPOSE OF REVIEW

Epilepsy and anticonvulsant medications may substantially alter endocrine homeostasis, including the male reproductive hormonal system.

RECENT FINDINGS

Seizures in medial temporal lobe structures, through their connectivity to the hypothalamus, alter the secretion of gonadotropins. Levels of circulating bioavailable testosterone are affected by changes in the level of binding proteins, which in turn may be affected by seizure medications. The use of older generation medications that induce the cytochrome P450 system is associated with an increase in sex hormone-binding globulin and lower bioactive testosterone. Sexual dysfunction, including decreased libido and decreased potency, and infertility, is seen commonly in men with epilepsy. However, its relation to sex hormone levels remains unclear. Comorbid depression and anxiety may be important confounding factors. Testosterone and sexual function appear not to be affected by the newer generation (noninducing) anticonvulsants.

SUMMARY

Epilepsy and its drug treatments are associated with alterations in hormonal and sexual function in men. Further study is needed to clarify the precise mechanisms behind these alterations, as some of the data conflict. More attention should be paid to this issue in male patients with seizures; when appropriate, treatment for psychiatric comorbidity and switches in anticonvulsant therapy may be worth consideration.

Antiepileptic drugs, sex hormones, and PCOS

Reproductive endocrine dysfunction in women with epilepsy is an important issue, and in recent years there is growing evidence to support the effect on sex hormones of both epilepsy per se and various antiepileptic drugs (AEDs). Focal epileptic discharges from the temporal lobe may have a direct influence on the function of the hypothalamic-pituitary axis, thereby altering the release of sex steroid hormones. The role of laterality and severity of epilepsy is still conflicting. The use of the liver enzyme-inducing AEDs--such as phenobarbital, phenytoin, and carbamazepine--can increase serum sex hormone-binding globulin concentrations, leading to diminished bioactivity of testosterone (T) and estradiol. Valproic acid, an enzyme inhibitor, has been associated with the occurrence of reproductive endocrine disorders characterized by high serum T, free androgen index, androstenedione, dehydroepiandrosterone sulfate concentrations, and with polycystic changes in ovaries and menstrual disorders. A better understanding of the effects of AEDs on sex hormones is key to selecting the appropriate AEDs and is crucial for reproductive health in female patients.

Hormonal alterations following seizures

Postictal increases in prolactin (PRL), luteinizing hormone, and follicle-stimulating hormone have been recorded in patients with both generalized tonic-clonic and partial seizures. Elevations of PRL and luteinizing hormone were seen immediately and at 20 minutes after generalized tonic-clonic seizures in male and female patients. Usually, PRL blood levels return to normal values within 1 hour. Previous studies have evaluated the utility of the transient increases in PRL, neuron-specific enolase, and S-100 protein as markers of epileptic seizures in children and adults. The conclusion was that measurement of serum PRL is a reliable confirmatory test in the presence of a seizure, but only modestly effective as a screening test for suspected seizures. Temporal lobe epilepsy is associated with abnormalities of reproductive physiology, but the mechanisms of hormonal dysregulation are not clear. A direct influence of epilepsy on the reproductive endocrine system is suggested by acute changes in PRL and gonadotropin levels following generalized and partial seizures, pointing to a possible relationship between temporolimbic epileptiform discharges and particular reproductive endocrine disorders. Chronic effects of the epileptic state and the acute impact of seizures could alter hypothalamic function, as indicated by downstream pulsatile secretion of luteinizing hormone. The brain controls reproductive function primarily through hypothalamic regulation of pituitary secretion regions of the hypothalamus. These are areas that are involved in the regulation, production, and secretion of gonadotropin-releasing hormone and receive extensive direct connections from the cerebral hemispheres, especially from temporolimbic structures, most notably from the amygdala, that are commonly involved in temporal lobe epilepsy. Significant relationships have been uncovered through which ictal and postictal effects of seizures and epilepsy may influence the function of this complex neuroendocrine system.

Laterality and location influence catamenial seizure expression in women with partial epilepsy

OBJECTIVE

The temporal distribution of seizures in women with localization-related epilepsy occurs periodically according to a model "clock" with the peak phase of occurrence corresponding to menstrual onset. The location and laterality of the epileptic lesion as well as patient age may affect periodicity.

METHODS

Baseline data from seizure and menstrual diaries of approximately 3 months duration were obtained from 100 women enrolled in a trial of hormonal therapy for localization-related epilepsy. Durations of individual cycles were normalized to a common menstrual phase and period. Normalized data were then combined to create distributions evaluated by localization (lobar: temporal [TL], extratemporal [XL], multifocal [MF], unknown), lateralization (left, right, bilateral, unknown), and age. Distributions were evaluated with analysis of variance (ANOVA) and curve-fitted by nonlinear least squares cosinor analysis.

RESULTS

A total of 71 patients had TL (left = 25, right = 29, bilateral = 17), 10 XL, 14 MF, and 5 unknown seizure foci. XL and MF seizures occurred randomly across the 28-day cycle. TL seizures (left = 875, right = 706) occurred nonrandomly (ANOVA p = 0.0003) and cyclically with peak occurrence near onset of menses ([value +/- SD] peak = 1.6 +/- 2.3 days, period = 27.0 days). Left-side TL seizures peaked cyclically at onset of menses (ANOVA p = 0.04, peak = 0.0 +/- 3.0 days, period = 30 days); right-side TL seizures occurred randomly. Age did not have a cyclical effect. Women below the median age had a significantly higher seizure rate than those above the median age.

CONCLUSION

Circalunar rhythms of seizures in women, and therefore, possibly strategies of hormonal treatments of catamenial epilepsy, vary with the neuroanatomic substrate of the seizure focus.

Consciousness and epilepsy: why are complex-partial seizures complex?

Why do complex-partial seizures in temporal lobe epilepsy (TLE) cause a loss of consciousness? Abnormal function of the medial temporal lobe is expected to cause memory loss, but it is unclear why profoundly impaired consciousness is so common in temporal lobe seizures. Recent exciting advances in behavioral, electrophysiological, and neuroimaging techniques spanning both human patients and animal models may allow new insights into this old question. While behavioral automatisms are often associated with diminished consciousness during temporal lobe seizures, impaired consciousness without ictal motor activity has also been described. Some have argued that electrographic lateralization of seizure activity to the left temporal lobe is most likely to cause impaired consciousness, but the evidence remains equivocal. Other data correlates ictal consciousness in TLE with bilateral temporal lobe involvement of seizure spiking. Nevertheless, it remains unclear why bilateral temporal seizures should impair responsiveness. Recent evidence has shown that impaired consciousness during temporal lobe seizures is correlated with large-amplitude slow EEG activity and neuroimaging signal decreases in the frontal and parietal association cortices. This abnormal decreased function in the neocortex contrasts with fast polyspike activity and elevated cerebral blood flow in limbic and other subcortical structures ictally. Our laboratory has thus proposed the "network inhibition hypothesis," in which seizure activity propagates to subcortical regions necessary for cortical activation, allowing the cortex to descend into an inhibited state of unconsciousness during complex-partial temporal lobe seizures. Supporting this hypothesis, recent rat studies during partial limbic seizures have shown that behavioral arrest is associated with frontal cortical slow waves, decreased neuronal firing, and hypometabolism. Animal studies further demonstrate that cortical deactivation and behavioral changes depend on seizure spread to subcortical structures including the lateral septum. Understanding the contributions of network inhibition to impaired consciousness in TLE is an important goal, as recurrent limbic seizures often result in cortical dysfunction during and between epileptic events that adversely affects patients' quality of life.

Disorders of reproduction in patients with epilepsy: primary neurological mechanisms

Reproductive disorders are unusually common among women and men with epilepsy. They are generally associated with and may be the consequence of reproductive endocrine disorders. Both epilepsy itself and antiepileptic drug use have been implicated in their pathophysiology. This review focuses on how temporolimbic dysfunction in epilepsy may disrupt normal neuroendocrine regulation and promote the development of reproductive endocrine disorders. The particular nature of the dysregulation may relate to the laterality and focality of the epilepsy and some hormonal changes may develop in close temporal relation to the occurrence of epileptiform discharges. In women, reproductive endocrine disorders include polycystic ovary syndrome, hypothalamic amenorrhea, functional hyperprolactinemia, and premature menopause. In men, hypogonadism may be hypogonadotropic, hypergonadotropic or related to hyperprolactinemia. The significance of these reproductive endocrine disorders is that they may contribute not only to sexual dysfunction and infertility but may also have an adverse impact on seizure control.

The relationship between polycystic ovary syndrome and antiepileptic drugs: a review of the evidence

Polycystic ovary syndrome (PCOS) is a serious endocrine disorder characterized by ovulatory dysfunction and hyperandrogenism that is thought to have a higher prevalence in women with epilepsy and perhaps bipolar disorder. Various theories have been offered to explain this higher prevalence of PCOS and other reproductive disorders in these patient populations, including the effects of the disease itself and of antiepileptic drugs, especially valproate, which may directly cause PCOS or indirectly lead to the disorder by causing weight gain that triggers insulin resistance, increased testosterone levels, and other reproductive abnormalities. A prospective, longitudinal study with larger cohorts in newly diagnosed women with epilepsy or bipolar disorder is needed to definitively characterize the relationship between antiepileptic drugs and PCOS. Until data from such a study are available, physicians need to be aware that there is a possibility of developing symptoms of PCOS in women of reproductive age who are treated with antiepileptic drugs. Despite this concern, the choice of antiepileptic drug for women with epilepsy or bipolar disorder should be based on the most effective agent for controlling neurologic symptoms.

Interictal EEG discharges, reproductive hormones, and menstrual disorders in epilepsy

We evaluated reproductive endocrine function in women with unilateral temporolimbic epilepsy and normal control subjects to assess the effects of epilepsy, epilepsy laterality, and antiepileptic drug use on the cerebral regulation of hormonal secretion. The findings indicate that reproductive endocrine function differs between women with epilepsy and normal control subjects. Significant differences exist at all levels of the reproductive neuroendocrine axis, that is, hypothalamus, pituitary, and peripheral gland. Differences show significant relationships to the epilepsy itself as well as to medication use. Reproductive neuroendocrine changes occur in a stochastic manner such that the laterality of unilateral temporolimbic discharges is associated with predictable directional changes in hormonal secretion at all levels of the reproductive neuroendocrine axis. These directional changes are consistent with the finding that different reproductive disorders may develop in relation to left- and right-sided temporolimbic epilepsy. Hormonal changes can show close temporal relationship to the occurrence of interictal epileptiform discharges and may vary in relation to the laterality of the discharges. Antiepileptic drugs differ in their effects on reproductive hormone levels. There are notable differences between enzyme-inducing and noninducing drugs. Menstrual disorders are more common among women with interictal discharges as well as women with abnormal hormonal findings.

Relationship of sexual dysfunction to epilepsy laterality and reproductive hormone levels in women

Sexual dysfunction has been reported to be common among women with epilepsy. Controlled studies, quantitative data, and investigations of potentially contributory factors, however, have been few. The purpose of this investigation was to determine if (1) sexual dysfunction is unusually common among women with partial seizures of temporal lobe origin (TLE), and (2) sexual dysfunction varies in relation to the laterality of EEG epileptiform discharges, antiepileptic drug use, and serum gonadal steroid levels. This controlled prospective investigation used a quantitative sexual rating scale and reproductive hormone measures to compare sexual dysfunction in women with left and right unilateral temporolimbic epilepsy and controls. Sexual dysfunction scores were significantly higher in women with TLE, and sexual dysfunction affected substantially more women with epilepsy than controls. Women with right-sided foci were affected more than women with left-sided foci. There was a significant inverse correlation between sexual dysfunction and bioactive testosterone levels in women with epilepsy as well as in controls. Serum estradiol was lower in women with TLE but did not correlate significantly with overall sexual dysfunction. The findings suggest that sexual dysfunction is significantly more common in women with right-sided epileptiform discharges than in controls and is inversely correlated with bioactive testosterone levels. The value of hormonal replacement or supplementation remains to be explored.

GnRH-immunoreactive fiber changes with unilateral amygdala-kindled seizures

PURPOSE

To assess whether unilateral amygdala seizures are associated with a change in the number and lateral distribution of gonadotropin releasing hormone (GnRH)-staining fibers in the ventromedial hypothalamus of female rats.

METHODS

The study compared three groups of female rats: (1) amygdala seizures induced by focal injection of kainic acid (KA); (2) saline injected controls; and (3) nai;ve controls. The animals were sacrificed at 4 weeks in the diestrus phase. GnRH fibers were counted in the ventromedial hypothalamus and compared among groups.

RESULTS

GnRH fiber counts were significantly lower in KA than saline and nai;ve animals ipsilaterally but not contralaterally.

CONCLUSIONS

This finding may support a potential mechanism by which (1) temporolimbic epilepsy may promote the development of reproductive endocrine disorders and (2) the laterality of the epilepsy may influence the particular nature of the reproductive endocrine disorder.

Effects of hemispheric lateralization and site specificity on immune alterations induced by kindled temporal lobe seizures

The effects of kindled seizures elicited from sites in the left and right temporal lobes on mitogen-induced proliferation (LPS, Con A, PHA) and induction of representative TH1 (IFN-gamma) and TH2 (IL-10, IL-4) cytokines were determined in activated rat splenocytes. With reference to cell proliferation, the changes depended on the hemispheric side and location of kindling. Kindling of the left side mediated significant increase in cell proliferation by LPS. Left side kindling resulted in decreased cell proliferation by PHA. Although right side kindling showed no change when taken together, further analysis showed that the reduced proliferation by PHA was mediated when the pyriform cortex was kindled with no change from amygdaloid nuclei. Similar hemispheric polarization was observed in the production of IL-10 and IFN-gamma by Con A-stimulated splenocytes in left side kindled rats. Hence, kindled temporal lobe seizures induced changes in specific immune functions. These effects are not only lateralized but are also specific with respect to the particular region kindled. Since epileptic patients have altered immune functions, this report contributes to our understanding of this complex immune-brain cross-talk in epilepsy.

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.