Cerebrospinal fluid corticotropin and cortisol are reduced in infantile spasms

Mechanisms of infantile epileptic spasms syndrome: What have we learned from animal models?

The devastating developmental and epileptic encephalopathy of infantile epileptic spasms syndrome (IESS) has numerous causes, including, but not limited to, brain injury, metabolic, and genetic conditions. Given the stereotyped electrophysiologic, age-dependent, and clinical findings, there likely exists one or more final common pathways in the development of IESS. The identity of this final common pathway is unknown, but it may represent a novel therapeutic target for infantile spasms. Previous research on IESS has focused largely on identifying the neuroanatomic substrate using specialized neuroimaging techniques and cerebrospinal fluid analysis in human patients. Over the past three decades, several animal models of IESS were created with an aim to interrogate the underlying pathogenesis of IESS, to identify novel therapeutic targets, and to test various treatments. Each of these models have been successful at recapitulating multiple aspects of the human IESS condition. These animal models have implicated several different molecular pathways in the development of infantile spasms. In this review we outline the progress that has been made thus far using these animal models and discuss future directions to help researchers identify novel treatments for drug-resistant IESS.

Biochemical mechanisms in pathogenesis of infantile epileptic spasm syndrome

The molecular mechanisms leading to infantile epileptic spasm syndrome (IESS) remain obscure. The only common factor seems to be that the spasms are restricted to a limited period of infancy, during a certain maturational state. Here the current literature regarding the biochemical mechanisms of brain maturation in IESS is reviewed, and various hypotheses of the pathophysiology are put together. They include: (1) imbalance of inhibitory (NGF, IGF-1, ACTH, GABA) and excitatory factors (glutamate, nitrites) which distinguishes the different etiological subgroups, (2) abnormality of the hypothalamic pituitary adrenal (HPA) axis linking insults and early life stress, (3) inflammation (4) yet poorly known genetic and epigenetic factors, and (5) glucocorticoid and vigabatrin action on brain development, pinpointing at molecular targets of the pathophysiology from another angle. An altered maturational process may explain why so many, seemingly independent etiological factors lead to the same clinical syndrome and frequently to developmental delay. Understanding these factors can provide ideas for novel therapies.

Neuroinflammation in Children With Infantile Spasms: A Prospective Study Before and After Treatment With Acthar Gel (Repository Corticotropin Injection)

The selective effectiveness of adrenocorticotropic hormone (ACTH) in treating infantile spasms suggests an underlying neuroinflammation. Because neuroinflammation is mediated by activated microglia, which express translocator protein (TSPO), we imaged neuroinflammation in children with infantile spasms using positron emission tomography (PET) with ¹¹C-PK11195 (PK), which selectively binds to TSPO. Children were studied prospectively before and following treatment with Acthar Gel (repository corticotropin injection). We hypothesized that PK-PET would show neuroinflammation (increased PET uptake) in cortical and/or subcortical structures before treatment, and that this inflammation will be abolished/reduced following Acthar Gel treatment. Eight children with infantile spasms (5 males; mean age 1.8±1.1, range 0.9-4.1 years) were recruited. After clinical and video electroencephalograph (EEG) evaluation and dynamic PK-PET scan, children underwent treatment with Acthar Gel over 4 weeks, followed by repeat clinical evaluation/video-EEG 2 weeks after initiation of treatment and repeat PK-PET 2 weeks after treatment completion. Visual and quantitative analysis of PK-PET scans were performed. We calculated regional binding potential (measure of receptor-ligand binding) using a reference tissue model. Focal areas of increased PK-binding were found in the pretreatment PK-PET in 5 children. Following treatment, these increases were either reduced or normalized and were associated with cessation (n=4) or significant reduction (n=1) of spasms and complete disappearance of hypsarrhythmia. One child showed increased binding potential in basal ganglia and thalamus, despite normalization of cortical binding potential; however, these increases were likely associated with death-related causes. This study suggests Acthar Gel-responsive neuroinflammatory changes in children with infantile spasms, supporting a potential role of neuroinflammation in the pathogenesis of infantile spasms.

Modeling epileptic spasms during infancy: Are we heading for the treatment yet?

Infantile spasms (IS or epileptic spasms during infancy) were first described by Dr. William James West (aka West syndrome) in his own son in 1841. While rare by definition (occurring in 1 per 3200-3400 live births), IS represent a major social and treatment burden. The etiology of IS varies - there are many (>200) different known pathologies resulting in IS and still in about one third of cases there is no obvious reason. With the advancement of genetic analysis, role of certain genes (such as ARX or CDKL5 and others) in IS appears to be important. Current treatment strategies with incomplete efficacy and serious potential adverse effects include adrenocorticotropin (ACTH), corticosteroids (prednisone, prednisolone) and vigabatrin, more recently also a combination of hormones and vigabatrin. Second line treatments include pyridoxine (vitamin B6) and ketogenic diet. Additional treatment approaches use rapamycin, cannabidiol, valproic acid and other anti-seizure medications. Efficacy of these second line medications is variable but usually inferior to hormonal treatments and vigabatrin. Thus, new and effective models of this devastating condition are required for the search of additional treatment options as well as for better understanding the mechanisms of IS. Currently, eight models of IS are reviewed along with the ideas and mechanisms behind these models, drugs tested using the models and their efficacy and usefulness. Etiological variety of IS is somewhat reflected in the variety of the models. However, it seems that for finding precise personalized approaches, this variety is necessary as there is no "one-size-fits-all" approach possible for both IS in particular and epilepsy in general.

Upregulations of CRH and CRHR1 in the Epileptogenic Tissues of Patients with Intractable Infantile Spasms

AIM

Infantile spasms (IS) are an age-specific epileptic syndrome with specific clinical symptom and electroencephalogram (EEG) features, lacking treatment options, and a poor prognosis. Excessive endogenous corticotropin-releasing hormone (CRH) in infant brain might result in IS. However, the data from human IS are limited. In our study, we investigated the expressions of CRH and its receptor type 1 (CRHR1) in surgical tissues from patients with IS and autopsy controls.

METHODS

Specimens surgically removed from 17 patients with IS, and six autopsy controls were included in the study. Real-time PCR, Western blotting, and immunostaining were used to detect the expressions of mRNA, protein expression, and distribution. The correlation between variates was analyzed by Spearman rank correlation.

RESULTS

The expressions of CRH and CRHR1 were significantly upregulated in the epileptogenic tissues of IS patients compared with the control group. CRH was distributed mainly in neurons, while CRHR1 was distributed in neurons, astrocytes, and microglia. The expression levels of CRH and CRHR1 were positively correlated with the frequency of epileptic spasms. Moreover, the expression of protein kinase C (PKC), which was an important downstream factor of CRHR1, was significantly upregulated in the epileptogenic tissues of patients with IS and was positively correlated with the CRHR1 expression levels and the frequency of epileptic spasms.

CONCLUSION

These results suggest that the CRH signal transduction pathway might participate in the epileptogenesis of IS, supporting the hypothesis that CRH is related to the pathogenesis of IS.

Increased precipitation of spasms in an animal model of infantile spasms by prenatal stress exposure

Infantile spasms (IS) represent a serious epileptic syndrome, called West syndrome (WS) that occurs in the early infantile age. Although several hypotheses and animal models have been proposed to explain the pathogenesis of IS, the pathophysiology of IS has not been elucidated. Recently, we proposed a hypothesis for IS under prenatal stress exposure (also called Zou's hypothesis) by correlating diverse etiologies and prenatal stresses with IS development. This research aims to determine the mechanism through which prenatal stress affects the offspring and establish the potential underlying mechanisms. Pregnant rats were subjected to forced swimming in cold water. Rat pups exposed to prenatal stress were administered with N-methyl-D-aspartate (NMDA). Exposure to prenatal stress sensitized the rats against development of NMDA-induced spasms. However, this phenomenon was altered by administering adrenocorticotropin. Prenatal stress exposure also altered the hormonal levels and neurotransmitter receptor expression of the developing rats as well as influenced the tissue structure of the brain. These findings suggest that maternal stress could alter the level of endogenous glucocorticoid, which is the basis of IS, and cerebral dysplasia, hypoxic-ischemic encephalopathy (HIE), inherited metabolic diseases, and other factors activated this disease in developmental brain.

Early life stress in epilepsy: a seizure precipitant and risk factor for epileptogenesis

Stress can influence epilepsy in multiple ways. A relation between stress and seizures is often experienced by patients with epilepsy. Numerous questionnaire and diary studies have shown that stress is the most often reported seizure-precipitating factor in epilepsy. Acute stress can provoke epileptic seizures, and chronic stress increases seizure frequency. In addition to its effects on seizure susceptibility in patients with epilepsy, stress might also increase the risk of epilepsy development, especially when the stressors are severe, prolonged, or experienced early in life. Although the latter has not been fully resolved in humans, various preclinical epilepsy models have shown increased seizure susceptibility in naïve rodents after prenatal and early postnatal stress exposure. In the current review, we first provide an overview of the effects of stress on the brain. Thereafter, we discuss human as well as preclinical studies evaluating the relation between stress, epileptic seizures, and epileptogenesis, focusing on the epileptogenic effects of early life stress. Increased knowledge on the interaction between early life stress, seizures, and epileptogenesis could improve patient care and provide a basis for new treatment strategies for epilepsy.

Corticosteroids for the treatment of infantile spasms: a systematic review

Adrenocorticotropic hormone (ACTH) and corticosteroids are the usual first-line treatment options for infantile spasms. Despite significant differences, these agents are often lumped together in this context. There is a need to systematically explore the efficacy of corticosteroids in the treatment of infantile spasms, especially in comparison to ACTH. This review identified and analyzed corticosteroid clinical trials and summarized their short-term efficacy and tolerability. Primary outcome was cessation of spasms and abolition of hypsarrhythmia on prolonged video electroencephalographic monitoring. Eight corticosteroid clinical trials were found with only 2 fulfilling the criteria for adequate design. The weighted-mean efficacy of corticosteroids to achieve primary outcome was 31% for these 2 methodologically adequate studies. Including reanalyzed data from 3 other studies, the corticosteroid efficacy was found to be 42%. On the basis of the available evidence, the efficacy of high-dose corticosteroids is similar to low-dose ACTH and inferior to high-dose ACTH, the current standard treatment.

Infantile spasms (West syndrome) in children with inborn errors of metabolism: a review of the literature

West syndrome (infantile spasms) is an epileptic encephalopathy that includes psychomotor deterioration. In rare cases, it is due to an inherited, progressive metabolic disease. More than 25 inborn errors of metabolism have been considered etiologic or predisposing factors for infantile spasms. This is a review of the literature on reported cases of children diagnosed with a metabolic disease who developed infantile spasms. This article presents in brief the most frequent inborn errors of metabolism that have been associated with West syndrome and also illustrates the importance of screening for inborn errors of metabolism in infantile spasms.

Short term outcomes of topiramate monotherapy as a first-line treatment in newly diagnosed West syndrome

Purpose

To investigate the efficacy of topiramate monotherapy in West syndrome prospectively.

Methods

The study population included 28 patients (15 male and 13 female children aged 2 to 18 months) diagnosed with West syndrome. After a 2-week baseline period for documentation of the frequency of spasms, topiramate was initiated at 2 mg/kg/day. The dose was increased by 2 mg/kg every week to a maximum of 12 mg/kg/day. Clinical assessment was based on the parents' report and a neurological examination every 2 weeks for the first 2 months of treatment. The baseline electroencephalograms (EEGs) were compared with the post-treatment EEGs at 2 weeks and 1 month.

Results

West syndrome was considered to be cryptogenic in 7 of the 28 patients and symptomatic in 21 patients. After treatment, 11 patients (39%) became spasm-free, 6 (21%) had more than 50% spasmsreduction, 3 (11%) showed less than 50% reduction, and 8 (29%) did not respond. The effective daily dose for achieving more than 50% reduction in spasm frequency, including becoming spasm-free, was found to be 5.8±1.1 mg/kg/day. Nine patients (32%) showed complete disappearance of spasms and hypsarrhythmia, and 11 (39%) showed improved EEG results. Despite adverse events (4 instances of irritability, 3 of drowsiness, and 1 of decreased feeding), no patients discontinued the medication.

Conclusion

Topiramate monotherapy seems to be effective and well tolerated as a first line therapy for West syndrome and is not associated with serious adverse effects.

Model of cryptogenic infantile spasms after prenatal corticosteroid priming

Infantile spasms (IS) is a devastating epilepsy syndrome of childhood. IS occurs in 3-12-month-old infants and is characterized by spasms, interictal electroencephalography (EEG) hypsarrhythmia, and profound mental retardation. Hormonal therapy [adrenocorticotropic hormone (ACTH), corticosteroids] is frequently used, but its efficacy is tainted by severe side effects. For research of novel therapies, a validated animal model of IS is required. We propose the model of spastic seizures triggered by N-methyl-d-aspartate (NMDA) in infant rats prenatally exposed to betamethasone. The spasms have remarkable similarity to human IS, including motor flexion spasms, ictal EEG electrodecrement, and responsiveness to ACTH. Interestingly, the spasms do not involve the hippocampus. Autoradiographic metabolic mapping as well as tagging of the areas of neuronal excitation with c-fos indicates a strong involvement of hypothalamic structures such as the arcuate nucleus, which has significant bilateral connections with other hypothalamic nuclei as well as with the brainstem.

Association between prenatal stress and infantile spasms: a case-control study in China

The present study investigated a possible correlation between prenatal stress and the onset of infantile spasms. A total of 120 infants (60 cases, 30 positive controls, and 30 negative controls) went through routine etiologic screening. The Pregnant Woman Life Event Scale was used to investigate and evaluate the degree of prenatal stress of the mothers in the three infant groups. Etiologic analyses indicated no statistical difference between the infantile spasms group and the other epilepsy control group. There was a significant difference in the degree of prenatal stress among mothers of the three infant groups, with higher maternal prenatal stress levels in the infantile spasms group than in the other epilepsy group (positive control) or the normal control group (P < 0.05). Regression analysis with the dummy variable indicated that the onset risk of infantile spasms correspondingly increased with the degree of maternal prenatal stress for stress levels 1-3 (out of four levels) (P < 0.05). Within a certain range, the onset risk of infantile spasms increases with the degree of prenatal stress.

Major adverse events associated with treatment of infantile spasms

Few studies have focused on tolerability and adverse events associated with natural adrenocorticotropic hormone injections for treatment of infantile spasms. Using a retrospective chart review of 130 patients, the authors compare major adverse events, weight and blood pressure changes, and unplanned medication changes associated with adrenocorticotropic hormone (ACTH) injections versus other antiepileptic drugs. Children treated with adrenocorticotropic hormone injections experienced significant short-term weight gain and blood pressure elevations, which were readily reversible with weaning off the drug. Twenty-three percent of patients treated with adrenocorticotropic hormone (14 of 60) and 17% of patients treated with other antiepileptic drugs (11 of 65) experienced a major adverse event during treatment. Few patients overall required a change in medication due to intolerable side effects. Despite early changes in weight and blood pressure, short courses of high-dose natural adrenocorticotropic hormone are generally well tolerated with no increased major adverse events when compared to antiepileptic drugs in the treatment of infantile spasms.

Maternal IgG suppresses NMDA-induced spasms in infant rats and inhibits NMDA-mediated neurotoxicity in hippocampal neurons

Maternal immunoglobulin G (IgG) was derived from Wistar rats that just delivered the new offsprings. We examined the effect of this maternal IgG on infantile spasms induced by N-methyl-d-aspartate (NMDA) in immature rats. Pup animals were treated subcutaneously with 10 mg/kg/day maternal IgG from day 11 to day 15 after birth followed by a single intraperitoneal dose of NMDA (15 mg/kg). Administration of maternal IgG decreased the severity and increased the number of ACTH immunoreactive cells in the cortex of rats with NMDA-induced spasms. Furthermore, maternal IgG inhibited NMDA-induced intracellular LDH activity in cultured hippocampal neurons in a dose-dependent manner. The results indicate that maternal IgG can attenuate NMDA-induced seizures. In infantile spasms, some factors may during pregnancy negatively affect the transfer of maternal IgG from mother to fetus thereby causing a decrease in the amount of protective maternal IgG.

Cerebrospinal fluid ACTH and cortisol in opsoclonus-myoclonus: effect of therapy

Opsoclonus-myoclonus syndrome is one of a few corticotropin (ACTH)-responsive central nervous system disorders of childhood. We measured cerebrospinal fluid ACTH and cortisol in 69 children with opsoclonus-myoclonus and 25 age- and sex-matched control subjects to determine endogenous levels and look for hypothesized differential hormonal effects of ACTH and corticosteroid treatment. Cerebrospinal fluid cortisol was 10-fold higher with ACTH treatment (n = 26), but was unchanged with oral steroid treatment (n = 18) or no treatment (n = 25). It was significantly higher in children receiving daily high-dose ACTH than alternate day ACTH. In ACTH-treated children, cerebrospinal fluid and serum cortisol were highly correlated (r = 0.96, P = 0.0001), with a mean ratio of cerebrospinal fluid to serum cortisol of approximately 1:10. Cerebrospinal fluid ACTH concentration did not differ significantly between untreated opsoclonus-myoclonus and control subjects but was lower with ACTH (-29%) or steroid treatment (-36%), suggesting feedback inhibition of ACTH release. These data delineate differences in the central effects of ACTH and corticosteroid therapy, as well as between high and low ACTH doses, and support the integrity of the brain-adrenal axis in pediatric opsoclonus-myoclonus.

Pathogenesis of infantile spasms: a model based on developmental desynchronization

Infantile spasms is a severe epileptic encephalopathy of infancy. The fundamental cause is unknown, although a number of predisposing conditions are recognized. In this article, the authors critically review current knowledge concerning the pathophysiologic basis of infantile spasms and propose a new model based on developmental desynchronization. It is suggested that infantile spasms may result from a particular temporal desynchronization of two or more central nervous system developmental processes, resulting in a specific disturbance of brain function. The disturbance of function is postulated to be crucially dependent on an unbalanced maturational pattern, in which certain brain systems become dysfunctional owing to divergent developmental status. An important aspect of this model is the idea that disturbed function of a specific kind can result from multiple causative factors, and so can be associated with a variety of different anatomic and/or biochemical abnormalities. Thus, this concept is compatible with the observed diversity of pathologic findings and multiplicity of etiological associations observed in infantile spasms patients.

ACTH treatment of infantile spasms: mechanisms of its effects in modulation of neuronal excitability

The efficacy of ACTH, particularly in high doses, for rapid and complete elimination of infantile spasms (IS) has been demonstrated in prospective controlled studies. However, the mechanisms for this efficacy remain unknown. ACTH promotes the release of adrenal steroids (glucocorticoids), and most ACTH effects on the central nervous system have been attributed to activation of glucocorticoid receptors. The manner in which activation of these receptors improves IS and the basis for the enhanced therapeutic effects of ACTH--compared with steroids--for this disorder are the focus of this chapter. First, a possible "common excitatory pathway," which is consistent with the many etiologies of IS and explains the confinement of this disorder to infancy, is proposed. This notion is based on the fact that all of the entities provoking IS activate the native "stress system" of the brain. This involves increased synthesis and release of the stress-activated neuropeptide, corticotropin-releasing hormone (CRH), in limbic, seizure-prone brain regions. CRH causes severe seizures in developing experimental animals, as well as limbic neuronal injury. Steroids, given as therapy or secreted from the adrenal gland upon treatment with ACTH, decrease the production and release of CRH in certain brain regions. Second, the hypothesis that ACTH directly influences limbic neurons via the recently characterized melanocortin receptors is considered, focusing on the effects of ACTH on the expression of CRH. Experimental data showing that ACTH potently reduces CRH expression in amygdala neurons is presented. This downregulation was not abolished by experimental elimination of steroids or by blocking their receptors and was reproduced by a centrally administered ACTH fragment that does not promote steroid release. Importantly, selective blocking of melanocortin receptors prevented ACTH-induced downregulation of CRH expression, providing direct evidence for the involvement of these receptors in the mechanisms by which ACTH exerts this effect. Thus, ACTH may reduce neuronal excitability in IS by two mechanisms of action: (1) by inducing steroid release and (2) by a direct, steroid-independent action on melanocortin receptors. These combined effects may explain the robust established clinical effects of ACTH in the therapy of IS.

Clinical analysis of West syndrome associated with phenylketonuria

OBJECTIVE

To explore the incidence and clinical characteristics of West syndrome associated with phenylketonuria (WS-PKU) and significance of early combination therapy of low phenylalanine (PHE) diet and anticonvulsants (antiepileptic drugs, AEDs) in WS-PKU.

SUBJECTS AND METHODS

Sixty-two WS-PKU patients (41 boys and 21 girls) out of 503 PKU patients were enrolled in the study. Age at PKU diagnosis varied from 4 months to 7 years old. Serum PHE levels were 20-38.5mg/dl. In the majority of cases, infantile spasms (IS) became manifest first preceding the PKU diagnosis, except eight cases in which spasms appeared after starting the diet therapy. All patients were subjected to mental and electroencephalographic (EEG) examination. Brain myelination was evaluated by using brain magnetic resonance imaging (MRI) with Staudt's standard.

RESULTS

WS-PKU patients accounted for 12.3% of PKU patients. No patients who were given low PHE diet before age 3 months suffered from WS, whereas 17 out of 156 patients who started the diet between age 4 and 12 months developed WS later (10.9%), and similarly, 45 out of 283 patients who started the diet after 12 months of age developed WS later (15.9%). Moderate and severe mental retardation were noted in 58.8% of patients who received the diet before age 1 and in 84.4% of those after age 1 (P<0.05). EEG displayed hypsarrhythmia and diffuse background abnormality. MRI scans showed delayed myelination mainly in the cerebral lobes and corpus callosum and abnormal high T(2)-signal intensity (100%) in the periventricular region around anterior and posterior horns of both lateral ventricles. With the start of diet, spasms began to decrease its frequency, but relapsed frequently (78%) when no AEDs were given. Seizure relapse was significantly lower when valproic acid or nitrazepam were given concomitantly with the diet (18.2%).

CONCLUSIONS

IS often occurred as the initial clinical sign of PKU. Early diagnosis of PKU and early therapy with low PHE diet seem to be highly effective in preventing WS.

How do the many etiologies of West syndrome lead to excitability and seizures? The corticotropin releasing hormone excess hypothesis

West syndrome (WS) is associated with diverse etiological factors. This fact has suggested that there must be a 'final common pathway' for these etiologies, which operates on the immature brain to result in WS only at the maturational state present during infancy. Any theory for the pathogenesis of WS has to account for the unique features of this disorder. For example, how can a single entity have so many etiologies? Why does WS arise only in infancy, even when a known insult had occurred prenatally, and why does it disappear? Why is WS associated with lasting cognitive dysfunction? And, importantly, why do these seizures--unlike most others--respond to treatment by a hormone, ACTH? The established hormonal role of ACTH in human physiology is to function in the neuroendocrine cascade of the responses to all stressful stimuli, including insults to the brain. As part of this function, ACTH is known to suppress the production of corticotropin releasing hormone (CRH), a peptide that is produced in response to diverse insults and stressors.The many etiologies of WS all lead to activation of the stress response, including increased production and secretion of the stress-neurohormone CRH. CRH has been shown, in infant animal models, to cause severe seizures and death of neurons in areas involved with learning and memory. These effects of CRH are restricted to the infancy period because the receptors for CRH, which mediate its action on neurons, are most abundant during this developmental period. ACTH administration is known to inhibit production and release of CRH via a negative feedback mechanism. Therefore, the efficacy of ACTH for WS may depend on its ability to decrease the levels of the seizure-promoting stress-neurohormone CRH.This CRH-excess theory for the pathophysiology of WS is consistent not only with the profile of ACTH effects, but also with the many different 'causes' of WS, with the abnormal ACTH levels in the cerebrospinal fluid of affected infants and with the spontaneous disappearance of the seizures. Furthermore, if CRH is responsible for the seizures, and CRH-mediated neuronal injury contributes to the worsened cognitive outcome of individuals with WS, then drugs which block the actions of CRH on its receptors may provide a better therapy for this disorder.

Infantile spasms: hypothesis-driven therapy and pilot human infant experiments using corticotropin-releasing hormone receptor antagonists

BACKGROUND AND RATIONALE

Infantile spasms (IS) are an age-specific seizure disorder occurring in 1:2,000 infants and associated with mental retardation in approximately 90% of affected individuals. The costs of IS in terms of loss of lifetime productivity and emotional and financial burdens on families are enormous. It is generally agreed that the seizures associated with IS respond poorly to most conventional anticonvulsants. In addition, in the majority of patients, a treatment course with high-dose corticotropin (ACTH) arrests the seizures completely within days, often without recurrence on discontinuation of the hormone. However, the severe side effects of ACTH require development of better treatments for IS. Based on the rapid, all-or-none and irreversible effects of ACTH and on the established physiological actions of this hormone, it was hypothesized that ACTH eliminated IS via an established neuroendocrine feedback mechanism involving suppression of the age-specific endogenous convulsant neuropeptide corticotropin-releasing hormone (CRH). Indeed, IS typically occur in the setting of injury or insult that activate the CNS stress system, of which CRH is a major component. CRH levels may be elevated in the IS brain, and the neuropeptide is known to cause seizures in infant rats, as well as neuronal death in brain regions involved in learning and memory. If 'excess' CRH is involved in the pathogenesis of IS, then blocking CRH receptors should eliminate both seizures and the excitotoxicity of CRH-receptor-rich neurons subserving learning and memory.

PATIENTS AND METHODS

With FDA approval, alpha-helical CRH, a competitive antagonist of the peptide, was given as a phase I trial to 6 infants with IS who have either failed conventional treatment or who have suffered a recurrence. The study was performed at the Clinical Research Center of the Childrens Hospital, Los Angeles. The effects of alpha-helical CRH on autonomic parameters (blood pressure, pulse, temperature, respiration) were determined. In addition, immediate and short-term effects on ACTH and cortisol and on electrolytes and glucose were examined. The potential efficacy of alpha-helical CRH for IS was studied, using clinical diaries and video EEG.

RESULTS

alpha-Helical CRH, a peptide, did not alter autonomic or biochemical parameters. Blocking peripheral CRH receptors was evident from a transient reduction in plasma ACTH and cortisol. No evidence for the compound's penetration of the blood-brain barrier was found, since no central effects on arousal, activity or seizures and EEG patterns were observed. In addition, a striking resistance of the patients' plasma ACTH to the second infusion of alpha-helical CRH was noted.

CONCLUSIONS

Peptide analogs of CRH do not cross the blood-brain barrier, and their effects on peripheral stress hormones are transient and benign. Nonpeptide compouds that reach CNS receptors are required to test the hypothesis that blocking CRH receptors may ameliorate IS and its cognitive consequences.

CSF ACTH and beta-endorphin in infants with West syndrome and ACTH therapy

Corticotrophin (adrenocorticotropic hormone, ACTH) and beta-endorphin levels of the cerebrospinal fluid (CSF) were determined in 16 infants with the West syndrome during individualized ACTH treatment. Prior to treatment, the levels of CSF ACTH were significantly higher in infants with cryptogenic spasms, normal perinatal events, or normal development than in infants with symptomatic spasms or delayed development. The CSF beta-endorphin levels did not differ among the groups. At response, the infants could be divided into three groups: (1) short-course, low-dose responders with a substantial CSF ACTH decline, (2) long-course, high-dose responders with no such effect (but with a tendency towards an upward incline), and (3) non-responders with no significant CSF ACTH changes. The changes in CSF beta-endorphin were somewhat similar to the changes in CSF ACTH, but the greater variability did not allow statistical significance.