Infantile spasms: some new theoretical aspects

Drug resistant epilepsies: A multicentre case series of steroid therapy

PURPOSE

Our study aimed to evaluate the effectiveness of corticosteroids on seizure control in drug-resistant epilepsies (DREs). Our primary goal was to assess the response to steroids for various underlying etiologies, interictal electroencephalographic (EEG) patterns and electroclinical seizure descriptions. Our second goal was to compare steroid responsiveness to different treatment protocols.

METHODS

This is a retrospective multicentre cohort study conducted according to the STROBE guidelines (Strengthening the Reporting of Observational Studies in Epidemiology). The following data were collected for each patient: epilepsy etiology, interictal EEG pattern, seizure types and type of steroid treatment protocol administered.

RESULTS

Thirty patients with DRE were included in the study. After 6 months of therapy, 62.7 % of patients experienced reduced seizure frequency by 50 %, and 6.6 % of patients experienced complete seizure cessation. Findings associated with favourable response to steroids included structural/lesional etiology of epilepsy, immune/infectious etiology and focal interictal abnormalities on EEG. Comparing four different steroid treatment protocols, the most effective for seizure control was treatment with methylprednisolone at the dose of 30 mg/kg/day administered for 3 days, leading to greater than 50 % seizure reduction at 6 months in 85.7 % of patients. Treatment with dexamethasone 6 mg/day for 5 days decreased seizure frequency in 71.4 % of patients. Hydrocortisone 10 mg/kg administered for 3 months showed a good response to treatment in 71 %.

CONCLUSIONS

In our study, two-thirds of patients with DRE experienced a significant seizure reduction following treatment with steroids. We suggest considering steroids as a potential therapeutic option in children with epilepsy not responding to conventional antiseizure medicines (ASM).

Efficacy of long-term adrenocorticotropic hormone therapy for West syndrome: A retrospective multicenter case series

OBJECTIVES

Long-term adrenocorticotropic therapy (LT-ACTH), which consisted of 2-4 weeks of daily injections of adrenocorticotropic hormone (ACTH) and subsequent months of weekly injections, was tried for relapsed West syndrome (WS) or other intractable epilepsies in small case reports. Our aim was to explore the efficacy of LT-ACTH for preventing WS relapse, as well as the prevalence of its adverse events.

METHODS

This is a retrospective, nationwide, multicenter case series of patients with WS who underwent LT-ACTH. Clinical information of the patients and protocol of LT-ACTH were collected from participating institutes in this study. We defined clinical response to ACTH as achievement of hypsarrhythmia and epileptic spasms resolution. Patients who responded to daily ACTH injections were identified and assessed whether they experienced WS relapse during/after the weekly ACTH injection period. The outcome was measured by the nonrelapse rate at 24 months after daily ACTH injections using the Kaplan-Meier method.

RESULTS

Clinical information of 16 children with WS was analyzed. The median age at LT-ACTH initiation was 14.5 months (range: 7-68 months). Thirteen (81%) patients had previously undergone conventional ACTH treatment. The LT-ACTH regimens comprised a median of 16 days of daily injections (range: 11-28 days) and 10 months of weekly injections (range: 3-22 months). Seven patients experienced WS relapse during/after subsequent weekly ACTH period, and the nonrelapse rate at 24 months after daily injections was estimated at 60.6% (95% confidence interval: 32.3%-80.0%). Height stagnation, hypertension, and irritability were observed; lethal adverse events were not reported.

SIGNIFICANCE

Our study firstly explored the efficacy of LT-ACTH for preventing WS relapse. LT-ACTH might be a treatment option for patients with relapsed or intractable WS; however, we note that our study is limited by its small sample size and the lack of an appropriate control group.

Disparate effects of hormones and vigabatrin on sleep slow waves in patients with West syndrome - An indication of their mode of action?

Synaptic downscaling during sleep, a physiological process to restore synaptic homeostasis and maintain learning efficiency and healthy brain development, has been related to a reduction of the slope of sleep slow waves (SSW). However, such synaptic downscaling seems not to be reflected in high-amplitude SSW. Recently we have shown reduced SSW slopes during hormonal treatment (adrenocorticotrophic hormone, prednisolone) in patients with West syndrome (WS). Yet, whether this reduction was related to successful treatment or reflects a specific effect of hormone therapy is unknown. Thus, we retrospectively analysed nap electroencephalograms of 61 patients with WS successfully treated with hormones, vigabatrin (VGB), or both. The slope of SSW during treatment (T1) and 2-7 months later (T2) when hormonal treatment was tapered off were compared between the treatment groups and healthy, age-matched controls. At T1 hormone treatment reduced the slope of low-amplitude SSW, whereas VGB increased the slope of high-amplitude SSW (linear mixed effect model: F_Group  = 7.04, p < 0.001; F_Amplitude  = 1,646.68, p < 0.001; F_{Group*Amplitude}  = 3.38, p < 0.001). At T2, untreated patients did not differ anymore from healthy controls, whereas those still under VGB showed the same alterations as those with VGB at T1. This result indicates a disparate effect of VGB and hormone on the SSW slope. In particular, hormones seem to reduce the slope of cortical generated low-amplitude SSW, similar to the physiological synaptic downscaling during sleep. Thus, a loss of functional neuronal connectivity might be an alternative explanation of the antiepileptic effect of hormonal treatment.

Pathogenesis and new candidate treatments for infantile spasms and early life epileptic encephalopathies: A view from preclinical studies

Early onset and infantile epileptic encephalopathies (EIEEs) are usually associated with medically intractable or difficult to treat epileptic seizures and prominent cognitive, neurodevelopmental and behavioral consequences. EIEEs have numerous etiologies that contribute to the inter- and intra-syndromic phenotypic variability. Etiologies include structural and metabolic or genetic etiologies although a significant percentage is of unknown cause. The need to better understand their pathogenic mechanisms and identify better therapies has driven the development of animal models of EIEEs. Several rodent models of infantile spasms have emerged that recapitulate various aspects of the disease. The acute models manifest epileptic spasms after induction and include the NMDA rat model, the NMDA model with prior prenatal betamethasone or perinatal stress exposure, and the γ-butyrolactone induced spasms in a mouse model of Down syndrome. The chronic models include the tetrodotoxin rat model, the aristaless related homeobox X-linked (Arx) mouse models and the multiple-hit rat model of infantile spasms. We will discuss the main features and findings from these models on target mechanisms and emerging therapies. Genetic models have also provided interesting data on the pathogenesis of Dravet syndrome and proposed new therapies for testing. The genetic associations of many of the EIEEs have also been tested in rodent models as to their pathogenicity. Finally, several models have tested the impact of subclinical epileptiform discharges on brain function. The impact of these advances in animal modeling for therapy development will be discussed.

Adrenocorticotropic hormone versus pulsatile dexamethasone in the treatment of infantile epilepsy syndromes

For treatment of intractable epilepsies, there are no data comparing conventional adrenocorticotropic hormone and pulsatile corticoid therapy with dexamethasone. A retrospective comparison of efficacy was therefore conducted for both forms of application. Between 1989 and 2001, a series of 11 children with West syndrome and 3 with Lennox-Gastaut syndrome were treated with adrenocorticotropic hormone (group 1); between 2003 and 2006, 7 children with West syndrome, 5 with electrical status epilepticus during slow sleep, and 2 with Lennox-Gastaut syndrome were treated with pulsatile corticoid therapy (group 2). In group 1 (n = 14), 9/11 West syndrome patients became seizure free, but none with Lennox-Gastaut syndrome (0/3). In group 2 (n = 14), 4/7 West syndrome patients became seizure-free, 1/2 with Lennox-Gastaut syndrome exhibited seizure-frequency reduction, and 2/5 patients with electrical status epilepticus during slow-wave sleep exhibited significant improvement according to electroencephalograms. In West syndrome, pulsatile corticoid therapy was an effective alternative treatment to adrenocorticotropic hormone, whereas in Lennox-Gastaut syndrome in general steroids did not lead to a significant seizure reduction. In electrical status epilepticus during slow-wave sleep, treatment with pulsatile corticoid therapy seems to be effective and should be investigated in a larger group of patients.

Role of brain inflammation in epileptogenesis

Inflammation is known to participate in the mediation of a growing number of acute and chronic neurological disorders. Even so, the involvement of inflammation in the pathogenesis of epilepsy and seizure-induced brain damage has only recently been appreciated. Inflammatory processes, including activation of microglia and astrocytes and production of proinflammatory cytokines and related molecules, have been described in human epilepsy patients as well as in experimental models of epilepsy. For many decades, a functional role for brain inflammation has been implied by the effective use of anti-inflammatory treatments, such as steroids, in treating intractable pediatric epilepsy of diverse causes. Conversely, common pediatric infectious or autoimmune diseases are often accompanied by seizures during the course of illness. In addition, genetic susceptibility to inflammation correlated with an increased risk of epilepsy. Mounting evidence thus supports the hypothesis that inflammation may contribute to epileptogenesis and cause neuronal injury in epilepsy. We provide an overview of the current knowledge that implicates brain inflammation as a common predisposing factor in epilepsy, particularly childhood epilepsy.

Focal epileptic spasms, involving one leg, manifesting during the clinical course of west syndrome (WS)

OBJECTIVES

Epileptic spasms (ES) in West syndrome (WS) are classified as being of the generalized seizure type. However, evidence of a focal neocortical origin has been proposed based mainly on surgical WS series. We report herein two infants with WS, whose ES subsequently evolved into focal ES of the right lower extremity.

METHODS

Medical records, electroencephalographic and neuroimaging findings were retrospectively analyzed.

RESULTS

A 2 year-old Japanese girl developed ES at 3 months of age. Focal ES of the right leg manifested one month after successful ACTH therapy performed at 6 months of age. Brief jerking of the right leg, every few seconds, occurred immediately after awakening. A 7 month-old girl with symptomatic WS had developed focal seizures with postural signs at 2 months of age. The seizures gradually diminished and had been replaced by ES by 3 months of age. ES gradually evolved into focal ES of the right leg. A video-polygraphic study demonstrated the ES with marked predominance in the right leg corresponding to a left sided predominant paroxysmal biphasic slow wave complex. Brain MRI revealed no abnormal findings although interictal EEG demonstrated left centro-parieto-temporal localized spike foci.

CONCLUSIONS

The focal ES of one lower limb, following treatment of ES in these two infants with WS, suggests the origin of the ES in the first case to be a neocortical focus involving the primary motor cortex representing the lower limb while that in the second case involves more widespread neocortical area with predominance in the same motor cortex as the first case.

Delayed myelination at the onset of cryptogenic West syndrome

To evaluate the prognostic value of delayed myelination at the onset of cryptogenic West syndrome, the relationship between the seizure or developmental outcome and myelination was examined. Cranial magnetic resonance imaging studies were performed in nine cryptogenic cases. Infantile spasms were controlled in all patients, but three cases showed a mild developmental delay at 2 years after onset. Delayed myelination was observed in three cases (33.3%) on T(1)-weighted images and in two cases (22.2%) on T(2)-weighted images. In the present study, neither the seizure outcome nor developmental status was positively correlated with the existence of delayed myelination at the onset of cryptogenic West syndrome.

Corticosteroids in the management of the paediatric epilepsies

Corticosteroids (predominantly prednisolone and hydrocortisone) and adrenocorticotropic hormone (ACTH) have been used in the treatment of the epilepsies for over 50 years. Over the past 30 years most reports have focused on epilepsy syndromes and epileptic encephalopathies resistant to treatment with the more conventional anticonvulsant and antiepileptic drugs (AEDs) and specifically West syndrome. There has been relatively little attention on the role of corticosteroids in treating other epilepsies.

Magnetic resonance imaging findings in infantile spasms: etiologic and pathophysiologic aspects

An etiologic evaluation of 86 patients with infantile spasms is presented and the place of cranial magnetic resonance imaging (MRI) findings within this spectrum is discussed. A total of 103 cranial MRIs, performed between 4 and 72 months of age, were analyzed and classified according to the etiologic and pathophysiologic aspects. Ninety-one percent of cases were diagnosed as symptomatic infantile spasms, and hypoxic-ischemic encephalopathy was the primary cause (30%). The most common involvement was thinning of the corpus callosum in 43 patients (50%), followed by dilation of cerebral ventricles in 32 (36%), delayed myelination in 23 (26.7%), lesions of diencephalic deep gray matter in 17 (19.7%), and enlargement of the subarachnoid space in 12 (14%). Thin corpus callosum and diffuse atrophy were changes mainly associated with hypoxic-ischemic encephalopathy, whereas delayed myelination seemed to be independent from a specific etiology. The results showed that cranial MRI may provide considerable information regarding not only the etiology but also the pathophysiology of infantile spasms.

Infantile spasms versus myoclonus: is there a connection?

Infantile spasms (IS) is usually classified as a form of "myoclonic epilepsy," but the nosology of this whole group of disorders is unclear. Evidence suggests that the spasms are subcortically mediated, but can be modified by input from the cortex, which is believed to be abnormally excitable and disorganized. The latter features may give rise to hypsarrhythmia. The whole issue of myoclonus rests on the phenotype of IS and precise measurements of the length of electromyographic (EMG) bursts. Based on scant EMG data, it would appear that the bursts during flexor spasms are too long for epileptic myoclonus. The nature of tonic spasms of even longer duration is not myoclonic. However, the infrequent spontaneous myoclonic jerks, which can occur without spasms, and head nodding could represent positive and negative myoclonus, respectively. Data can be collected easily through techniques such as back-averaging to resolve the issue of classification and localization of motor phenomena.

Infantile spasms: criteria for an animal model

Infantile spasms is an epilepsy syndrome with several distinctive features, including age specificity during infancy, characteristic semiology (epileptic spasms), specific electroencephalographic patterns (interictal hypsarrhythmia and ictal voltage suppression), and responsiveness to the adrenocorticotropic hormone (ACTH). There is no adequate animal model of infantile spasms, perhaps due to these clinically unique features, that is specific for the developing human brain. An informative animal model would provide insights into the pathophysiology of this syndrome and form the basis for the development of innovative therapies. This chapter considers criteria for an "ideal" animal model of infantile spasms, as well as "minimal" criteria that we consider essential to yield useful information. Two animal models of infantile spasms have been described in rodents: seizures induced by corticotropin-releasing factor and N-methyl-D-aspartic acid. Neither of these models conforms exactly to the human analog, but each possesses intriguing similarities that provide testable hypotheses for future investigations.

The mystery of the Doctor's son, or the riddle of West syndrome

Although the eponym "West syndrome" is used widely for infantile spasms, the originators of the term and the time frame of its initial use are not well known. This article provides historical details about Dr. West, about his son who had infantile spasms, and about the circumstances leading to the coining of the term West syndrome.

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.

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.

Age dependent changes in some immune system parameters and GFAP immunoreactivity in genetically absence epileptic rats

The present study evaluated the contribution of some peripheral immunological parameters and GFAP immunoreactivity at different ontogenic stages of non convulsive absence epilepsy in WAG/Rij rats. For this, 2- and 6-month-old WAG/Rij rats, and the aged-matched control Wistar-albino rats were used. After collecting blood samples from all rats, the CD3 + (T cells), CD4 + (T helper), CD8 + (T cytotoxic), CD19 + (B cells) and CD25 + (IL-2 receptor, active T cell) cell ratios were determined by indirect immunofluorescence method and, serum IgG, IgA, IgM levels were evaluated by using rat radial immunodiffusion plates. After decapitation, brains were dissected and, GFAP staining was evaluated in the areas of caudate nucleus, thalamus, hippocampus, amygdala and cerebellum by immunohistochemistry. CD3 + cells and IgM levels increased with age in WAG/Rij rats. However, GFAP + astrocytes were decreased with age in caudate nucleus, thalamus, amygdala, and cerebellum of WAG/Rij rats. In the genetically absence epileptic rats, the humoral immunity was found to be affected more and activated by age. Additionally, astrocytes in thalamus and caudate nucleus that are the most important areas in the pathogenesis of absence epilepsy, were found to be decreased with age in WAG/Rij rats. From the results, it can be concluded that peripheral immunological parameters together with astrocytic activity may participate in the etiopathogenesis of absence epilepsy.

Vein of Galen malformation and infantile spasms

Recently, there has been increasing interest in the study, characterization, and management of infantile spasms. With technological advances, it is now possible to determine a specific diagnosis on many patients with infantile spasms, thus broadening the spectrum of conditions associated with this electroclinical syndrome. We report a child with infantile spasms who also had a vascular malformation of the vein of Galen. Both clinical and electroencephalographic findings improved rapidly after endovascular treatment of the vascular anomaly, suggesting a possible association.

Vigabatrin in the treatment of infantile spasms

Infantile spasms (IS) have been conventionally treated with adrenocorticotropic hormone (ACTH), which is often associated with significant side effects. This study assessed the efficacy of vigabatrin (VGB) as an alternative in the treatment of IS and compared the efficacy of VGB in symptomatic vs cryptogenic patients. The study retrospectively reviewed 25 infants with IS (19 symptomatic, six cryptogenic) who were treated with VGB. Of the symptomatic group, 13 (68.4%) of 19 had clinical improvement, and 15 (78.9%) had electroencephalographic improvement. Three (50%) of six in the cryptogenic group had clinical improvement, and two (33%) had electroencephalographic improvement. Overall, three patients demonstrated clinical spasm control but electroencephalographic deterioration or persistence of hypsarrhythmia coupled with further cognitive decline. Four of the six partial clinical responders had deterioration of spasms with additional VGB dosage increases. VGB is comparable with ACTH in effectiveness for treatment of symptomatic IS. Higher doses of VGB may sometimes cause deterioration rather than further improvement, and therefore an optimum dosage of VGB needs to be titrated for every patient. Persistent electroencephalographic abnormalities and even electroencephalographic deterioration despite clinical control have been observed with VGB treatment; electroencephalographic monitoring during VGB treatment is recommended.

ACTH therapy for infantile spasms: a combination therapy with high-dose pyridoxal phosphate and low-dose ACTH

Combination therapy consisting of high-dose pyridoxal phosphate (40-50 mg/kg/day) and low-dose synthetic ACTH (0.01 mg/kg/day) was prescribed in 28 children with infantile spasms. Monotherapy with pyridoxal phosphate provided excellent seizure control in 3 of the 28 (11%) patients. ACTH was subsequently added to the regimen of the remaining 25 patients. As of 1 month after discontinuing the ACTH treatment, 21 of the 25 (84%) patients had experienced no seizures. The mean interval until seizure control was achieved was 4.1 days after the start of treatment with ACTH. The 21 patients have been monitored for a mean of 34.9 months (range 2-81 months); 6 patients (29%) have had recurrences of infantile spasms, and 10 (48%) have experienced normal development. Fourteen of the 28 patients (50%) have had transient increases in liver enzymes, but none of the patients developed more serious side effects.

Adrenocorticotropic hormone therapy for infantile spasms alters pyruvate metabolism in the central nervous system

To clarify the mechanism of action of adrenocorticotropic hormone (ACTH) in treating infantile spasms, we evaluated the effects of ACTH on the metabolism of pyruvate in the central nervous system (CNS) of children with infantile spasms. We measured the levels of lactate and pyruvate in cerebrospinal fluid (CSF) and serum, before and during ACTH treatment in 12 children with infantile spasms. We evaluated statistically any correlation between the observed metabolic changes and the clinical response of ACTH. ACTH therapy significantly elevated the levels of lactate and pyruvate in the CSF and serum. The effect was not dose-dependent. During ACTH therapy, the serum levels of lactate and pyruvate and the ratio of lactate to pyruvate (L:P ratio) were unrelated to these levels in CSF. Patients who showed a good initial response to treatment had a significantly higher CSF level of pyruvate and a lower L:P ratio during therapy than did those with a poor initial response. This is the first report that ACTH therapy administered for infantile spasms alters pyruvate metabolism in the CNS. This metabolic change may be involved in part in the action of ACTH in relieving infantile spasms.

West syndrome: cerebrospinal fluid nerve growth factor and effect of ACTH

West syndrome is a strictly age-limited encephalopathy of early infancy with unknown pathogenesis. It is often progressive, leading to mental retardation. Neurotrophic factors are important for the regulation of neuronal survival and differentiation, and their expression is influenced by hormones. Levels of beta-nerve growth factor in the cerebrospinal fluid were examined by two-site enzyme-linked immunosorbent assay method. Human antigen was used as a standard. We present data on largely normal levels of nerve growth factor in the cerebrospinal fluid of infants with cryptogenic etiology, but low or negligible levels in infants with symptomatic etiology, and very high levels in infants with symptomatic postinfectious etiology. Treatment with ACTH led to a greater increase in patients with a good response than in those with a poor response. Low nerve growth factor in patients with symptomatic infantile spasms possibly reflects massive neuronal death. The regression seen in these infants and their poor response to ACTH therapy may be due in part to lack of growth factors supporting neuron survival. This study, previously only demonstrated in animal models, is the first to depict nerve growth factor gene activity in humans as modulated by steroids.

Infantile spasms: seasonal onset differences and zeitgebers

The health records of 76 infants with infantile spasms (IS) were reviewed retrospectively. The distribution of seizure onset was examined with respect to calendar month, annual changes in day length (photoperiod), and global solar radiation (GSR). IS onset was more frequent during the months with low GSR and short photoperiods. The greatest frequency of IS onset was in December and January (22 cases, 29%); the lowest was in April and May (8 cases, 10.5%). IS onset frequency (f) was more than twice as great in the months with a short photoperiod (10Light-14Dark) and a low GSR (f = 11) as compared with months with a long photoperiod (16Light-8Dark) and a high GSR (f = 5). IS onset frequency was 2.2-fold greater in months with a short photoperiod and a low GSR. This finding suggests that environmental photoperiodic factors (zeitgebers) may play a role in the onset of IS.

How do cryptogenic and symptomatic infantile spasms differ? Review of biochemical studies in Finnish patients

Infants with cryptogenic infantile spasms seem to differ from those with symptomatic spasms in having a higher cerebrospinal fluid corticotropin content, different levels of corticotropin release after exogenous vasopressin, higher serum levels of progesterone, higher dehydroepiandrosterone: androstenedione ratio (during corticotropin therapy), a higher cerebrospinal fluid gamma-aminobutyric acid content, and higher cerebrospinal fluid nerve growth factor concentrations. It remains to be seen whether the biochemical differences between the two groups are specific or only happen to correlate with the early brain damage. However, these differences would explain many pathophysiologic features of infantile spasms.

Risk factors of infantile spasms compared with other seizures in children under 2 years of age

To analyze the magnitude of the risk factors for infantile spasms, we evaluated the records of 80 children with infantile spasms, 474 children with other types of epilepsy, 2,196 children with febrile seizures, and 262 children with CNS infections. There was a family history of seizures in 13.8% of children with infaNtile spasms, 28.5% of children with other forms of epilepsy, 25.5% of children with febrile seizures, and 5.3% of children with CNS infections. Children with a family history of seizures were 2.82 times more likely to have infantile spasms, 7.05 time more likely to have other epilepsy, and 6.08 time more likely to have febrile seizures than controls (children with CNS infections). However, a family history of seizures increased the risk for infantile spasms only in the cryptogenic group. Children with infantile spasms were significantly more likely to have cerebral palsy, microcephaly, hydrocephaly, CNS malformations, neonatal hypoxia, or neonatal seizures than children with other types of epilepsy, febrile seizures, or CNS infections. There was a modest genetic predisposition to seizures in children with infantile spasms. However, our data suggest a much stronger association with underlying neurologic abnormalities, mainly neonatal seizures, neonatal hypoxia, and CNS malformations.

Combination therapy of infantile spasms with high-dose pyridoxal phosphate and low-dose corticotropin

A new combination therapy, high-dose pyridoxal phosphate (40 to 50 mg/kg daily) and low-dose corticotropin (0.01 mg [0.4 IU]/kg daily), was tried in 28 children with infantile spasms. Monotherapy with pyridoxal phosphate provided excellent seizure control in three (11%) of the 28 subjects. Corticotropin was subsequently added to the regimen of the remaining 25 patients. At 1 month after discontinuing corticotropin, 21 (84%) of the 25 patients experienced no seizures, and 22 (88%) of the 25 showed improvement in their electroencephalographic findings. The mean interval until achievement of seizure control was 4.1 days after the initiation of corticotropin. The outcome in the 21 patients has been followed for a mean period of 34.9 months (range, 2 to 81 months). Of these 21 patients, six (29%) have had relapses of infantile spasms, and 10 (48%) have experienced normal development. Transient increases in liver enzymes occurred in 14 (50%) of the 28 patients, but none of the patients developed more serious side effects. The investigators conclude that combination therapy with high-dose pyridoxal phosphate and low-dose corticotropin is a promising new therapy.

Cerebrospinal fluid corticotropin and cortisol are reduced in infantile spasms

Infantile spasms respond to ACTH, and levels of the hormone in cerebrospinal fluid of untreated infants with this disorder were found to be lower than in age-matched controls. In this study we analyzed cerebrospinal fluid cortisol and ACTH using improved immunoassays in a larger cohort of infants with infantile spasms. Analysis of 20 patients and 15 age-matched controls revealed significantly lower levels of both ACTH and cortisol in the cerebrospinal fluid. These data, combined with the efficacy of ACTH and glucocorticoids for infantile spasms, support an involvement of the brain-adrenal-axis in this disorder.

Decreasing perinatal mortality: unchanged infantile spasm morbidity

The present study examined whether changes in the incidence of infantile spasms could be used to evaluate changes in the quality of pre- and perinatal care over time. 107 children in 1960 to 1976, and 102 in 1977 to 1991, developed infantile spasms in southern Finland. The number of small-for-gestational age (SGA) infants and infants with neonatal hypoglycaemia decreased significantly. Brain malformations, malformation syndromes and patients with tuberous sclerosis increased; this probably reflects the development of more refined neuroradiological screening methods. SGA infants are probably more apt to develop infantile spasms than preterm infants appropriate for gestational age. Early prenatal factors seem to play a major role in the genesis of infantile spasms. Little can be done to reduce the incidence of infantile spasms, but every effort should be made to reduce the number of SGA infants by good prenatal care. Treatment of hypoglycaemia is important because infantile spasms might be preventable in these infants.

ACTH does not control neonatal seizures induced by administration of exogenous corticotropin-releasing hormone

ACTH has been used extensively for treatment of massive infantile spasms (MIS) and other intractable seizures. The mechanisms by which ACTH exerts anticonvulsant effects are unknown. ACTH is a neuropeptide with both endocrine and neuromodulatory properties; its efficacy against MIS could derive from intrinsic anticonvulsant properties or from hormonal effects, either directly or through glucocorticoids. We tested ACTH activity against exogenous corticotropin-releasing hormone (CRH)-induced seizures in the infant rat model. CRH was administered into the cerebral ventricles of 85 infant rats aged 5-13 days. ACTH was used either 20-60 min before CRH administration or "chronically" (pretreatment with four doses of ACTH every 6 h, before CRH administration). In a separate group of rat pups, we measured plasma corticosterone to ascertain ACTH availability. Administration of CRH, an age-specific endogenous convulsant, resulted in a prolonged series of seizures after 2- to 55-min latency. There was no difference in latency between controls (9.5 +/- 1.2 min) and ACTH-treated rats (12.4 +/- 2.8 min for combined acute and chronic groups). CRH-induced seizure duration (88.2 +/- 9 vs. 74.7 +/- 9.4 min) and severity of seizures was also unchanged by ACTH treatment. ACTH reached the circulation and caused significant increase in plasma glucocorticoids. ACTH does not block the convulsant action of exogenous CRH in infant rats. An alternative mechanism for the anticonvulsant effect of ACTH may be suppression of synthesis and secretion of an endogenous convulsant, i.e., CRH.

Effects of ACTH treatment on cerebral phosphorus metabolites in infants with the West syndrome

Concentrations of phosphorus metabolites in brains of 4 infants with the West syndrome were measured by 31P MRS before and during ACTH treatment. Although intracellular pH, phosphocreatine/ATP ratio and phosphocreatine/inorganic phosphate ratio in the patients were similar to those in the controls and did not change after the ACTH treatment, phosphomonoesters/phosphodiesters ratio in the patients always decreased with ACTH treatment. These results indicate that ACTH may accelerate the maturation of phospholipids metabolism in infant brains, and the observed change may relate to the efficacy of ACTH treatment against the West syndrome.

Treatment of infantile spasms

OBJECTIVE

To summarize and evaluate the literature regarding the clinical features, epidemiology, etiology, pathophysiology, and treatment of infantile spasms.

DATA SOURCES

A literature search of articles from January 1966 to July 1993 using MEDLINE, EM-Base, and Current Concepts/Life Sciences, as well as bibliographies of relevant articles.

STUDY SELECTION

All identified original and review publications regarding the clinical features, epidemiology, etiology, pathophysiology, and treatment of infantile spasms were reviewed. Emphasis was placed on original studies published since 1975.

DATA EXTRACTION

Data from published research were extracted and evaluated according to study design, sample size, dosing regimen, outcome measures, and treatment efficacy and safety.

DATA SYNTHESIS

Infantile spasms constitute a rare epileptic syndrome with a poor long-term prognosis for normal intellectual development. The spasms are characterized by a brief symmetric contraction of the muscles of the neck, trunk, and/or extremities, often occurring in a series of 2 to more than 100 spasms during a single episode. The disorder is age-specific, with the peak onset of symptoms occurring between 2 and 8 months of age. Spasms of no identifiable cause in infants with normal development prior to the onset of infantile spasms are classified as cryptogenic or idiopathic, whereas those with an identifiable cause are classified as symptomatic. Long-term prognosis is best in cryptogenic cases, with 30-70 percent attaining normal intellect compared with 5-19 percent in symptomatic cases. The etiology and pathophysiology are not well understood. Recent theory postulates that infantile spasms may be caused by an excess of corticotropin-releasing hormone activity during infancy. The suspected association between the whole-cell pertussis vaccine and infantile spasms is coincidental. Few well-designed, prospective, controlled clinical trials for the treatment of infantile spasms have been conducted.

CONCLUSIONS

Standard anticonvulsants such as phenytoin, the barbiturates, carbamazepine, and the succinimides have been ineffective. Of the anticonvulsants, only the benzodiazepines, valproic acid, and vigabatrin have shown efficacy in reducing spasm frequency and severity. Hormonal therapy with adrenocorticotropic hormone (ACTH) and/or prednisone has been the most frequently studied treatment modality and appears to be the most effective. Hormonal therapy achieves complete spasm control in 50-75 percent of infants within four weeks of initiation. Opinions differ regarding the relative efficacy between ACTH and prednisone, the need for early initiation of hormonal treatment, and the benefits of high dosages of ACTH (> 40 units/d). No treatment has been shown conclusively to improve the long-term intellectual development of these infants. Neurosurgery may be the treatment of choice in select cases when a localized central nervous system abnormality can be demonstrated. Well-designed, blind, prospective clinical trials are needed to answer definitively many lingering questions regarding the treatment of infantile spasms.

Putative neurotransmitter abnormalities in infantile spasms: cerebrospinal fluid neurochemistry and drug effects

The neuropharmacologic basis of infantile spasms and the mechanism by which adrenocorticotropic hormone (ACTH) exerts its therapeutic effects are unknown. This is a critical review of cerebrospinal fluid neurotransmitters or their metabolites in infantile spasms before and during treatment with ACTH, and of clinical drug trials with drugs acting on neurotransmission. Cerebrospinal fluid studies have shown lower gamma-aminobutyric acid (GABA), ACTH, and 5-hydroxyindoleacetic acid concentrations in patients with infantile spasms compared to controls, elevated lysine and glutamate, variable or no differences in homovanillic acid, 3-methoxy-4-hydroxyphenylglycol, norepinephrine, corticotropin-releasing hormone, and beta-endorphin. Chronic treatment with ACTH in infantile spasms reduces cerebrospinal fluid GABA, beta-endorphin, and somatostatin, increases norepinephrine and tyrosine, and has variable or no effect on homovanillic acid, 3-methoxy-4-hydroxyphenylglycol, 5-hydroxyindoleacetic acid, histamine, and tryptophan. Small therapeutic trials with drugs that act through different neurotransmitters such as methysergide, alpha-methylparatyrosine, various benzodiazepine agonists, and vigabatrin lend some support to a role for GABA and monoamines in infantile spasms. These data, though promising, provide only a hint of potential neurotransmitter disturbances, and more basic and clinical data are needed.

Pathophysiology of massive infantile spasms: perspective on the putative role of the brain adrenal axis

Massive infantile spasms are an age-specific seizure syndrome of infancy. Uniquely, the spasms respond to hormonal manipulation using adrenocorticotropic hormone (ACTH) or glucocorticoids. A hypothesis explaining the efficacy of hormonal therapy, age-specificity, multiple causative factors, and spontaneous resolution of infantile spasms is presented. Corticotropin-releasing hormone (CRH), an excitant neuropeptide suppressed by ACTH/steroids, is implicated. Evidence for the age-specific convulsant properties of CRH is presented, and a putative scenario in which a stress-induced enhancement of endogenous CRH-mediated seizures is discussed. Clinical testing of the CRH-excess theory and its therapeutic implications are suggested.

Light chain ratios and concentrations of serum immunoglobulins in children with epilepsy

Serum immunoglobulin G, A and M concentrations and their respective kappa/lambda (kappa/lambda) light chain ratios were studied in 26 children with epilepsy. Fifteen had cryptogenic West syndrome or Lennox-Gastaut syndrome and 11 had other forms of childhood epilepsy. The results were compared to the data of a reference group of healthy children. The mean serum IgG and IgM concentrations were respectively 2.2 g/l (P = 0.007) and 0.4 g/l (P = 0.016) higher in the 26 children with epilepsy compared to the reference group. The kappa/lambda ratios of total serum immunoglobulins, IgG and IgM were respectively 0.10 (P = 0.057), 0.20 (P = 0.001) and 0.14 (P = 0.005) lower in the children with epilepsy than in the reference group. IgA concentration and IgA kappa/lambda ratio were not affected. There were no significant differences between the kappa/lambda ratios of the West and Lennox-Gastaut epilepsy and the other types of childhood epilepsies. The results are further evidence of reciprocal interaction between the nervous system and the immune system in childhood epilepsy.

Brain-adrenal axis hormones are altered in the CSF of infants with massive infantile spasms

Massive infantile spasms (MIS), a seizure disorder unique to infants, is considered an age-dependent response of the immature brain to various insults and stressors. The seizures improve with ACTH and glucocorticoids, both major components of the brain-adrenal axis. We hypothesized that CNS levels of these hormones are abnormal in infants with MIS and studied CSF from 14 infants with MIS and 13 age-matched controls by analysis for corticotropin-releasing hormone (CRH), ACTH, cortisol, and interleukin-1-beta. ACTH levels in CSF of patients were significantly lower than those of controls, but differences in cortisol levels between patients and controls were not statistically significant. CRH levels in both groups were similar and fluctuated diurnally. These results indicate an alteration of specific CNS components of the brain-adrenal axis in MIS.

Rapid diazepam introduction (venous or rectal) in childhood epilepsy: taxonomic and therapeutic considerations

Rapid diazepam (DZP) introduction was investigated in 24 children with different types of cryptogenic or symptomatic generalized epilepsy and EEG epileptic "status" with EEG and pharmacologic monitoring. In 12 cases DZP was given intravenously and in another 12 by the rectal route. In general, intravenous administration proved more rapid and more effective as to high blood levels of DZP and the arrest of the paroxysmal activity. However, when the results were correlated to the different forms of paroxysmal EEG activity it was apparent that cases with a typical hypsarrhythmic EEG pattern under the age of 12 months and cases with unorganized paroxysmal activity over the age of 12 months are insensitive or only slightly sensitive to both intravenous and rectal introduction. A number of taxonomic and therapeutic considerations are presented.

Chaos, balance, and development: thoughts on selected childhood epilepsy syndromes

Age-specific epilepsy syndromes raise important questions about developmental susceptibility to seizures and epileptogenesis and about the effect of seizures on function. The diagnosis and treatment of these syndromes has been enhanced by the use of modern science and technology. Epidemiologic studies have changed our approach to febrile convulsions. This developmental seizure disorder is benign and self-limited. We have been forced to think carefully about threshold, therapy, and whether other seizures in childhood may be equally benign. This framework of developmental specificity can also be applied to West syndrome, especially with respect to neurophysiology, neurochemistry, neuroimaging, and epidemiology--the types of seizures, clustering, variations associated with sleep, PET scans, and therapy. Rasmussen's syndrome and other unilateral developmental epilepsies are progressive but remain confined to a single hemisphere. However, they usually are devastating to global neurologic function. They are models for examining the impact of epilepsy in one pathologic hemisphere on the function of the entire brain. Current therapy for this condition is hemispherectomy. Recovery of function after this major surgery is striking and provides clues to brain organization. The analysis of these three syndromes provides windows on the dynamic, changing central nervous system of the child and may lead to better understanding and therapy for other seizure disorders.

Cholinergic system disturbance in the West syndrome

The effects of drug on the cholinergic system (atropine and physostigmine) were evaluated in acute tests in 12 infant patients with the West syndrome (WS) and in 12 older ones who had suffered from WS at typical ages, displaying various types of epileptic symptoms. In both groups paroxysmal EEG activity was inhibited by physostigmine and enhanced by atropine. In two infants who had frequent clinical seizures, the seizures were temporarily blocked by physostigmine. These effects in WS are different from those reported in some other experimental and clinical epilepsies, where physostigmine has a proepileptic and atropine often an antiepileptic effect, thus indicating that a cholinergic system disturbance may occur in patients with WS.

Infantile spasms

Infantile spasms constitute a relatively rare disorder of infancy and early childhood; their onset is usually within the first 6 to 8 months of life. A large percentage of patients with this disorder (85-90 per cent) show various degrees of retardation. Infantile spasms typically occur in clusters immediately on arousal, or soon thereafter, but rarely occur while the infant is actually asleep. The usual interictal EEG pattern associated with infantile spasms is hypsarrhythmia, but infantile spasms may occur in the absence of this EEG pattern. The pathophysiology of infantile spasms is not known, but recent evidence suggests that certain regions in the brain stem that are associated with sleep cycling may be responsible for the clinical and EEG manifestations of this disorder. At present, the only known effective treatment for infantile spasms is ACTH or corticosteroids. The therapeutic efficacy of these two agents is relatively equal, and one drug may be effective if the other drug fails. The effectiveness of certain traditional anticonvulsants (valproic acid and the benzodiazepines) and pyridoxine in the treatment of infantile spasms has not been adequately assessed. The long-term mental and developmental outcome of patients with infantile spasms is poor. The only factor that appears to be important in terms of long-term outcome is whether the patient is initially classified as cryptogenic or symptomatic, with the cryptogenic patients having the better outcomes. Approximately half of the infantile spasm patients will continue to have other types of seizures after their spasms stop.

Chronic ACTH treatment: influence on 5-HT2 receptors and behavioral supersensitivity induced by 5,7-dihydroxytryptamine lesions

The capacity of the serotonin (5-HT) precursor 5-HIP to induce the ACTH-responsive myoclonic-convulsive disorder infantile spasms in patients with Down's syndrome has been cited as evidence for altered serotonergic neurotransmission in infantile spasms. Since there is no animal model of infantile spasms, the suitability of behavioral supersensitivity (myoclonus) evoked by 5-HTP in rats with 5,7-dihydroxytryptamine (DHT) lesions as a model was tested by determining the effect of chronic treatment with ACTH (40 IU/kg) on 5-HTP-evoked myoclonus. In rats treated with DHT as adults, ACTH administration did not alter the "serotonergic behaviors," such as myoclonus, induced by 30 mg/kg 5-hydroxytryptophan (5-HTP), but induced a small significant increase in Bmax of neocortical 5-HT2 sites of the DHT group, with no change in rats without lesions. In rats treated with DHT as neonates, there was also no significant difference in behaviors evoked by several doses of 5-HTP. These data suggest that ACTH minimally modifies the effects on 5-HT receptors of DHT lesions, but the intracisternal DHT model is not a suitable model for infantile spasms because chronic ACTH was not antimyoclonic.

Serologic HLA typing in infantile spasms

Serologic HLA typing was performed on 29 patients with infantile spasms and hypsarrhythmic patterns in their electroencephalograms (EEGs). There were no significant increases in the frequencies of HLA-A, B, and C antigens in the infantile spasm group as compared with controls. However, there was a significant increase in the frequency of DRw52 in the infantile spasm patients (90%) as compared with controls (72%) (p less than 0.05). In addition, 3 of 12 white infantile spasm patients demonstrated the complete B18,DR3 (DRw52) haplotype; none of 150 control white subjects showed this haplotype. These findings contribute to evidence that immunological mechanisms may be involved in the pathophysiology of infantile spasms.

Preliminary report of a multi-center study on the West syndrome

During a 12-month period, 54 infants with the West syndrome (10 idiopathic, 44 symptomatic) referred to 10 major children's hospitals for initial treatment were evaluated to obtain comprehensive data on clinical findings and current treatment modalities. Prominent features included prevalence of prenatal and perinatal etiologies, severe neurological deficits and disturbed psychomotor development as well as patient-specific spectrum of seizure manifestations. Characteristic behavioural abnormalities before onset of spasms are an early indicator for the West syndrome. Therapeutic management varied considerably. Response to ACTH/steroid regiments was more favourable than to non-ACTH/steroid regimens. The most frequent serious adverse reactions during the initial treatment period were arterial hypertension and infections. Improved therapeutic strategies based on detailed initial patient assessment and systematic monitoring of beneficial effects and adverse reactions are necessary for future trials.

Interactions of ACTH4-10 and ACTH1-24 with L-[3H]glutamate binding sites and GABA/benzodiazepine/picrotoxin receptor complexes in vitro

The effects of ACTH4-10 and ACTH1-24 on L-[3H]glutamate (Glu) binding sites and GABA/benzodiazepine/picrotoxin receptor complexes in vitro were investigated. ACTH4-10 and ACTH1-24 inhibited [3H] Glu and [3H] muscimol binding concentration-dependently, while [3H] flunitrazepam (FNP) and [35S] t-butylbicyclophosphorothionate (TBPS) binding were not affected. These ACTH fragments also inhibited GABA-stimulated [3H] FNP binding. These results suggest that ACTH and its fragments may act as anticonvulsants by antagonizing glutamate binding, their interaction with GABA-A sites may relate to the other central nervous effects of ACTH than the anticonvulsant activity.

Hypothalamo-pituitary-adrenal function in infantile spasms: effects of ACTH therapy

The metyrapone test was used to study the hypothalamo-pituitary-adrenal function in ten children with infantile spasms, before and after ACTH treatment. The hypothalamo-pituitary-adrenal response was normal before ACTH treatment in almost all children. After ACTH, the responses of two children were suggestive of a diminished pituitary reserve; three were suggestive of decreased adrenal as well as decreased pituitary reserve, and one suggested either adrenal hyperplasia with normal pituitary reserve, or appropriate response to a developing medical stress. We suggest that, in children being treated with ACTH, the dosage of ACTH should be gradually tapered, AM cortisol levels should be monitored, and high-dose steroids should be included when treating medical stress.

Infantile spasms following near-drowning: a report of two cases

We report the occurrence of infantile spasms following near-drowning in two children with previously normal development. In both cases, the episode of near-drowning occurred well after the 1st year of life, and the age at onset of spasms (20 and 34 months, respectively) was unusually late. The possible significance of these two cases in relation to the pathophysiological mechanism underlying infantile spasms is briefly discussed.

Identification of infants at risk for infantile spasms by neonatal polygraphy

Reevaluation of neonatal EEGs and polygraphic tracings of 40 infants with infantile spasms and/or hypsarrhythmia resulted in the constitution of a compound score for the identification of infants at risk for infantile spasms by neonatal EEG. The score comprises 8 distinct items: 2 concern behavioral characteristics, 6 abnormality of EEG background activity and paroxysmal events. A tracing registered at conceptional age 36 to 44 weeks (eventually up to 50 weeks) presenting at least 4 of these 8 items is scored positive for the risk of evolving hypsarrhythmia. In a prospective study the polygraphic tracings of 941 newborn infants were evaluated for risk: 18 infants suffering from perinatal distress and 7 newborns with malformations of the brain were scored positive and all 25 developed infantile spasms and/or hypsarrhythmia. One infant with later infantile spasms was missed by the scoring system. None of the remaining infants scored negative manifested infantile spasms. Thus, correct positive prognostication was 100% and false negative 0.1%. By conventional EEG 5 out of 8 patients with infantile spasms were correctly predicted. The high validity of the risk-score based on polygraphic tracing between conceptional age 36 to 44 weeks may allow pre-onset treatment preventing secondary mental deterioration due to hypsarrhythmia and infantile spasms.