Elsevier

Pediatric Neurology

Volume 24, Issue 2, February 2001, Pages 89-98
Pediatric Neurology

Review article
Infantile spasms

https://doi.org/10.1016/S0887-8994(00)00238-1Get rights and content

Abstract

Infantile spasms constitute both a distinctive seizure type and an age-specific epilepsy syndrome that have been extensively described for over a century. Standardization of the classification of infantile spasms has evolved, culminating in recent recommendations for separately recognizing and distinguishing the seizure type (spasms or epileptic spasms) and the epilepsy syndrome of infantile spasms (West syndrome). More-detailed descriptions of the clinical and electrographic features of epileptic spasms and hypsarrhythmia have emerged. Advances in neuroimaging techniques have revealed clues about pathophysiology and increased the etiologic yield of the diagnostic evaluation of patients with infantile spasms. Adrenocorticotrophic hormone remains the treatment of choice for many neurologists. Recent controlled studies support vigabatrin as first-line therapy, and open-label studies suggest that topiramate, lamotrigine, and zonisamide may be useful in treating spasms. Recent reports of visual-field constriction with vigabatrin may limit its use. Surgical treatment has been used successfully in a select subgroup of patients with secondarily generalized spasms from a single epileptogenic zone. Although the prognosis for most patients with infantile spasms remains poor, further studies identifying predictors of favorable prognosis and recent advances in understanding the pathophysiology of infantile spasms offer hope of safer and more-effective therapies that improve long-term outcome.

Introduction

In 1841, West described infantile spasms as a unique seizure type with associated devastating developmental consequences in his own son [1]. Uncertainty remains regarding many aspects of infantile spasms, including basic definitions and classification, seizure phenomenology, etiology, and pathophysiology, and the impact of treatment on eventual developmental outcome. Within the past decade, some of these controversial issues have been clarified, but many questions remain. This article reviews the major features of infantile spasms, focusing on how recent developments have improved our understanding and approach to this challenging condition.

Section snippets

Terminology and classification

The term infantile spasms has been used to refer to either a seizure type or an epilepsy syndrome, causing confusion among clinicians and in the medical literature. Although the infantile spasm seizure type is an essential component of the infantile spasms syndrome, patients with the syndrome of infantile spasms may have other seizure types in addition to spasms. Conversely, seizures indistinguishable from infantile spasms may occur in other noninfantile epileptic syndromes. Partial seizures

Epidemiology

Incidence rates of infantile spasms are remarkably similar among different studies from various regions of the world, ranging from approximately two to five per 10,000 live births [9], [10], [11], [12], [13], [14]. The lifetime prevalence of infantile spasms at age 10 years has been estimated at 1.5 to 2 per 10,000 children [10], [13]. The consistently lower prevalence rates of infantile spasms among children compared with incidence can most likely be attributed to the relatively high mortality

Clinical manifestations

Spasms may have variable features but generally consist of brief muscle contractions involving the neck, the trunk, and the extremities in a symmetric bilateral fashion [16]. Using EEG video analysis, spasms have been categorized into three subtypes (flexor, extensor, and mixed flexor-extensor) on the basis of postural manifestations and patterns of muscle involvement during the seizure [16], [17], [18]. Flexor spasms typically involve flexion of the neck, trunk, and extremities, resulting in

EEG features

The classic interictal EEG pattern of patients with epileptic spasms is hypsarrhythmia (Fig 1). Although it is widely accepted that epileptic spasms are typically associated with hypsarrhythmia, there are little data on the proportion of patients with clinical spasms that do not have hypsarrhythmia because almost all studies of infantile spasms include hypsarrhythmia as a diagnostic criteria. Although the combination of epileptic spasms and hypsarrhythmia constitute the essential features of

Etiology and pathophysiology

The reported percentage of total infantile spasms cases classified as symptomatic has risen over the years as etiologies have become identified more readily. In the early 1980s, most studies found identified symptomatic etiologies in approximately 45-60% of patients [15], [19], [21]. More recent studies have consistently classified 70-80% of patients into the symptomatic group [12], [14], [22]. This trend can be attributed mostly to the improved sensitivity of diagnostic testing, especially

Treatment

Because of the poor prognosis of infantile spasms, treatment is usually initiated quickly and aggressively after diagnosis, often at the risk of serious side effects, with the hope of changing the natural history of the disease. Although a vast literature concerning treatment of infantile spasms exists, there has been an abundance of methodologic problems and a paucity of well-designed clinical trials. The often subtle nature of epileptic spasms makes uncontrolled clinical reports of spasm

Prognosis

Many studies have examined the long-term prognosis of patients with infantile spasms. Although there is substantial variability in specifics reported from different studies, by all accounts the majority of patients with infantile spasms suffer a poor outcome with respect to chronic epilepsy, mental retardation, and other neurodevelopmental disabilities.

Epileptic spasms resolve spontaneously without treatment or with treatment in the majority of patients, usually by midchildhood [20], [23], [88]

Conclusions

Children with infantile spasms represent one of the greatest challenges for pediatric neurologists. Accurate diagnosis depends on a thorough understanding of the clinical and electrographic features of spasms. Diagnostic evaluation should use a rational approach for identifying potential etiologies of symptomatic infantile spasms. Decisions about treatment should take into account the poor prognosis of infantile spasms, conflicting data about the impact of treatment on long-term outcome, and

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      This improvement continues for most children after two years and maybe beyond 5, even though spasm control and arrest of hypsarrhythmia were obtained within two months of diagnosis in 95% of our patients. For the whole cohort, 44% (81% of those with NIE) achieved a DQ within the normal range compared to 10–30% previously reported in the literature [1, 2, 10, 11]. This DQ improvement could be explained partly by our high responder rate (95%) with no late spasm relapse.

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