Home > Diagnoses & Conditions > Infantile Spasms > Description
Infantile Spasms - Description
Description
Infantile spasms (IS) are a type of seizure seen in infancy that occur as the main feature of a seizure syndrome known as West syndrome. Though the terms West syndrome and IS are used interchangeably, IS is preferred. Infantile spasms generally consist of an acute onset of stiffening of the legs and arms while bending forward and may be asymmetrical. They do not usually occur during sleep, but are often observed upon awakening in the morning and after naps. They can be subtle and are sometimes confused with the Moro reflex or colic. IS may appear as:- extension/stiffening of the trunk, arms, and legs
- flexing at the waist, especially obvious when sitting
- thrusting arms to side or across chest
- repetitive head bobbing or nodding
- drawing up of legs to the chest when lying down.
West syndrome/IS is diagnosed when an infant, approximately 3-6 months of age, has spasms that are present in clusters and in great numbers (up to 100 spasms in a cluster and sometimes many clusters a day), developmental delay, and a characteristic EEG pattern called hypsarrhythmia (high amplitude chaotic abnormal pattern). See EEG example of hysarrhthymia (Epilepsy.com) for an example of this EEG pattern. Other seizure types are also seen in 30 to 50% of infants with this syndrome. Spasms usually stop as the infant gets older, but other seizure types often take their place (see the Prognosis section, below).
There are two kinds of IS, symptomatic and idiopathic that have dramatically different prognoses. In symptomatic IS, a specific etiology can be identified through history, physical exam, or testing. Tuberous sclerosis and perinatal asphyxia are the most common symptomatic etiologies. Other causes include cortical brain malformations, metabolic disorders (e.g., maple syrup urine disease, pyridoxine dependency, nonketotic hyperglycemia, phenylketonuria), chromosomal abnormalities, other neurocutaneous syndromes, infection, including prenatal infections (e,g, congenital CMV), and tumor. Of children with IS, 85-90% of children with IS have the symptomatic type. [Pellock: 2010]
Infants with idiopathic IS have normal development and neurologic exams at the onset of spasms and a higher likelihood of "growing out" of them, particularly if the spasms respond well to medication. This suggests that early diagnosis and treatment may affect the outcome in children with idiopathic IS, although children who do and do not respond to medication may represent different populations that we are yet unable to otherwise differentiate. [You: 2009]
Some neurologists identify a third group, cryptogenic IS, in which children at the onset of the spasms are either delayed developmentally or have an abnormal neurologic exam at the onset of the spasms but no specific cause can be identified.
Genetics
Many of the causes of infantile spasms are genetic in origin; including tuberous sclerosis, metabolic disorders, and chromosomal abnormalities. The ARX and CDKL5 genes are associated with infantile spasms in some infants. [Guerrini: 2007] [Bahi-Buisson: 2008]Prognosis
Overall:The prognosis for children with IS depends on the etiology of the spasms and whether or not there is developmental delay and an abnormal neurologic exam at the time of presentation. A good outcome is associated with a lack of identifiable etiology, normal neurologic exam and development at the time of presentation, older age at onset, and a relatively quick and complete response to treatment of the spasms. Most infants with IS have poor outcomes. Overall, 70-90% of children with IS will have intellectual disability, usually severe to profound. 50% will develop some signs of cerebral palsy, and a smaller percentage of children will demonstrate autistic symptoms. [Partikian: 2009] [Mackay: 2004] Development may be improved with early, effective treatment,although the optimal regimen is not known. [Hamano: 2007] [Kivity: 2004] Between 40 and 60% of children with IS will develop Lennox-Gastaut syndrome, a refractory epilepsy syndrome of childhood. [Zupanc: 2009] The evolution from IS to Lennox-Gastaut syndrome may be decreased by early, effective treatment, although there is only circumstantial evidence for this. [You: 2009]
By group:
Treatment is more likely to result in complete or near-complete recovery in those with idiopathic IS than in symptomatic or cryptogenic IS. [Partikian: 2009] [Mackay: 2004]
Prevalence
0.15 to 0.2 per 1000 children 10 years of age or younger. [Mackay: 2004]Helpful Articles
PubMed search for articles on Infantile Spasms in children for the last 3 years
Shields WD.
Infantile Spasms: Little Seizures, BIG Consequences.
Epilepsy Curr.
2006;6(3):63-9.
PubMed abstract / Full Text
Infantile Spasms Module Authors
| Authors: | Lynne M Kerr MD, PhD, 1/2011 Matthew Sweney MD, 1/2011 Paula Peterson APRN, PNP, 1/2011 Denise Nielsen MD, 1/2011 |
| Content Last Updated: | 4/2011 |
The authors listed above are responsible for the overall Infantile Spasms Module. Authors contributing to individual pages in the module are listed on those pages.
Page Bibliography
Bahi-Buisson N, Nectoux J, Rosas-Vargas H, Milh M, Boddaert N, Girard B, Cances C, Ville D, Afenjar A, Rio M, Héron D, N'guyen
Morel MA, Arzimanoglou A, Philippe C, Jonveaux P, Chelly J, Bienvenu T.
Key clinical features to identify girls with CDKL5 mutations.
Brain.
2008;131(Pt 10):2647-61.
PubMed abstract
Guerrini R, Moro F, Kato M, Barkovich AJ, Shiihara T, McShane MA, Hurst J, Loi M, Tohyama J, Norci V, Hayasaka K, Kang UJ,
Das S, Dobyns WB.
Expansion of the first PolyA tract of ARX causes infantile spasms and status dystonicus.
Neurology.
2007;69(5):427-33.
PubMed abstract
Hamano S, Yoshinari S, Higurashi N, Tanaka M, Minamitani M, Eto Y.
Developmental outcomes of cryptogenic West syndrome.
J Pediatr.
2007;150(3):295-9.
PubMed abstract
Kivity S, Lerman P, Ariel R, Danziger Y, Mimouni M, Shinnar S.
Long-term cognitive outcomes of a cohort of children with cryptogenic infantile spasms treated with high-dose adrenocorticotropic
hormone.
Epilepsia.
2004;45(3):255-62.
PubMed abstract
Mackay MT, Weiss SK, Adams-Webber T, Ashwal S, Stephens D, Ballaban-Gill K, Baram TZ, Duchowny M, Hirtz D, Pellock JM, Shields
WD, Shinnar S, Wyllie E, Snead OC 3rd.
Practice parameter: medical treatment of infantile spasms: report of the American Academy of Neurology and the Child Neurology
Society.
Neurology.
2004;62(10):1668-81.
PubMed abstract / Full Text
Partikian A, Mitchell WG.
Neurodevelopmental and Epilepsy Outcomes in a North American Cohort of Patients With Infantile Spasms.
J Child Neurol.
2009;.
PubMed abstract
Pellock JM, Hrachovy R, Shinnar S, Baram TZ, Bettis D, Dlugos DJ, Gaillard WD, Gibson PA, Holmes GL, Nordl DR, O'Dell C, Shields
WD, Trevathan E, Wheless JW.
Infantile spasms: a U.S. consensus report.
Epilepsia.
2010;51(10):2175-89.
PubMed abstract
Although evidence based guidelines were published in 2004, many questions remained about the diagnosis, evaluation, and management
of infantile spasms. This article develops consensus guidelines regarding some of those questions.
You SJ, Kim HD, Kang HC.
Factors influencing the evolution of West syndrome to Lennox-Gastaut syndrome.
Pediatr Neurol.
2009;41(2):111-3.
PubMed abstract
Zupanc ML.
Clinical evaluation and diagnosis of severe epilepsy syndromes of early childhood.
J Child Neurol.
2009;24(8 Suppl):6S-14S.
PubMed abstract