Internal Medicine

Infantile spasms (IS)


Catastrophic childhood epilepsy characterised by a triad of infantile spasms, hypsarrhythmia on electroencephalogram (EEG) and subsequent/concurrent intellectual disability

  • Catastrophic childhood epilepsy (due to the difficulty of controlling seizures and the association with mental retardation)


This epileptic disorder of infancy or early childhood was first described by Dr William James West in 1841 in his son, hence named West syndrome. It is characterized by the triad of infantile spasms, hypsarrhythmia, and retardation. The EEG pattern (hypsarrhythmia) was illustrated by Gibbs. The description of Dr. West is exhaustive: the spasms begun when his son was 4 months old and are described accurately. “The bowing and relaxing of the head and trunk would be repeated alternatively at intervals of few seconds and from ten to twenty or more times at each attack that would continue not more than two or three minutes …sometimes two, three or more attacks in the day. The child appeared frightened and screamed…. he neither possessed the intellectual vivacity or the power of holding himself upright or using his limbs, and his head falls without support.” Dr. West assumed that spasms were caused by an irritation of the nervous system, perhaps caused by teething. The used remedies were no avail. The patient died in an institution at the age of 20 years.


Cryptogenic IS:

IS with no discernible aetiology

Symptomatic IS :

Identified etiology and/or significant developmental delay at the time of spasm onset
  • Tuberous sclerosis complex (TSC) (M/C associated disease)

Clinical features

Infantile spasms initially are diagnosed in children younger than 12 months of age in 90% of cases. The peak incidence of new diagnoses is between approximately 4 and 7 months of age. Once spasms begin, the natural history is for continued spasms or an increase in spasms over time. Without treatment, the frequency of spasms typically does not wax and wane, such that the patient has long symptom-free periods, as a patient might with other seizure types.

Distribution of infantile spasm according to age of onset | Khreisat W. H. (2011). Clinical profile of infants with hypsarrhythmia. Acta informatica medica : AIM : journal of the Society for Medical Informatics of Bosnia & Herzegovina : casopis Drustva za medicinsku informatiku BiH, 19(3), 149–152.

Infantile spasms:

Classically characterized clinically by symmetric, brief (few seconds or less) jerking spells that involve the head, neck, arms, legs, and abdomen which may consist of flexion, extension, or a combination of flexion-extension
  • Often occur in clusters and clusters often occur during sleep-wake transitions
  • More frequently during waking hours than during sleep
  • Return to baseline mental state within seconds after the spasm

Developmental delay or regression

Developmental delay predates the onset of spasms in most cases


Diagnostic algorithm for infantile spasms. As noted, imaging has the highest yield, followed by genetic studies. *, Patients with a convincing history of infantile spasms and abnormalities other than hypsarrhythmia on EEG, may proceed to imaging without repeat EEG. If the concern for infantile spasms is significant and development is affected, it is not recommended to wait for EEG abnormalities, as up to 1/3 of patients may not have hypsarrhythmia. Treatment should begin once imaging is complete unless there is concern for infection and other work-up is needed. EEG, electroencephalogram; MRI, magnetic resonance imaging; ACTH, adrenocorticotrophic hormone; SNP, single nucleotide polymorphism; CGH, comparative genomic hybridization. | Nelson G. R. (2015). Management of infantile spasms. Translational pediatrics, 4(4), 260–270.

Electroencephalogram (EEG):

  • Hypsarrhythmia: High-amplitude, chaotic slowing of generalized distribution without interhemispheric synchronization and with multifocal epileptiform discharges throughout
Spontaneous sleep Eight month old male baby. Hypsarrhythmia. Continuous diffuse irregular slow waves mixed with multifocal spikes. Absence of normal sleep features. | Fois A. (2010). Infantile spasms: review of the literature and personal experience. Italian journal of pediatrics, 36, 15.

MRI brain scans:

Highest yield tool in identifying an underlying etiology of infantile spasms.


Hormonal therapies, including adrenocorticotropic hormone (ACTH) and corticosteroids, and vigabatrin have the most evidence to support their use in infantile spasms. Infantile spasms often are difficult to treat with some patients needing a repeat course of therapy or a second therapy

  • Hormonal therapy: Adrenocorticotropic hormone (ACTH) and corticosteroids (M/effective single therapy for short‐term treatment)
  • Vigabatrin
Treatment algorithm. Suggested sequence of treatment, with etiology incorporated. Data is inadequate to recommend a consistent first-line therapy, except in the case of tuberous sclerosis. It is recommended to try two first-line therapies before moving on to other options, as there is less data to support the second-line treatments. Studies have reported patients that respond to ACTH after failing corticosteroids and vice-versa. | TSC, tuberous sclerosis complex; ACTH, adrenocorticotropic hormone; EEG, electroencephalogram. | Nelson G. R. (2015). Management of infantile spasms. Translational pediatrics, 4(4), 260–270.


The overall prognosis of children with infantile spasms is poor. Up to 50% have long-term developmental and neurologic deficits. Many continue to have seizures, although the spasms may evolve into other types of seizures as the patient ages. These seizure types are also often hard to control with standard treatments. Patients with no specific underlying etiology (cryptogenic) tend to have better neurologic and developmental outcomes than patients with other significant underlying etiologies.

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