Clinical features of infantile spasms

The most typical manifestations are the spasms.

• spasms present as brief symmetrical contractions of musculature of the neck, trunk and extremities lasting up to several seconds
• they occur in clusters which may vary from a few to more than a hundred per cluster
  • a cluster can be from less than a minute to more than 10 minutes in duration
• they may vary from subtle, single, spasms such as a head nod or tonic eye rolling, to full body flexor, extensor or mixed spasms occurring in clusters many times throughout the day (1)
• in majority of events, there is an initial phasic component lasting less than 1 to 2 seconds, followed by a less intense but generally more sustained tonic contraction, which could last up to about 10 seconds.
  • the tonic phase may be absent and only the initial phasic component is present in some infants
• spasms may vary according to several factors
  • the muscle groups involved - flexor, extensor or mixed
    • mixed spasms - in 50% of cases
    • flexor spasms - in 42% of the cases
  • the intensity of the contraction
  • position of the infant during the attack (supine or sitting)
• tends to occur more often on awakening or when falling asleep
• irritability or crying is frequent during or after the spasms (1,2,3)

The observer may note the following sequence of events in a stereotypical infantile spasm:

• with the body held rigid, both arms are held with the elbows extended and the shoulders abducted to 90 degrees
• with the elbows still extended, the arms are bought into the midline
• as the seizure ends the infant usually cries as they regain normal consciousness.

In the longer term there is often cognitive impairment and cerebral palsy.

Reference:

• (1) Wheless JW et al. Infantile spasms (West syndrome): update and resources for pediatricians and providers to share with parents. BMC Pediatr. 2012;12:108
• (2) Fois A. Infantile spasms: review of the literature and personal experience. Ital J Pediatr. 2010;36:15.
• (3) Nelson GR. Management of infantile spasms. Transl Pediatr. 2015;4(4):260-70.