The underlying etiology of infantile spasms (West syndrome): Information from the International Collaborative Infantile Spasms Study (ICISS)

John P. Osborne, Stuart W. Edwards, Fabienne Dietrich Alber, Eleanor Hancock, Anthony L. Johnson, Colin R. Kennedy, Marcus Likeman, Andrew L. Lux, Mark Mackay, Andrew Mallick, Richard W. Newton, Melinda Nolan, Ronit Pressler, Dietz Rating, Bernhard Schmitt, Christopher M. Verity, Finbar J. K. O'Callaghan, on behalf of the participating investigators

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To determine the underlying etiologies in a contemporary cohort of infants with infantile spasms and to examine response to treatment.


Identification of the underlying etiology and response to treatment in 377 infants enrolled in a clinical trial of the treatment of infantile spasms between 2007 and 2014 using a systematic review of history, examination, and investigations. They were classified using the pediatric adaptation of International Classification of Diseases, Tenth Revision (ICD‐10).


A total of 219 of 377 (58%) had a proven etiology, of whom 128 (58%) responded, 58 of 108 (54%) were allocated hormonal treatment, and 70 of 111 (63%) had combination therapy. Fourteen of 17 (82%, 95% confidence interval [CI] 59% to 94%) infants with stroke and infarct responded (compared to 114 of 202 for the rest of the proven etiology group (56%, 95% CI 48% to 62%, chi‐square 4.3, P = .037): the better response remains when treatment allocation and lead time are taken into account (odds ratio 5.1, 95% CI 1.1 to 23.6, P = .037). Twenty of 37 (54%, 95% CI 38% to 70%) infants with Down syndrome had cessation of spasms compared to 108 of 182 (59%, 95% CI 52% to 66%, chi‐square 0.35, P = .55) for the rest of the proven etiology group. The lack of a significant difference remains after taking treatment modality and lead‐time into account (odds ratio 0.8, 95% CI 0.4 to 1.7, P = .62). In Down syndrome infants, treatment modality did not appear to affect response: 11 of 20 (55%) allocated hormonal therapy responded, compared to 9 of 17 (53%) allocated combination therapy.


This classification allows easy comparison with other classifications and with our earlier reports. Stroke and infarct have a better outcome than other etiologies, whereas Down syndrome might not respond to the addition of vigabatrin to hormonal treatment.
Original languageEnglish
Pages (from-to)1861-1869
Number of pages9
Issue number9
Early online date16 Aug 2019
Publication statusPublished - 7 Sept 2019


  • West syndrome
  • etiology
  • infantile spasms

ASJC Scopus subject areas

  • Neurology
  • Clinical Neurology


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