Infantile Spasms

We have previously discussed how knowing some basic pediatric topics can help you deliver excellent care to the patient you see in the Emergency Department. Sure, maybe you don’t want to remember all of the various infant formulas out there, but a little bit of understanding to serve you and your patients well. Similarly, a knowledge of some basic pediatric milestones and growth parameters can be very useful to you! Along with assisting you in recognizing issues like failure to thrive, familiarity with what infants should and should be doing can help you find those clues when searching through the giant haystack on subtle presentations. Another example of that is primitive reflexes. What appears to be an exaggerated moro reflex may not be that simple. Let’s take a minute to digest a morsel on Infantile Spasms:

Infantile Spasms: Basics 

• Also known as, “Infantile Epileptic Spasms Syndrome” or IESS (Zuberi 2022)
• Often used interchangeably with West Syndrome, although strictly speaking, West Syndrome is the triad of 1. Infantile spasms 2. Developmental regression and 3. Hypsarrhythmia on EEG (Wheless 2012)
• Seizure disorder of early infancy (Smith 2025, Wheless 2012)
  • Presents anywhere from the first week of life up to around 5 years old (Smith 2025),
  • Usually seen between 3 and 7 months
  • 90% of cases are seen in the first year of life (Wheless 2012) 
• Presentation ranges from subtle to the more obvious “jack knife” movements (Smith 2025, Wheless 2012)
• Infantile spasms are associated with future cognitive and motor delays; early identification and treatment improves outcomes (Widjaja 2014)

• Etiologies include:
  • Structural abnormalities of the brain, such as cortical dysplasia (Smith 2025, Pellock 2010)
  • Genetic abnormalities,
    • Trisomy 21 (Smith 2025, Pellock 2010)
    • Infantile spasms are also closely associated with tuberous sclerosis (Smith 2025)
  • Metabolic abnormalities, such as infantile hypoglycemia (Smith 2025, Pellock 2010)
  • Infections, including meningitis, encephalitis, and congenital infections – think TORCH (Smith 2025, Riikonen 1993)
  • Injuries and insults to CNS development in the perinatal and postnatal periods, such as hypoxic-ischemic encephalopathy (Smith 2025, Pellock 2010)
  • Anywhere from 10-40% of children will have no identifying cause (called cryptogenic infantile spasms) (Smith 2025, Wheless 2012, Pellock 2010)

Infantile Spasms: Clinical Features 

• Sudden, brief, clustered spasms (Zuberi 2022, Pellock 2010) 
• Often see flexion and extension movements of the head, neck, trunk, and extremities (Zuberi 2022, Pellock 2010)
  • Think: bending forward at the waist, throwing arms to the side, bending at the knee, throwing the head backwards, stiffening of the arms and legs (Boston Children’s Hospital, 2023)
  • Sometimes referred to as “jack knife” movements (Smith 2025)
• Symptoms can also be much more subtle and include frequent blinking or abnormal eye movements, head bobbing, or changes in breathing pattern (Smith 2025, Wheless 2012)
• Sometimes, signs of developmental regression start around the first noted spasms: the infant no longer rolls from front to back or back to front, they’re less socially interactive, or they’re fussy and more irritable (Smith 2025, Wheless 2012, Zuberi 2022)

Infantile Spasms: Differential 

• Other seizure types 
• Brain injuries, brain masses, CNS infections  
• Startle reflex 
• Esophageal reflux 
• Benign myoclonus 

Infantile Spasms: Evaluation and Diagnosis 

• EEG
  • Looking for the characteristic hypsarrhythmia pattern: high voltage spikes and slow waves (Zuberi 2022)
• MRI
  • Looking for structural abnormalities (Smith 2025, Pellock 2010)
• Blood, urine, and sometimes CSF testing
  • Looking for specific metabolic and genetic markers of disease (Smith 2025)
  • You’re friendly pediatric neurologist and geneticist can help with the specific tests: there’s a lot! 
• Admission to expedite the evaluation is completely reasonable… since… early diagnosis will help lead to early treatment.

Infantile Spasms: Treatment 

• Most importantly: earlier initiation of treatment can help prevent developmental regression (Widjaja 2015) 
• Treatment plans vary: options include ACTH, steroids, and anti-epileptics 
  • ACTH: adding supplemental corticotropin decreases the amounts of corticotropin-releasing hormone in the body, which is thought to trigger spasms (Smith 2025) 
  • Steroids: high dose oral prednisolone; also helps lower amounts of corticotropin-releasing hormone (Wheless 2012)
  • Vigabatrin: inhibits the enzyme that attacks GABA, so increases CNS GABA levels (Smith 2025)
    • Most helpful when infantile spasms are secondary to tuberous sclerosis (Wheless 2012)
• Other medications include our more typical anti-epileptics: levetiracetam, valproic acid, topiramate (Pellock 2010, Song 2017)
• Ketogenic diets are sometimes utilized (Song 2017)
• Rarely, when indicated: surgical removal of structural CNS lesions (Wheless 2012)

Infantile Spasms: Prognosis 

• The best prognosis occurs when treatment is initiated within 1 month of symptom onset (Widjaja 2015, Pellock 2010)
• Mortality varies wildly, and is often based on etiology: 3 to 33% (Smith 2025)
• Spasms are associated with other seizure disorders and psychomotor developmental delay or regression (Smith 2025)
  • Infants have a higher risk for cognitive and motor delays, autism spectrum disorder, among others (Wheless 2012) 
  • Parents sometimes note regression of developmental milestones such as rolling, sitting, crawling, babbling, and social smiles (Smith 2025)
• Spasms can sometimes improve or go away completely with treatment, only to be replaced with different types of seizure activity in the future (Smith 2025)

Moral of the Morsel 

• Keep your eyes open for it! Infantile spasms are a rare form of infantile epilepsy, but do present to our EDs.
• Videos can be very helpful! As the family if they have any videos of the concerning events.
• It can be subtle! While the jack-knife is a bit more obvious, be alert to the subtle presentations too.
• Got MRI and EEG? Yes, admission to help obtain MRI imaging and EEG is often your best course of action when concerned about possible infantile spasms!

Resources 

• Smith MS, Matthews R, Rajnik M, et al. Infantile Epileptic Spasms Syndrome (West Syndrome) [Updated 2024 Feb 1]. In: StatPearls [Internet]. Treasure Island (FL): StatPearls Publishing; 2025 Jan-. 
• Wheless JW, Gibson PA, Rosbeck KL, et al. Infantile spasms (West syndrome): update and resources for pediatricians and providers to share with parents. BMC Pediatr. 2012 Jul 25;12:108. doi: 10.1186/1471-2431-12-108. PMID: 22830456; PMCID: PMC3411499.
• Widjaja E, Go C, McCoy B, et al. Neurodevelopmental outcome of infantile spasms: A systematic review and meta-analysis. Epilepsy Res. 2015 Jan;109:155-62. doi: 10.1016/j.eplepsyres.2014.11.012. Epub 2014 Nov 22. PMID: 25524855.
• Pellock JM, Hrachovy R, Shinnar S, et al. Infantile spasms: a U.S. consensus report. Epilepsia. 2010 Oct;51(10):2175-89. doi: 10.1111/j.1528-1167.2010.02657.x. PMID: 20608959.
• Riikonen R. Infantile spasms: infectious disorders. Neuropediatrics. 1993 Oct;24(5):274-80. doi: 10.1055/s-2008-1071556. PMID: 8309517.
• Zuberi SM, Wirrell E, Yozawitz E, et al. ILAE classification and definition of epilepsy syndromes with onset in neonates and infants: Position statement by the ILAE Task Force on Nosology and Definitions. Epilepsia. 2022 Jun;63(6):1349-1397. doi: 10.1111/epi.17239. Epub 2022 May 3. PMID: 35503712.
• Boston Children’s Hospital. Infantile Spasms. Boston Children’s Hospital. Updated July 2023. Available from: https://www.childrenshospital.org/conditions/infantile-spasms
• Song JM, Hahn J, Kim SH, et al. Efficacy of Treatments for Infantile Spasms: A Systematic Review. Clin Neuropharmacol. 2017 Mar/Apr;40(2):63-84. doi: 10.1097/WNF.0000000000000200. PMID: 28288483.
• Mackay MT, Weiss SK, Adams-Webber T, et al. Practice parameter: medical treatment of infantile spasms: report of the American Academy of Neurology and the Child Neurology Society. Neurology. 2004 May 25;62(10):1668-81. doi: 10.1212/01.wnl.0000127773.72699.c8. PMID: 15159460; PMCID: PMC2937178.