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What are infantile spasms (IS)?
IS are a rare but serious form of epilepsy that is characterized by sudden limb movements known as “spasms”. The spasms typically begin in the first year of life, when the baby is between 3 and 8 months of age, and in almost all cases have their onset prior to 3 years of age1,2. It is common for IS to be misdiagnosed as normal startle reflexes or colic. The incidence of IS ranges from 2 to 3.5 cases per 10,000 live births1,3,4.
IS are often seen in children with West syndrome, an epileptic encephalopathy that is accompanied by neurodevelopmental regression and cognitive impairment1,3. The interictal electroencephalogram (EEG) often shows hypsarrhythmia, a high-amplitude irregular pattern of brain activity1,3,5. If the spasms and hypsarrhythmia cannot be controlled, the child may continue to have severe chronic epilepsy and cognitive delay for life5. The spasms themselves are usually outgrown by age 5, but the cognitive delay continues, and the child often develops other forms of drug-resistant seizures, such as those of Lennox-Gastaut syndrome6. Research has found that 9-35% of children with IS also have autism spectrum disorder2,6.
How do you recognize infantile spasms?
IS are subtle and often go unnoticed since they tend to occur for less than 5 seconds7. Most of the seizures involve arm raising and/or extension, flexion at the waist, wide-eyed blinks or dropping of the head7. IS typically occur in clusters and often occur upon awakening or during early phases of sleep, though they can be present at other times8.
What are the underlying causes of infantile spasms?
IS has a wide variety of causes. Some cases of IS can be attributed to chromosomal abnormalities and genetic mutations, including mutations in the CDKL5, ARX, and DCS genes2. Many children with IS also have a genetic disorder called Tuberous Sclerosis complex, which arises from mutations in the TSC1 and TSC2 genes and results in brain malformations2,5. Other known etiologies of IS include fragile X syndrome, focal cortical dysplasia, and Down syndrome5,7. IS may also be acquired via infection, stroke, hypoxic-ischemic insults, or metabolic abnormalities2,5. In the case of cryptogenic IS, there is no underlying or detectable cause3.
How are infantile spasms diagnosed?
If a parent suspects that their child has IS, it is suggested that the spasms be captured on video and shown to a clinician to determine whether the movements are truly spasms2. An EEG is then ordered, and the child is diagnosed with IS if an EEG shows hypsarrhythmia5,7. The clinician may also suggest getting a magnetic resonance imaging (MRI) of the child’s brain to identify potential etiologies2. Pre-symptomatic EEG monitoring has been recommended in “at risk” children in an effort to predict the onset of IS and start early treatment.
Treatment options
- Upon diagnosis of IS, vigabatrin, an anti-seizure drug, is typically prescribed as the first line of treatment in an effort to stop the seizures and eliminate hypsarrhythmia3,5. If vigabatrin treatment is unsuccessful, then hormone therapy, including adrenocorticotropin (ACTH) injections or prednisolone (oral steroids), is used as a second line of treatment2,3.
- Research indicates that combination therapy may also offer significant benefits to IS patients in controlling the seizures; in particular, vigabatrin combined with prednisolone1,2.
- If the child has drug-resistant IS, then alternative treatment options, such as brain surgery or ketogenic diet therapy, should be considered2.
- Early diagnosis and treatment are imperative since the seizures are often associated with poor long-term neurodevelopmental outcomes and cognitive impairment2,5,8. Additionally, earlier treatment of IS may help reduce healthcare utilization6.
References
(1) Hahn J, Park G, Kang HC et al. (2019) Optimized treatment for infantile spasms: vigabatrin versus prednisolone versus combination therapy. J Clin Med 8:1591.
(2) Kelley SA & Knupp KG (2018) Infantile Spasms – Have we made progress? Curr Neurol Neurosci 18:27
(3) Widjaja E, Go C, McCoy B, Snead OC (2015) Neurodevelopmental outcome of infantile spasms: A systematic review and meta-analysis. Epilepsy Res 109: 155-162
(4) Jia JL, Chen S, Sivarajah V, Stephens D, Cortez MA (2018) Latitudinal difference on the global epidemiology of infantile spasms: systematic review and meta-analysis. Orphanet J Rare Dis 13: 216
(5) Dulla, CG (2018) Utilizing animal models of infantile spasms. Epilepsy Curr 18: 107-112
(6) Gold L, Schepman PB, Wang WJ, Philbin M, Niewoehner J, Damal K, Hansen RN (2016) Healthcare costs and resource utilization in patients with infantile spasms treated with H.P Acthar gel. Adv Ther 33:1293-1304
(7) Tapp S, Anderson T, Visootsak J (2015) Neurodevelopmental outcomes in children with Down syndrome and infantile spasms. J Pediatr Neurol 13(2): 74-77
(8) Gul Mert G, Herguner MO, Incecik F, Altunbasak S, Sahan D, Unal I (2017) Risk factors affecting prognosis of infantile spasms. Int J Neurosci 127(11): 1012-1018