{
 "topic": "Infantile Spasms",
 "slug": "infantile-spasms",
 "category_id": 15728,
 "summary": "Recognizing infantile spasms and West syndrome, their varied etiology led by tuberous sclerosis, the hypsarrhythmia EEG signature, and why urgent evaluation and treatment matter for development.",
 "written_by": "claude-sonnet",
 "references": [
  {
   "title": "Cover",
   "author": "Vitalsource Download",
   "pages": [
    8365,
    8474,
    8555,
    9114
   ]
  },
  {
   "title": "Pediatric Clinical Practice Guidelines & Policies, 18th Edition",
   "author": "American Academy of Pediatrics",
   "pages": [
    456
   ]
  },
  {
   "title": "Zitelli and Davis' Atlas of Pediatric Physical Diagnosis: Expert Consult - Online",
   "author": null,
   "pages": [
    638,
    639
   ]
  },
  {
   "title": "Update in Pediatrics",
   "author": null,
   "pages": [
    570
   ]
  },
  {
   "title": "Textbook of Pediatric Gastroenterology, Hepatology and Nutrition (Stefano Guandalini, Anil Dhawan)",
   "author": null,
   "pages": [
    983
   ]
  },
  {
   "title": "Pediatric Board Study Guide",
   "author": null,
   "pages": [
    1083
   ]
  },
  {
   "title": "Netters Pediatrics (Florin \u0422., Ludwig St.)",
   "author": null,
   "pages": [
    492
   ]
  },
  {
   "title": "Illustrated Textbook of Paediatrics (Tom Lissauer, Will Carroll)",
   "author": "Lissauer, Tom,Carroll, Will",
   "pages": [
    521
   ]
  }
 ],
 "short": [
  {
   "title": "In short",
   "content": "- Infantile spasms are sudden, forceful, highly stereotyped, brief (a few seconds) contractions of the neck, trunk, and extremities \u2014 flexor, extensor, or mixed flexor-extensor type \u2014 occurring in clusters (several to over 100 spasms per cluster) lasting minutes to hours, with near-immediate return to baseline between spasms.\n- Also called salaam attacks or Blitz-Nick-Salaam-Krampfe; onset typically between 3\u201312 months of age (peak 4\u20136 months), essentially always before age 2.\n- Spasms are strongly tied to the sleep-wake transition \u2014 most frequent on falling asleep or awakening \u2014 and are often initially mistaken for colic, hiccups, or gastroesophageal reflux.\n- West syndrome = the triad of infantile spasms, hypsarrhythmia on EEG, and developmental delay/regression. Hypsarrhythmia is a chaotic, high-voltage, irregular, asynchronous slow-wave pattern with multifocal spikes across all head regions; a burst-suppression pattern may appear in sleep.\n- Etiology is varied: cerebral malformations/dysgenesis, metabolic disorders, congenital infection, hypoxic-ischemic injury, neurocutaneous disorders (notably tuberous sclerosis, the single most common identifiable cause, accounting for about 7\u201325% of cases), and genetic epilepsies (e.g., trisomy, PKU). Up to 20% of cases are idiopathic/cryptogenic.\n- Neuroimaging is abnormal in 70\u201380% of affected children; children with an identifiable underlying cause have a higher rate of developmental impairment than those with unknown (cryptogenic) cause.\n- More than 50% of patients with infantile spasms go on to develop other forms of epilepsy later in life; a subset progresses specifically to Lennox-Gastaut syndrome (intellectual disability, multiple seizure types, slow spike-wave EEG pattern).\n- Urgent evaluation is essential once infantile spasms are suspected \u2014 MRI brain, EEG, and metabolic/genetic testing \u2014 because the underlying cause may be treatable and prompt treatment of the spasms themselves can improve developmental outcome.\n- Behavioral arrest during the spasm, and any developmental arrest or regression around the same time, are important clinical clues distinguishing true infantile spasms from benign infant behaviors (Sandifer syndrome tied to feeding, benign paroxysmal vertigo, infantile shuddering, infantile gratification phenomenon/self-stimulatory behavior) \u2014 none of which cause loss of responsiveness.\n- Diagnosis is not always obvious at first: caregivers often describe self-hugging/flexion movements in clusters, crying between spasms, worse just before sleep or on waking \u2014 a description that should prompt EEG rather than reassurance."
  }
 ],
 "long": [
  {
   "title": "Definition",
   "content": "Infantile spasms are sudden, forceful, highly stereotyped, simultaneous contractions of the hips, trunk, neck, and extremities, each lasting only a few seconds. They may appear as sudden flexion or extension of the extremities with variable involvement of each body region, and are classified as flexor, extensor, or mixed flexor-extensor type. Spasms are usually bilateral, though they rarely appear to predominantly affect one side. They occur explosively in clusters \u2014 sometimes up to hundreds of spasms per day \u2014 lasting minutes to hours, with near-immediate return to baseline between individual spasms; while spasms vary between patients, each individual patient's pattern is highly stereotyped. The condition is also known by the older terms salaam attack and Blitz-Nick-Salaam-Krampfe. When infantile spasms occur together with the EEG finding of hypsarrhythmia and developmental delay or regression, the combination is called West syndrome."
  },
  {
   "title": "Epidemiology",
   "content": "Infantile spasms typically begin before age 2 years, with onset most commonly between 3 and 12 months of age and a peak age at onset between 4 and 6 months. Spasms are strongly linked to the sleep-wake cycle, occurring with greatest frequency on falling asleep or waking up, and are often preceded or accompanied by loss of visual (ocular) pursuit and developmental arrest. More than half of patients with infantile spasms go on to develop other forms of epilepsy later in life, and a recognized subset evolves specifically into Lennox-Gastaut syndrome (intellectual disability, multiple seizure types, and a slow spike-wave EEG pattern)."
  },
  {
   "title": "Etiology",
   "content": "The etiology of infantile spasms is varied and includes cerebral malformations (neuronal migration disorders), metabolic disorders, congenital infections, hypoxic-ischemic (anoxic) injury, neurocutaneous disorders, and genetic conditions (including trisomy and phenylketonuria). Tuberous sclerosis is the single most common identifiable cause, accounting for roughly 7\u201325% of cases across sources. Despite this range of identifiable causes, up to 20% of cases remain idiopathic or cryptogenic. Children with a known underlying disorder have a higher incidence of developmental impairment than those whose infantile spasms arise from an unknown (cryptogenic) cause."
  },
  {
   "title": "Clinical features",
   "content": "The clinical picture is often initially mistaken for benign conditions: early in the disorder, infantile spasms can resemble colic, hiccups, or gastroesophageal reflux, and caregivers often describe self-hugging or flexion movements occurring in clusters, with the infant crying in between spasms, and events more frequent just before sleep or upon awakening. Behavioral arrest during the spasm is a characteristic and important clue that distinguishes it from benign infant movements. Developmental arrest or regression accompanying the onset of spasms is another critical clue and should prompt urgent evaluation rather than reassurance. Several benign, non-epileptic entities can mimic infantile spasms or other pediatric seizures but do not cause loss of responsiveness: Sandifer syndrome (infantile gastroesophageal reflux with tonic-spasm-like posturing, consistently tied temporally to feeding), benign paroxysmal vertigo (a precursor to later childhood migraine), infantile shuddering (brief rapid side-to-side head/trunk shaking), paroxysmal dystonia in older children, tics (suppressible, urge-preceded stereotyped movements), and the infantile gratification phenomenon (self-stimulatory stereotyped leg-crossing/pelvic pressure movements, most common in girls, that stop with distraction and are a benign, self-soothing behavior akin to thumb-sucking)."
  },
  {
   "title": "Diagnostics",
   "content": "Urgent evaluation is warranted once infantile spasms are suspected, since the underlying cause may reflect a significant neurologic disturbance (neuronal migration disorder, metabolic disorder, genetic epilepsy) and prompt treatment of the spasms has the potential to improve developmental outcome. Workup includes EEG, MRI of the brain, and metabolic and genetic testing. The classic EEG finding is hypsarrhythmia: a chaotic, disorganized interictal pattern with high-voltage, irregular, asynchronous slow waves occurring over all head regions, intermixed with multifocal spike discharges; a burst-suppression pattern may be seen during sleep. Neuroimaging is abnormal in 70\u201380% of affected children, reflecting how often a structural cause underlies the syndrome. When infantile spasms, hypsarrhythmia, and developmental delay or regression occur together, the diagnosis is West syndrome."
  }
 ],
 "clinical": [
  {
   "title": "Management",
   "content": "When a caregiver describes clusters of brief, stereotyped flexion or extension movements of the neck, trunk, and limbs \u2014 especially occurring around sleep transitions, with crying between events and any accompanying developmental regression \u2014 do not dismiss this as colic, reflux, or a benign startle; obtain an urgent EEG to look for hypsarrhythmia and refer promptly to pediatric neurology, since treatment initiated early has the potential to improve long-term developmental outcome. Pursue MRI of the brain and metabolic/genetic testing in parallel to identify a treatable underlying cause (e.g., tuberous sclerosis, a structural malformation, a metabolic disorder), since roughly 70\u201380% of affected children have an abnormal MRI and identifying the cause both guides treatment and informs the family about developmental prognosis (children with an identified underlying cause carry a higher risk of developmental impairment than cryptogenic cases).\n\nDistinguish infantile spasms from benign look-alikes using the presence or absence of behavioral arrest and developmental regression: Sandifer syndrome is tied consistently to feeding, benign paroxysmal vertigo and infantile shuddering do not impair responsiveness, and the infantile gratification phenomenon stops with distraction \u2014 none of these produce the loss of responsiveness characteristic of a true spasm. Counsel families that West syndrome (the triad of spasms, hypsarrhythmia, and developmental delay/regression) carries a guarded prognosis and that over half of affected children develop other epilepsy types later, including in some cases progression to Lennox-Gastaut syndrome, so ongoing neurologic follow-up after the acute spasms are controlled remains important even if the spasms themselves respond to treatment."
  }
 ]
}