Difference between revisions of "West Syndrome (Infantile Spasm)"

Revision as of 11:18, 13 July 2017

West syndrome

Background

• Severe epilepsy syndrome with the triad:
  • Infantile spasm
  • Hypsarrhythmia
  • Mental retardation
• Onset: 90% in the first 12 months after birth, with a peak onset between 4 and 6 months
• Incedence: 3 to 5/10,000 live births
• 2% of childhood epilepsies
• Classified according to etiology (old International League Against Epilepsy (ILAE) classification)
  • Symptomatic (almost any disorder than can cause brain damage) ie:
    • Trisomy 21 (Down syndrome)
    • Trauma
    • Infectious (meningitis, encephalitis)
    • Metabolic disorders (ie maple syrup urine disease, mitochondrial encephalopathy, pyridoxine dependency)
    • Hydrocephalus/microcephaly
    • Tuberous sclerosis
    • Ischemic encephalopathy
  • Cryptogenic
    • If a symptomatic cause is most probable, however the cause is not identified.
    • 8-42% of the West syndromes
  • Idiopathic
    • 9-14% of the West syndromes
    • In contrast to cryptogenic West, there is a normal development until the onset.
    • No MRI abnormalities
• New International League Against Epilepsy (ILAE) classification:
  • Genetic
  • Structural/metabolic
  • Unknown

Clinic

• Psychomotor arrest or regression
• Spasms, sudden contraction of the trunk en limb lasting around 2 - 10 seconds
  • Flexor spasm (Salaam spasm): Rapid bending of the head and torso forward and simultaneous raising and bending of the arms, similar to the greeting between muslims (Salaam)
  • Extensor spasm: Extension of the neck and trunk and with extension and abduction of the limbs
  • Mixed spasm
• 1 to 30 clusters/day of 20 to 100 spasms each cluster

EEG

Interictal:

• Hypsarrhythmia: high voltage, chaotic, slow waves and spikes in all cortical areas. The spikes originate from multiple foci and have no rhythmical or repetitive organization.
• The typical hypsarrhythmia is usually seen in the early stage of West syndrome
• The EEG gradually evolves to a more synchronized, with increased hemispheric synchronization en symmetry.
• Hypsarrhytmia is most pronounced in sleep and the patients have reduces or absent non-REM sleep.
• Other interictal patterns: diffused (encephalopathic) or focal slowing, multifocal Spike slow wave complex
• The EEG can evolve towards a EEG seen in Lennox Gastaut Syndrome

Ictal EEG

• High-voltage, frontal dominant, generalized slow-wave transient followed by voltage attenuation

West syndrome with hypsarrhytmia (multifocal spike and slow waves, with little organization) in a 8 months old girl (average)