Understanding Infantile Spasms

 This is to demonstrate the character of Infantile spasms, a form of seizures which are characterized to have an Extensors muscles Spasms or Rigidity involving Neck ,Trunk and extremities, you may notice that the child seems to be fine , with no constitutional manifestations with no signs of delayed developmental motor or social milestones, (consider at this age a recent inability to sit unassisted ) most likely to be cryptogenic Infantile spasms.which have an excellent prognosis.
though you may consider associated developmental regression signs in West syndrome or secondary to Tuberous Sclerosis.

typically infantile spasms presents between 4-8 Months of age.

these features and this characteristic video is important to understand because it excludes the need to perform a lumbar puncture to exclude meningitis, and as you could listen from the video the best next step to confirm is to do an EEG which would show Bizzare spike and waves AKA "hypsarrhythmia" 
 

I delayed to mention that the suggested pathogenesis of infantile spasms is increased CRH release from the hypothalamus which increases neurological excitability (however still couldn't understand why it always involves extensors muscles or why it occurs preferentially in head and trunk ?) , this is only to clear any confusion that the suggested treatment would be ACTH administration,or sometimes Predinisone administration.

 though I would recommend further readings in this topic if you are interested in pediatrics Neurology.