Infantile spasms

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INFANTILE spasms are a relatively rare seizure disorder of infancy and early childhood. Referred to in the literature as massive spasms, flexion spasms, jackknife seizures, infantile myoclonic seizures, etc., they have been recognized as an epileptic phenomenon since they were first described by West in 1841.1 The triad of infantile spasms, retardation, and the electroencephalographic (EEG) pattern, hypsarrhythmia, has become known as West's syndrome.

Although a considerable amount of world literature pertaining to this disorder has accumulated, the classifications and clinical descriptions of the seizures, based largely on routine bedside observation, have been highly variable, and this lack of uniformity has led to confusion and controversy.

The development of long-term polygraphic/video monitoring techniques in the 1970s2 improved our understanding of the clinical manifestations of this disorder and also provided, for the first time, an objective means of studying the effects of therapy on the EEG and on seizure frequency.

In this chapter, we will characterize infantile spasms briefly and address some of the more controversial and still unresolved issues, including therapy and pathophysiology.


Infantile spasms usually begin within the first 6 to 8 months of life; the incidence has been estimated to be 1 per 4,000 to 6,000 live births.3 Familial occurrence of infantile spasms is rare, and there is no clear evidence to suggest a preponderance of one sex over the other.4


The spasm of infantile spasms is usually a brief contraction of the muscles of the neck, trunk, and extremities, typically occurring bilaterally and symmetrically.. . .



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