Which clinical history findings are characteristic of infantile spasm (West syndrome)?

Updated: Jan 11, 2019
  • Author: Tracy A Glauser, MD; Chief Editor: Stephen L Nelson, Jr, MD, PhD, FAACPDM, FAAN, FAAP  more...
  • Print

Spasms begin with a sudden, rapid, tonic contraction of trunk and limb musculature that gradually relaxes over 0.5-2 seconds. Contractions can last 5-10 seconds. The intensity of spasms may vary from a subtle head nodding to a powerful contraction of the body. Infantile spasms usually occur in clusters, often comprised of several dozen spasms, each separated by 5-30 seconds. Spasms frequently occur just before sleep or upon awakening. They can be observed during sleep, although this is rare.

Spasms can be flexor, extensor, or a mixture of flexion and extension. Flexor spasms consist of brief contractions of the flexor muscles of the neck, trunks, and limbs, resulting in a brief jerk. They may resemble a self-hugging motion and often are associated with a cry. The patient then relaxes, and the jerk repeats. These attacks occur in clusters throughout the day and last anywhere from less than 1 minute to 10-15 minutes or longer in some patients.

Extensor spasms consist of contractions of the extensor musculature, with sudden extension of the neck and trunk and with extension and abduction of the limbs. Extensor spasms and asymmetrical or unilateral spasms often are associated with symptomatic cases.

Mixed spasms are the most common type, consisting of flexion of the neck and arms and extension of the legs or of flexion of the legs and extension of the arms. In different series, the frequency of the 3 spasm types were 42-50% mixed, 34-42% flexor, and 19-23% extensor.

Interictal manifestations

An arrest or regression of psychomotor development accompanies the onset of spasms in 70-95% of patients.

Family history

A family history of infantile spasms is uncommon, but as many as 17% of patients may have a family history of any epilepsy.

Did this answer your question?
Additional feedback? (Optional)
Thank you for your feedback!