Startle Reflex

What is the “Startle Reflex” used for?

• The startle reflex is a mass myoclonic reflex that is normal in infants and young children.

How to perform the “Startle Reflex”?

• The infant is placed supine with all four limbs in natural extension. 
• The reflex is elicited by making a sudden loud noise or by tapping the infant’s sternum. 
• The normal response is for the elbows and knees to flex (not extend, as in the Moro response) and the hands to remain closed. 

What is the positive result?

• The startle reflex appears at birth and is present through life. 
• Its absence indicates severe hypotonia. 
• An asymmetric response may be due to obstetric brachial plexus paralysis.