Moro and palmar grasp reflexes in neonatal examination
THE CONTEXT
The responses and maturation of neonatal reflexes help characterize neurological development and identify abnormal findings.
Eliciting and interpreting the Moro reflex
•
Elicit the Moro reflex by slightly raising and suddenly dropping the baby's head while continuing to support the neonate with the hand.
•
The response begins with hand opening and upper-limb extension and abduction, followed by anterior flexion in an embracing movement with an audible cry.
•
Hand opening is present by 28 weeks of gestation, extension and abduction by 32 weeks, and anterior flexion by 37 weeks.
•
The Moro reflex normally disappears by 3–6 months.
•
A generalized central nervous system disturbance is the most common cause of a depressed or absent Moro reflex. An asymmetrical Moro reflex indicates root plexus injury.
Palmar grasp maturation
•
Palmar grasp is present at 28 weeks of gestation and is strong by 32 weeks.
•
At 37 weeks, the grasp is strong enough to allow lifting of the neonate.
•
By four months, palmar grasp becomes less consistent, allowing voluntary grasp to appear.