Grasping and sucking reflexes

1. Big picture

Grasping and sucking reflexes are primitive reflexes, also called frontal release signs. They are normal in infants, but they should be suppressed in healthy adults by mature frontal cortical control. If they reappear in an adult, they suggest loss of frontal inhibitory control, usually due to frontal lobe disease or diffuse cerebral damage.

For the exam, the key idea is simple:

Primitive reflexes in an adult = frontal release signs = usually frontal lobe or diffuse cortical pathology.

They are not tendon reflexes and they are not pyramidal signs like Babinski. They are signs of disinhibition of primitive motor patterns.