• CLINICAL NEUROLOGY

The palmomental reflex is considered to be one of the frontal release signs, also known as primitive reflexes.1 These reflexes include utilisation behaviour, grasping, rooting, sucking and snouting, but not pouting—any reflex involving a strike is a myotactic stretch reflex and indicates an upper motor neurone lesion.2 Present in some mammals where they may confer some survival benefits, these reflexes are thought to be present early in human development, to be supressed during cortical maturation, but to re-emerge in the presence of neurological disease affecting the frontal lobes. Typically elicited by gently scratching an orange stick from the proximal to distal aspect of the thenar eminence, a positive palmomental reflex is when there is a single synchronous contraction of the ipsilateral mentalis muscle, that is, a twitch at the chin.3

At face value, the palmomental reflex is perhaps the perfect stereotype of the neurologist's art: visually arresting …