Glabellar reflex

Glabellar reflex is a neurological reflex that is elicited by repetitive tapping on the forehead. The reflex is named after the glabella, the space between the eyebrows and above the nose. The normal response is for the eyelids to blink in response to the first one or two taps. If the blinking continues, this is known as Myerson's sign, which is often associated with Parkinson's disease and other neurological disorders.

Mechanism

The glabellar reflex is mediated by the trigeminal nerve and the facial nerve. The trigeminal nerve senses the tapping on the forehead, and the facial nerve causes the eyelids to blink. In healthy individuals, the reflex is inhibited by the frontal lobe of the brain after the first one or two taps. If the blinking continues, this suggests that there is a problem with the frontal lobe's inhibitory function.

Clinical significance

The glabellar reflex is used in neurological examinations to assess the function of the frontal lobe and the trigeminal and facial nerves. A positive glabellar reflex (i.e., continued blinking in response to tapping) is known as Myerson's sign. This sign is often seen in patients with Parkinson's disease, but it can also be seen in other neurological disorders, such as progressive supranuclear palsy and corticobasal degeneration.

See also

• Neurological examination
• Parkinson's disease
• Trigeminal nerve
• Facial nerve