Overview
The glabellar reflex is a primitive reflex - normally present in infants and absent in adults. In patients with frontal lobe damage or or Parkinsonism, 'frontal release' signs such as glabellar, grasp, suck, snout and palmomental reflexes will be present.
How to Elicit
- Percuss repeatedly between the eyebrows, looking for reactive blinking.
Interpretation
- Increased - ongoing blinking without habitualizationParkinsonism or frontal lobe pathology
- Normal - up to five blinks and then no further blinking following habitualization
- Decreased - no blinking in response to stimulusUpper or lower motor neuron weakness
Increased Glabellar Reflex
Look For
- Ongoing blinking in response to glabellar tap, without habitualisation.
Causes of Increased Glabellar Reflex
- Parkinsonism
- Frontal lobe pathology
Reduced Glabellar Reflex
Look For
- Lack of blinking in response to glabellar tap.
Causes of Reduced Glabellar Tap
- Ophthalmic nerve (V1) lesion
- Facial nerve (VII) lesion
- Pons / medullary lesion
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