The approach to facial weakness is to first determine if it is an upper motor neuron lesion (spares forehead) or a lower motor lesion (involves forehead). An upper motor neuron lesion suggests the lesion is above the brainstem while a lower motor neuron involves the facial nucleus or the nerve itself.
Characterize Weakness
Differential Diagnosis Medical History
Associated Symptoms Five Senses
IF YES, evaluate for ipsilateral CN6 involvement (Pontine lesion)
Rashes
Other Symptoms
Prior Workup
House-Brackmann scale of severity of facial nerve dysfunction
Gross: normal symmetry at rest Forehead: moderate-good function Eye: complete closure with minimal effort Mouth: slight asymmetry
Gross: normal symmetry at rest Forehead: slight to moderate movement Eye: complete closure with effort Mouth: slightly weak with maximum effort
Gross: obvious weakness and/or disfiguring asymmetry Forehead: no movement Eye: incomplete closure Mouth: asymmetric with maximal effort
Gross: barely perceptible motion/asymmetry at rest Forehead: no movement Eye: incomplete closure Mouth: slight movement