**3. Emotional vs. volitional facial paresis**

Perhaps the most difficult and poorly understood component of facial palsy is the distinction between voluntary and emotionally driven facial expressions. It must be appreciated that human facial emotional expression is a complex phenomenon resulting from the summation of activity of a large-scale neural network in the cerebral cortex [2]. Gower's description provides an early description of a clinical dissociation between voluntary and emotionally driven facial expressions [3, 4]. Emotional facial paresis results in impaired activation of face muscles with emotion but normal

voluntary activation. In contrast, volitional facial paresis such as Bell's palsy results in facial weakness on voluntary effort while emotional movements are preserved [5].
