Bell's palsy — peripheral CN VII lesion affecting the entire hemi-face (including forehead).

Bell's palsy is an idiopathic lower-motor-neuron (peripheral) lesion of CN VII, often associated with HSV-1 reactivation and inflammation in the facial canal. Classic features: acute onset, unilateral, complete hemi-facial weakness (including forehead and eye closure — distinguishing it from a central/stroke cause which spares the forehead), hyperacusis, decreased taste on anterior 2/3 of tongue, and decreased lacrimation. Treatment: high-dose corticosteroids within 72 hours ± antivirals; eye protection.