Cervical branch of the facial nerve in leprosy.

This study demonstrates that the platysma is occasionally palsied in leprosy and that this only occurs when the facial nerve already has some other palsy. That there needs to be a facial palsy before there can be a platysma palsy is strongly suggested, in that there was no case of an isolated platysma palsy. Patients, regardless of age or other factors, could mimic a platysma contraction. This obviates the need for electrical testing to examine for a platysma palsy. It also means that a nonfunctioning platysma on clinical examination is, in fact, a palsied platysma. While lagophthalmos is regularly examined for, and any obvious facial paresis would be noticed, less severe forms of facial muscle paresis will only be found if formally examined for. The mechanism whereby the facial nerve is involved in leprosy is not clarified, but our findings suggest that proximal spread of a lesion that began in the zygomatico-temporal branches and reaches to the facial nerve trunk is more likely than new lesions developing de novo in other peripheral facial nerve branches. That the primary lesion is within the facial nerve trunk in all cases but we only see the frequent zygomatic sequelae due to secondary factors is not excluded.