Congenital unilateral lower lip palsy.

Thirty-nine cases of congenital facial asymmetry, in which one corner of the mouth does not dip downward symmetrically with the other, are presented. The author has termed this condition 'congenital unilateral lower lip palsy' (CULLP). CULLP was the most frequent condition in congenital facial anomalies seen in our clinic. Complaints were purely cosmetic. No functional disorders in pronouncing labial sounds or in suckling were noticed. As for pathogenesis, an insufficiency of the unilateral depressor labii inferior muscle is the most likely cause. An important point is that the lower lip, when drawn down, is normal, whereas the contralateral lip is paralysed. As far as facial asymmetry is concerned, CULLP is a minor deformity. Nevertheless, possible association with other anomalies must be seriously considered when examining patients, especially neonates. As for treatment, selective facial nerve blocking is successfully done in our clinic.