Congenital hypoplasia of the depressor anguli oris muscle in the differential diagnosis of facial paralysis.

Facial paralysis presents an interesting diagnostic challenge. Etiologies ranging from facial nerve neuromas and CPA tumors to inflammatory disease and traumatic injuries need be considered and evaluated. However, an asymmetric facial appearance may result from abnormalities of facial musculature as well as facial innervation. Two cases of congenital hypoplasia of the depressor anguli oris muscle, a child and an adult, are reviewed to examine its presentation and diagnostic differentiation from other forms of facial paralysis. Photographs presenting the facial deformity and electrodiagnostic studies will be reviewed.