Moebius syndrome is characterized by paralysis of the facial muscles (diplegia), resulting in an inability to produce facial expressions corresponding to common emotions. This paralysis leaves the child with an unchanging, mask-like face. Cranial nerves VI and VII specifically are affected; involvement of these nerves is a primary criterion for diagnosis of Moebius syndrome. In addition to facial diplegia, characteristics include tongue hypogenesis, high nasal bridge, inability to close eyelids, ear deformities, and limb anomalies including clubfoot.
Congenital paralysis of the facial nerve, occurring in the absence of other neurological deficits. It may be unilateral or bilateral.