[Facial asymmetry with crying: a neurophysiological study and clinical account of this entity]

The objectives of this study were to determine in our newborn population the frequency of facial asymmetry during crying or congenital hypoplasia of the depressor anguli oris muscle (DAOM) without associated major malformations and to evaluate the contribution of electrophysiological studies in the diagnosis of this anomaly.

We performed a prospective study of the living newborns with facial asymmetry which did not need to be admitted to the hospital and that were delivered without the use of forceps in our hospital during 4 consecutive years. Newborn evaluation included physical examination, facial nerve electroneurography and DAOM electromyography.

This anomaly without major malformations was present in 0.348/1,000 newborns. Electrophysiological studies demonstrated a normal latency in the facial nerve electroneurography and an absence or reduced number of motor unit potential without signs of denervation in the electromyography.

Diagnosis of this entity is important to exclude facial nerve palsy. Only a physical examination is necessary for a correct diagnosis.