Introduction: Facial asymmetry during crying in neonates is an important entity which might be due to an underlying true paralysis of the facial nerve or due to the benign overlooked diagnosis of congenital absence of the depressor angularis oris muscle (DAOM).
Case report: We report a full-term newborn delivered by normal spontaneous vertex delivery with uneventful pregnancy and Apgar score of 9 and 10 at 1 and 5 minutes respectively. His parents are first-degree cousins with 4 living normal siblings. His birth weight was appropriate for his gestational age. His initial neonatal assessment was normal apart from facial asymmetry during crying in the form of deviation of the angle of the mouth to the left with an otherwise normal facial appearance. The facial asymmetry disappears at rest (without crying). This condition usually poses a diagnostic dilemma. Developmental and traumatic facial paralysis and being part of some syndromes like Mobius and CHARGE syndromes are among the most important differential diagnosis but the disappearance of the facial asymmetry at rest is diagnostic of absent DAOM which is a relatively common but missed diagnosis.
Conclusions: Pediatricians should be aware about the diagnosis of DAOM in neonates with asymmetric crying face if the face was completely normal at rest with deviation of the angle of the mouth on crying which disappears on rest.
Keywords: Facial asymmetry; depressor angularis oris muscle; neonate.
© The Author(s) 2022.