Isolated Congenital Facial Nerve Aplasia in a 13-Year-Old Child: Imaging Findings and Long-Term Functional Adaptation.

Facial nerve palsy at birth is an uncommon neurological condition that may arise from perinatal trauma or developmental abnormalities involving the facial nerve or its nucleus. While traumatic facial palsy is relatively common and often demonstrates spontaneous recovery, developmental causes such as facial nerve hypoplasia or aplasia are rare and usually associated with persistent deficits. In many cases, developmental facial palsy occurs as part of congenital syndromes involving multiple cranial nerves or systemic anomalies. Isolated absence of the facial nerve without associated syndromic features is extremely rare. This case report presents the case of a 13-year-old child with isolated congenital left facial nerve palsy who presented with the inability to completely close the left eye and mild facial asymmetry since birth. High-resolution magnetic resonance imaging (MRI) demonstrated a complete absence of the facial nerve on the affected side. While most previously reported cases are described in infancy with limited evidence regarding long-term outcomes, this case demonstrates gradual functional adaptation despite congenital facial nerve absence.