Congenital facial nerve agenesis.

We present a case of a seven-year-old child with a congenital facial palsy, diagnosed at birth, who subsequently developed a non-tuberculous mycobacterial (NTM) infection of the ipsilateral parotid gland. This required parotid exploration to treat the NTM disease with the intention of identifying and protecting the facial nerve to preserve any residual facial nerve function. At operation, thorough exploration revealed the complete absence of the nerve both at the stylomastoid foramen and more peripherally within the substance of the parotid gland. Exploration of the facial nerve for congenital facial paralysis is not normally indicated. Surgical treatment, if required, tends to involve the use of techniques such as cross facial nerve and free vascularized muscle grafting. To our knowledge this is the first reported case of complete congenital facial nerve agenesis, diagnosed incidentally during a surgical procedure for an unrelated condition.