Bilateral facial nerve palsy is an exceedingly rare condition and presents a diagnostic challenge. Bilateral facial nerve palsy may result from cranial trauma, congenital abnormalities, inflammation, infiltration, or infection, but is rarely associated with syphilis. Here, we report a case of syphilis in which bilateral facial nerve palsy was the only initial symptom.

A 22-year-old man presented at our emergency department with isolated bilateral facial nerve palsy. Results for initial serum and cerebrospinal fluid examinations were normal, including the rapid plasma reagin titer. One week later, the patient developed rashes on the torso, palms, and soles. At this time, a high serum rapid plasma reagin titer was detected, and the Treponema pallidum particle agglutination test was positive. Once the tests were confirmed, the patient admitted to a history of unprotected sexual behavior. Penicillin G treatment was effective, and a 3-month follow-up examination demonstrated a complete recovery.

We recommend that syphilis be considered when diagnosing sexually experienced young men presenting with bilateral facial nerve palsy, even in the absence of skin manifestations. Failure to recognize facial signs of syphilis could result in inappropriate management, affecting the patient’s clinical outcome.