Facial Synkinesis Patient Reported Outcome Measure 45-Item Survey (FSP-45)

Background: Facial synkinesis (FS) is a common and disabling sequelae of facial nerve injury, yet no validated, condition-specific patient-reported outcome measure (PROM) exists to assess its functional and psychosocial effects. This study aimed to develop and validate a reliable, patient-centered instrument for individuals with FS. Methods: This prospective, multi-phase validation study (2023–2025) was performed at a tertiary academic medical center in accordance with established recommendations for PROM development and reported following guidelines for observational studies. The process included three phases: instrument development informed by direct patient input, content validation by international experts, and assessment of test–retest reliability. Ninety-nine patients with FS and 25 experts participated. Psychometric evaluation of the 45-item Facial Synkinesis PROM (FSP-45) included internal consistency using Cronbach’s α and test–retest reliability using intraclass correlation coefficients. Results: In Phase 1, 44 patients (mean age 55 years) informed a 67-item draft. In Phase 2, 25 experts evaluations resulted in a refined 46-item measure across five domains: symptoms, involuntary movements, daily activity limitations, social impact, and self-perception. In Phase 3, 55 patients (mean age 50 years) completed the questionnaire twice, approximately one month apart. Cronbach’s α values ranged from 0.888 to 0.943 initially and 0.905 to 0.963 on retest. Intraclass correlation coefficients ranged from 0.553 to 0.839, indicating moderate to excellent test–retest reliability. Conclusion: The FSP-45 demonstrates strong reliability and internal consistency, capturing the physical and psychosocial burden of FS in adults. Responsiveness to clinical change and minimal clinically important difference remain to be established.