The Neck Disability Index Reflects Allodynia and Headache Disability but Not Cervical Musculoskeletal Dysfunction in Migraine

OBJECTIVE: The Neck Disability Index (NDI) is a self-rated disability tool originally developed for whiplash-associated disorders and validated in cervical musculoskeletal conditions. It is now commonly used to assess neck disability in migraine, but it is unknown whether NDI scores relate to migraine and hypersensitivity, cervical musculoskeletal dysfunction, or both. This single-blinded observational study aimed to determine whether the presence of cervical musculoskeletal dysfunction, migraine features, and hypersensitivity predict NDI scores and whether alternate versions of the NDI (NDI-physical, NDI-8, NDI-5) relate more to cervical musculoskeletal dysfunction. METHODS: Migraine and neck pain features, the Headache Impact Test (HIT-6), NDI, Allodynia Symptom Checklist (ASC12), and pressure pain thresholds were assessed in 104 participants with migraine and neck pain, 45 previously identified with cervical musculoskeletal dysfunction and 59 without. The NDI score was regressed on the presence or absence of cervical dysfunction, migraine features, HIT-6, total pressure pain threshold, and ASC12 while accounting for neck pain features. The presence of cervical dysfunction was regressed on the scores of NDI versions. RESULTS: The ASC12 (standardized ß = 0.20) and HIT-6 (standardized ß = 0.18) were significantly predictive of total NDI score, as were neck pain intensity (standardized ß = 0.32) and frequency (standardized ß = 0.44). No scores from alternate NDI versions related to cervical dysfunction. CONCLUSION: The NDI score is a complex measure of neck disability influenced by migraine disability and hypersensitivity beyond the presence of cervical musculoskeletal dysfunction. This has implications for the clinical interpretation of NDI scores in patients with migraine. IMPACT: Many patients with migraine and neck pain report neck disability; therefore, it is important to understand if migraine impacts neck disability. The results of this study indicate that clinicians need to consider migraine-related disability and hypersensitivity when managing neck disability in this population.