Cervical musculoskeletal function is variable in tension-type headache: A cluster analysis.

OBJECTIVES: This study was conducted to (1) consider the causes of neck pain in tension-type headache (TTH) by investigating how the patients with TTH, idiopathic neck pain (INP), and healthy controls group together based on the presence of cervical musculoskeletal dysfunction; and (2) determine any differences in TTH features, pain sensitivity, tenderness scores, and active trigger points between clusters. BACKGROUND: Neck pain is common in TTH, yet its source is still unclear. Pain sensitivity, tenderness, and active trigger points are also found in individuals with TTH. Understanding the complexity of neck pain mechanisms in TTH is important for management. METHODS: The study was conducted at The University of Queensland, Australia, from October 2022 to 2024. This cross-sectional study involved 80 participants with TTH, 25 INP, and 27 healthy controls. Participants were assessed with a comprehensive set of musculoskeletal tests to identify any cervical disorder, including kinematics (range of motion, velocity, and accuracy), segmental joint dysfunction, muscle function (cranio-cervical flexion test, cervical flexor, and extensor endurance), and joint position sense. Pain sensitivity was assessed using pressure pain thresholds, cold pain thresholds, wind-up ratio, and pain with musculoskeletal testing. Pericranial tenderness and active trigger points were assessed. Cluster analysis was used to group participants' performance across all musculoskeletal tests. RESULTS: Two mild-to-moderately strong clusters were formed (total n = 132). Cluster 1 (n = 85) contained 25 of 27 (92.6%) healthy controls, classified as normal cervical function. Cluster 2 (n = 47) contained 22 of 25 (88.0%) participants with INP, classified as cervical musculoskeletal disorder. Of the 80 participants with TTH, 57 (71.2%) were in cluster 1 (normal cervical function), noting that 52 of 57 (91.2%) reported neck pain. The remaining 23 of 80 (28.8%) were in cluster 2 (cervical musculoskeletal disorder). They reported higher neck pain intensity (p = 0.006) and had decreased pressure pain thresholds in the neck (p = 0.001) compared to participants with TTH in cluster 1. Pain with testing was detected in participants with TTH in both clusters. There were no differences in tenderness (p = 0.571) and active trigger points (p = 0.061) between TTH clusters. CONCLUSIONS: Approximately 30% of participants with TTH clustered with participants with a cervical musculoskeletal disorder, reflected by the collective presence of cervical segmental joint, movement, and muscle dysfunction. This suggests a potential peripheral cervical nociceptive source. Over 70% of this TTH cohort clustered with healthy controls despite the presence of neck pain, indicating that the neck pain is likely part of the headache pathophysiology. Furthermore, pain with testing, neck tenderness, and active trigger points were independent of a cervical musculoskeletal disorder, again suggesting that they are driven by headache pathophysiology. The cluster structure supports differences in cervical musculoskeletal function in individuals with TTH. These results should prompt a rethink of indications for treating the neck in each individual with TTH.