Association Between Intensity of Pain and Impairment in Onset and Activation of the Deep Cervical Flexors in Patients With Persistent Neck Pain

Objectives: This study evaluates the relationship between clinical symptoms and the function of the deep cervical flexor muscles in women with persistent neck pain. Methods: Thirty-two women with a history of neck pain more than 6 months participated in the study. Measures for neck pain area, intensity, duration, and perceived disability were taken. Electromyography was acquired from the deep cervical flexor muscles by a nasopharyngeal electrode suctioned over the posterior oropharyngeal wall as the patients performed 2 tasks: rapid arm movements (shoulder flexion and extension) and isometric craniocervical flexion contractions. Results: The patients' average score for the Neck Disability Index (0 to 50) was 11.0 +/- 2.6 and their average pain intensity rated on a visual analog scale (0 to 10) was 4.7 +/- 1.8. A correlation was observed between the average intensity of pain rated on the visual analog scale and the normalized electromyography amplitude recorded from the deep cervical flexors during the craniocervical flexion contractions (r=-0.36; P<0.05). Furthermore, the relative onset of the deep cervical flexors during rapid shoulder flexion was positively correlated with the average intensity of pain (r=0.50; P<0.01). No significant correlations were identified between the amplitude and the onset of activation of the deep cervical flexors and the duration of pain, area of pain, or Neck Disability Index score of the patient. Discussion: This study shows a relationship between the levels of neck pain intensity and the function of the deep cervical flexor muscles in women with persistent neck pain but not in other clinical features, such as location or duration of the disorder. These findings may partially explain the heterogeneity in motor control impairments in patients with neck pain.