Investigating cervical flexion-relaxation ratio in subjects with cervical lateral spinal stenosis compared with asymptomatic controls: A case control study.

Introduction: The cervical flexion-relaxation ratio (FRR) is known as a quantitative measure of the ability of the cervical extensor muscles to relax during the full flexion of the cervical spine. Compared with subjects suffering from non-specific neck pain, the changes occurring in the pattern of the neck muscles' functions in cases with cervical spinal stenosis are not yet well understood. Therefore, this study aimed to compare cervical FRR in subjects with cervical lateral spinal stenosis and asymptomatic controls.

Methods: In total, 25 subjects with cervical lateral spinal stenosis (aged 44.7 ± 10.4) and 25 asymptomatic individuals (aged 44.3 ± 10.8) were included in this study. These participants performed full-neck flexion, and at the same time, the electrical activity of the cervical erector spinae (CES) muscles was recorded bilaterally. Cervical FRR was further calculated by analyzing the electromyographic data recorded for each muscle.

Results: The mean cervical FRR was significantly lower (P = 0.015) and the FRR asymmetry (ΔFRR) was significantly higher (P = 0.003) in the patients than asymptomatic controls. In addition, the cervical FRR of the involved side was significantly lower in the subjects with cervical pain compared with that in the non-involved one (P = 0.004). There was also a significant difference in the cervical extension (CE) angle between both study groups (P < 0.001), while the cervical flexion (CF) angle was not different (P = 0.25).

Conclusion: According to the study results, FRR and its asymmetry in the subjects with cervical lateral spinal stenosis were significantly different from that in asymptomatic controls and the CE angle declined in these subjects.