Investigating Cervical Flexion-Relaxation Ratio in Patients with Cervical Lateral Spinal Stenosis Compared with Asymptomatic Controls: a case control study

Background: 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. In this sense, the variations in the cervical FRR indicate some changes in the neuromuscular pattern of extensor muscles, and consequently, their functions. Compared with patients 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 patients with cervical lateral spinal stenosis and asymptomatic controls. Methods In total, 25 patients 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 (EMG) data recorded for each muscle. Results The mean cervical FRR was significantly lower (P<0.05) and the FRR asymmetry (∆FRR) 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 patients 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 (P0.05). Conclusion According to the study results, it was concluded that the neuromuscular pattern of the cervical muscles could change asymmetrically and the CE angle could decline in individuals with cervical lateral spinal stenosis. Therefore, such patients will be more susceptible to biomechanical changes and persistent pain if the cervical muscles are not considered in their treatment.