Cervical Paraspinal Muscle Fatty Infiltration is Directly Related to Extension Reserve in Patients With Cervical Spine Pathology

Study Design/Setting: Retrospective review of a prospectively collected database. Objective: The objective of this study was to determine the relationship between paracervical muscle area, density, and fat infiltration and cervical alignment among patients presenting with cervical spine pathology. Background Context: The impact of cervical spine alignment on clinical outcomes has been extensively studied, but little is known about the association between spinal alignment and cervical paraspinal musculature. Methods: We examined computed tomography scans and radiographs for patients presenting with cervical spine pathology. The posterior paracervical muscle area, density, and fat infiltration was calculated on axial slices at C2, C4, C6, and T1. We measured radiographic parameters including cervical sagittal vertical axis, cervical lordosis, T1 slope (T1S), range of motion of the cervical spine. We performed Pearson correlation tests to determine if there were significant relationships between muscle measurements and alignment parameters. Results: The study included 51 patients. The paracervical muscle area was higher for males at C2 ( P =0.005), C4 ( P =0.001), and T1 ( P =0.002). There was a positive correlation between age and fat infiltration at C2, C4, C6, and T1 (all P <0.05). The cervical sagittal vertical axis positively correlated with muscle cross-sectional area at C2 ( P =0.013) and C4 ( P =0.013). Overall cervical range of motion directly correlated with muscle density at C2 ( r =0.48, P =0.003), C4 ( r =0.41, P =0.01), and C6 ( r =0.53. P <0.001) and indirectly correlated with fat infiltration at C2 ( r =−0.40, P =0.02), C4 ( r =−0.32, P =0.04), and C6 ( r =−0.35, P =0.02). Muscle density correlated directly with reserve of extension at C2 ( r =0.57, P =0.009), C4 ( r =0.48, P =0.037), and C6 ( r =0.47, P =0.033). Reserve of extension indirectly correlated with fat infiltration at C2 ( r =0.65, P =0.006), C4 ( r =0.47, P =0.037), and C6 ( r =0.48, P =0.029). Conclusions: We have identified specific changes in paracervical muscle that are associated with a patient’s ability to extend their cervical spine.