Spinal Cord Tract Integrity in Degenerative Cervical Myelopathy

Degenerative cervical myelopathy (DCM) is the most common cause of spinal dysfunction globally. Despite surgical intervention, motor dysfunction may persist in many patients. The purpose of this study was to comprehensively examine specific spinal cord tract changes in patients with DCM, to better understand potential substrates for compensatory recovery of function.

Cervical spinal cord MRI scans with diffusion tensor imaging were performed in patients with DCM and in healthy volunteers. Spinal Cord Toolbox was used to register the PAM50 template, which includes a probabilistic atlas of the white matter tracts of the spinal cord, to the imaging data. Fractional anisotropy (FA) was extracted for each tract at C3 above the level of maximal compression and compared between patients with DCM and healthy volunteers and between patients with mild vs moderate to severe DCM.

We included 25 patients with DCM (13 mild and 12 moderate to severe) and 6 healthy volunteers. FA was significantly reduced in DCM subjects relative to healthy volunteers for the lateral corticospinal tract (mild DCM vs healthy ∆ = -0.13, P = .018; moderate to severe DCM vs healthy ∆ = -0.11, P = .047), fasciculus gracilis (mild DCM vs healthy ∆ = -0.16, P = .010; moderate to severe DCM vs healthy ∆ = -0.13, P = .039), and fasciculus cuneatus (mild DCM vs healthy ∆ = -0.16, P = .007; moderate to severe DCM vs healthy ∆ = -0.15, P = .012). There were no differences in FA for all tracts between mild and moderate-to-severe DCM subjects.

Patients with DCM had altered diffusion tensor imaging signal in their lateral corticospinal tract, fasciculus gracilis, and fasciculus cuneatus in comparison with healthy volunteers. These findings indicate that DCM is characterized by injury to these structures, which suggests that other tracts within the cord could potentially act as substrates for compensatory motor recovery.