BACKGROUND: In degenerative cervical myelopathy (DCM), the dynamics of disease progression and the outcome after surgical decompression vary interindividually and do not necessarily correlate with radiological findings. OBJECTIVE: To improve diagnostic power in DCM by better characterization of the underlying pathophysiology using navigated transcranial magnetic stimulation (nTMS). METHODS: Eighteen patients with DCM due to cervical spinal canal stenosis were examined preoperatively with nTMS. On the basis of the initial Japanese Orthopedic Association (JOA) Score, 2 patient groups were established (JOA ≤12/>12). We determined the resting motor threshold, recruitment curve, cortical silent period, and motor area. Accordingly, 8 healthy subjects were examined. RESULTS: Although the resting motor threshold was comparable in both groups (P = .578), the corticospinal excitability estimated by the recruitment curve was reduced in patients (P = .022). In patients with only mild symptoms (JOA > 12), a compensatory higher activation of non-primary motor areas was detected (P < .005). In contrast, patients with severe impairment (JOA ≤ 12) showed a higher cortical inhibition (P < .05) and reduced cortical motor area (P < .05) revealing a functional restriction on the cortical level. CONCLUSION: Based on these results, we propose a new concept for functional compensation for DCM on the cortical and spinal level, ie corticospinal reserve capacity. nTMS is a useful tool to noninvasively characterize the pattern of functional impairment and compensatory reorganization in patients suffering from DCM. The change in nTMS parameters might serve as a valuable prognostic factor in these patients in the future.
BACKGROUND: In degenerative cervical myelopathy (DCM), the dynamics of disease progression and the outcome after surgical decompression vary interindividually and do not necessarily correlate with radiological findings. OBJECTIVE: To improve diagnostic power in DCM by better characterization of the underlying pathophysiology using navigated transcranial magnetic stimulation (nTMS). METHODS: Eighteen patients with DCM due to cervical spinal canal stenosis were examined preoperatively with nTMS. On the basis of the initial Japanese Orthopedic Association (JOA) Score, 2 patient groups were established (JOA ≤12/>12). We determined the resting motor threshold, recruitment curve, cortical silent period, and motor area. Accordingly, 8 healthy subjects were examined. RESULTS: Although the resting motor threshold was comparable in both groups (P = .578), the corticospinal excitability estimated by the recruitment curve was reduced in patients (P = .022). In patients with only mild symptoms (JOA > 12), a compensatory higher activation of non-primary motor areas was detected (P < .005). In contrast, patients with severe impairment (JOA ≤ 12) showed a higher cortical inhibition (P < .05) and reduced cortical motor area (P < .05) revealing a functional restriction on the cortical level. CONCLUSION: Based on these results, we propose a new concept for functional compensation for DCM on the cortical and spinal level, ie corticospinal reserve capacity. nTMS is a useful tool to noninvasively characterize the pattern of functional impairment and compensatory reorganization in patients suffering from DCM. The change in nTMS parameters might serve as a valuable prognostic factor in these patients in the future.
Authors: Aria Nouri; Joseph S Cheng; Benjamin Davies; Mark Kotter; Karl Schaller; Enrico Tessitore Journal: J Clin Med Date: 2020-02-16 Impact factor: 4.241
Authors: Aria Nouri; Enrico Tessitore; Granit Molliqaj; Torstein Meling; Karl Schaller; Hiroaki Nakashima; Yasutsugu Yukawa; Josef Bednarik; Allan R Martin; Peter Vajkoczy; Joseph S Cheng; Brian K Kwon; Shekar N Kurpad; Michael G Fehlings; James S Harrop; Bizhan Aarabi; Vafa Rahimi-Movaghar; James D Guest; Benjamin M Davies; Mark R N Kotter; Jefferson R Wilson Journal: Global Spine J Date: 2022-02