Article
The corticospinal reserve – surgical decompression restores cortical motor excitability and function in cases of mildly symptomatic degenerative cervical myelopathy
Die Kortikospinale Reserve – die Wiederherstellung der Erregbarkeit und Funktionalität des Motorkortex nach operativer Dekompression bei Patienten mit moderater cervikaler Myelopathie
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Authors
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Anna Zdunczyk
- Charité Universitätsmedizin, Klinik für Neurochirurgie, Berlin, Deutschland
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Leona Kawelke
- Charité Universitätsmedizin, Klinik für Neurochirurgie, Berlin, Deutschland
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Carolin Weiß Lucas
- Universitätsklinikum Köln, Klinik für Neurochirurgie, Köln, Deutschland
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Sandro Krieg
- Klinikum rechts der Isar, Technische Universität München, Klinik für Neurochirurgie, München, Deutschland
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Kathleen Seidel
- Inselspital, Universitätsspital Bern, Department of Neurosurgery, Neurocenter and Regenerative Neuroscience Cluster, Bern, Schweiz
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Thomas Picht
- Charité Universitätsmedizin, Klinik für Neurochirurgie, Berlin, Deutschland
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Peter Vajkoczy
- Charité Universitätsmedizin, Klinik für Neurochirurgie, Berlin, Deutschland
| Published: | June 4, 2021 |
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Outline
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Objective: We have recently shown an adaptive reorganization of the corticospinal network in patients with degenerative cervical myelopathy (DCM) which led to the concept of the “corticospinal reserve capacity”. In patients suffering from mild symptoms (JOA>12) and preserved reserve an increased neuronal recruitment and disinhibition with enlarged motor area was observed. In contrast, severely symptomatic patients (JOA<12) with an exhausted reserve presented with a restricted motor area, reduced corticospinal conductivity and increased inhibition. The current prospective multicenter trial has been designed to validate the new pathophysiological concept.
Methods: 120 patients with DCM from four spine centers in Germany and Switzerland. were examined preoperatively and 9 months after surgical decompression with navigated transcranial magnetic stimulation (nTMS). On the basis of the initial Japanese Orthopedic Association (JOA) Score three patient groups were established (JOA≤12, 13-15, >15). Corticospinal excitability was determined by navigated transcranial magnetic stimulation (nTMS) with the following parameters: Resting motor threshold (RMT), recruitment curve (RC), cortical silent period (CSP) and motor area.
Results: In patients with moderate symptoms (JOA 13-15) we encountered a compensatory increased motor cortex activation (motor area: p.<05; JOA 13-15: 308,5 + 213,3 vs. JOA <12: 225,7 + 159,5). Surgical decompression led to a recovery of corticospinal excitability expressed by an increased RC (p.<05; RC preop 9,21+ 5,0 vs. follow up 11,72 + 5,4 p<.05) and a favorable functional outcome (JOA preop 14,0+1,1 vs. JOA follow up 14,5+1,5). In contrast, patients with severe symptoms (JOA<12) presented a reduced excitability of cortico-cortical axons reflected by an elevated RMT (p<.05; JOA <12: 43,8 + 11,4 vs. JOA >15: 39,2 + 8,4) and a reduced RC slope (p<.05; JOA <12: 8,4+ 4,8 vs. JOA 15-17: 11,1+ 5,2). The diminished cortical motor area (p<.05, see above) further revealed a functional restriction on the cortical level. In this group no improvement in RC was detected (RC preop 8,4+ 4,8 vs. RC follow up 10,0 + 4.3) after surgical decompression which was further reflected in a lack of significant clinical recovery of symptoms (JOA preop 10+1,3 vs. JOA follow up 11,4+2,7).
Conclusion: In summary our prospective multicenter trial confirmed our concept for functional reorganization in patients suffering from DCM, i.e. the “corticospinal reserve capacity”. It became apparent that the individual pattern of compensation is a sensitive marker to objectify the state of the disease and functional reserve and may therefore indicate imminent non-reversible clinical deterioration. This innovative approach to evaluate patients suffering from DCM might improve current concepts of clinical diagnostics and impact future treatment strategies.
