Article
The corticospinal reserve capacity – reversible reorganisation of motor area and excitability in degenerative cervical myelopathy
Die kortikospinale Reservekapazität – die reversible Reorganisation des Motorareals und der Erregbarkeit bei zervikaler Myelopathie
Search Medline for
Authors
-
Anna Zdunczyk
- Charité – Universitätsmedizin Berlin, Klinik für Neurochirurgie, Berlin, Deutschland
-
Leona Kawelke
- Charité – Universitätsmedizin Berlin, Klinik für Neurochirurgie, Berlin, Deutschland
-
Thomas Picht
- Charité – Universitätsmedizin Berlin, Klinik für Neurochirurgie, Berlin, Deutschland
-
Peter Vajkoczy
- Charité – Universitätsmedizin Berlin, Klinik für Neurochirurgie, Berlin, Deutschland
| Published: | May 8, 2019 |
|---|
Outline
Text
Objective: We have recently shown a compensatory reorganization of the corticospinal network in patients with degenerative cervical myelopathy which led to the concept of the “corticospinal reserve capacity”. In patients suffering from mild symptoms (JOA>12) and preserved reserve an increased motor area due to recruitment of supplementary motor areas (M2) was observed. In contrast, severely symptomatic patients (JOA<12) with an exhausted reserve presented with a restricted motor area, reduced recruitment curve and increased inhibition. We now investigated how the status of the corticospinal reserve impacts postoperative outcome and whether these compensatory changes are reversible.
Methods: 20 patients with a cervical degenerative myelopathy were examined preoperatively and at 9 months follow up with navigated transcranial magnetic stimulation (nTMS). Based on the initial JOA score two patient groups were established (JOA12 ≥12 and JOA<12). We determined the resting motor threshold (RMT), recruitment curve (RC), cortical silent period (CSP) and motor area for the FDI muscle.
Results: The RMT showed no difference in the follow up measurement for both groups. Surgical decompression led to a reconstitution of motor area size and let to a good clinical recovery in the severely symptomatic patient group (JOA<12, p=.03). In patients with preoperatively mild symptoms (JOA>12) and preserved corticospinal reserve no significant change in motor area size was detected. However, the increased recruitment of supplementary motor areas and disinhibition recovered after 9 months (JOA>12 M2 area preoperative/follow up p=.02; CSP preoperative/follow up p=.03). Patients who didn’t benefit from surgery also didn’t present a reconstitution of corticospinal excitability.
Conclusion: Compensatory mechanisms and their reconstitution after decompressive surgery could be detected in patients with degenerative cervical myelopathy, therefore confirming the concept of the corticospinal reserve capacity. If surgical decompression led to a reconstitution of motor area size in patients with an exhausted reserve, this was also reflected in a good clinical recovery. In patients with no recovery of excitability, progressive disease was observed.
