Cutaneous and Mixed Nerve Silent Period Recordings in Symptomatic Paroxysmal Kinesigenic Dyskinesia

Julien Cogez1, *, Olivier Etard2, 3, Nathalie Derache1, 4, Gilles Defer1
1 CHU de Caen, Service de Neurologie, CHU de Caen, Caen, F-14000, France
2 CHU de Caen, Service D’explorations Fonctionnelles du Systeme Nerveux, Caen, F-14000, France
3 Université de Caen Basse-Normandie, UFR de Médecine, Caen, F-14000, France
4 INSERM, INSERM U923, CHU de Caen, Caen, F-14000, France

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Creative Commons License
© Cogez et al.; Licensee Bentham Open.

open-access license: This is an open access article licensed under the terms of the Creative Commons Attribution-Non-Commercial 4.0 International Public License (CC BY-NC 4.0) (, which permits unrestricted, non-commercial use, distribution and reproduction in any medium, provided the work is properly cited.

* Address correspondence to this author at the Service de Neurologie, CHU de Caen, France; Tel: 0231064624; Fax: 0231063307; E-mail:



The underlying neurophysiologic mechanism responsible for secondary paroxysmal kinesigenic dyskinesia (PKD) is still unclear. Here, we study the pathogenesis of PKD in two patients with a demyelinating lesion in the spinal cord.


Electromyogram recordings from affected arms of two patients with spinal cord lesions presenting PKD were compared with our laboratory standards. The cutaneous silent period (CuSP), mixed nerve silent period (MnSP) and coincidence period (CiP), defined as the common period between the CuSP and MnSP, were recorded.


A large decrease in the MnSP and disappearance of the CiP were observed in our patients, which was secondary to simultaneous extinction of the third portion of the MnSP, while the CuSP was normal. The MnSP and CiP were normal after recovery.


Our results demonstrate that the third portion of the MnSP and the CuSP do not correspond to the same physiologic process. These findings suggest that PKD patients have abnormal spinal interneuron integration.

Keywords: Cutaneous silent period, Dystonia, Mixed nerve silent period.