A 22‐year‐old right‐handed man presented with a 1‐year history of abnormal movements of his neck and upper back, which started gradually 2 weeks after sustaining a blunt impact in that region during martial arts training. He experienced severe, focal, non‐neuropathic pain. The patient did not report any premonitory sensations or relief after movement initiation. On examination, there were non‐rhythmic, jerky movements of the left side of the neck and upper back which were not semicircular or writhing in quality. These movements tended to diminish with muscle activation and on recumbency (Video 1). Cervical and thoracic MRI studies were normal.
Video 1.
The abnormal movements documented when the patient was standing resolved during recumbency.
Electrophysiological evaluation included surface electromyography (EMG) of the left levator scapulae, trapezius, cervical paraspinal and sternocleidomastoid muscles. We also recorded electroencephalography (EEG) activity from the C3 electrode (reference to contralateral mastoid). During the study, the abnormal movements started once the subject was instructed that the study had begun. They were readily entrainable (Supplementary material). These two characteristics demonstrated internal inconsistency. EEG/EMG back‐averaging revealed a Bereitschaftpotential preceding movement onset (Fig. 1), confirming the functional nature of the movements. 1
Figure 1.
(A) Surface electromyographic recordings of the left sternocleidomastoid (SCM), levator scapulae (LevSc), trapezius (Trap), and cervical paraspinal (C. Par) muscles. The vertical blue lines denote the moments in which the subject was informed that the study was starting and ending. (B) Bereitschaftpotential during EEG–EMG back‐averaging. EEG, electroencephalography; EMG, electromyography.
In this case, the timeline and phenomenology of the post‐traumatic abnormal movements could suggest peripherally‐induced abnormal movements of the scapular region, such as the dancing dorsal quadrilaterals syndrome. 2 This patient's abnormal movements resolved in the supine position, when applying pressure to the affected region, and during voluntary activation of involved muscles. These characteristics have been reported in peripherally‐induced abnormal movements. However, peripherally‐induced movement disorders are usually preceded by chronic neuropathic pain in the region affected by the injury or trauma, which this patient did not have. Moreover, peripherally‐induced abnormal movements tend to include semi‐rhythmic, writhing, or semicircular contractions in addition to jerky and sustained contractions. Finally, electrophysiological testing was consistent with a functional origin as it demonstrated signs of inconsistency and the Bereitshaftpotential.
The difficulty in differentiating peripherally‐induced movements from functional movements was pointed out by Pandey et al. 3 This publication reported three cases of post‐traumatic, semi‐rhythmic shoulder movements, with two cases having clinical features of functional origin but without electrophysiological confirmation of such nature.
In sum, a functional etiology should be considered in any movement disorder appearing after an injury. The mechanisms by which peripheral trauma can lead to both functional and organic movement disorders remain unclear. It has been proposed that alterations in peripheral sensory input following injury and leading to central sensorimotor reorganization over several months could account for the delayed onset of these movements after trauma and possibly the spread to adjacent muscles. 4 Similar mechanisms could be shared by both functional and organic etiologies. Recently proposed theoretical frameworks, such as the predictive coding theory, could help further hypothesize about the underlying pathophysiology of functional movement disorders. 5 This case also underscores the importance of electrophysiological assessment in accurately diagnosing complex movement disorders.
Author Roles
(1) Research project: A. Conception, B. Organization, C. Execution; (2) Statistical Analysis: A. Design, B. Execution, C. Review and Critique; (3) Manuscript Preparation: A. Writing of the first draft, B. Review and Critique;
F.V.: 1A, 3A
M.M.: 1A, 3A
A.J.E.: 3B
K.J.L.: 3B
Disclosures
Ethical Compliance Statement: As this is not research, only a clinical vignette, no IRB approval is required. A written consent was obtained from the patient for this manuscript and video. We confirm that we have read the Journal's position on issues involved in ethical publication and affirm that this work is consistent with those guidelines.
Funding Sources and Conflicts of Interest: The authors declare that there are no funding sources or conflicts of interest relevant to this work.
Financial Disclosures for Previous 12 Month: FV and MM have no financial disclosures to report. AE has received grant support from the NIH and the Michael J. Fox Foundation; personal compensation as a consultant/scientific advisory board member for Neuroderm, Amneal, Acadia, Avion Pharmaceuticals, Acorda, Kyowa Kirin, Supernus (formerly, USWorldMeds), NeuroDiagnostics, Inc (SYNAPS Dx), Intrance Medical Systems, Inc., Praxis Precision Medicines, and Herantis Pharma; and publishing royalties from Lippincott Williams & Wilkins, Cambridge University Press, and Springer. He co‐founded REGAIN Therapeutics and is co‐inventor of the patent “Compositions and methods for treatment and/or prophylaxis of proteinopathies.” He serves on the editorial boards of the Journal of Parkinson's Disease, Journal of Alzheimer's Disease, European Journal of Neurology, Movement Disorders Clinical Practice, and JAMA Neurology. KL has consulted for Takeda; has received honoraria from the International Parkinson and Movement Disorder Society; and has received research support from Acadia, Bluerock, the Del Monte Institute for Neuroscience at the University of Rochester, the National Institutes of Health (National Institute of Neurological Disorders and Stroke), Roche and Takeda.
Supporting information
Data S1. Motor Entrainment: Figure A shows the change in the movement on the trapezius when the patient is taping at 5 Hz with the thumb (APB). Figure B shows the coherence between trapezius and APB at 5 Hz.
Acknowledgments
None.
Data Availability Statement
The data that support the findings of this study are available on request from the corresponding author. The data are not publicly available due to privacy or ethical restrictions.
References
- 1. Merchant SHI, Vial‐Undurraga F, Leodori G, van Gerpen JA, Hallett M. Myoclonus: an electrophysiological diagnosis. Mov Disord Clin Pract 2020;7(5):489–499. [DOI] [PMC free article] [PubMed] [Google Scholar]
- 2. Lizarraga KJ, Thompson PD, Moore HP, Mizraji G, Gershanik OS, Singer C, et al. Dancing dorsal quadrilaterals: a novel peripherally induced movement disorder. JAMA Neurol 2019;76(3):351–354. [DOI] [PMC free article] [PubMed] [Google Scholar]
- 3. Pandey S, Nahab F, Aldred J, Nutt J, Hallett M. Post‐traumatic shoulder movement disorders: a challenging differential diagnosis between organic and functional. Mov Disord Clin Pract 2014;1(2):102. [DOI] [PMC free article] [PubMed] [Google Scholar]
- 4. Carnero‐Pardo C, Sanchez‐Alvarez JC, Gomez‐Camello A, Minguez‐Castellanos A, Hernandez‐Ramos FJ, Garcia‐Gomez T. Myoclonus associated with thoracodorsal neuropathy. Mov Disord 1998;13(6):971–972. [DOI] [PubMed] [Google Scholar]
- 5. Friston K. The free‐energy principle: a unified brain theory? Nat Rev Neurosci 2010;11(2):127–138. [DOI] [PubMed] [Google Scholar]
Associated Data
This section collects any data citations, data availability statements, or supplementary materials included in this article.
Supplementary Materials
Data S1. Motor Entrainment: Figure A shows the change in the movement on the trapezius when the patient is taping at 5 Hz with the thumb (APB). Figure B shows the coherence between trapezius and APB at 5 Hz.
Data Availability Statement
The data that support the findings of this study are available on request from the corresponding author. The data are not publicly available due to privacy or ethical restrictions.