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JMD > Epub ahead of print
Hassan, Khan, and Badshah: Re: Comments on “Chorea as a Presentation of SARS-CoV-2 Encephalitis: A Clinical Case Report”
Dear Editor,
The accurate differential diagnosis between myoclonus and chorea by neurological examination without electrophysiological studies is occasionally difficult, since not only myoclonus but also chorea may present irregular jerky movements. Myoclonus is defined as a sudden, brief, lightning-like muscle contraction. Furthermore, myoclonus includes both muscular contraction phenomenology (positive myoclonus) and inhibition of muscular contraction phenomenology (negative myoclonus) [1]. There are various etiologies and pathogenesis of myoclonus, most often categorized into cortical, subcortical, or spinal myoclonus. However, the pathophysiology of chorea is mainly implicated in dysfunction of the basal ganglia motor circuitry.
The first video of the patient showed abnormal movements that were involuntary, abrupt, nonstereotyped, irregular, sometimes large-amplitude, and unpredictable on the right leg and arm, defined as chorea by the authors [2]. However, as pointed out in the letter [3], myoclonus was also observed in the first video, and all abnormal movements in the other videos appear to be myoclonus [2]. Therefore, the patient may have a combination of abnormal movements due to both myoclonus and chorea.


Ethical Standard

Not applicable.

Conflicts of Interest

The authors have no financial conflicts of interest.

Funding Statement


Author Contributions

Conceptualization: Muhammad Hassan. Data curation: Muhammad Hassan. Investigation: Naveed Ullah Khan. Methodology: Mazhar Badshah. Software: Naveed Ullah Khan. Supervision: Mazhar Badshah. Writing—original draft: Naveed Ullah Khan. Writing—review & editing: Mazhar Badshah, Muhammad Hassan.


1. Marsden CD, Hallett M, Fahn S. The nosology and pathophysiology of myoclonus. In: Marsden CD, Fahn S, editors. Movement Disorders. London: Butterworths; 1982:196–248.

2. Hassan M, Syed F, Ali L, Rajput HM, Faisal F, Shahzad W, et al. Chorea as a presentation of SARS-CoV-2 encephalitis: a clinical case report. J Mov Disord 2021;14:245–247.
crossref pmid pmc
3. Walker RH. Comment on “Chorea as a Presentation of SARS-CoV-2 Encephalitis: A Clinical Case Report”. J Mov Disord 2021;Dec. 7. [Epub]. Available from: https://doi.org/10.14802/jmd.21068.
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