The effect of voluntary movement with non‐dominant finger on the delay time of involuntary movement in a patient of mirror movement disorder

Abstract

Mirror movement disorder is a condition in which intentional movements of one side of the body are mirrored by involuntary movements of the other side. This symptom is mainly observed in the distal upper limbs. Mirror movement disorder is present in patients with a variety of movement disorders, such as dystonia, Parkinson's disease, and essential tremor as well as in congenital nervous system disorders. Mirror movement disorder is also observed in healthy subjects even in several members of the same family with no other neurological signs (Congenital mirror movement disorder). Although it is known that mutations in the DCC or RAD51 gene is involved in the congenital mirror movement disorder, it is still far from the understanding of the mechanism in congenital mirror movement disorder since its prevalence is thought to be less than 1 in 1 million. In this study, we found the healthy child and her father who had mirror movement. We report the quantitative analysis of the mirror movement using videotape recording. We obtained informed consent for the videotape recording and the experimental procedures from all subjects. In the subject of the child, we recorded the movement of both index fingers during pressing the button of the picture book by right index finger. The movement of the left index finger was observed 33 ms after pressing, and the maximum speed of the movement was comparable. In the subject of her father, we recorded the movement of both fingers during we asked him to move right or left one finger. The delay time between right (dominant) and left (non‐dominant) fingers was 24 ± 8 ms when we asked him to move the dominant finger. However, this value was significantly increased when the non‐dominant fingers were asked to move (133 ± 47 ms). In conclusion, child and her father had same symptoms; the involuntary movement was observed after voluntary movement with delay time. Increased delay time between voluntary and involuntary movement during the non‐dominant fingers were asked to move might be due to use‐dependent plasticity. This should be studied in the future study with anatomical/physiological examination of the brain and comprehensive inspection of genes.This abstract is from the Experimental Biology 2019 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.