Prevalence and Clinical Characteristics of Mirror Movements in a Chinese Cohort of Parkinson's Disease Patients.

BACKGROUND AND OBJECTIVES: Mirror movements (MMs) are involuntary movements produced by the contralateral homologous muscles during voluntary activity. MMs have been observed in age-related neurological movement disorders, including Parkinson's disease (PD), but they are not widely recognized. This study described the frequency and clinical features of MMs in PD patients from a tertiary care center in Eastern China. METHODS: A total of 140 PD patients were evaluated using a standardized videotaping protocol. A clinical scale was used to compare the amplitude, distribution, and proportion of mirroring between the suspended and supported positions. Classic motor and nonmotor symptoms (NMS), including rapid eye movement sleep behavior disorder (RBD), constipation, and hyposmia, were compared between patients with and without MMs. The relationship between MMs and the Movement Disorder Society-Sponsored Revision of the Unified Parkinson's Disease Rating Scale (MDS-UPDRS) motor score was also explored. RESULTS: MMs were more pronounced when the less affected limb was suspended. In total, 82 of the 140 (58.6%) PD patients exhibited MMs. There were no significant differences in age, disease duration, age at disease onset, gender, Hoehn and Yahr score, prevalence rates of RBD, constipation, and hyposmia, or MDS-UPDRS tremor, rigidity, and bradykinesia scores between PD patients with and without MMs. The unilateral MM score was positively correlated with the contralateral limb MDS-UPDRS motor score and negatively correlated with the ipsilateral limb MDS-UPDRS motor score. CONCLUSIONS: MMs are common in PD, and suspending the limb is recommended to detect MMs. Further studies are needed to investigate changes in MMs with disease progression and their association with NMS.