Mirror movements in essential tremor: prevalence and relationship to mini-mental status test scores

Area of Science:

• Neurology
• Neuroscience
• Movement Disorders

Background:

• Mirror movements (MM) are involuntary, symmetrical movements of one limb mirroring voluntary movements of the contralateral limb.
• MM are observed in various neurological conditions, including essential tremor (ET), and may indicate a motor release sign.
• Cognitive dysfunction, particularly executive dysfunction and dementia, is also reported in ET patients, raising questions about a shared underlying pathology.

Purpose of the Study:

• To investigate whether mirror movements (MM) serve as a simple clinical marker for early cognitive impairment or dementia in essential tremor (ET).
• To determine if the presence of MM in ET patients correlates with cognitive function, specifically executive function.

Main Methods:

• A cross-sectional study involving 148 patients with essential tremor (ET).
• Cognitive function was assessed using the Folstein Mini-Mental State Exam (FMMSE) and the Modified Mini-Mental Status Examination (mMMSE).
• The presence or absence of mirror movements (MM) was recorded for each participant.

Main Results:

• Mirror movements (MM) were identified in a high proportion of ET cases (77.7%, n=115/148).
• No statistically significant differences in FMMSE or mMMSE scores were found between ET participants with and without mirror movements, even after accounting for age.
• These findings indicate a lack of association between MM and cognitive performance in this ET cohort.

Conclusions:

• While mirror movements (MM) are prevalent in essential tremor (ET), they do not appear to be a reliable indicator of cognitive decline or dementia in these patients.
• The study suggests that MM are not a useful clinical marker for detecting early cognitive changes in ET.
• Further research may be needed to explore other potential biomarkers for cognitive impairment in ET.