Mirror movement refers to involuntary movements on one side of the body that mirror or replicate the voluntary movements made on the opposite side. These movements are simultaneous, contralateral, and identical to the intended movement
. Key characteristics:
- Mirror movements occur when an intentional movement on one side of the body is involuntarily mirrored by the opposite side, often affecting homologous muscles
- They most commonly involve the upper limbs, especially the hands and fingers, but can also affect legs and feet
- In healthy children, mild mirror movements are normal and typically disappear by around age 7 to 10
- Persistence or reappearance of mirror movements in adults is considered abnormal and may be associated with neurological disorders
Types and causes:
- Congenital mirror movement disorder is a rare genetic condition where these mirrored movements are present from infancy and persist throughout life. It mainly affects manual dexterity but does not impair intelligence or lifespan
- Acquired mirror movements can develop later in life due to neurological diseases such as Parkinson’s disease, stroke, cerebral palsy, or other neurodegenerative and movement disorders
- Minor physiological mirroring can occur in healthy adults under fatigue or demanding motor tasks but is usually subtle
Clinical relevance:
- Mirror movements can interfere with tasks requiring independent use of both hands, such as typing or playing musical instruments
- They provide important clinical clues in diagnosing and understanding various neurological conditions
- Quantitative assessment of mirror movements can be done using electromyography (EMG) to measure involuntary muscle activation during voluntary contraction
In summary, mirror movements are involuntary, mirrored motions on one side of the body that accompany voluntary movements on the other side, seen physiologically in children and pathologically in certain neurological disorders
