Persistence of congenital mirror movements after hemiplegic stroke

Area of Science:

• Neuroscience
• Neurology
• Human Physiology

Background:

• Mirror movements (MMs) are involuntary, symmetrical movements of one limb during voluntary, unilateral movements of the contralateral limb.
• Hereditary congenital MMs typically manifest in childhood and are often associated with specific genetic mutations.
• The underlying neurobiological mechanisms of MMs, particularly in adults with persistent congenital forms, require further elucidation.

Observation:

• A 76-year-old man with a history of hereditary congenital mirror movements (MMs) experienced a persistence of these movements in his paretic hand post-ischemic stroke.
• The MMs were observed during voluntary movements of the unaffected contralateral arm, indicating a complex interplay between the stroke and the pre-existing MMs.
• Functional magnetic resonance imaging (fMRI) was employed to assess brain activity during motor and sensory tasks involving both affected and unaffected hands.

Findings:

• fMRI data indicated heightened activity in the ipsilateral primary motor cortex (M1) during motor tasks performed with both hands.
• A significant reduction in transcallosal inhibition, the process by which one hemisphere of the brain inhibits the other, was observed.
• These neuroimaging findings suggest that altered motor cortex excitability and impaired interhemispheric communication are key factors in the generation of MMs.

Implications:

• The study provides novel insights into the neurophysiological underpinnings of persistent congenital mirror movements in an adult patient.
• The findings suggest that stroke can exacerbate or unmask underlying neurological mechanisms contributing to MMs.
• Understanding these mechanisms may pave the way for targeted therapeutic interventions for individuals with mirror movements and related motor control disorders.