Mirror Movements After Stroke Suggest Facilitation From Nonprimary Motor Cortex: A Case Presentation

When stroke occurs in adulthood, mirror movements (MMs: involuntary movements occurring in one hand when performing unilateral movements with the contralateral hand) in the paretic hand rarely occur. We present a case of an apparently healthy 54-year-old male presenting MMs in his left (non-dominant) hand. Further evaluation revealed diminished strength and dexterity in left hand, increased spinal excitability, decreased corticospinal excitability, occurrence of ipsilateral motor responses, enlarged cortical motor representation and imaging findings consistent with a previously undiagnosed right-subcortical stroke. MMs and ipsilateral motor responses may reflect the increased spinal motor neurons' excitability sustained by the spared non-primary ipsilesional motor areas.