Mirror movement: application of movement-related cortical potentials.

In a patient with Kallmann's syndrome (hypogonadotropic hypogonadism and anosmia) manifesting mirror movement, cortical potentials associated with unilateral and bilateral simultaneous voluntary middle finger extensions were studied. Premovement negative slope, which has been shown to reflect preparatory excitation of motor cortex corresponding to the voluntary movement, was recorded bilaterally in this patient in spite of intended unilateral hand movement. It is suggested that mirror movement in this particular patient is generated by unintended excitation of the opposite motor cortex.