Persistent mirror movements: Functional MR imaging of the hand motor cortex

PURPOSE: To compare cortical areas involved in hand motor function in patients with persistent motor movements with those in healthy control subjects by using functional magnetic resonance (MR) imaging. MATERIALS AND METHODS: Nine patients (five patients with autosomal-dominant mirror movements, three with Kallmann syndrome, one with Wildervanck syndrome) and 10 healthy control subjects participated in the study. Functional MR imaging was performed at 1.5 T with a two-dimensional fast low-angle shot sequence. Participants were imaged while performing sequential finger-thumb opposition and during a rest period. RESULTS: During unimanual intentional movements, MR imaging in all control subjects showed increased signal intensity along the superior bend of the central sulcus contralateral to the moved hand. This increase was predominantly located in a region that included the medial part of the precentral gyrus. In contrast, MR imaging in patients with mirror movements showed bilateral activity in the medial region of the precentral gyrus. CONCLUSION: Bifurcations of the corticospinal tract may not be solely responsible for mirror movements. Bilateral activity of the primary motor cortex seems to play an additional role.