Cathodal tDCS of the parietal cortex combined with mirror therapy improved hand dexterity in a case of focal dystonia

Background and aims. The role of not-invasive brain stimulation (NIBS) as an add-on treatment to motor training in children suffering from focal dystonia has described in the literature with contrasting results. The study is aimed at describing the clinical and functional outcome observed in a 13-years-old girl suffering from hand dystonia and undergone NIBS combined with mirror therapy. Methods. We report the case of a 13-years-old girl suffering from hand dystonia following right hemisphere lesion in the basal ganglia area, due to cerebrovascular accident occurred in the infancy. At the basal assessment she showed a complete muscle strength recovery, a quite normal gait pattern, but a complete impairment in left hand dexterity due to hand muscle dystonia. She had already undergone several training protocols, including splint wearing and repeated botulinum toxin injections. These last induced a partial resolution of muscle contraction at rest, without any improvement in hand dexterity. We proposed the following treatment protocol: daily sessions (20 minute each) of cathodal tDCS on the right sensorimotor cortex (P4), 1 mA, followed, in the same morning, by 20minutes mirror therapy, for five consecutive days. Functional status was assessed using the Fugl-Meyer upper limb score at baseline (T0), after treatment end (T1) and one month later (T2). Moreover, a fMRI was performed at T0 and T1, in order to look what brain networks were activated during the left and right limb movements. Results. The NIBS was well tolerated. No adverse events were complained for. The Fugl-Meyer score increased from 21/66 (T0) to 29/66 (T1) and up to 30/66 (T2). The fMRI showed a significant reduction of brain activation under active left limb movement after treatment. Conclusions. Parietal cortex inhibition via cathodal tDCS at the lesioned hemisphere was effective at reducing dystonia, improving voluntary movement and inducing the reorganization of brain networks.