ANODAL TRANSCRANIAL DIRECT CURRENT STIMULATION (TDCS) APPLIED TO THE MOTOR CORTEX AMELIORATES FREEZING OF GAIT IN PATIENTS AFFECTED BY PARKINSON’S DISEASE

Background: Progression of Parkinson’s disease (PD) is frequently characterized by the occurrence of freezing of gait (FOG), which generally does not improve with dopaminergic therapy and with current available surgical therapies. Recent evidences show that motor symptoms may be ameliorated by means of non-invasive brain stimulation techiniques in PD (transcranial current direct stimulation, TDCS; repetitive transcranial magnetic stimulation, RTMS). Objective: To investigate the efficacy of anodal TDCS in the treatment of FOG in PD. Excitatory anodal tDCS was applied unilaterally to the motor and premotor cortices controlateral to the most affected leg. Methods: randomized, double-blind, sham-controlled study. TDCS was applied consecutively for 5 days to 8 patients who were randomly assigned to anodal or sham TDCS. Efficacy of the interventions was investigated after the 1st, the 5th stimulation, 1 week, 2 weeks and 1 month after the start of the trial. Clinical assessment was performed by Stand Walk Sit test (SWS), UPDRS, Freezing of Gait Questionnaire (FOG-Q), Gait and Falls Questionnaire (GFQ), and the Parkinson's Disease Questionnaire (PDQ-39). 5 patients also underwent gait analysis. All patients received stimulation when “on” medication. Results: anodal TDCS compared to the sham significantly improved gait and FOG starting from the first stimulation. The effect was evident up to 1 month from the first treatment. Conclusion: Anodal TDCS of the motor and premotor cortex is safe and it may have therapeutic potential for FOG in patients with PD. TDCS might determine release of dopamine in the caudate and putamen. Alternatively excitation of the less active motor cortex may restore an inter-hemispheric balance, as it has been recently hypothesized as possible mechanism at the origin of FOG.