54. Cerebellar-cortical-subcortical connectivity in patients with Progressive Sopranuclear Palsy (PSP) is modulated by cerebellar intermittent theta burst stimulation

Abstract

Progressive-Sopranuclear-Palsy (PSP) is an atypical parkinsonian syndrome. Recent imaging studies revealed specific cerebellar abnormalities able to discriminate PSP from other parkinsonisms. Moreover, transcranial magnetic stimulation (TMS) studies demonstrated a subclinical cerebellar involvement in PSP compatible with the severe degeneration of dentate nucleus. Thus, we applied an intermittent theta burst stimulation (iTBS) protocol over the cerebellum on PSP patients to investigate the cerebello-thalamo-cortical circuits. To characterize the physiological effects of 2 weeks of iTBS applied bilaterally over the cerebellum, we examined cerebellar brain inhibition (CBI), the intracortical inhibition (SICI) and facilitation (ICF), in addition to resting-state functional magnetic resonance (fMRI) and clinical rating state assessment. Cerebellar iTBS increased the deficient functional connectivity in CBI. No effects were seen for SICI and ICF. Resting-state fMRI revealed an increased signal in the head of the caudate nucleus bilaterally. Clinical data showed a significant improvement of dysarthria in all patients and of gait. These findings provide further functional evidence of increasing the excitability of the cerebellar hemispheres by means of iTBS resulted in an improvement of the cerebello-thalamo-cortical circuits, related with some mild clinical improvement. Identify and develop new therapeutic strategies to improve clinical symptoms on PSP patients.