Feasibility and preliminary signal of cerebellar intermittent theta burst stimulation for static balance in cerebellar ataxia: a pilot study.

This study explored the short-term effects of 50 Hz cerebellar intermittent theta burst stimulation (iTBS) on static balance and prefrontal cortical activation in patients with cerebellar ataxia (CA). Ten patients with CA (4 males; mean age, 57.6 ± 9.1 years) underwent iTBS over the bilateral cerebellum for five consecutive days (8 min/session, 80% active motor threshold); static balance was assessed using a Balance Trainer 4 (BT4) under eyes-open (EO) and eyes-closed (EC) conditions at baseline (V0), immediately post-intervention (V1), and 6 weeks post-treatment (V2). Clinical scales (K-SARA, K-MBI, SF-36-K) and functional near-infrared spectroscopy (fNIRS) during a dual-task toe-tapping paradigm (motor + mental subtraction) were also administered to evaluate motor and cognitive responses. Significant, albeit transient, improvements in postural balance were observed at V1 relative to V0: under EO conditions, anterior-posterior sway (ΔY) and total displacement (Δd) decreased significantly (p < 0.05), and under EC conditions, medial-lateral sway (ΔX) also improved (p < 0.05); however, these effects were not sustained at V2. Regarding safety, dizziness was the most frequently reported adverse event, occurring in 5 of 10 participants (50%); all events were mild-moderate, transient, and resolved without treatment discontinuation. In conclusion, 50 Hz cerebellar iTBS was well tolerated and transiently enhanced postural stability in CA patients, and combined fNIRS monitoring demonstrated cortical engagement during cognitive-motor integration, supporting fNIRS as a real-time brain imaging biomarker for exploring the neurophysiological mechanisms underlying iTBS-induced modulation of the cerebello-fronto-cortical loop.