Dentato–Rubro–Thalamic Tract–Targeted Cerebellar Deep Brain Stimulation for Post-Stroke Spasticity and Dystonia: preliminary experience

Introduction Post-stroke motor impairment with spastic hemiparesis remains a significant therapeutic challenge, as conventional rehabilitation and pharmacological strategies often fail to achieve sustained functional recovery. Neuromodulation targeting cerebellar pathways, particularly the dentato-rubro-thalamic tract (DRTT), may provide an alternative therapeutic approach. Methods The study reports the first three cases of chronic post-ischemic stroke-related spastic hemiparesis and dystonic features treated with deep brain stimulation (DBS) targeting the DRTT at the level of the dentate nucleus after unsuccessful botulinum toxin therapy and intensive rehabilitation. Directional DBS systems were implanted using tractography-guided targeting. Clinical outcomes were assessed preoperatively and during sequential stimulation at 130 Hz, 70 Hz, and 30 Hz (each for six weeks), followed by a three-week stimulation-off phase. Outcome measures included the Modified Ashworth Scale (MAS), Fugl-Meyer Assessment of the Upper Limb (FMA-UL), Chedoke Arm and Hand Activity Inventory (CAHAI), Unified Dystonia Rating Scale (UDRS), and modified Rankin Scale (mRS). Results FMA-UL scores progressively improved as stimulation frequency decreased, with mean improvements of 12.3% at 130 Hz, 14.7% at 70 Hz, and 18.4% at 30 Hz. A partial decline was observed during the stimulation-off phase (12.2%). Functional performance (CAHAI) showed the greatest improvement at 30 Hz (11.9%) and decreased to 6.6% during the stimulation-off period. Proximal spasticity was modestly reduced in the shoulder and elbow by approximately one MAS point during stimulation but returned to baseline stimulation-off. Distal spasticity remained largely unchanged. Dystonic features demonstrated frequency-dependent improvement, most pronounced at 30 Hz (43.9%), with partial persistence after stimulation discontinuation (27.5%). Global disability (mRS) remained stable or showed mild improvement. Conclusions Preliminary findings suggest that DRTT-targeted cerebellar DBS, particularly at lower frequencies, may offer a promising adjunctive treatment for post-stroke spasticity and motor impairment refractory to conventional therapies. These initial observations from an ongoing clinical trial require confirmation in larger cohorts with extended follow-up.