Interleaved stimulation in globus pallidus internus deep brain stimulation in a case of adult-onset Huntington's disease

BACKGROUND: Huntington’s disease (HD) is an autosomal dominant neurodegenerative disorder caused by pathological expansion of CAG repeats in the HTT gene. A higher CAG repeat count (≥ 55) is generally associated with an earlier age at onset, more rapid disease progression, and a less favorable prognosis. In recent years, deep brain stimulation (DBS) targeting the globus pallidus internus (GPi) has been explored as a therapeutic intervention for medically refractory chorea; however, the available clinical evidence is largely limited to small case series and case reports, and optimal programming often requires balancing therapeutic efficacy against stimulation-related adverse effects. Here, we report an Asian patient with adult-onset HD and a high CAG repeat burden, in whom GPi-DBS using interleaved stimulation (ILS) improved motor symptoms while minimizing stimulation-induced side effects. CASE PRESENTATION: A 28-year-old Asian female with genetically confirmed HD (56 CAG repeats) presented with rapid progression from focal myoclonus of the right thumb to generalized, disabling chorea refractory to pharmacological treatment. Bilateral GPi-DBS was performed. Initial monopolar stimulation yielded limited therapeutic benefit, with only a 12.0% improvement in the Unified Huntington’s Disease Rating Scale–Total Motor Score (UHDRS-TMS), and was associated with blurred vision and gait freezing. Bipolar stimulation increased motor improvement to 30.9%, but induced dysarthria and bradykinesia. Subsequent interleaved stimulation resulted in a 58.2% improvement in motor function without persistent adverse effects. This therapeutic benefit was sustained over a 12-month follow-up period. CONCLUSION: This case provides clinical evidence from an Asian patient with adult-onset Huntington’s disease and a high CAG repeat burden, who underwent bilateral GPi-DBS with ILS. It supports ILS-DBS as an advanced programming strategy capable of optimizing clinical outcomes in HD when conventional programming approaches are limited by stimulation-induced adverse effects, and highlights the importance of individualized postoperative management. Further studies in larger cohorts are warranted to validate the efficacy and safety of ILS-DBS in HD.