Paper of the Month 10/2025

Lange F, Guarin DL, Mosert S, Karrasch B, Roothans J, Weigl B, Navratil P, Daniels C, Odorfer T, Brandt G, Mahlknecht P, Krauss JK, Runge J, Kühn AA, Deuschl G, Volkmann J, Peach R, Reich MM.

NPJ Parkinsons Dis. 2025 Oct 23; 11(1): 308. doi: 10.1038/s41531-025-01177-8. PMID: 41131044.

Abstract

Pallidal deep brain stimulation (DBS) for dystonia can induce bradykinesia. We analyzed retrospective (n = 55) and prospective (n = 11) cohorts to identify risks and anatomical substrates for this side effect. Bradykinesia was prevalent (60-72%), with female sex, older dystonia onset, shorter disease duration, and crucially, stimulation pulse width identified as key predictive factors. Probabilistic mapping isolated a posterolateral globus pallidus internus “sour spot” for bradykinesia, which was spatially distinct from therapeutic “sweet spots” and demonstrated patient-level predictive power in cross-validation (R² = 0.16, p = 0.0013). Kinematic analysis showed reducing stimulation selectively improved movement frequency without altering amplitude. The effect appears mediated by local grey-matter modulation, not major white matter tracts. These findings suggest programming strategies using shorter pulse widths while avoiding the identified sour spot can mitigate bradykinesia without sacrificing antidystonic benefit.