Pallidal lead placement in dystonia: leads of non-responders are contained within an anatomical range defined by responders

J Neurol. 2020 Jun;267(6):1663-1671. doi: 10.1007/s00415-020-09753-z. Epub 2020 Feb 17.

Abstract

Background: Deep brain stimulation (DBS) within the pallidum represents an effective and well-established treatment for isolated dystonia. However, clinical outcome after surgery may be variable with limited response in 10-25% of patients. The effect of lead location on clinical improvement is still under debate.

Objective: To identify stimulated brain regions associated with the most beneficial clinical outcome in dystonia patients.

Methods: 18 patients with cervical and generalized dystonia with chronic DBS of the internal pallidum were investigated. Patients were grouped according to their clinical improvement into responders, intermediate responders and non-responders. Magnetic resonance and computed tomography images were co-registered, and the volume of tissue activated (VTA) with respect to the pallidum of individual patients was analysed.

Results: VTAs in responders (n = 11), intermediate responders (n = 3) and non-responders (n = 4) intersected with the posterior internal (GPi) and external (GPe) pallidum and the subpallidal area. VTA heat maps showed an almost complete overlap of VTAs of responders, intermediate and non-responders. VTA coverage of the GPi was not higher in responders. In contrast, VTAs of intermediate and non-responders covered the GPi to a significantly larger extent in the left hemisphere (p < 0.01).

Conclusions: DBS of ventral parts of the posterior GPi, GPe and the adjacent subpallidal area containing pallidothalamic output projections resulted in favourable clinical effects. Of note, non-responders were also stimulated within the same area. This suggests that factors other than mere lead location (e.g., clinical phenotype, genetic background) have determined clinical outcome in the present cohort.

Keywords: Clinical outcome; Deep brain stimulation; Dystonia; GPi stimulation; Volume of tissue activated (VTA).

MeSH terms

  • Adolescent
  • Adult
  • Aged
  • Deep Brain Stimulation* / methods
  • Dystonic Disorders / diagnostic imaging
  • Dystonic Disorders / genetics
  • Dystonic Disorders / therapy*
  • Electrodes, Implanted*
  • Female
  • Globus Pallidus / anatomy & histology*
  • Globus Pallidus / diagnostic imaging
  • Globus Pallidus / surgery
  • Humans
  • Male
  • Middle Aged
  • Outcome Assessment, Health Care*
  • Retrospective Studies
  • Torticollis / diagnostic imaging
  • Torticollis / genetics
  • Torticollis / therapy*
  • Young Adult