Infratentorial Morphometry and Deep Brain Stimulation Outcome in Cervical Dystonia

Abstract

AbstractBackgroundCervical dystonia is a movement disorder, characterised by involuntary head and neck muscle contractions. Although deep brain stimulation (DBS) of the globus pallidus internus (GPi) is an effective treatment option, motor outcomes can vary even when sufficient targeting accuracy is achieved. Increasing evidence supports a role of brainstem and cerebellum dysfunction in cervical dystonia pathogenesis.ObjectiveTo determine whether morphometry of brainstem and dentate nuclei, and DBS stimulatory overlap with cerebello-thalamic tracts modelled from normative connectivity, were related to DBS clinical motor outcomes.Methods27 patients with idiopathic cervical dystonia underwent bilateral targeting of the GPi. and were separated into suboptimal and optimal motor outcome groups. Dentate nuclei and brainstem volumes were quantified in association with clinical outcomes. A brainstem shape analysis was conducted and used as a seed to assess connectivity from a normative structural connectome. Patient-specific electrodes were modelled to quantify stimulatory overlap with the GPi and proximity to cerebellothalamic tracts.ResultsGPi implantation accuracy did not significantly differ between groups. Significantly reduced dentate nuclei and brainstem volumes were observed in patients with poorer clinical outcomes. Regional surface shape change of the brainstem was also observed in patients with poorer responses. Fibre tracking from this area intersected cerebellar, pallidal and cortical motor regions. Electrode field intersection with the non-decussating dentatorubrothalamic tract in the right, and in both hemispheres were also positively associated with clinical outcome.ConclusionsVariability in cerebellar and brainstem morphometry, and stimulation of non-decussating cerebello-thalamic pathways may contribute to the mediation of DBS motor outcomes.