Deep Brain Stimulation of the Internal Pallidum Modulates the Mesencephalic Locomotor Pathway in Improved Cervical Dystonic Patients.

BACKGROUND

Deep brain stimulation of the internal globus-pallidus (GPi-DBS) improves focal dystonia, often incompletely. GPi-DBS modulates pallido-thalamo-cortical pathways; however, involvement of descending pathways, including the mesencephalic locomotor region (MLR), has been proposed.

OBJECTIVES

To investigate structural connectivity for predicting outcomes.

METHODS

We retrospectively analyzed 21 focal dystonia patients with GPi-DBS. Dystonia was assessed pre- and postoperatively. Contacts were localized, volumes of tissue activated (VTA) modeled, and structural connectivity quantified using probabilistic tractography and each patient's VTA to filter a normative connectome from two healthy cohorts.

RESULTS

GPi-DBS induced mean improvement of 48.2% (SD 37.4%) in TWSTRS (p = 0.0003) and 26.7% (SD 63.4%) in BFMDRS (p = 0.068) in cervical dystonia patients. The sweet-spot was within sensorimotor GPi. For the 15 cervical dystonia patients, VTA-MLR connectivity positively correlated with TWSTRS improvement (p = 0.048), with no significant VTA-thalamic connectivity association (p > 0.30).

CONCLUSIONS

Cervical dystonia improvement depends on the GPi-MLR pathway, supporting tractography to optimize DBS efficacy.