Dorsal GPi/GPe DBS Induced Dyskinesia

Objective: To describe stimulation-induced dyskinesia (SID) observed in Parkinson’s disease (PD) patients with globus pallidus internus (GPi) deep brain stimulation (DBS)

Background: While SID is commonly seen in STN DBS patients, it is rarely reported with GPi DBS. Few studies correlated the incidence of SID with precise anatomic localization of the stimulation site. Although typically effective in improving motor symptoms of PD and suppressing problematic dyskinesia, dorsal GPi/GPe DBS can rarely precipitate SID

Design/Methods: Four patients with PD treated with GPi DBS developed SID. GPi DBS lead localization was performed using a delayed postoperative CT fused with a preoperative MRI and a patient-specific 3-D morph of a modified Schaltenbrand and Bailey brain atlas. We analyzed the occurrence of dyskinesia, the precise lead location, and the active DBS contact used for chronic treatment

Results: Three of the four patients were implanted with bilateral, and one with unilateral, GPi DBS. Five of seven leads were deemed optimally placed (OP) and two suboptimally placed (SP) in the GPI based on imaging and programming thresholds. Four leads produced SID (OP n=2, SP n=2, right n=1, left n=3). SID occurred when dorsal (contacts 2, 3), but not ventral (contacts 0, 1) DBS contacts were activated. Stimulation at dorsal contacts provided motor benefit and were more likely to be used for chronic DBS. SID was voltage dependent in three patients and was elicited at stable parameters for testing (135Hz and 90μs). One patient developed leg dyskinesia at higher frequency (180Hz)

Conclusions: Dorsal GPi stimulation can be pro-kinetic, but rarely produces contralateral dyskinesia. The finding was confirmed in n=4 patients however these patients were selected based on the occurrence of SID during GPI DBS programming. We suspect that SID incidence is low in GPI DBS patients. Studies of tractography and volume of tissue activation (VTA) may clarify relevant circuitry of the GPe/GPi