Prevalent placement error of deep brain stimulation electrode in movement disorders (technical considerations)

Deep brain stimulation is an effective and safe technique. Displacement of the electrode relative to the optimal stimulation site can lead to insufficient effect and sometimes to the need of operative electrode re-position.

This study was aimed to analyse targeting accuracy of deep brain stimulation electrode implantation to subthalamic nucleus (STN) and globus pallidus internus (Gpi). It detected possible causes of inaccuracy and prevalent shift to certain direction.

Targeting accuracy was analysed in 47 patients with Parkinson´s disease (PD) and 11 patients with dystonia with bilateral implantation of deep brain stimulation electrodes between years 2009 and 2016.

A shift of electrode to prevalent direction was observed on the left side to medial and posterior and on the right side to lateral direction. Greater shift was observed on the left side and in a higher angulation of trajectory laterally. Movement of the electrode, because of its traction in anchoring device, was identified as a possible factor for prevalent electrode shift. Calibration of stereotactic coordinates to correct prevalent shift was used.

Targeting inaccuracy is the result of accumulation of errors in individual steps of electrode implantation. Direction of the shift can be random or it can be toward a prevalent direction. A correction of prevalent error can prevent a suboptimal electrode placement (Tab. 3, Fig. 11, Ref. 29).