White matter tracts lesions and decline of verbal fluency after deep brain stimulation in Parkinson's disease

Abstract

Decline of verbal fluency (VF) performance is one of the most systematically reported neuropsychological adverse effects after subthalamic nucleus deep brain stimulation (STN-DBS). It has been suggested that this worsening of VF may be related to a microlesion due to the electrode trajectories. We describe the disruption of surrounding white matter tracts following electrode implantation in Parkinson's disease (PD) patients with STN-DBS and assess whether damage of fiber pathways is associated with VF impairment after surgery. We retrospectively analyzed 48 PD patients undergoing bilateral STN DBS. The lesion mask along the electrode trajectory transformed into the MNI 152 coordinate system, was compared with white matter tract atlas in Tractotron software, which provides a probability and proportion of fibers disconnection. Combining tract- and atlas-based analysis reveals that the trajectory of the electrodes intersected successively with the frontal aslant tract, anterior segment of arcuate tract, the long segment of arcuate tract, the inferior longitudinal fasciculus, the superior longitudinal fasciculus, the anterior thalamic radiation, and the fronto striatal tract. We found no association between the proportion fiber disconnection and the severity of VF impairment 6 months after surgery. Our findings demonstrated that microstructural injury associated with electrode trajectories involved white matter bundles implicated in VF networks.

Keywords: Parkinson's disease; deep brain stimulation; microlesion; subthalamic nucleus; verbal fluency; white matter tracts.

Figure 1

3D reconstruction of one subject: frontal aslant fasciculus. The lesion mask along the electrode trajectory transformed into the MNI 152 coordinate system was compared with white matter tract atlas in Tractotron software. The left frontal aslant tract is one of the most significantly damaged tract

Figure 2

3D reconstruction of one subject: superior longitudinal fasciculus I, II, and III and inferior longitudinal fasciculus. The electrode impacted the three components of the superior longitudinal fasciculus and crossed the inferior longitudinal fasciculus [Color figure can be viewed at http://wileyonlinelibrary.com]

Figure 3

3D reconstruction of one subject: arcuate fasciculus. The most posterior track of the electrodes damaged the arcuate fasciculus [Color figure can be viewed at http://wileyonlinelibrary.com]

Figure 4

3D reconstruction of one subject: fronto striatal fasciculus and anterior thalamic radiation. The distal portion of the electrode crossed successively the fronto striatal fasciculus and the anterior thalamic radiation [Color figure can be viewed at http://wileyonlinelibrary.com]