In patients with Parkinson’s disease, verbal fluency (VF) decline is a well-known adverse cognitive effect of subthalamic nucleus deep brain stimulation (STN DBS). The mechanisms behind VF decrease, whether caused by stimulation, lesioning or a combination of Verbal fluency declines, are unknown. Beyond the previously documented effects of active contact sites, this study determined the specific effects of VF. A total of 56 individuals with idiopathic PD who had bilateral STN DBS were included in the study. Researchers compared the pre-and postoperative phonemic and semantic VF ratings. On postoperative imaging, features of the electrode trajectory such as distance from the falx cerebri, distance from the superior frontal sulcus, and caudate nucleus penetration on postoperative imaging. To investigate the link between VF change and demographic, illness, and electrode trajectory characteristics, the author employed t-tests, Pearson’s correlation, and multiple linear regression analyses.
After correcting for the active contact site, the laterality of entrance into the left superior frontal gyrus (SFG) predicted a larger phonemic VF decline (sr2=0.28, p<0.001). Caudate nucleus penetration did not affect VF change in either hemisphere (P > 0.05). The SFG’s lateral penetration in the left hemisphere is linked to worsening phonemic VF and stronger explanatory power than active contact location. Lesioning of the lateral SFG–Broca region pathway, which is involved in language function, could explain this.
