Deep brain stimulation of the subthalamic nucleus in Parkinson's disease: Relationship between the electrode trajectory and cognitive decline.

INTRODUCTION: It remains to be clarified whether penetration of the caudate nucleus increases the risk of cognitive decline in patients with Parkinson's disease (PD) undergoing deep brain stimulation (DBS) of the subthalamic nucleus (STN).

METHODS: A retrospective analysis of pre/postoperative neuropsychological changes was performed with 46 consecutive patients with PD who underwent DBS of the STN. In particular, to evaluate the possible relationship between cognitive changes and DBS lead trajectories, repeated-measures ANCOVAs were conducted to analyze the effects of group (23 patients with vs 23 patients without penetration of the caudate nucleus) and time (T0 vs T1) for each neuropsychological test.

RESULTS: A statistically significant main effect of time was observed in the Trail Making Test - Part B (TMT-B), as well as in both the phonemic and semantic (F [1, 44] = 35.59, p < 0.001, PrtEta2  = 0.447) verbal fluency tasks, and the results suggested postoperative cognitive decline. However, no significant interaction effects of time and group were observed. The results indicated that the extent of the decline was comparable between the caudate and non-caudate penetration groups, and no relationship was found between cognitive changes and caudate penetration.

CONCLUSION: Although postoperative cognitive decline was observed in some attentional-executive functions, which were assessed by the verbal fluency and TMT-B tasks, the trajectory passing through the caudate appeared not to increase the risk of cognitive decline in patients with PD undergoing DBS of the STN.