Nonablative surgical procedures for treatment of PD involve either unilateral or bilateral implantation of high-frequency stimulation electrodes into deep brain nuclei. Studies detailing neuropsychological outcomes after unilateral globus pallidus (GPi) deep brain stimulation (DBS) have supported the neurobehavioral safety of this technique (113,157), although a few studies have demonstrated minor postoperative declines in verbal fluency (158-160). The majority of studies indicate that even bilateral GPi stimulation is cognitively well tolerated (161-163), although in isolated cases, cognitive declines can occur (152,164).
There are few studies evaluating cognitive outcomes after thalamic DBS, but preliminary findings suggest that this procedure is associated with minimal cognitive morbidity up to one year after surgery (165-167). Indeed, subtle and limited cognitive improvements might be witnessed after thalamic DBS.
The majority of DBS procedures now target the subthalamic nucleus (STN). Modest decrements in verbal fluency are the most commonly reported adverse cognitive sequelae associated with STN DBS (16,17,168). Findings regarding possible postoperative declines and/or improvements in global cognitive abilities, memory, attention, and executive functions are less consistent (113,169). When considered in the context of the important benefits of surgery on motor functions, mood state, and quality of life (170), the cost of possible minor and/or transient cognitive declines in a minority of well-selected patients seems to be overshadowed by the benefits. Preliminary evidence indicates that elderly patients (older than 69 years), as well as those patients displaying presurgical cognitive deficits, might be at greater risk for neurobehavioral morbidity after STN DBS.
Was this article helpful?