Neuropsychological effects after chronic subthalamic stimulation and the topography of the nucleus in Parkinson's disease.
OBJECTIVE
The neuropsychological effects of chronic subthalamic nucleus (STN)-deep brain stimulation (DBS) as a treatment for Parkinson's disease are variable. Whether these side effects result from the target per se or current diffusion into neighboring structures is uncertain. In this study, the relationship between clinical outcomes and coordinates of active contact are analyzed and compared between patients with and without neuropsychological sequelae.


METHODS
Thirty-eight Parkinsonian patients who underwent bilateral STN-DBS were enrolled in this retrospective cohort study. They were followed for at least 12 months. During the follow-up period, they were divided into two groups for comparison; Group A included patients with neuropsychological side effects and Group B was composed of patients without neuropsychological side effects. The position of the active contact of the electrode was defined with postoperative magnetic resonance imaging scans according to the midcommissural line. Active contact coordinates and clinical outcomes were compared for the two groups.


RESULTS
Among the 38 Parkinsonian patients who underwent STN-DBS, eight patients who had neuropsychological side effects were assigned to Group A; the other 30 patients were assigned to Group B. In Groups A and B, the mean follow-up periods were 13.9 and 12.1 months, respectively, the Unified Parkinson's Disease Rating Scale motor score was improved by 53.4 and 45.2% (P = 0.24), respectively, and the levodopa equivalent daily dosage was decreased by 68.4 and 46.4% (P = 0.16), respectively. The mean coordinates of active contact in both Groups A and B were x = 10.1 and 10.5 mm, respectively, y = -2.8 and -3.9 mm, respectively, and z = -6.3 and -6.2 mm, respectively, relative to the midcommissural point. A significant difference was observed on the y axis (P = 0.01).


CONCLUSIONS
When taking spatial influence into consideration, the neuropsychological effects of chronic STN-DBS were related to a significant anteriorly located active contact within the ventral STN in this preliminary study. This might suggest the existence of topography of STN in patients with Parkinson's disease concerning limbic and associative circuits.
Tsai
Sheng-Tzung
ST
Department of Neurosurgery, Division of Functional Neuroscience, Tzu Chi General Hospital, Tzu Chi University, Hualien, Taiwan.
Lin
Sheng-Huang
SH
Lin
Shinn-Zong
SZ
Chen
Jen-Yeu
JY
Lee
Chi-Wei
CW
Chen
Shin-Yuan
SY
D003072:Cognition Disorders / Q000175:diagnosis* / Q000209:etiology; D046690:Deep Brain Stimulation / Q000009:adverse effects* / Q000379:methods*; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D009422:Nervous System Diseases / Q000175:diagnosis* / Q000209:etiology; D010300:Parkinson Disease / Q000175:diagnosis* / Q000534:rehabilitation*; D020531:Subthalamic Nucleus; D016896:Treatment Outcome