Lead placement is confirmed via intraoperative MER (Microelectrode Recording) and stimulation testing.
Target Efficacy Matrix
STN (Subthalamic)
Medication Reduction Lead
Impact Profile
Superior for medication reduction (up to 50%). Improves tremor, rigidity, and bradykinesia.
Nuances & Risks
Higher risk of mood/cognitive fluctuation and dysarthria.
GPi (Globus Pallidus)
Dyskinesia Control Lead
Impact Profile
Unbeatable for L-dopa induced dyskinesia control. More stable cognitive profile.
Nuances & Risks
Lower potential for dramatic PD medication reduction.
Vim (Thalamus)
Isolated Tremor Lead
Impact Profile
Extremely effective for tremor-dominant PD only. No effect on other symptoms.
Nuances & Risks
Ineffective for gait disturbances or global rigidity.
Guidelines & Evidence
Clinical Details
Section 1
When to Use
When to Use
Planning for functional neurosurgery in medication-refractory movement disorders.
Evaluating phenotypic dominance (e.g. Tremor vs Dyskinesia) to tailor site selection.
Section 2
Formula & Logic
Subthalamic Nucleus (STN)
STN DBS interrupts pathological synchronous oscillations in the indirect motor pathway. It allows for a substantial reduction in Levodopa equivalent daily dose (LEDD), but is contraindicated in patients with significant cognitive impairment due to the risk of worsening executive dysfunction.
Globus Pallidus internus (GPi)
GPi DBS directly inhibits the output of the basal ganglia to the thalamus. Ideal for patients experiencing profound Levodopa-induced dyskinesias, or in patients where medication reduction is not the primary goal.
Ventral Intermediate Nucleus (VIM)
Focuses purely on the cerebello-thalamo-cortical circuit responsible for tremor. Offers profound reduction in both ET and Parkinsonian tremor, but does not alter limb rigidity or gait freezing.
