PMC6593871_01
(A) Bilateral STN lead location, the STN (orange), globus pallidus internus (light green), globus pallidus externus (light blue), and red nucleus (red) are shown for reference; (B) Volume of tissue activated (VTA) in the initial programming setting (red), L-STN (C+;2-), R-STN (C+;10-), 60 us pulse width, 130 Hz frequency, and 3.0 V; (C) VTA in the second programming setting (dark blue): L-STN (C+;1-;3-), R-STN (C+;9-;11-), 90 us pulse width, 130 Hz frequency, and 2.0V; (D) VTA in the final programming setting (green): L-STN (C+;2-), R-STN (C+;10-), 90 us pulse width, 60 Hz frequency, and 4.5 V.
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F1
After a multidisciplinary assessment, the patient underwent bilateral placement of STN-DBS leads (3389, Medtronic, Minneapolis, Minnesota USA; Figure 1A). Three months after surgery, motor symptoms continued to be improved with stable stimulation parameters: amplitude 3.0 V, pulse width 60 mus, frequency 130 Hz in monopolar mode bilaterally with left STN (C+;2-) and right STN (C+;10-) (Figure 1B). Multiple programming sessions and attempts of double monopolar stimulation using different amplitudes (Figure 1C) provided transient benefit in her FoG. We then adjusted the stimulation and applied low-frequency settings as follows: Left STN (C+;2-), Right STN (C+;10-), amplitude 4.5 V, pulse width 90 mus, and frequency 60 Hz (Figure 1D).
MDS-UPDRS sub-scores of levodopa challenge test. (A) FoG and axial scores of levodopa challenge test in the off-stimulation state. (B) FoG and axial scores of levodopa challenge test in the on-stimulation state. FoG score: MDS-UPDRS item 3.11; Axial score: the sum of MDS-UPDRS item 3.1 (speech), 3.2 (facial expression), 3.3 (neck), 3.9 (arising from chair), 3.10 (gait), 3.11 (FoG), 3.12 (posture stability), 3.13 (posture), and 3.14 (body bradykinesia); Total score: MDS-UPDRS part III total score. Stimulation parameters: L-STN (C+;1-;3-), R-STN (C+;9-;11-), 90 us pulse width, 130 Hz frequency, and 2.0 V. MDS-UPDRS, Movement Disorder Society Sponsored Revision of the Unified Parkinson's Disease Rating Scale; FoG, freezing of gait.
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F2
Once stimulation was turned off, the patient developed a recurrence of FoG which gradually improved after levodopa (FoG score improved from 4 to 1), along with other axial symptoms (Figure 2). In the on-med/on-stim state, the patient developed persistent, severe FoG and gait difficulties for several hours after levodopa intake [FoG score increased from 2 to 4 with the axial score from 22 to 27] (Figure 2).
Fiber tracking from different VTAs of three programming settings. VTA, volumes of tissue activated; Frontal Sup, superior frontal gyrus; Frontal_Sup_Med, medial frontal gyrus; SMA, supplementary motor area. The initial, second, and final programming settings are referred to Figure 1.
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F3
Notably, there was a decrease in the connectivity of the left VTA and these regions during the improvement of "on" FoG (Figure 3).