PMC8843015_01
PMC8843015_02
(A) Directional lead, (B) microelectrode recordings (MER), (C) local field potential (LFP) recordings, and (D) adverse effects by type of stimulation according to neurophysiological findings. (A) Longitudinal and axial scheme of the directional lead, showing the lead marker and the four contact levels: the two middle levels are split into three segmented contacts, spanning 120 degrees (1-2-3 more ventral and 3-4-5 more dorsal) and the highest (8) and lowest (1) contacts are ring-shaped. (B) Sample of MER from patient. Up: Spontaneous subthalamic nucleus (STN) spike activity. Down: STN spike activity during passive wrist extension movement (underlined), showing the driving effect. (C) LFP recording. Left: Scheme of bipolar montage between the lowest ring electrode and every inferior segmented contact level and between the highest ring electrode and every superior segmented contact level. (C) Right: Example of a bipolar LFP recording (sonogram mode) during 340 s (X-axis), with presence of activity in the beta band (13-35 Hz) in all the bipolar derivations (Y-axis), more prominent in derivation 1-4. (D) Adverse effects by type of stimulation. (D-1) Up left: Ring mode stimulation elicited mirthful laughter in the patient. Down left: Axial representation of theoretical volume of tissue activation (VTA) in ring mode stimulation [2-3-4]:C+. Right: Fast fourier transformation of intraoperative STN activity recorded from the left macroelectrode (bipolar montage 1-2, 1-3, 1-4), showing a clear beta (14.6 Hz) peak over contact (4). (D-2) Up left: Directional stimulation (4):C+ did not elicited adverse effects in the patient. Down left: Axial representation of theoretical volume of tissue activation (VTA) in directional mode stimulation (4):C+. Right: Fast fourier transformation of intraoperative STN activity recorded from the left macroelectrode (bipolar montage 1-2, 1-3, 1-4), showing a clear beta (14.6 Hz) peak over contact (4).
fneur-12-786166-g0001.jpg
PMC8843015_04_fneur-12-786166-g0001.jpg
F1
These leads have four contact levels: the two middle levels are split into three segmented contacts, spanning 120 degrees, and the highest and lowest contacts are ring-shaped (Figure 1A). The final position of the electrode and segmented contacts were determined according to best the MER (outstanding single-neuron activity and driving responses to active/passive limb movements) (Figure 1B). We used a bipolar montage between the lowest ring electrode and every inferior segmented contact level, and between the highest ring electrode and every superior segmented contact level (Figure 1C). Neurophysiological findings showed higher beta power at 14.7 Hz over contact 3 on the right STN and at 14.6 Hz over contact 4 on the left STN (Figure 1D).
PMC8843015_03
PMC8843015_04
(A) Directional lead, (B) microelectrode recordings (MER), (C) local field potential (LFP) recordings, and (D) adverse effects by type of stimulation according to neurophysiological findings. (A) Longitudinal and axial scheme of the directional lead, showing the lead marker and the four contact levels: the two middle levels are split into three segmented contacts, spanning 120 degrees (1-2-3 more ventral and 3-4-5 more dorsal) and the highest (8) and lowest (1) contacts are ring-shaped. (B) Sample of MER from patient. Up: Spontaneous subthalamic nucleus (STN) spike activity. Down: STN spike activity during passive wrist extension movement (underlined), showing the driving effect. (C) LFP recording. Left: Scheme of bipolar montage between the lowest ring electrode and every inferior segmented contact level and between the highest ring electrode and every superior segmented contact level. (C) Right: Example of a bipolar LFP recording (sonogram mode) during 340 s (X-axis), with presence of activity in the beta band (13-35 Hz) in all the bipolar derivations (Y-axis), more prominent in derivation 1-4. (D) Adverse effects by type of stimulation. (D-1) Up left: Ring mode stimulation elicited mirthful laughter in the patient. Down left: Axial representation of theoretical volume of tissue activation (VTA) in ring mode stimulation [2-3-4]:C+. Right: Fast fourier transformation of intraoperative STN activity recorded from the left macroelectrode (bipolar montage 1-2, 1-3, 1-4), showing a clear beta (14.6 Hz) peak over contact (4). (D-2) Up left: Directional stimulation (4):C+ did not elicited adverse effects in the patient. Down left: Axial representation of theoretical volume of tissue activation (VTA) in directional mode stimulation (4):C+. Right: Fast fourier transformation of intraoperative STN activity recorded from the left macroelectrode (bipolar montage 1-2, 1-3, 1-4), showing a clear beta (14.6 Hz) peak over contact (4).
fneur-12-786166-g0001.jpg
PMC8843015_04_fneur-12-786166-g0001.jpg
F1
These leads have four contact levels: the two middle levels are split into three segmented contacts, spanning 120 degrees, and the highest and lowest contacts are ring-shaped (Figure 1A). The final position of the electrode and segmented contacts were determined according to best the MER (outstanding single-neuron activity and driving responses to active/passive limb movements) (Figure 1B). We used a bipolar montage between the lowest ring electrode and every inferior segmented contact level, and between the highest ring electrode and every superior segmented contact level (Figure 1C). Neurophysiological findings showed higher beta power at 14.7 Hz over contact 3 on the right STN and at 14.6 Hz over contact 4 on the left STN (Figure 1D).
Lead location confirmation. Fusion of postoperative CT scan with preoperative 3T axial MRI, using Elements  software (Brainlab ) and Guide XT  software (Boston Scientific, Valencia, California), showing the final position of bilateral directional leads (orange) within the subthalamic nucleus (STN; green) and the red nucleus (red). The left lead was slightly medialized inside the STN and a small volume of tissue activated (VTA; pink sphere) was generated close to contact 3, to highlight its position in the ventromedial region of the nucleus.
fneur-12-786166-g0002.jpg
PMC8843015_04_fneur-12-786166-g0002.jpg
F2
Optimal lead location was confirmed by fusing postoperative 3D CT and preoperative 3T MRI, and 3D X-ray was used to assess lead orientation (Figure 2).
PMC8843015_05
PMC8843015_06
Tractography study. Representation of the associative fibers stimulated when contact 3 in the left STN was activated at 1.5 mA, 60 mus, and 130 Hz. (A) Coronal flair 3T MRI view, with segmentation of bilateral red nucleus (red), bilateral STN (green), directional leads (orange), and VTA (pink sphere) generated with contact 3 stimulation. Fibers toward the prefrontal cortex in the left side are represented in blue. (B) Close view of the left directional lead, left STN and the fibers passing through the VTA generated (in contact 3) toward the frontal region. Images obtained with Elements  software (Brainlab ) and Guide XT  software (Boston Scientific).
fneur-12-786166-g0003.jpg
PMC8843015_06_fneur-12-786166-g0003.jpg
F3
Associative fibers showed the shortest distance to contact number 3 (Figure 3).