Leksell coordinate frame

Magnetic resonance imaging (MRI) was scanned after fixation of the stereotactic Leksell Coordinate Frame (Elekta®, Stockholm, Sweden). These scans were then fused and registered with the MRI performed before surgery in the surgical planning system. Based on the indication provided by Schiff et al. ], the bilateral CM-pf were targeted. Multi-channel microelectrodes (leadpoint, Medtronic, USA) were implanted, and the electrical signals were recorded from 10 mm above the target down to 2 mm below it and we used the signal within a 1mm range above and below the target as the data for subsequent analysis. All procedures were conducted under general anesthesia. The administration of propofol and sevoflurane, which could influence neuronal firing, were discontinued 20 min prior to the microelectrode recording (MER). Two quadripolar electrodes (PINS L302, Beijing PINS) were positioned at the target site based on the microelectrode trajectory on both sides. To assist more accurate localization, the LFP signals were filtered out to enhance the observation of firing activities. Postoperative CT OR 1.5T MRI were performed to verify the position of DBS electrodes (Fig. S1).

The radiosurgical procedures were all performed by the same neurosurgeon (JR). Patients were unilaterally treated in the left thalamus. As described previously 6 (link) , the Leksell® coordinate frame (Elekta AB, Stockholm, Sweden) was applied under local anaesthesia. Special care was taken to place the stereotactic frame parallel to the orientation of the anterior commissure-posterior commissure (AC-PC) line to minimize head tilt and rotation. Treatment planning was performed using the Leksell GammaPlan software (versions 8.3.1 up to 10.1.1).
The centre of the target, determined by Guiot's diagram, was placed 2.5 mm above the AC-PC line, 11 mm lateral to the wall of the third ventricle, and three-twelfths of AC-PC distance on the Guiot scheme in front of the PC. It should be noted that variations in the y plane of the "Guiot" target were related to individual variations in the CA-CP length, having a mean of 25.11 mm (23-28.30 mm). In addition, a unique 4-mm isocentre was used for beam blocking to optimize the gradient of the dose towards the internal capsule. The prescribed dose was 130 Gy (maximum dose) for all patients.