Im Zweifel lieber Rot - Die Reduktion der Levodopa-Äquivalenzdosis ein Jahr nach STN-THS bei Parkinson-Krankheit kann mit der individuellen Konnektivität am Stimulationsort vorhergesagt werden

To investigate if and how motor improvement 12 months after deep brain stimulation (DBS) in the subthalamic nucleus (STN) and reduction of levodopa equivalent dose (LED) are associated with individual structural connectivity analyzed by Subject sPEcific brain Connectivity display in the Target REgion (SPECTRE) (i).

Patients with Parkinson's disease who had given informed consent to our DBS registry were selected for this analysis, whenever the following data were available: preoperative and 12 months postoperative follow up LED, preoperative 3T MRI including diffusion-weighted MRI, postoperative cCT and stimulation parameters at 12 months follow up (FU₁₂).

MDS-Unified Parkinson's Disease Rating Scale (MDS-UPDRS) III was conducted in the Medication OFF state preoperatively, and Med OFF Stimulation ON state at FU₁₂.

Reduction of LED was calculated as the ratio of follow up values divided by preOP values and motor improvement as the difference of FU₁₂ and preOP values of MDS-UPDRS III.

For generation of individual SPECTRE maps limbic/associative/sensorimotor (green/blue/red), cortical schemes defined in MNI space were warped to subject space (cf. i) and in a tract weighting approach 500 probabilistic streamlines per voxel were seeded in the volumes of activated tissue (VATs) to compute their cortical associations (Fig.1).

The relation between individual connectivity patterns, represented by the color proportion of the voxels and motor improvement 12 months after STN-DBS was estimated by calculating linear regressions correcting for age and disease duration as covariates.

43 patients from our DBS registry fulfilled the criteria and were included in the analysis. MDS-UPDRS III values were available in 36 patients. Regression analyses found a significant positive association for red/sensorimotor connectivity (t=2.51, p=.02) and a trend for a negative association for green/limbic connectivity (t=-1.96, p=.06) predicting LED reduction (Fig.1), but no significant results in models for motor improvement itself.

Individual connectivity derived by SPECTRE imaging can predict LED reduction after STN-DBS and may therefore be helpful for the definition of the optimal DBS electrode position, its implantation and DBS programming. The missing association with motor improvements may be due to MDS-UPDRS III reflecting motor performance in specific situations while LED reduction signals long-term motor functioning.