¹H-MRS experiences after bilateral DBS of the STN in Parkinson’s disease
Llumiguano C, Auer T, Kosztolanyi P, Kovacs N, Schwarcz A, Doczi T, Balas I.

Objective: The objective of this study was to evaluate the changes of the brain metabolites concentrations (NAA – N acethyl aspartate, Cho - choline, Crea – creatinine) in patients with Parkinson’s disease (PD) before and after bilateral deep brain stimulation (DBS) of the subthalamic nucleus (STN).

Methods: Thirteen patients were evaluated at baseline and repeatedly three months after surgery. The NAA/Chol, NAA/Crea, Chol/Crea ratios were determined by single voxel ¹H-MRS studies on 1.0 T unit using stimulated echo acquisition mode (STEAM) sequence (TR/TM/TE: 2000/10/30 ms). Spectra were obtained from right and left globus pallidus (Gp), and fronto-basal cortex (FBC). The patients were also assessed according to the Unified Parkinson’s Disease Rating Scale (UPDRS) part III, in the "medication-on" and "medication-off' conditions. Results: In all patients motor scores (UPDRS III) improved significantly (Student’s T test: p< 0.01). In all patients, decreased NAA/Cho ratios were observed from the selected voxels in left and right Gp, however significant increase of NAA/Cho, NAA/Crea, and decrease of Chol/crea ratio was observed in FBC after surgery in patients with clinical improvement. Complications were in one case transient and in other case permanent complication developed following STN DBS implantations.

Conclusions: Significant improvements were observed in the motor scores (UPDRS III) and in cortex NAA/Cho, NAA/Crea ratio increased significantly following bilateral DBS of the STN. These improvements were strongly correlated with improvements in motor function, primarily with regard to bradykinesia. Our results suggest that NAA/Cho and NAA/Crea ratio may be a valuable criterion for evaluation of Parkinson’s disease patients with the clinical improvement following DBS of the STN. ¹H-MRS may be a useful utility for the aid in better understanding the pathophysiologic process in Parkinson’s disease patients on the basis of the variation of NAA/Cho, NAA/Crea ratio.