gms | German Medical Science

Objective: The aim of our study was to investigate which cerebral fibre tracts are involved in the alleviation of parkinsonian tremor in deep brain stimulation.

Methods: 21 patients with Parkinson’s disease and bilaterally implanted electrodes in the subthalamic nucleus were investigated. In 6 of those patients parkinsonian tremor was present in 11 hemibodies contralateral to the investigated brain-hemispheres. Diffusion weighted images (DWI) with 64 gradient directions were included in the routine preoperative imgaging procedure for deep brain stimulation. Post-operative CT scans were fused to the DWI data set and the position of the individual contacts of the electrodes were determined. Probabilistic fibretracking was performed with seed regions based on each individual contact of the electrodes and the resulting anatomical fibre tracts were determined. We compared the depicted fibre tracts between contacts, which effectively (<=2V) reduced the tremor (> 50%) with the fibre tracts of contacts that did not.

Results: 14 (31.8%) of the 44 contacts achieved a reduction of the contralateral tremor (>50%) with an amplitude <= 2.0V. Effective contacts were significantly more often associated with the fasciculus thalamicus, the ansa and fasciculus lenticularis, and fibres passing through the zona incerta (p<0.05) than non-effective contacts. Fibres of the ipsi- and contralateral dentate-rubro-thalamic tract were not depicted differently between effective and non-effective contacts.

Conclusion: As opposed to essential tremor, in parkinsonian tremor the dentate-rubro-thalamic tract does not seem to be the anatomical structure involved in tremor reduction. More likely, stimulated pallido-thalamic fibres play the major role concerning the alleviation of parkinsonian tremor.