Andreas Nowacki, Ines Debove, Frédéric Rossi, Janine Ai Schlaeppi, Katrin Petermann, Roland Wiest, Michael Schüpbach and Claudio Pollo
Deep brain stimulation (DBS) of the posterior subthalamic area (PSA) is an alternative to thalamic DBS for the treatment of essential tremor (ET). The dentato-rubro-thalamic tract (DRTT) has recently been proposed as the anatomical substrate underlying effective stimulation. For clinical purposes, depiction of the DRTT mainly depends on diffusion tensor imaging (DTI)–based tractography, which has some drawbacks. The objective of this study was to present an accurate targeting strategy for DBS of the PSA based on anatomical landmarks visible on MRI and to evaluate clinical effectiveness.
The authors performed a retrospective cohort study of a prospective series of 11 ET patients undergoing bilateral DBS of the PSA. The subthalamic nucleus and red nucleus served as anatomical landmarks to define the target point within the adjacent PSA on 3-T T2-weighted MRI. Stimulating contact (SC) positions with reference to the midcommissural point were analyzed and projected onto the stereotactic atlas of Morel. Postoperative outcome assessment after 6 and 12 months was based on change in Tremor Rating Scale (TRS) scores.
Actual target position corresponded to the intended target based on anatomical landmarks depicted on MRI. The total TRS score was reduced (improved) from 47.2 ± 15.7 to 21.3 ± 10.7 (p < 0.001). No severe complication occurred. The mean SC position projected onto the PSA at the margin of the cerebellothalamic fascicle and the zona incerta.
Targeting of the PSA based on anatomical landmarks representable on MRI is reliable and leads to accurate lead placement as well as good long-term clinical outcome.
Eric Bardinet, Manik Bhattacharjee, Didier Dormont, Bernard Pidoux, Grégoire Malandain, Michael Schüpbach, Nicholas Ayache, Philippe Cornu, Yves Agid and Jérôme Yelnik
The localization of any given target in the brain has become a challenging issue because of the increased use of deep brain stimulation to treat Parkinson disease, dystonia, and nonmotor diseases (for example, Tourette syndrome, obsessive compulsive disorders, and depression). The aim of this study was to develop an automated method of adapting an atlas of the human basal ganglia to the brains of individual patients.
Magnetic resonance images of the brain specimen were obtained before extraction from the skull and histological processing. Adaptation of the atlas to individual patient anatomy was performed by reshaping the atlas MR images to the images obtained in the individual patient using a hierarchical registration applied to a region of interest centered on the basal ganglia, and then applying the reshaping matrix to the atlas surfaces.
Results were evaluated by direct visual inspection of the structures visible on MR images and atlas anatomy, by comparison with electrophysiological intraoperative data, and with previous atlas studies in patients with Parkinson disease. The method was both robust and accurate, never failing to provide an anatomically reliable atlas to patient registration. The registration obtained did not exceed a 1-mm mismatch with the electrophysiological signatures in the region of the subthalamic nucleus.
This registration method applied to the basal ganglia atlas forms a powerful and reliable method for determining deep brain stimulation targets within the basal ganglia of individual patients.