Article
Corticospinal tract diffusion tensor imaging in deep brain stimulation procedure for Parkinson’s disease: Correlation to intraoperative stimulation and to clinical outcome at one year
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Authors
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Kajetan von Eckardstein
- Universitätsmedizin Göttingen, Klinik für Neurochirurgie, Göttingen, Deutschland
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Friederike Sixel-Döring
- Paracelsus-Elena-Klinik, Kassel, Deutschland
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Claudia Trenkwalder
- Paracelsus-Elena-Klinik, Kassel, Deutschland
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Veit Rohde
- Universitätsmedizin Göttingen, Klinik für Neurochirurgie, Göttingen, Deutschland
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Vesna Malinova
- Universitätsmedizin Göttingen, Klinik für Neurochirurgie, Göttingen, Deutschland
| Published: | June 18, 2018 |
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Outline
Text
Objective: In subthalamic deep brain stimulation (DBS), lead placement is influenced by pyramidal motor side effects upon stimulation. Thus, we postulate that electrode proximity to the corticospinal tract (CST) as visualized by diffusion tensor imaging (DTI) will influence intraoperative as well as postoperative stimulation results.
Methods: We reviewed consecutive DBS procedures in 18 patients. For means of comparability, only electrodes implanted into the target point (x = +/- 12; y = -4, z = -4 mm) were included (n=28). Implanted leads were segmented in postop HCT scans and were matched with the preop MRI. DTI tractography of the CST was performed, using the hand knob as seeding point (BrainLab iPlan 3.0; FA threshold 28, min. length 60 mm). The closest distance between the tip of the lead and the CST in the axial plane was manually recorded. The results were compared to intraoperative stimulation side effects, as documented. Furthermore, the imaging was correlated to a side specific motor symptom ratio at one year follow-up (UPDRS-3, Unified Parkinson Disease Rating Scale, recorded for motor symptoms only on each side separately; stimulation ON medication OFF postop divided by medication OFF preop).
Results: Distances between leads and calculated tracts differed surprisingly with a median of 2.5 mm, in spite of homogenous protocol. Of 14 trajectories with proximity of <= 2.5 mm, 4 hemispheres showed signs of intraop capsule stimulation with higher amplitudes of 3 and 4 mA; in 15 distant trajectories (>2.5 mm), motor stimulation side effected were observed in 4 hemispheres as well. Interestingly, but not within statistical significance (t-test, p=0.13), we found a trend toward better motor control at one year in patients with closer spatial relation between lead and calculated CST.
Conclusion: We did not see any relation between intraop stimulation results and distances between lead and DTI based CST calculation. Unexpectedly, yet not statistically significantly, closeness of the lead to the CST correlated to a better clinical motor outcome. With a sufficient therapeutic width, motor symptoms observed with higher amplitudes should therefore not exclude a trajectory for final lead implantation, as a clinically favorable outcome is possible.
