Article
Electrophysiological proof of the correct display of the internal capsule with diffusion-weighted imaging during DBS surgery for Parkinson’s disease
Elektrophysiologischer Nachweis der korrekten Darstellung der Capsula interna mittels diffusionsgewichteter MRT im Rahmen der Tiefenhirnstimulation (DBS) bei Morbus Parkinson
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Authors
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V. A. Coenen
- Neurochirurgische Klinik, Universitätsklinikum der RWTH Aachen
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C. Fromm
- Neurologische Klinik, Universitätsklinikum der RWTH Aachen
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M. Kronenbürger
- Neurologische Klinik, Universitätsklinikum der RWTH Aachen
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P. Reinacher
- Neurochirurgische Klinik, Universitätsklinikum der RWTH Aachen
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R. Becker
- Neuroradiologie, Universitätsklinikum Aachen (UKA), Aachen
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V. Rohde
- Neurochirurgische Klinik, Universitätsklinikum der RWTH Aachen
| Published: | May 4, 2005 |
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Outline
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Objective
To find electrophysiological proof that magnetic resonance diffusion-weighted imaging (DWI) correctly displays the position of the internal capsule (IC).
Methods
In six consecutive patients with Parkinsons’s disease (age: 58.5±12.3 years) 10 pyramidal tracts were studied during DBS surgery. Imaging studies were performed on a 1.5 T Philips Gyroscan NT (Philips Medical Systems, Best, Netherlands). A DWI sequence was obtained with the patient already in a stereotactic frame (Leksell G-Frame, Elekta, Sweden). Electrophysiological measurements (microelectrode recordings and macrostimulation) and DBS placment were accomplished with a Leadpoint® system (Medtronic, USA). Trajectories most promising for hitting the STN after microelectrode recording were chosen. Clinically apparent capsular effects were tested for with increasing current strenghts (1-6 mA; 130 Hz; 60 msec). The effective electrode positions were noted. For the correlation of electrophysiological and imaging data, the Framelink 4.0 software (Medtronic SNT, USA) was used. A single DWI data set (antero-posterior read-out gradient) was fused automatically to the T1W planning data. Segmentation of the IC was done manually. Imaging data were exported to a standard personal computer and further analysis was done with standard software (Photoshop, V7.0, Adobe Systems, Inc., Mountain View, CA). The distances between individual electrode positions that yielded capsular responses and the IC were measured and compared with current spread data obtained from the literature.
Results
Capsular effects were elicited in four patients bilaterally. In two patients, effects could only be observed unilaterally. Macrostimulation yielded capsular responses in 22 measurements. Image analysis and comparison with electrophysiological data led to concordant findings in 18 measurements (81%). For eight out of 10 ICs (80%) analysis indicated a correct display of the IC with DWI.
Conclusions
In future studies DWI should be replaced by diffusion tensor imaging. Furthermore, pure clinical evaluation of capsular effects ought to be enhanced with EMG recordings. The data suggest that the IC is correctly displayed with DWI. The results support the use of DWI or DTI for the planning and performance of surgery in the vicinity of the IC as is already done.
