|Reference code: ||PT/FB/BL-2004-112.10|
|Location: ||Arquivo PCA - Pasta 15/2004|
|Improvement of transcranial magnetic stimulation (TMS) coils for psychiatric applications|
|Publication year: ||2008|
To design and test new coils for transcranial magnetic stimulation of deep brain structures. Efficient stimulation of structures such as the nucleus accumbens and other limbic regions is necessary for the successful application of TMS in psychiatry.
TMS coils specially designed for deep stimulation (H1 and H2 coils) were tested on 31 normal subjects and on 50 drug resistant patients suffering from major depression. Numerical methods were used to predict the electric field induced by these coils and to investigate ways to improve their performance.
In normal subjects rTMS stimulation at 1, 10 or 20 Hz was well tolerated with no major side effects. Auditory thresholds measured by audiograms indicated no hearing loss of any of the subjects. No evidence was found for a possible deterioration in cognitive performance due to rTMS. No epileptic convulsions were experienced.
TMS treatment 5 days per week for 4 consecutive weeks was well tolerated by the depressed subjects, with no major side effects or adverse physical outcomes. The average HAM-D scale dropped significantly from 31.3 ± 5.0 prior to TMS to 16.2 ± 9.9 on the day after completion of therapy. There was no significant difference between the coils, however the H1 coil tended to induce greater antidepressant effects. The CANTAB performed before, during and after the study indicated selective improvement in cognitive functions, especially spatial memory and executive function.
Numerical calculations based on 3D models of the H1 and H2 coils placed over the head phantom produced results in good agreement with measured values. Clear improvements in coil performance (stimulus intensity, depth and focality) were predicted only when iron cores were added to the coils.
The safety and effectiveness of the novel H1 and H2 coils were demonstrated. The use of high permeability cores is the best way to improve the performance of these coils.
Roth Y, Amir A, Levkovitz Y, Zangen A, “Three-dimensional distribution of the electric field induced in the brain by transcranial magnetic stimulation using figure-8 and deep H-coils”, J Clin Neurophysiol, 2007, 24:31-
8.; Salvador R, Miranda P C, Roth Y, Zangen A, “High-permeability core coils for Transcranial Magnetic Stimulation of deep brain regions”, 29th Annual International Conference of the IEEE Engineering in Medicine and Biology Society, Lyon, France, August 2007.
|Accessibility: ||Document does not exist in file|
|Miranda, P. C.|
|Secondary author(s): |
|Roth, Y., Correia, L., Salvador, R.|
|Document type: |
|Number of reproductions: |
|Miranda, P. C., Roth, Y., Correia, L., & Salvador, R. (2008). Improvement of transcranial magnetic stimulation (TMS) coils for psychiatric applications. In Aquém e além do cérebro. Behind and beyond the brain. Proceedings of the 7th Symposium of Fundação Bial. Porto: Fundação Bial.|
|Indexed document: ||No|
|Keywords: ||Transcranial magnetic stimulation (TMS) / Stimulation / Deep / Depression / Psychiatry|
Improvement of transcranial magnetic stimulation (TMS) coils for psychiatric applications