Access to MRI is limited for patients with deep brain stimulation (DBS) implants due to safety hazards, including radiofrequency (RF) heating of tissue surrounding the leads. Computational models provide an exquisite tool to explore the multi-variate problem of RF heating and help better understand the interaction of electromagnetic fields and biological tissues. This paper presents a computational approach to assess RF-induced heating, in terms of specific absorption rate (SAR) in the tissue, around the tip of bilateral DBS leads during MRI at 64MHz/1.5 T and 127 MHz/3T. Patient-specific realistic lead models were constructed from post-operative CT images of nine patients operated for sub-thalamic nucleus DBS. Finite element method was applied to calculate the SAR at the tip of left and right DBS contact electrodes. Both transmit head coils and transmit body coils were analyzed. We found a substantial difference between the SAR and temperature rise at the tip of right and left DBS leads, with the lead contralateral to the implanted pulse generator (IPG) exhibiting up to 7 times higher SAR in simulations, and up to 10 times higher temperature rise during measurements. The orientation of incident electric field with respect to lead trajectories was explored and a metric to predict local SAR amplification was introduced. Modification of the lead trajectory was shown to substantially reduce the heating in phantom experiments using both conductive wires and commercially available DBS leads. Finally, the surgical feasibility of implementing the modified trajectories was demonstrated in a patient operated for bilateral DBS.

The objective of this study was to evaluate the effects of repetitive Transcranial Magnetic Stimulation (rTMS) on motor signs in Parkinson's disease (PD). Medline, Embase, CINAHL, Web of Science, Scopus bibliographic, and Google Scholar databases were searched. Relevant controlled clinical trials published between January 1985 and October 2007 were extracted, reviewed, and validated according to the study protocol. The outcome of interest was the motor section of the Unified Parkinson's Disease Rating Scale (UPDRS). We calculated the effect size for the included studies. Sensitivity analysis was performed to further assess factors that may change the results. Ten randomized, controlled clinical trials were included in the meta-analysis. Pooling of the results from these trials yielded an effect size of -0.58 in UPDRS for high-frequency rTMS studies and no significant effects for low-frequency rTMS studies. The benefit of high-frequency rTMS on motor signs in PD was confirmed by the meta-analysis. Lower frequency rTMS had little effect on motor signs in PD.

This meta-analysis fails to demonstrate the efficacy of probiotics in maintaining remission and preventing clinical and endoscopic recurrence in CD. It is suggested to use probiotic preparations containing a mixture of lactobacillus with E. coli or Saccharomyces.