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peripheral neuropathy, peripheral vessel disease, wound and ulcer healing, obstructive
sleep apnea, tinnitus, and a variety of chronic pain syndromes. A multivariate analysis
did not reveal significant results (p > 0.2). In general, studies suffered from poor description. The parameters most often insufficiently described were related to magnetic exposure (magnet dimension and strength and distance to target tissue). Overall, the current
evidence is considered to be lacking or of low quality that a static magnetic field could
reduce pain or disability (Kroeling et al. 2009; Colbert et al. 2009).
6.2.3.3.1 Interference
Neodymium-iron-boron (NdFeB) magnets are small in size but produce strong magnetic
fields, which may interfere with the function of cardiac pacemakers and implantable cardioverter-defibrillators (ICDs). The maximum distance resulting in device interference
was 3 cm. No significant differences were found with respect to device manufacturer
and device types (Wolber et al. 2007).
6.2.3 Magnetic Targeting
Ferromagnetic or superdiamagnetic (nano)particles are introduced into the patient for
targeting tumors or for local delivery of drugs or heat. SPIONs have diverse diagnostic
and potential therapeutic applications in the CNS. Their application may improve disease detection, therapeutic monitoring, and treatment efficacy especially in the context of
antiangiogenic chemotherapy and anti-inflammatory medications (Weinstein et al. 2010).
Because they are incorporated into the body and are in close contact with tissues, at
their surface, magnetic particles generate local static magnetic fields, which expose the
target region and their pathway out of the body.
Magnetic vehicles, namely magnetic capsules and nanoparticles, are attractive for
delivery of therapeutic agents. They can be targeted to specific locations in the body
through the application of a magnetic field gradient and locally deliver therapeutic
agents. The magnetic localization of a therapeutic agent results in the concentration of
the therapy at the target site, consequently reducing or eliminating the systemic drug
side effects (Polyak and Friedman 2009).
To support drug delivery, SPIONs are coated by organic substances (e.g., phospholipids, fatty acids, polysaccharides, and polymers). The largest class of particles (0.3–
3.5 μm) is applied orally, the most common sizes (60–150 nm) and ultra-small SPIONs
(USPIO) of about 10–40 nm are injected.
However, their therapeutic use in treating CNS pathologies in vivo is limited by their
inability to traverse biological barriers that may cause insufficient local accumulation
and retention. This could be overcome by the combined use of focused ultrasound
and magnetic targeting, which synergistically delivers therapeutic doses of magnetic
nanoparticles across the blood–brain barrier (BBB) (Liu et al. 2010).
Hollow capsules are loaded with active substances (e.g., a dye) and coated with magnetite (Fe 3 O 4 ) nanoparticles. Magnetic fields (295 kHz, 3.9 mT) may be successfully
utilized also for triggering drug delivery by using magnetic nanoparticles for drug transport and releasing substances on demand. This is enabled by selective electromagnetic