Emerging medical applications based on non-ionizing electromagnetic fields from 0 Hz to 10 THz

Figures & data

Table 1 Terminology and frequency ranges of the parts of the non-ionizing EMF spectrum that is covered in this review

Classification	Sub-class/division	Abbreviation	Frequency
Static fields	Static electric fields Static magnetic fields	SEF SMF	0 Hz
Low frequencies	Extremely low frequency electric or magnetic fields	ELF EF ELF MF	1–<300 Hz
	Intermediate frequency electromagnetic fields	IF EMF	300 Hz–<100 kHz
High frequencies	Radiofrequency electromagnetic fields (“radiowaves”)	RF EMF	100 kHz–<300 MHz
	Microwaves	MW	300 MHz–<30 GHz
	Millimeter waves	MMW	30 GHz–<300 GHz
	Terahertz waves	THz	300 GHz–10/30 THz

Table 2 EMF tumor treatment methods used in clinical oncology or at the research stage

Technology /modality	Physical characteristics	Action mechanism	Condition for treatment	Clinical studies^a
Hyperthermia/ radiofrequency ablation (RFA)	Invasive treatment during surgical procedure using a needle or a RF-EMF probe.	Tumor necrosis via thermal ablation	Mainly used for the treatment of liver metastases.	+
Nanoparticles assisted radio frequency ablation (NP-RFA)	Non-invasive loading of tumors with nanoparticles, which are externally exposed to RF-EMF. The generated heat inducing an inside-out hyperthermia.	Tumor necrosis via thermal ablation by improved efficacy of thermal damage.	NP-RFA in combination with radiotherapy for treatment of recurring glioblastoma and recurring breast cancer.	−
Tumor treating fields (TTFields)	Invasive application of electrodes to the skin, 200 kHz electric fields, for 18 hrs daily.	Mitotic spindle disruption, anti-proliferative effect of cancer cells. Molecular mechanism is unknown.	Treatment of glioblastoma following tumor resection and radiation therapy.	−
Tumor specific frequency modulated RF-frequency	Non-invasive treatment by a spoon-shaped antenna in the mouth; 27.12 MHz carrier frequency modulated with cancer specific frequencies of 1873.5 Hz, 2221.3 Hz, 6350.3 Hz, and 10,456.4 Hz; SAR <2 W/kg; whole body exposure for 3 hrs/day.	Mitotic spindle disruption, anti-proliferative effect of cancer cells. Molecular mechanism is unknown.	Treatment of advanced hepatocarcinoma and its metastases.	−
Electroporation (EP)	Electric fields; 300–400 mV for <1 ms in vitro; train of eight EPs of 100 μs; invasive 1000 V/cm; non-invasive 1300 V/cm.	Induction of tumor/cell death by the formation of aqueous pores in the lipid bilayer.	Treatment of solid tumors.	+

Note: ^aPresence (+) or absence (-) of randomized clinical trials.

Table 3 Overview of emerging EMF-based technologies for treatment of pathological conditions associated with the nervous system

Technology/modality	Physical characteristics	Action mechanism	Condition for treatment	Clinical studies^a
Vagal nerve stimulation (VNS)	Invasive (implanted neurostimulator) or non-invasive (external stimulator) delivery of electric pulses to left afferent nervus vagus. Pulse frequencies 20–30 Hz, durations <500 µs, 0.25–3.0 mA, given as on-off cycles (e.g., 30–90 s on, 5 mins off).	Incomplete knowledge about how VNS modulate the CNS. Additionally, it has been suggested that VNS activates the cholinergic anti-inflammatory pathway, which could affect both CNS and peripheral organs.	FDA approved for treatment of refractory epilepsy and major depression disorder. Also used for treatment of chronic pain, migraine. Some studies of treatment of other conditions.	+
Repetitive transcranial magnetic stimulation (rTMS)	Static or time-varying MF delivered by external coils to selected regions of the brain. Low (≤1 Hz) of high –frequency (>5 Hz) pulses, at B-field strength strong enough to cause E-fields capable of neuronal firing. Treatment provided during single or multiple sessions (each lasting tens of minutes).	Low frequencies cause decrease in neuronal excitability, high frequencies increase cortical excitability. Long-term effects on neurotransmitter actions and synaptic plasticity.	Treatment of resistant depression (FDA approved). A number of other conditions have been treated in occasional studies.	+
Deep brain stimulation (DBS)	Electrical currents delivered by electrodes in various nuclei of the brain. Up to hundreds of Hz, 10s-100s µs long pulses; weak currents (mA).	Unclear.	FDA approved for treatment of essential tremor, Parkinson's disease, and obsessive compulsive disorder. Tested also for epilepsy, depression and a number of other psychiatric disorders.	+
Transcranial pulsed electromagnetic field (tPEMF)	Externally located coils (e.g., helmet contained) deliver MF (50 Hz, mT levels, square wave pulses, similar to bone healing PEMF) to skull, inducing E-fields in brain tissue (0.1–4.0 mV/cm).	Induced E-fields far below neuronal firing level. Suggested mechanisms include activation of receptor tyrosine kinase signal transduction pathway, and graded depolarization of membrane potentials.	Therapy resistant depression.	+
Low frequency magnetic field (LF MF)	Sine wave MF delivered either continuously or as pulses. f≤300 Hz, typically 50 Hz. Flux densities (sub) mT levels for different periods of time.	Unclear mechanism, although both effects on neural transmission and on neurotrophic action has been proposed.	Nerve regeneration in spinal cord injuries	−

Note: ^aPresence (+) or absence (-) of randomized clinical studies.