Electrotherapy and Magnetotherapy


Electrotherapy: takes advantage of the polarising, stimualting and thermal effects of electric current.

Polar effects result when applying DC. If AC is applied then this may result in either the stimulation of tissues or heating.

Application of DC – Galvanotherapy:

A) Iontophoresis serves for therapeutic introduction of medicaments having an electrical charge by means of the polar effect of DC. The application is done using two flat electrodes. The active electrode is situated over the place of the body where the medicament should be introduced. The indifferent electrode is situated on the opposite side of the body. This electrode is connected with the pole inverse to the change of the medicament. The conductive coupling is ensured by an indifferent electrolyte. The medicament, held in a slice of sponge underneath the active electrode, is transported into the skin when the active electrode is connected to the DC source.
The current density varies between 1A/m² to 5A/m². The time of application is between 20min to 30min.

Iontophoresis from anode: K, Li, Ca, Mg, Cu, Zn, procaine, acetylcholine, and neomycin.
Iontophoresis from cathode: Cl, Br, I, acetate anion, salicylate anion, vit. C, penicilin.

B) During Galvanisation DC passes through tissues. The mechanism of action is not yet know, however, it is known to:

  • increase local metabolism
  • accelerate diffusion
  • increase perfusion,
  • accelerate reabsorption of inflammations
  • alleviate pain.

Galvanisation is mostly used if a patient has inflammations or degeneration of the locomotory system, the nervous system, or the circulatory system.

Application of AC and Electric Impulses – Electrostimulation:

Stimulating impulses caused by AC can be classified into two groups:

  1. Rapid current increase impulses – They are used to stimulate muscles, produce electroanaesthesia and electrosleep. It is also used to treat rhythm injuries.
  2. Slow current increase and decrease – They are used to stimulate non-innervated skeletal muscles, smooth muscles and vegetative nerves.

Relevant paper regarding electrosleep: I-Electrosleep Therapy – A double-blind trial

Examples of electrostimulation:

A) Defibrillator – It often happens that patients suffering from heart attack enter ventricular fibrillation (desynchronised heart rhythm). A defibrillator applies a single electrical impulse of high strength by means of two electrodes, placed over the heart region. This current causes all the heart muscle fibres to contract at the same time. This resets the heart (SAN and AVN), and if successful the heart returns to the normal rhythm.defimax2000B) Pacemaker – It is a pulse generator, with a stable(70 bpm)or variable frequency, introduced in the wall of the right ventricle – next to the SAN. This regulates the heartbeat in patients with heart rhythm problems.
184_pacemaker-dwg

C) Electrostimulated Breathing – is artificially stimulated breathing electrostimulation of the phrenic nerve which contracts the diaphragm.
f2010-1520phrenic20nerve20stimulator

D) Electroconvulsive Therapy – AC (I=0.5A to 1.0A) is conducted between the temples of the patient. The current produces generalised convulsions and unconsciousness.
It is a therapy often used in psychiatry for patients with emotional disorders. 68884574_3shock

E) Diadynamic Currents – Is a type of electrostimulation that combines galvanic and pulse components. They are used in therapy for their hyperaemic(increasing blood flow), analgesic, and antioedematous effects.

F) Interference currents – AC(f=1Hz to 100Hz) obtain during interference of electric currents from two different circuits with different frequencies(For instance, =2500Hz and =2550Hz, where f¹-f² =50Hz) can be used to achieve the desired electrotherapeutic effects at different regions in the body. The advantage of interference currents is that they overcome the skin resistance easily due to the high frequency.

With increasing AC frequency, the stimulation effect diminishes while the heating effect increases.

Magnetotherapy: is based on magnetoelectric effects

Recommended reading: https://burningscience.wordpress.com/biophysics/5-1-basic-concepts-and-principles-of-electricity/

Magnetoelectric effects: 

Low voltage currents can be induced by magnetic fields (either by Lorentz’s forces, or Faraday Currents) inside tissues. These can influence membrane receptors and in thwis way trigger different biochemical reactions.

Electromagnetic Induction

Magnetomechanic effects:

In a strong magnetic field, a reorientation of diamagnetic and paramagnetic molecules takes place with the aim of minimising their free energy inside the field.
In variable, strong, fields translation and rotatory movements begin to occur, but in living systems these effects are negligible.

The variable magnetic field is more effective, therefore almost all commercially available magnetotherapeutic sources generate alternating(f=50Hz) or pulsed fields(f=2 to 50Hz).

The main acting mechanism of magnetic fields on living organism seems to be the induction of electric currents. These influence membrane systems of cells, by acting on membrane receptors and ionic channels. As a result, membrane permeability and metabolic activity of the cells may be increased.

These primary effects may trigger complex changes in tissues:

  • vasodilatation
  • relaxation of muscle spasms
  • analgesia
  • anti-inflammatory effects
  • anti-oedematous effects

Magnetic induction for therapeutic purposes is low and varies between 4mT to 80mT. The frequency of alternating fields corresponds to the normal frequency of AC (50Hz). Exposure time depends on the area to be treated and ranges from 15min to 45min. The number of applications in series is 10-30.

Magnetotherapy is mainly used in the treatment of chronic diseases of joints, muscles and nerves.

Notes Compiled by Andrei Cociug.