Electrotherapy (1) Lecture Notes PDF

Magnetic Therapy  Students’ Learning Objectives  Define magnetic therapy.  Distinguish between static and pulsed magnetic field.  Describe production of magnetic therapy.  Recognize biological effect of magnetic therapy.  Describe indication and contraindication of magnetic therapy.  Appl...

Magnetic Therapy  Students’ Learning Objectives  Define magnetic therapy.  Distinguish between static and pulsed magnetic field.  Describe production of magnetic therapy.  Recognize biological effect of magnetic therapy.  Describe indication and contraindication of magnetic therapy.  Apply magnetic therapy to patient.  Magnetic Therapy Magnets have been used for therapeutic purposes for more than 2,000 years AD. Greek healers in AD 200 used magnetic rings as a treatment for arthritis. Defined as treatment of illness using magnets and magnetism. Safe, noninvasive modality commonly prescribed and administered by physical therapists for its analgesic, anabolic and anti-inflammatory effects.  The electromagnetic nature of our body  The human body is an electromagnetic organism.  Electricity flows through the nerves in our bodies the same way electricity flows through an electrical wire.  All systems from the molecular level to the organ level are more or less in motion.  Thus, in living tissue we mostly find alternating fields as well as combination of electric field and magnetic field. Static magnets versus Pulsed magnetic field Static magnets Static (Permanent) magnetic fields which can be created by various permanent magnets as well as by passing direct current through a coil. Pulsed magnetic field Time varying magnetic field which refer to either alternating current or sinusoidal magnetic field. These are modulated at a slower speed or frequency (1-100 Hz) with various pulses, shape and cycle pattern. The strength of the magnetic field is expressed in tesla (T) or gauss (G). The relationship of tesla to gauss is 1 G = 10-4 T. Physical Principles of Magnets Magnetic Field Produced by permanent magnets Magnets are metals, such as iron, that exhibit an attractive or repulsive force. The number of lines per unit area representing the magnetic field is proportional to the magnitude of the field.  When two north or two south poles are brought close together, the force is repulsive. When two opposite poles (one north and one south pole) are brought close together, the force is attractive. Magnetic Field Produced by a wire Electrical current passing in a wire generates magnetic field in a circular form around the wire. The intensity of the field is directly proportional to the amount of current carried by the wire. If a person grasps a conductor in one's right hand with the thumb pointing in the direction of the current, the fingers will circle the conductor in the direction of the magnetic field.  Magnetic Field Produced by a Coil When a current carrying conductor is formed into a loop or several loops to form a coil, a magnetic field develops that flows through the center of the loop or coil along its longitudinal axis and circles back around the outside of the loop or coil.  Biological Effects of Magnetic Fields The effectiveness of Pulsed magnetic field therapy is not through heat production. Patients with implants other than pacemakers may be treated. Fractures also may be treated with casts since magnetic fields permeate all materials. o At the cellular level o On the Inflammatory Process o In pain relief o On the blood circulation  At the Cellular Level  All living cells within the body have potentials between the inner and outer membrane of the cell which are fixed under the normal healthy circumstances.  Different cells, e.g. muscle cells and nerve cells, have different potentials of about -70 mV.  When cells are damaged, these potentials changes, causing the attraction of positive sodium ions into the cell and negative trace elements and proteins out of the cell. The net result is that liquid is attracted into the interstitial area and swelling or edema occurs. The application of pulsed magnetic fields has been shown to help the body to restore normal potentials at an accelerated rate which help to re-balance the distribution of ions across the cell membrane. o Influence the ATP production. o Increase the supply of oxygen and nutrients. o Improve the removal of waste via the lymphatic system. o Aiding the healing of most wounds and reducing swelling faster.  On the Inflammatory Process Altering the cell membrane potential and realigning the ions into the correct position. Inflammatory edema and hematoma formation were decreased. Affect the white blood cells that are surrounding the injury and fighting the disease, so ↑phagocytosis. Improve circulation, allowing greater volume of blood for natural healing and removal the toxic products.  In Pain Relief  Pain is transmitted as an electric signal, which encounters gaps at intervals along its path.  A charge of about -70mV exists across the inner and outer membranes, but when a pain signal arrives it raises this to +30mV.  This action causes channels to open in the membrane, triggering the release of a chemical transmitter and allowing ions to flow into the synaptic gap.  The cell then re-polarizes to its previous resting level. The application of pulsed magnetic field affects the quiescent potential of the membrane, lowering it to a hyper-polarized level of -90mV. When a pain signal is detected, the voltage must now be raised to a relatively higher level in order to fire the synaptic vesicles. Since the average change of potential required to reach the trigger voltage and cause the synaptic vesicle to release the chemical transmitter is too great, the pain signals is blocked. I.e. Transmission is effectively blocked since the pain signal is unable to raise the potential to the level required to trigger the release of the chemical transmitter Increase blood and lymph circulation reducing inflammation and easing pain. Interferes with pain perception as the magnets stimulate production of endorphin (the body’s natural pain killer).  On the Blood Circulation  The blood contains iron and when magnets are applied, the magnetic field penetrates through the surrounding tissues and blood stream.  The iron is attracted to the magnetic field, this causes movement within the blood stream that causes the blood flow to improve.  When the body’s blood flow is increased oxygen, nutrients and hormones including endorphins are distributed to the organs and tissues much more effectively and quickly.  o Soft tissue healing o Bone disorders o Joint disorders General o Neurological disorders and nerve regeneration uses of o Antimicrobial Effects magnetic o Stress Reduction o Energy Enhancement therapy o Increased Athletic Endurance and Performance  Soft Tissue Healing Increasing collagen synthesis, angiogenesis, and bacteriostasis. Magnetic field enhance wound epithelialization and provides indications of early contraction. It enhances o Ionic transport. o Amino acid uptake. o fibroblast migration. o Adenosine triphosphate (ATP) and protein synthesis. o increases the arteriolar diameters.  Bone Disorders Pulsed magnetic field has been shown to have an effect on the bone repair (non-union fractures, osteotomies and hip arthroplasty) via a number of different mechanisms: o Stimulate calcification: stimulate the metabolism of calcium ion uptake by the cell. o Increased blood supply. o Increased rate of bone formation by osteoblasts.  Joint Disorders Magnetic field has been shown to be effective in treating joint disorders (osteoporosis, osteoarthritis, and rheumatoid arthritis) by improving their symptoms such as pain, swelling, tenderness. Magnetic field promotes healing in damaged musculoskeletal tissues by: o Reducing inflammation o Increasing vascularization o Stimulating synthesis of collagen and glycosaminoglycans o Proliferation of fibroblasts, chondroblasts and osteoblasts.  Neurological Disorders  Magnetic fields have a beneficial effect in aiding the regeneration process and functional recovery in damaged peripheral nerves.  Magnetic insoles reduce the symptoms of pain, burning, numbness, and tingling and increase muscular strength in cases of Foot and Leg Problems associated with diabetic neuropathy.  Antimicrobial Effects Increasing the immune function through the oxygenation of white corpuscles, an important part of the immune system. Augment the body's natural ability to resist a variety of germs like viruses, bacteria, and fungi. Stress Reduction A magnetic field applied to the head calms as well as induces a hypnotic sleeping effect on the brain by stimulating the hormone melatonin. Melatonin is known to be anti-stressful, producing a sedating effect in insomnia.  Energy Enhancement As the cell performs its daily functions, it becomes depolarized. Depolarized cells equal a tired person. It is believed that magnetic energy has the ability to reach every cell. Enhances vitality throughout the body as a whole.  Contra-indications and precautions for magnetotherapy  Do not use magnets near cardiac pacemakers, insulin pumps, or any other internal or external electronic devices because magnets may interfere with the control of these devices.  Do not place magnets over the low back or pelvic region of a woman during pregnancy because the effect on the fetus is unknown.  Avoid placing magnets over or near cancerous tissues to prevent the possibility of facilitating growth or spread of the cancer by magnetic fields.  A protective barrier between the skin and the magnet may help to prevent skin irritation. DUAL MODE