Interferential currents
• Medium frequency alternating currents with frequency of
3000 – 6000Hz.
• They stimulate sensory and motor nerves and meet with little
skin resistance (4000 Hz = 40 Ω per 100cm2).
• Low frequency currents have high skin resistance
(50 Hz = 3200 Ω per 100cm2) and allow only small proportion
of current to pass through the skin.
• Negligible skin resistance is offered to high frequency currents
and heat is produced in the tissues.
Interferential therapy
• Pass two medium frequency alternating
currents which are slightly out of phase in to
the tissues and make a low frequency
current.
• At the point where the two currents
intersect, intensity of the combined current
will increase and decrease rhythmically and
it is called amplitude modulation.
Interferential therapy
• Physiological effects
– Relief of pain
– Motor stimulation
– Absorption of exudate
Interferential therapy
• Indications
– Pain
– Muscle spasm
– Oedema
– Haematoma
– Chronic ligament lesions
– Trigger spots in myofascial syndromes
– Stress incontinence
Interferential therapy
• Contraindications
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Arterial disease
DVT
Infective conditions
Pregnant uterus
Danger of haemorrhage
Malignant tumours
Pace makers
During menstruation over abdomen
Open wounds
Unreliable patients
Dermatological conditions
Interferential therapy
• Dosage
– Intensity
– Beat frequency
– Carrying frequency
– Treatment time
– Treatment schedule
Types of electrodes
• Metal plate electrodes and pads
• Quadripolar electrodes and pads
Types of electrodes
• Suction cup electrodes
• Quadripolar suction cup
electrode
Interferential therapy
Types of application
– Pain point or trigger point application: as a
bipolar technique, anode over the pain point &
cathode adjacent to it.
– Nerve trunk application: two electrodes are
placed along the course of the appropriate peripheral
nerve where the nerve is superficial.
Types of application
– Paravertebral application: place the electrodes on
both sides of the spine at the level of the nerve root
supplying the painful area. If several nerve roots are
involved , the electrodes may be applied alongside the
spine at the highest and lowest nerve root levels.
– Muscular application: two electrodes are placed on
the either end of the muscle belly.
– Transregional application: to treat a joint, electrodes
are placed either side of the joint.
Interferential therapy
• Dangers
– Burns
– Shocks
– Haematoma
Advantages
– Large doses of current can be passed to the body
without chemical burns.
– Decreased skin sensation is not a contraindication.
– Current can be localized more effectively in a
specific region.
– Metal is not a contraindication.
– It can not be given directly to cancer areas but the
radiating pains can be treated.
– It can combine with treatment like ultra sound.