Interferential Therapy

What is IF?

  • Used since 1950s
  • Deep form of electrical stimulation
  • More comfortable than TENS as skin less impendance
  • Can use either 2 or 4 poles
    • 2 pole= interference in machine
    • 4 poles= interference in the tissues
  • evidence- no difference in treatment effects

Treatment effects IF

Primary

Secondary

  • Pain relief similar to TENS
  • Muscle stimulation- can be used for muscle weakness+exercise

⬇ evidence

  • Increased blood flow
  • Reduced odema

How do you do IF?

  • 4 Pads cross the affected area
  • Current passes from one pad to the other
  • Electrical currents cross and interfere with each other, hence interferential
  • Patient will feel tingling in the area
  • May increase to a weak muscle contraction

Sweep

  • Nerves will accommodate to a constant signal , and a sweep is used to overcome this
  • Limited evidence to justify one form of sweep over another
    • Triangular sweep pattern
    • Rectangular sweep pattern
    • Trapezoidal sweep pattern

IF Basics

  • Skin usually washed to remove excess oils and to moisten it
  • Pads should be thoroughly wet for even transmission
  • If just using 2 electrodes, use the yellow circut
  • Electrodes attached by bandages/straps
  • When turned on patient should experience tingling sensation on and around the site
  • Give the patient a warning notice that they will have a tingling sensation that should not feel like a burn
  • Increase intensity- may need to slightly adjust due to accommodation

Contraindications & Precautions

Contraindications

  • Pregnancy in foetal region (trunk and pelvis)
  • Specialised tissue (eyes & testes)
  • Active implants (pacemaker)
  • Epilepsy (neck)
  • Bleeding tissue
  • Over chest area
    Local contraindications
  • Malignancy
  • Active epiphysis
  • Broken skin
    Precautions
  • Local circulation insuffiency
  • Devitilised tissue (following radiotherapy)
  • Eczema/ dermatitis
  • TB
    _ Patient level of understanding
  • Sensory loss
  • Pulmonary embolism/ Deep vein thrombosis or anti coagulant history (vacuum electrodes only)

Suggested Treatment Regime

Pain

  • Via pain gate (Acute & Chronic) 90-130Hz (15mins)
  • Via opioid effect (chronic pain only) 4Hz constant (15mins)
    Circulation
  • 0-100Hz (20-30 mins)
    Muscle stimulation
  • 10-50Hz (15mins)

Practical application of IF


  • Justify use of IF
  • Check for contraindications or precautions
  • Plan area / environment/ position of therapist and patient
  • expose area to be treated
  • sharp blunt sensation check
  • set up machine ( watch for cables trailing hazards)
  • Clean skin and dampen sponges
  • Apply transducer pads to surface
  • Set dosage
  • Electrode position, sweep, delivery of sweep, treatment time
    • check for skin irritation

Pain gate

Descending inhibition endogenous opioiods

  • In the CNS there are 3 opioid receptors which regulate the neurotransmission of pain signals.
  • They are G protein-coupled receptors Their activation leads to a reduction in neurotransmitter release and cell hyperpolarisation, reducing cell excitability.
  • Our body contains endogenous opioids which can modulate pain physiologically
  • 3 types of endogenous opioids
    B-endorphins- binds to mu opioid receptors
    Dynorphins- binds to kappa opioid receptors
    Enkephalins- bind to delta opioid receptors
  • opioids reduce pain transmission at the dorsal horn by inhibiting excitatory neurotransmitter release
  • Melzack and wall (1965)
  • non-painful input closes the nerve gate to painful input and prevents pain sensation from reaching the CNS.
  • This is done by the stimulation of large, myelinated fibres such as a-alpha and a-beta.
  • Due to the myelin they are faster than a-delta and c nerve nociceptors that cause pain.
  • The impulses reach the dorsal horn before the noxious (painful) stimuli the inhibitory neurone is stimulated and acts as a gate and blocks the pain signal from the projector neurone from reaching the brain