Hey guys.... welcome back to my another blog. In the previous blog I talked about 'Bones & Joints'....
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Hi this is "PhysioZon" , here I give you guys various information about physiotherapy..
Today's topic based on electrotherapy which is "TENS or Transcutaneous Electrical Nerve Stimulation"...
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# What is Electrotherapy?
: Electrotherapy is the use of electrical energy as a medical treatment.
Electrotherapy is primarily used in physical therapy for-
• relaxation of muscle spasms.
• prevention and retardation of disuse atrophy.
• increase of local blood circulation.
• muscle rehabilitation and re-education.
• electrical muscle stimulation.
• maintaining and increasing range of motion.
• management of chronic and intractable pain including diabetic neuropathy[2].
• acute post-traumatic and post-surgical pain.
• post surgical stimulation of muscles to prevent venous thrombosis.
• wound healing , etc.
Various types of electrical equipments are present in physiotherapy for treatment, like - UST, IFT, TENS, UVR, SWD, IRR, LASER, etc.
Today's topic is TENS. I will explain other topics in future blogs...stay tuned...
# What is TENS?
: TENS or Transcutaneous Electrical Nerve Stimulation is the application of a pulsed rectangular wave current via surface electrodes on the patient's skin.
•Pulse shape = usually rectangular,
•Pulse width = it is often fixed at 100μs or 200μs. It also can vary from 50μs-300μs.
•Frequency = it is 2Hz-600Hz. Commonly used 150Hz.
•Intensity = it can be varied from 0mA-60mA.
# Types of TENS?
: There are 4 types of TENS. They are -
1) High TENS -
•Pulse shape = bipolar asymmetric.
•Pulse width = 50μs-100μs.
•Frequency = 50Hz-100Hz.
•Duration = 20-60 minutes for one sitting.
2) Low TENS -
•Pulse shape = monophasic.
•Pulse width = 150μs-300μs.
•Frequency = 1Hz-5Hz.
•Duration = 20-30 minutes per sitting.
3) Brief intense TENS -
•Pulse shape = monophasic.
•Pulse width = 50μs-250μs.
•Frequency = 80Hz-150Hz.
•Duration = 15 minutes per sitting.
4) Burst TENS -
•Pulse shape = asymmetric biphasic.
•Pulse width = 50μs-200μs.
•Frequency = 50Hz-100Hz.
•Duration = 20-30 minutes per sitting.
# How does it work?
A) TENS apparatus = i) Large mains units are available to produce the current, but often small units made to be placed in the patient's pocket and utilising batteries are preferred.
ii) Current is often generated by battery operated machines in which circuits modify the battery's output in such a way that it will have a stimulatory effect.
iii) Many different types of TENS apparatus are manufactured and consequently some knowledge of the parameters within which a particular unit operates is required by the therapist.
iv) Conductive rubber electrodes covered with a conductive gel in order to gain good skin contact are placed on the patient's skin.
v) The electrodes can be bandaged onto the patient or fixed with adhesive tape. The wires connecting the electrodes to the unit can be strategically concealed by clothing.
B) Positioning of electrodes =
i) Electrode positioning is an area of considerable debate and a number of approaches may be used.
ii) Make sure the machine is switched off before attaching the pads to skin. Position of the pads side of the painful area, at least 2.5 cm apart.
iii) Pads can be placed over acupuncture points,motor points or trigger points. It can be placed over the appropriate dermatome or spinal segment.
iv) Also can be placed over the appropriate peripheral nerve. This also determined by the taget muscle or muscle group either single or in relation to other muscles.
C) Electrode placement pattern =
i) Unilateral placement - it allow the stimulation of one limb or half of a muscle pair.
ii) Bilateral placement - it allow the stimulation of both limbs or both halves of a muscle pair.
iii) Unipolar - only one of two essential leads and the electrode connected to it are placed over the target area affected by the stimulation,this electrode is treatment electrode.
iv) Qadri-polar - involve the use of two sets of electrodes each originating from its own channel. It may be considered the concurrent application of two bipolar circuit. This technique could be used with stimulation of agonist and antagonist.
v) Also could be used in crossed pattern for large flat area as back.
D) Methods of applying TENS =
Once the electrodes have been placed, the TENS can be applied and one of two methods used. They are,
i) High TENS : When TENS is applied in this way, the stimulation will cause impulses to be carried along large diameter afferent nerves, and this can produce presynaptic inhibition of transmission of nociceptive Aδ and C fibers at the substantia gelatinosa of the pain gait. There is also the possibility that as the frequency of stimulation is sufficiently high a physiological block of transmission could be caused in the nociceptive fibers. Thus the patient is aware of the strong tingling sensation but nociceptive traffic is reduced.
This high intensity will produce a tetanic muscle contraction.
ii) Low TENS : When TENS is applied in this way, the nociceptive stimulus is carried towards the cerebrum, its passage through the mid brain will cause the PAG (periaqueductal area of grey matter) and raphe nucleus to interact to cause the release of opiate like substances at cord level. The enkephalins and β-endorphins released have the effect of blocking forward transmission in the pain circuits. This mechanism operates when pain relief is attained with acupuncture.
Low TENS gives a sharp almost nociceptive stimulus and possibly a muscle twitch.
# Indications of TENS :
1) Frozen shoulder, movement restrictions.
2) Post operative pain.
3) Menstruation pain.
4)Low back pain, headache.
5) Arthritis, neuralgia.
6) Sports injuries. etc.
# Contraindications of TENS :
1) Over head,neck,eyes,etc.
2) Patient with pacemaker.
3) Patient with cardiac conditions (the chest wall).
4) Patient who has allergic response.
5) Patient with open scars.
6) Patients who are unable to co-operate with therapist.
7) Patient with metal implant.
8) Over pelvis, abdomen,trunk during pregnancy. etc.
References= Clayton's Electrotherapy, Textbook of Electrotherapy by Jagmohan Singh.
Hope these information will help you a lot...
Other topics will be in future blogs...
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