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What is tens machine (Transcutaneous electrical nerve stimulation)?
Transcutaneous electrical nerve stimulation(tens machine) is a non-invasive technique of peripheral nerve stimulation.
It involves the use of a low voltage current that passes through the skin (to stimulate peripheral nerves) to relieve pain.
It consists of a sticky pad called electrodes that we attach to the skin where the pain is situated.
It blocks the message or impulse going to the spinal cord or brain which helps in relieving pain sensation.
TENS is best known for relieving chronic pain.
How does TENS Unit work?
When TENS Unit is switched off, electrodes are placed near the area of pain by the certified therapist.
On turning on the unit, it passes the electrical signal through the skin to stimulate the peripheral nerve to relieve pain.
This works mainly on two theories:-
1). Electrical signal blocks the nerve cell that blocks the transmission of pain so that it cannot reach your brain or spinal cord.
2). Electrical nerve stimulation increases the release of endorphins, which are the body’s natural pain-killer chemicals.
Modes of TENS
1). Conventional TENS (high TENS):-
- It is the most commonly used technique
- During Conventional TENS, low-intensity pulsed currents are administered at high frequencies
- Physiological intention – To stimulate large diameter non-noxious afferent (A beta) to produce segmental analgesia, Strong painful paresthesia (prickling sensation) with minimal muscle activity
- Electrodes are placed at the site of pain
- Analgesic profile – usually rapid onset and offset.
- Intensity – 12 – 30 mA
- · Frequency – 10 -200 Hz
- · Commonly used – 80 – 120 Hz
- · Pulse width – 50 – 80 microseconds
- · Duration – 20 -60 minutes
2). Acupuncture-like TENS (low TENS):-
- It is used less often.
- It last more than conventional tens.
- Physiological intention – To stimulate cutaneous and motor afferents to produce extra segmental analgesia, Strong comfortable muscle twitching.
- Electrode placed at the site of pain, motor nerve, acupuncture point, myotomes
- There may be delayed onset and offset
- Intensity – 30mA
- Frequency – 2-5 Hz
- Pulse width – 150 – 300 Hz
- Duration – 30 -40 minutes
3). Brief intense TENS:-
- Physiological intention – To stimulate small diameter cutaneous afferents to produce counter-irritation
- It produces Painful sensation.
- Electrodes are placed at the site of pain, dermatomes, nerve trunk
- Rapid onset and delayed offset
- Intensity – as tolerated
- Frequency – 125 – 250 Hz
- Pulse width – 200 -250 microseconds
- Duration – 5 – 15 minutes
4). Burst TENS:-
- Physiological intention – To produce pain relief through stimulation of endogenous opiates
- Comfortable intermittent prickling sensation
- Electrodes are placed at the site of pain, motor nerve, acupuncture points, dermatomes
- It is Long-lasting
- Intensity – comfortable sensation
- Frequency – 50 -100 Hz, with a burst
- Pulse width – 50 – 200 microseconds
- Duration – 20 – 30 minutes
For what we use TENS therapy
We use this modality for the treatment of pain, some conditions for which we use this modality include:-
- tens machine for low back pain
- tens machine for sciatica
- tens machine for musculoskeletal pain
- tens machine for postoperative pain
- tens machine for chronic pelvic pain
- tens machine for osteoarthritis
- tens machine for fibromyalgia
- tens machine for tendinitis
- tens machine for diabetic neuropathy
- tens machine for orofacial pain
How to use Transcutaneous electrical nerve stimulation (TENS) Unit?
TENS machines are small battery-operated machines and can be used while we are working.
You can put it in your pocket or hold it in your hand hence, a portal device.
First, consult your health professional or a certified therapist before using the TENS Unit.
Make sure that the machine is switched off then place the Electrode or pads on either side of the painful area, at least 2.5cm (1 inch) apart.
Different sites where TENS electrodes can be applied:-
- Painful area
- Peripheral nerve
- Spinal nerve root
- Other specific points ( Acupuncture, trigger, or motor points)
Turning the unit on and adjusting its strength
On turning on the TENS unit, you will feel a slight tingling sensation pass through your skin.
A dial on the machine will help you to control the strength of the electrical impulse.
Start with a low setting and gradually increase the setting until the sensation feels strong and comfortable.
If the sensation starts to feel pain then reduce it slightly.
After you switch off the machine, remove the electrodes from your skin.
Advantages of Transcutaneous electrical nerve stimulation (tens machine)
- User-friendly and safe to be used
- It is cheaper than regular prescription of analgesic
- Precaution and contradiction are few and side-effects are minimal
Disadvantages of Transcutaneous electrical nerve stimulation (tens machine)
- Some patients fail to tolerate this electrical sensation and fails to respond to this program
- Skin irritation due to allergic reaction to the conductive medium or tape
- A chemical burn may result
Where it should not be used? (Contraindication)
- Patients with a pacemaker (implantable device) -Do not use TENS over the area where an electronic device is implanted.
- Patients with allergy – Do not use it if the patient has an allergic reaction to medium or tape
- Epilepsy – Do not apply these electrodes to your head, neck, or shoulder
- Treatment while driving – Do not use it while driving or operating machinery
- Deep vein thrombosis or thrombophlebitis – Do not use the TENS unit as it may increase the blood circulation, which may increase the risk of dislodging a blood clot.
- Pregnancy – Do not use it in this situation