Transcutaneous electric nerve stimulation uses the low voltage electric current to relieve the pain. It is the battery powered device that produces the current through electrodes placed on the skin. The electrodes are placed on the trigger points where there is pain. TENS is the method of pain relief. It is not the permanent method to cure the pain, but for the short term relief TENS is used. TENS is a safe method. It reduces the ability to transmit the pain signals to brain and spinal cord.
TYPES OF TENS
There are three types:-
CONVENTIONAL TENS ( high)
It is used to activate large diameter fibres afferent to elicit extra segmental analgesia. It produces the high frequency, low intensity current to produce strong effect but it is comfortable. The stimulation of this TENS is 30 minutes.
ACUPUNCTURE TENS ( low)
It is used for small diameter nerve fibres afferent to elicit segmental analgesia. It produces the low frequency, high intensity current. The duration is about 20 minutes.
BRIEF INTENSE TENS
It is used to activate small diameter nerve fibres afferent to elicit extra segmental analgesia. It is a high frequency, high intensity TENS that produces maximum paraesthesia. The duration is no more than five minutes.
Large main units are available, but small unit is mainly used with batteries. Conductive rubber electrodes covered with a conductive gel to gain good contact is placed on the patient skin. The electrodes can be bandaged onto patient skin or place with adhesive tape. The electrodes can be placed over
(a) Acupuncture points, motor points, trigger points.
(b) The area of greatest intensity of pain
(c) The appropriate dermatome
(d) The appropriate peripheral nerve
Whichever position is selected for electrodes, it is required to check if the skin under the electrodes has intact sensory mechanism.
The intensity of Modality can be adjusted by the dial according to the site and severity of pain.
It is the number of electric pulses per second. High frequency pulses range from 80-120 cycles per minute. These pulses are used for acute pain. For chronic pain, low frequency pulses are used which range from 1-20 cycles per minute.
The number of treatment strategies are adopted:
1.The patient may have a single day treatment session of upto 40 min duration.
2. The patient may connected to portable unit all the time and:
(a) the treatment unit switched ON when required
(b) The unit left ON most of the time.
USES OF TENS
TENS is a useful method in relieving pain. Some uses are described below:
It is used to relieve pain both chronic and acute. It is used without prescription. TENS modulate and supress pain signals in brain. It is used to treat
1. Labour pain
2. Postoperative pain
3. Period pain
4. Joint pain
5. Back pain
It may also decrease pain that result from following conditions:
2. Diabetic neuropathy
5. Endometriosis( painful disorder of uterus)
6. Spinal cord injury
A continuous application of TENS with high frequency and long duration pulses could produce electrolyte reactions. It is contraindicated over:
1.It should be used over the eyes due to increased intra ocular pressure.
2.It should not be used on the front of neck due to risk of acute hypotension ( due to vasovagal response).
3.It should not be placed on the broken skin or wound, however may be placed around the wound.
4.Over tumors should not be placed as this may increase cancerous cell growth.
5.Pregnant women should avoid the use of TENS over abdominal areas and lower back.
6.May induce seizures in epileptic patients.
7.TENS should not be used on people with Cardiac pacemaker. This may cause interference and also the failure of that device.