Transcutaneous Electrical Nerve Stimulator (TENS)

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1. TENS – T ranscutaneous E lectrical N erve S timulator

2. INTRODUCTION Pain is man’s oldest enemy and for centuries, medicine has searched for an innocuous, non-destructive, non-invasive, well tolerated and effective way of relieving pain that is both efficient and practical. People feel pain when a signal travels through nerve fibers to the brain for interpretation. It is found that a therapy that uses low-voltage electrical current blocks the pathway of transmission of pain, in order to provide pain relief. These electrical impulses seem to jam pain signals travelling along the nerve pathways before they can reach to the spinal cord and brain . The same electrical impulses also stimulate the body to produce natural pain relievers called endorphins and enkaphalins. The electrical impulses required for electrotherapy to relieve pain are provided by an instrument called TENS.

3. TENS therapy has been used to relieve both chronic (long lasting) and acute (short-term) pain.  TENS units may help treat the symptoms like neck and back pain, joint pain, post-operative pain, myofascial pain, neuropathic pain, labor pain and period pain. Two types of waveforms are optimally and equally effective in relieving pain – square and spike wave. Electrodes are placed at specific sites on the body for treatment of pain. The current travels through the electrodes and into the skin stimulating specific nerve pathways to produce a tingling or massaging sensation that reduces the perception of pain. Surface Paste-less electrodes / Conducting pads TENS

4. TENS DEVICE A TENS machine is a small, battery-operated device that delivers small electrical impulses when the device is switched ON, with the help of electrodes. Typically the stimulator is based around a 500ms spike pulse, having an adjustable amplitude of 0 to 75mA and an adjustable frequency of 12 to 100 pulses per second. Instruments having similar specifications except they produce square waveform, have a pulse frequency range of 20-200Hz, pulse width from 0.1 to 1.0ms and pulse amplitude of 0-120V with maximum output current as 25mA. Instrument is powered by three standard flashlight b atteries of 1.5V each, gives about 100 hours of c ontinuous operation.

5. Transcutaneous or skin surface application of electrical stimulus is accomplished by application of conducting pads to various trigger points, acupuncture sites or even peripheral nerves. Skin irritation at the site of electrode application is diminished by the use of carbonized rubber electrodes applied with a tincture of Benzoin interface. The skin electrode system must be designed so as to minimize impedance variations with motion. TENS electrodes are commonly molded from an elastomer such as silicon rubber, loaded with carbon particles to provide conductance. Comformatibility is achieved by making electrode thin. A thin electrode may exhibit an impedance which is not negligible as compared to impedance of the interface and tissue under it. Thus, the design of an electrode with the required comfortability and current distributing properties become a compromise in electrode geometry and material properties.

6. TYPES OF CURRENT USED Asymmetrical Biphasic Monophasic Symmetrical Biphasic Spike

7. TECHNIQUES OF TENS APPLICATION Conventional or High Frequency TENS : creates fast relief, may stop the pain-spasms cycle, relief is short lived. Acupuncture or Low Frequency TENS : activation of endorphins by suppression of pain pathway, longer lasting pain relief however slower to begin. Frequency usually 1-5Hz and Pulse Width 200-300µs. Brief Intense TENS (hyper stimulation Analgesia) : similar to high frequency TENS, highest frequency is 100Hz and pulse width is 200µs. It’s intensity is very high but to the subject’s tolerable level. Treatment time is 15mins. Burst Mode TENS : similar to low frequency TENS, short series of pulses with high frequency that are repeated at low frequency. Used for general chronic pain relief. Modulated TENS : frequency varies between different settings and uses a cyclical to help reduce nerve adaptation. Useful for acute and chronic pain relief.

8. TENS Electrode Placement

9. Implantable device S uch as defibrillator, bone growth stimulator, etc. TENS could cause these devices to malfunction. Pregnancy TENS therapy should not be applied to the abdomen, pelvic area, lower back or to acupuncture points. Cancer Not to apply electrodes to areas of the body where there is known or suspected cancer. Epilepsy If the patient has/had a history of epilepsy, TENS impulses could cause seizures. Heart disease TENS shouldn't be applied if the patient has/had heart failure or arrhythmias. Deep Vein Thrombosis TENS therapy may increase blood circulation, which may increase the risk of dislodging a blood clot. CONDITIONS WHEN TENS THERAPY SHOULDN’T BE USED

10. PROs Portability N on-Invasive E asy to use at home I mmediate Effect PROs AND CONs CONs O nly treats the symptoms of pain, it will not actually treat what’s causing the pain. D oesn’t provides long term solution, it is probably used for short term. 10

11. Thank You !