Transcutaneous Electrical Nerve Stimulator (TENS)

Transcutaneous electrical nerve stimulation (TENS) is a nonpharmacologic and noninvasive treatment for pain from a variety of painful conditions. A small, portable, battery-powered device that has leads connected to electrodes. Electrodes (sticky patches) are placed on your skin using self-adhesive pads. 
The TENS unit sends painless electrical impulses through the electrodes to the nerves under your skin, which you feel as a tingling sensation. The electrical impulses can block or reduce the pain signals going to the spinal cord and brain, which can help reduce or relieve pain or muscle spasm. TENS devices also help stimulate your body to produce higher levels of its own natural painkillers, called "Endorphins".

For most people, TENS is a safe treatment with little or no associated side effects. It is available for home use. You should always follow the manufacturer's specific instructions to be safe. Have your physical therapist or doctor to show you the proper way to use the machine, and follow the instructions carefully.

Types of TENS:

1. Conventional(High frequency stimulation) - This high rate and most common mode of TENS can be applied during the acute or chronic phase pain. Onset of pain relief is relatively fast but lasts only for a shorter period of time. Tolerable to most patient. Duration of treatment is 20-60 minutes.

2. Acupuncture-like(Low-frequency stimulation) - A strong low rate TENS can be applied during the chronic phase of pain. Duration of treatment is 30-40 minutes and duration of pain relief is long-lasting(an hour or more). More uncomfortable and less tolerable type.

3. Burst Intense(Pulse burst) - A combined characteristic of both high and low rate TENS but more tolerable than low rate TENS. Onset of pain relief is similar to low rate TENS. Duration of treatment is 20-30 minutes. Duration of pain relief is long-lasting(hours).

4. Brief Intense(High-intensity) - This mode provide rapid onset, short-term pain relief during painful procedures(wound debridement, deep friction massage, joint mobilization or passive stretching). Duration of treatment is usually 15 minutes.         

Electrode Placement:

• Over the painful area
• Over the nerve supplying the painful area
• Acupuncture sites
• Proximal or distal to pain site, or even on the opposite side of the body
• Segmentally related myotomes
• Trigger points

Indications:

• Postoperative pain
• Chronic pain
• Arthritis
• Sports injuries -  bone fractures
• Period pain
• Acute pain relief during labor and delivery
• Phantom pain

Contraindications:

• Cardiac pacemaker or another type of implanted electrical device fitted
• Epilepsy or a heart rhythm disorder(consult your doctor)
• During first trimester of pregnancy
• Allergic reaction to the electrodes (it's possible to get hypoallergenic electrodes)
• Broken skin, varicose veins, recent scarring in the area, or over areas of reduced sensation
• While driving or operating machinery
• Near water, such as in the bath or shower
• Over lower abdominal/uterus during pregnancy
• Over the anterior transcervical area - the front or side of your neck
• Cause of pain is not known or is not diagnosed.
• In the mouth, close to the eyes, or temple area

Procedure:

• Check the area to be treated for contraindications and precautions.
• Check the unit - batteries, knobs, electrodes.
• Turn the control knobs to the off position before you start.
• Use rubbing alcohol to clean the skin where the electrodes will be placed. Let your skin dry.
• Position the self-adhesive pads either side of the painful area, at least 2-3 cm apart.
• Switch on the machine slowly and turn it up gradually until you feel a tingling sensation.
• TENS machines are designed so that you can move around with them working.
• At the end of the session turn the machine off and disconnect the electrodes from the machine.
• Check the area being treated for irritations; clean the area with soap and water.
• Clean the rubber electrodes with soap and water to remove the gel; Do not wash the self-adhesive type of pad.
• Remove the battery from the TENS and replace it with a charged battery. Charge the battery so that it will be ready for another treatment.
• You can use TENS throughout the day for as long as you like provided you do the same process as mentioned above

Therapeutic Ultrasound

English: http://rheumatoidarthritis-symptoms.com - Rheumatoid Arthritis in the hands (Photo credit: Wikipedia)

Ultrasound in the medical community is used according to different purpose. It can be a diagnostic tool by imaging internal structures; the tumoricidal effects will help cancer patients in the destruction of tissue or as a valuable therapeutic agent in physical therapy. Ultrasound is one of the common deep heating therapeutic modality used by physical therapists today. Ultrasound consists of inaudible high‐frequency mechanical vibrations that produce thermal and nonthermal effects. The vibrations are created when an electrical energy is converted to acoustic energy through mechanical deformation of the piezoelectric crystal within the transducer/probe. The sound waves that pass through the skin causes a local deep heating and usually no sensation of heat will be felt by the patient. 




Therapeutic Effects

• Scar tissue breakdown by gentle massage of muscles, tendons and/ or ligaments in the treated area 
• Decrease joint stiffness
• Pain relief from the reduction of swelling and edema
• Increase local blood flow reduces local swelling and chronic inflammation
• Decrease muscle spasm

Nonthermal Effects

• Stimulation of tissue regeneration
• Increase macrophage responsiveness
• Pain relief from tissue relaxation
• Speed up soft tissue repair from increased blood flow
• Increase blood flow according to some studies promotes fracture healing
• Increase skin and cell membrane permeability enhance the cell repair effects of the inflammatory response, especially in soft tissue injuries

Indications                                                                                                                                         

• Ligament Sprains
• Muscle Strains
• Tendonitis
• Joint Inflammation
• Plantar fasciitis
• Metatarsalgia
• Facet Irritation
• Impingement syndrome
• Bursitis
• Rheumatoid arthritis
• Osteoarthritis
• Scar tissue adhesion
• Bone fracture
• Contracture
• Trigger point
• Dermal ulcer
• Plantar wart
• Pain

          

Contraindications

• Vascular abnormalities - thrombophlebitis
• Impaired pain or temperature sensory deficits
• Directly on the abdomen of pregnant women
• Directly over active epiphyseal regions (growth plates) in children
• Metal implants below the area being treated
• Local acute infection 
• Over the eyes, skull, testes, or cervical ganglia
• Over local malignancy
• Over the spine after laminectomy
• Over cemented prosthetic joint

Treatment Parameters

The treatment will be based on the diagnosis and the desired effects. Define the duration, frequency, duty cycle and intensity of treatment. 

Therapeutic ultrasound is in the frequency range of about 75 and 3 MHz. A frequency setting of 1 MHz is used for heating deeper tissues (up to 5 cm). A setting of 3MHz produces a higher temperature with a depth of penetration of less than 2 cm. 

The ultrasound can be administered using a pulsed or a continuous transmission mode. The pulsed mode is used in situations where a heating effect is not desirable, such as a fresh injury with acute inflammation because it minimizes the thermal effects (nonthermal effect). A continuous mode is effective in elevating the tissue temperature to produce the thermal effects on the tissues (due to the absorption of the sound waves). Nonthermal effects are from cavitations, micro-streaming, and acoustic streaming.

Ultrasound is applied using a transducer in three different techniques. One is in direct contact with the skin, the other way is to slightly hold one half-inch above a body part for water immersion technique, and lastly the indirect contact using a fluid-filled bag (bladder technique). The direct contact technique can be either the stationary or moving techniques. In the moving technique, the transducer should continuously move in a small circular manner or in a longitudinal stroke over the treated area. Each motion should cover half of the previous circle or stroke. The water immersion technique is recommended if the area to be treated is smaller than the diameter of the available transducers or if the body area is irregular with bony prominences. The body part is immersed in a plastic or rubber basin (no metal) filled with tap or degassed water. Move the transducer in a longitudinal stroke while keeping a 1/2' to 1' distance from the skin. The bladder technique is also ideal for bony prominent areas. This technique uses a thin plastic bag (surgical gloves or balloon) filled with water and is placed on the area to be treated. A coupling media are applied and slowly move the transducer on top of the bag.

The application requires a coupling medium (gels) applied on the area to be treated to reduce surface friction and assist transmission of the ultrasonic waves by preventing reflection of the waves away at the soft tissue air interface. Besides gels as a coupling media, mineral oil is can also be used. Different media have also different acoustic impedance that affects the transmission and absorption of the ultrasound. A two media having the same impedance will produce maximal transmission of energy or else a greater the difference in impedance, the greater the reflection that will occur, and therefore, the smaller the amount of energy that will be transferred.

The ultrasound intensity of continuous US is normally set between 0.5 to 2 W/cm2 of thermal effects while pulsing US normally set between 0.5 to 0.75 W/cm2 with a 20% duty cycle. Maximum energy absorption in the soft tissue occurs from 2 to 5 cm. Intensity decreases as the US waves penetrate deeper. They are absorbed primarily by connective tissue: ligaments, tendons, and fascia.

A typical ultrasound treatment will take from 3-5 minutes, depending on the size of the area being treated. Larger areas require duration of 5 minutes.

Duty cycles are the portion of treatment time that ultrasound is generated during the entire treatment or a Pulse ratio, which determines the proportion of time that the machine is ON compared with the OFF time. Some machines use ratios, and some percentage.

• In continuous US, the machine continuously generates ultrasound, giving 100% duty cycle and produces thermal effects.
• In pulsed US, a 50% duty cycle if the machine US generation (ON) have equal duration with machine in not generating US (OFF). This is a pulse ratio of 1:1.This is the nonthermal effects. 
• If the duty cycle is 20%, the US generated (ON) is 20% of the treatment, while the other percentage the machine is not generating US (OFF). This is the machine pulsed at a ratio of 1:4

Mode              Pulse Ratio                            Duty Cycle

Continuous                                                          100%

Pulsed                  1:1                                           50%

                             1:2                                           33%

                             1:3                                           25%

                             1:4                                           20%

                             1:9                                           10%

Phonophoresis

This is a non-invasive way of administering medications to tissues below the skin. This transdermal delivery of medication is recommended for patients who are uncomfortable with injections. Medications regularly used include anti-inflammatory agents or analgesics (cortisone). It is effective with both continuous and pulsed techniques.

Related articles

• Therapeutic Ultrasound
• The Role of Physical Therapy in Treating Chronic Pain
• Ultrasound for Wound Healing
• How ultrasound helps wound heal THREE TIMES faster
• Ultrasound Speeds Up Healing Times for Skin Ulcers Among Diabetics, Elderly
• Ultrasound can accelerate wound healing

Hot Moist Packs

These are the commercially available superficial heating modality used by many PT clinics and hospitals to provide moist heat. This consists of a silicate gel enclosed in a cotton canvas fabric. Silicate gel is the main property because it absorbs more water and when it is immersed in  hot water it provides a considerable store of heat energy that last 30 to 40 minutes. Heating is through conduction and has little to or no effect on the temperature of  deeper tissues. Hot packs are available in different size and shape to fit different body areas.

Physiologic Responses:

• Increases circulation - promotes soft-tissue healing
• Increases muscle temperature - decreases pain and stiffness
• Relaxes spasm 

Treatment Parameters:

• Hot packs are stored in a tank filled with hot water between 70 to 75 degrees Celcius.
• Application of the packs requires six to eight layers of towels around the hot pack to provide thermal insulation thus lessening the danger of burn
• Ideally, it should be applied on top of the patient. If the patient lies on top of the hot pack additional toweling is required
• Check skin after five minutes for excess or sign of a burn.
• Call the attention of the PT for discomfort
• Applied at least 20 to 30 minutes to achieve the desired effects

Method of Application:

One-towel method

• Fold four towels in half, width-wise.
• Place each towel on top of the other, forming eight layers of toweling.
• Place towels on the treatment area.
• Place pack on towels and cover pack with folded towel to retard heat loss.

Two-towel method

• Fold two towels lengthwise and
• Place one perpendicular over the other, forming a cross.
• Place pack in the center of the towels.
• Fold the ends of the towels over the pack, forming eight layers of toweling on top of the pack. Invert pack placing the eight layers of toweling on the patient.

Contraindications and Precautions:

• Impaired skin sensation
• Circulatory dysfunction - varicose veins, DVT, and arterial diseases
• Taking analgesic drugs
• Infections and open wounds - danger of cross-contamination
• Cancer and tuberculosis - may enhance the progression of the disease
• Gross edema
• Impaired cognitive - lack of comprehension
• Deep x-ray therapy
• Liniments
• Pregnancy - should not be applied directly over the uterus
• Fever
• Acute inflammation
• Presence of metal implants 
• Advanced age
• Menses - increases menstrual flow if applied to the lower back or over the pelvis

Advantages:

• Easy to apply
• Saves time for personnel
• Efficient in heat conduction
• Available in different sizes and shape to fit clinical needs
• Has more sedative effects than dry heat
• Low cost
• Long life
• Patient acceptance

Disadvantages:

• Not easily applied around shoulders and hips
• Somewhat heavy
• Cannot be used on extremely sensitive patients
• May cause skin rash

Alternatives:

Hot Compress 

• Ideal for home use; an alternative to hot moist pack
• Greater heat loss and need constant change.
• Place the towel in hot water and wrung out t properly if you use this method of application.

Hot Water Bottle

• A rubber hot water bottle applied in the same way as hot moist packs
• Ideal for home use

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