Interferential Therapy – The Professional Answer To Chronic Pain Relief

   Since 1953 interferential therapy has been used in clinics and hospitals to immediately provide pain relief for chronic and acute pain patients.  Originally developed in Austria by Dr. Hans Nemec it is one of a number of electrical stimulation techniques used in modern pain control by physiotherapists, M.D.’s, and D.C.’s.


     Interferential therapy arrived approximately the same time as did the discovery of the use of cortisone, phenylbutazone and other new drug treatments.  It was relegated as a form of palliative treatment and almost led to its virtual disappearance but for its use in clinics and hospitals for patients needing immediate pain relief. 


     During the late 1960 and 70’s it was found that many of the new drugs also provided very undesirable side effects and,  as more drugs were coming down the pipeline,  there developed some serious side effects including death when they were combined, or used in conjunction with, other pain and non pain medications.   Often the effect of the drugs resulted in not pain cessation but in altered levels of consciousness which affected daily living.


     It is known that external electrical stimulus can excite tissues, specifically neural tissue which affects movement, and sensory perceptions.   Certain excitable neural tissues and the rate (frequency) for excitation are as follows:


·        0- 5 Hz           sympathetic nerves

·        0-10 Hz          unstriped muscle

·        1-50 Hz          motor nerves

·        10-150 Hz      parasympathetic nerves

·        90 – 150 Hz    sensory nerves



    One of the problems in stimulating the neural tissue is the dry outer layer of the skin, corneal tissue, has a relatively high resistance level and impedes the flow of the electrical current to the target neural tissues.  The high resistance is what led to the development of interferential therapy.


      Basically interferential is called such due to the “interference” of two currents crossing each other and the summation (beating) of those currents lead to a new current.  This new current is the stimulatory current that affects the neural tissue.   The purpose of the higher frequency is with increased frequency comes increased penetration.  There is no magic to the interferential frequencies of 4,000 and 4001 to 4,150.   Generally speaking if the frequency were increased to 10,000 then the potential of less resistance may be better but the practicality is to find the optimal frequency that is therapeutically efficacious and technologically achievable.


    In theory when two currents are administered with some form of a crossover pattern there occurs a summation of the electrical energy that is greater than either individual current as a stand alone current.  It is along the point of crossover energy that the stimulatory frequency is in the range of 1 – 150 pulses per second (PPS), another term for frequency.  The neural tissues are now excited by the new current created.


     In pain control the sensory nerves are the targeted tissues that affect pain relief.  It is the stimulation of these nerves that “block” (Melzack/Wall Gate Control Theory) the transmission of the pain impulse to the spinal cord for sensory perception in the brain. 


      For clinical use interferential has been used due to it’s immediacy to block the transmission as the patient is treated.  When the patient enters the clinic or doctor’s office it is with the active transmission of the pain impulse to the brain.  During the treatment the cross currents of the interferential treatment interfere with the pain stimulus by stimulating the sensory nerves, rather than allowing the pain impulse of the C-fibers (carrier of the pain impulse) to reach the spinal cord.    Following treatment most patients find the treatment has provided what is called “residual” or “carryover pain relief” and the restoration of the pain message is delayed for some time period following interferential treatment. 


        When the interferential treatment can be rendered on an as needed basis, outside a medical facility, the patient can effect the delay of the return of the pain stimulus for hours, progressing to days, weeks or months. 

         Watch our interferential video which shows the clinical and Infrex Plus combination interferential tens unit that is suitable for clinical or at home use.


When Placebo Is Not Placebo


    Often when traditional technologies fail to work it’s not uncommon for a new treatment to be dismissed as “it’s the placebo effect”, if it helps the patient.  This is so very common with the chronic pain patient and could possibly be the worse use of the term “placebo” in medicine and regulatory parlance.


     Here’s some background on the path the chronic pain patient takes.


    The pain could be of “unknown etiology” or it could be a disease process such as fibromyalgia, RSD, Carpal Tunnel Syndrome, or the common secondary diagnosis of sciatica.   The issue though is crystal clear.  The symptom has become the diagnosis simply because the patient’s problem can not be corrected and the pain is not eliminated.


    Prior to the diagnosis evolving to “chronic pain” the patient exhibits her/himself as a patient that has come for medical attention due to pain.  The initial exam generally consists of a preliminary diagnosis being made and then a treatment protocol is designed for that patient.  In most cases such as protruding disc, degenerative disc disease, Tic Doloreux as examples there is a physical cause of the pain and if that is discovered via lab tests, radiology, observation etc. then the cause of the pain is discovered and treated.  The pain goes away because the causative factor is discovered and treated, or the cause is determined and the patient is educated that it could be a viral causation and, time, is the healer with treatment only for the symptomatic pain until the virus is gone or the condition is untreatable.


     In most situations it will be something simple to eradicate the problem such as antibiotics, anti-inflammatories, aspirin, ibuprofen, rest, hot/cold modalities, or physical therapy.  The pain symptom goes away and the medical team no longer sees the patient since there is no problem.  Cause has been treated and pain is no longer present.  Patient is “well”.


     However, there are a certain percentage of the above patients that the treatment protocol did not work.  Those patients did everything they were told to do yet the pain persists and they continue to visit the doctor complaining the pain is not getting better and may actually be getting worse.  If the doctor is a primary care physician it is now the patient is referred out to some other specialty such as neurology, rheumatology, orthopedics, neurosurgery, chiropractic or some one else.  New tests begin, review of old tests continues and the treating medical specialist knows, or should know, the traditional remedies did not work.  An important point to remember is when the patient has reached this point in the treatment of “pain” the success rate at this point for these patients is 0 %.  It is no longer valid to state that “80% of these patients get better with bed rest and aspirin”.  These patients did not.


       If the patient continues to experience pain any previous diagnosis may be ruled out and a new diagnosis emerges.   The new “diagnosis” is “chronic pain” possibly “due to”, or “of unknown etiology”.  It is this point in time that the medical profession and other alternative practitioners admit the reason the patient is experiencing pain is “unknown or untreatable”.  


     This is where the use of the term “placebo” is lost or misused.  At this point in time the previous statements about how patients that have been treated successfully blur the reality that the chronic patient has been down the traditional path, unsuccessfully, so now the patient population is vastly different than the patients who were treated successfully.  It is no longer valid to reference treatments following this stage to be shown as being “placebo”.   It is better for our understanding to advance the concept those treatments now that work may be due to our misunderstandings, rather than the fall back phrase “placebo”.   Anything that stops the pain is a treatment methodology that is new and has a positive outcome when all previous treatments failed. 


       It’s so common for positive treatment outcomes to be written off as “placebo”, even if only a sugar pill, but the goal of all people who choose to help other people is to achieve the goals of helping by stopping the condition.   With chronic pain patients the condition is “continuing, recurrent pain”.


      Are there quacks?  Yes.  Are there shysters? Yes.  Are there those who proclaim to treat, accept money for doing so, yet don’t.   Yes. 


    It’s better to try to understand and to not defer to prejudicial statements when by attempting to understand and clarify correctly would better serve the chronic pain patient.

Video of A Clinical Interferential Unit and the Infrex Plus Combination Tens and Interferential Used In Chiropractic Clinic For Pain Treatments

     Many patients in pain go to clinics to get immediate pain relief and the therapy used is interferential therapy with a clinical interferential unit.  This video shows a standard clinical interferential unit and the Infrex Plus combination tens and interferential modes in a self help unit to use as needed at home, work outside clinics and hospitals. 

Muscle Pain - How To Stop, Prevent and Control It

   For most chronic pain patients muscle pain is very excruciating pain,  however it is avoidable and treatable using interferential therapy for immediate relief and prevention when used on a systematic schedule. 

   For many chronic pain patients there is a continuing problem associated with muscle pain. The patient may experience tightness, tension in an area, and in the worst of situations, actual spasms causing excruciating pain. Spasticity often is present following surgical procedures such as total knee replacement or other invasive surgical procedures where the muscle tissue is literally cut. To go into spasm, following cutting, is extremely agonizing. As a general rule pain in muscles is one of the simpler pain syndromes that can be totally eliminated using electrotherapy such as tens or interferential therapy. The biggest issue is not to treat muscle pain, but to prevent it from ever occurring in the first place.

   One of the warnings for anyone using a tens unit, transcutaneous electronic neural stimulator, or an interferential unit, such as the Infrex Plus,  is this:

  • "This device should not be worn while driving or operating machinery...."

   The purpose of the statement is that during stimulation it is not uncommon for a patient's muscles to actually relax and the patient is able to lose the tenseness, the pain, and becomes drowsy because the muscle pain and tightness evaporates. It is more common for any chronic pain patient that has been experiencing muscle pain continuously for long periods of time. The change is welcome relief.

   The best treatment protocol is to never allow the muscle pain to start but with chronic pain patients it's rare for any patient to have effective intervention prior to the muscle pain starting. Muscle pain is generally a secondary pain originating due to guarding, shielding, and posturing due to original pain sourcing.

   Most patients are aware when their muscles start to "tighten", they become uncomfortable and are warning of impending pain. The precursors are:

  • Loss of motion
  • Extreme tightness -not unusual to palpate and the muscles hard as rock
  • Posture shifting to avoid additional stress to the muscle group
  • Potential headaches - especially for upper shoulder, neck areas

   It is when the precursors are noticed that defensive intervention is needed. The process can be halted and reversed with proper treatment. By using electrodes that cover much of the neural origins of the muscle group a pleasant sensation is introduced using the tens or interferential unit on a "high" setting (equal to or greater than 70 pps - pulses per second for tens, 4,070 pps for interferential). The pleasant sensory sensation actually reduces the tension and prevents further guarding/shielding before the muscle pain starts.

   Using interferential for short 20 - 30 minute treatment time periods can stop the muscle pain completely when used as a preventive for several weeks. If a patient experiences tightness then a proper treatment would be to treat the muscles early in morning prior to starting the day or late at night prior to sleeping. The relaxing treatments may help the patient actually sleep, or prevent muscle tightness as the person begins activities which normally result in muscle pain. Also if the patient engages in activities during the day that normally results in muscle pain then by using a portable tens or portable combination Interferential & Tens device the unit can be worn and actually on for treatment while the activity is being performed.

   Over time the use of interferential to prevent muscle pain and tightness seems to be a form of biofeedback for the patient who learns to "slow down and relax" once the precursor symptoms start. There is knowledge there is a physical modality to use if needed and eventually the modality is used less frequently since the pain patient now has control.

   With interferential due to the much longer carryover pain relief, which tens does not have, a simple arnica pain patch worn around the muscle may be sufficient for effective prevention and the pain totally eliminated.

   It is the small steps of pain prevention that helps the chronic pain patient survive and prosper.

 One of the problems most chronic pain patients have is getting good, long lasting sleep so the patient can rest.  Often the lack of sleep only exacerbates the pain problems and the two, lack of sleep and pain, feed off each other.
    Here is a method to suppress the pain and restore the sleep.  Our goal is to increase the sleep period from the time the patient lies down and extend the sleeping over greater time until we've reached a beneficial sleep that allows the patient to rest and recuperate.
    Each night prior to going to bed take a few minutes to rest and put your feet up.  If best then do this in the bed so you do not have to get up to go to bed.  Put the Infrex on, high interferential mode, and set for a 30 minute cycle of treatment.   We hope to diminish the pain and also relax any tense muscles.  Do this for a week and see if this doesn't help.  
   Couple of extra tips to go with this:
  • If 30 minutes isn't enough then you can literally set Infrex to "continuous" and go to sleep with the unit on.  That is not a problem and will not cause you any problems.
  • Might try a warm, moist heat pack over painful area with the Infrex electrodes underneath the pack in the painful area.  The combination of carryover thermal pain relief is extended by the interferential treatment and the increased blood flow into the area allows for better conduction of the electricity throughout the painful region.
  • Can place a Lavender Aromatherapy Patch on your chest to wear during night to help relax.  If your insurance purchased unit for you these patches may be a covered cost so no out of pocket cost to you.
  • This is one of my favorite remedies!!  Try sipping a cup of chamomile tea ( one of main ingredients in "Sleepytime" tea) to calm you down and get ready to rest.
       Here is a study done, found on WEBMD,  on the use of dorsal column stimulators- DCS- (implanted spinal devices) that discusses the sleep/pain cycle and how the DCS may be beneficial.  My advice is go with interferential first as the origin of the tens units were from testing for a DCS device and it was found the external device provided similar benefits without surgery, costs, and build up of scar tissue which created it's own set of future problems.


  Constant Passive Motion Machines ( CPM) Why To Use and Benefits:




One of the larger issues for total knee replacement patients, and physicians, is keeping the patient active and moving so the rehab time is minimized and further health issues not created by the time of immobility. Over the past 2 decades it has become common practice to place the patient's leg into what is called a "constant motion machine" (CPM) and the leg and knee joint are moved immediately following surgery. This is done to:

  • minimize atrophy to the surrounding musculature tissue
  • increase blood flow into and out of the surrounding tissues
  • retard the degree of atrophy one has following immobilization
  • maintain the physical actions of the muscles to move fluids away from the injured tissues and prevent edema
  • prevent loss of elasticity in the affected tissues

   Generally the CPM machine is activated immediately upon the patient being moved to the hospital room following surgery. Over time it has been shown that the recovery time is shortened and pain decreased using one of these CPM machines. The problem is, often due to the pain the operative procedure produces, the CPM machine can be viewed by the patient as a constant pain machine when in fact the overall long term effect is to decrease and prevent pain by getting the patient healed and functional movement restored.

   By using interferential therapy at the same time the constant passive motion machine is used there are even greater advantages for the total knee replacement patient such as:


  • interferential treatment minimizes the pain using the CPM machine

  • electricity has been shown to accelerate tissue repair and healing

  • negative charges of electrotherapy actually move fluids away from the joint and tissues minimizing edema

  • interferential therapy increases carryover pain relief so the patient is more comfortable for longer time periods

  • interferential therapy aids the muscles to relax and minimizes muscle spasticity which also minimizes pain

   When interferential therapy is chosen as the mode of treatment on the Infrex Plus unit, along with a constant passive motion machine, patient outcomes are improved, rehab. time is diminished, and pain is minimal. The patient regains the ability to walk without pain and in a shorter, more pleasant time frame.

What Is Piriformis Syndrome?

  Piriformis syndrome is a pain and discomfort condition much like sciatica, except due to a very dissimilar source.  Piriformis syndrome is sometimes referred to as back pocket disease. People that keep a wallet in their back pocket and sit on it throughout the day often develop symptoms of pain in the rear and down the leg. In this ailment, the sciatic nerve is compressed by the piriformis muscle.  Piriformis Syndrome is an entrapment neuropathy in which a tight and/or inflamed piriformis muscle compresses the sciatic nerve, the largest nerve in the body, producing radicular type of symptoms. There are many causes of this problem to altered foot biomechanics to poor hip joint function.  Piriformis syndrome occurs when part of the sciatic nerve becomes entrapped, compressed, or irritated by this muscle. The syndrome can be very persistent and painful.  It is estimated that six percent of all patients with sciatica have piriformis syndrome.

  The existence of piriformis syndrome has been doubted for years, but with the power of the Internet the reality of this syndrome has finally reached a tipping point. Previously, it was not even considered as a diagnosis, in others it was quickly ruled out.  Chiropractors note that piriformis syndrome seems to occur most in those people who don't stretch adequately before exercise. People who are obese, or who spend much of their time sitting (as on workdays) and then are active on the weekends might be prone to the condition.

  Located deep within the gluteal (buttock) muscles PFS can reek havoc with the body, causing extreme discomfort, pain and inconvenience in general. This muscle is deep inside the body, under the gluteals. The sciatic nerve passes directly under the piriformis muscle. Tension in the soft tissue of the piriformis, gluteal and other related muscles is usually the cause behind it. Such tension may be caused by incorrect posture, sports, and improper exercise.

  Women may be affected more frequently than men, with some reports suggesting a six-fold incidence among females.
Piriformis syndrome also causes sciatica. Its treatment is much less invasive and severe than the treatment of herniated lumbar disks.

How To Diagnose Piriformis Syndrome -

  Diagnosis of piriformis syndrome is mostly clinical and requires a high suspicion for the diagnosis as many of the symptoms can be somewhat vague. Patients are often tender over the attachments and length of the muscle especially at the greater trochanter on the thigh bone or femur. It includes an empirically-based interactive means to determine the probability that a given case of sciatica is due to piriformis syndrome.

  If it hurts to touch a point that's in the middle of one side of your buttocks, you probably have piriformis syndrome. This chronic condition is very difficult to diagnose, because other injuries may produce exactly the same symptoms.

   In the Piriformis Syndrome, you feel pain, tingling and a numb sensation in your buttock region. You can feel ache in the mid butt area that radiates through the whole of back legs. Trying to stretch the piriformis muscle has been suggested as a way of diagnosing the problem - if it hurts to stretch it, you may have piriformis syndrome. The instructions for stretching it are: Lie flat on your face on a bed. The prognosis for most individuals with piriformis syndrome is good. Once symptoms of the disorder are addressed, individuals can usually resume their normal activities.

Symptoms of Piriformis Syndrome -

   The first symptom suggesting piriformis syndrome would be pain in and around the outer hip bone. The tightness of the muscle produces increased tension between the tendon and the bone which produces either direct discomfort and pain or an increased tension in the joint producing a bursitis.

How To Treat Piriformis Syndrome -

  Diagnosis and treatment of Piriformis syndrome should be carefully and extensively done. Multimodality treatments should be considered before jumping into surgery or the like. Therapy for piriformis syndrome often begins with progressive stretching exercises that are simple to do at home or the office and require no equipment. One easy exercise, for example, involves standing with the left foot flat on the floor and the right foot flat on a chair so that the right knee is at a 90 degree angle with the floor.

   Targeting the piriformis is done with a single knee to the chest with painful side cross-over. The stretching exercises are performed three times a day, five times each time, maintaining the stretch between 5-10 seconds. If the muscle pain is causing altered  gait, slow down and start therapy before causing additional end  injury.

  One of the main ways a person can treat piriformis syndrome without seeing a doctor, according to, is to apply heat to the buttocks region. Patients should also work to stretch the muscles in the buttocks and hips to help relieve the spasm and inflammation. A person with piriformis syndrome has irritation and inflammation of the sciatic nerve .  Usually people with piriformis syndrome do not like to sit. When they do sit down, they tend to sit with the sore side buttock tilted up rather than sitting flat in the chair.

  There are a number of preventative techniques that will help to prevent piriformis syndrome, including modifying equipment or sitting positions, taking extended rests and even learning new routines for repetitive activities.

  Besides stretching, there a couple of therapies that can greatly assist in treating piriformis syndrome. Ultrasound can be used to provide an anti-inflammatory effect to a swollen piriformis.  Stretching is not only a treatment but also a preventive. 

   Patients with piriformis syndrome may also find relief from ice and heat. Ice can be helpful when the pain starts, or immediately after an activity that causes pain.  If pain is persistent during stretching then a combination of warm moist therapy with Infrex treatment during and after exercising may be most beneficial.  The thermal effects of warm moist heat have limited residual pain relief, however the carryover pain relief from interferential therapy may provide total comfort extending from one stretching session to the next. 

   The warm moist heat also attracts blood to the area and the interferential treatment goes deeper into the human tissue structure due to decreased electrical resistance.

  Inactive and weak gluteal muscles can also be a predisposing factor of the syndrome. The Gluteus maximus is important in both hip extension and in aiding the piriformis in external rotation of the thigh. Most patients also need gluteal strengthening.  Try to maintain flexibility in the hip joints, including the iliopsoas, iliotibial band (ITB) and gluteal muscles. This will help prevent injuries caused by friction.


The following citations were used to compile this article:



   Interferential therapy has been around since 1951, originating in Germany, as a method to ease the pain the chronic pain patient suffered. The patient would come in to the Doctor's office or hospital for a treatment from the interferential machine and stop the pain during the treatment and for an extended period of time following the treatment, referred to as carryover pain relief.

   The reason for the inhouse treatment was the equipment was very expensive and it needed a large supply of electricity to work. The interferential machine actually goes off and on over 8,000 times per second as compared to the traditional TENS unit ( transcutaneous electronic nerve stimulator) which does so only 150 times per second. This demand for electrical energy exceeded the ability of electrical engineers working with portable battery systems to develop any form of battery which could meet the excessively high demands of a clinical interferential machine. Literally throughout the history of interferential therapy the problem in making the units available for self treatments has revolved around the high demand for electrical energy and the ability to have that capacity yet still be a small, portable device.

   A simple analogy is if one were asked to fill a 10 gallon tank with a one gallon bottle of water and the person could not go back to refill the bottle. Obviously it can't be done and the time period to try would be 1/10th since the bottle would be exhausted of all water after one discharge. Battery systems also have a "limited capacity" of electrical energy and interferential exhausts most of that capacity very rapidly. Typically when anyone tried to manufacture a truly "portable interferential device" and used a 9 volt, triple A, or AA disposable or rechargeable battery system, the batteries had no charge left in less than 5 minutes. To create more capacity meant the batteries would require a wheelbarrow to transport them in which means portability is lost.

   Practically speaking there is no economical way to overcome the battery problems, yet maintain portability, other than by engineering a unit with an AC adaptor. Once you have an AC adaptor then the entire grid that supplies electricity is now available. Most people have access to some form of wall outlet so a unit can be plugged in to the outlet and treatment can begin. By using an AC adaptor pain patients no longer have to go to clinics or hospitals for treatments and can self treat with lasting carryover pain relief.

   The Infrex Plus on interferential mode using rechargeable batteries has an extended life of approximately 80 minutes before the batteries are fully discharged.  This was accomplished by energy saving engineering and wave form adjustment coupled with pre-modulation inside the unit. Clinical interferential treatments are generally for 20 minute duration so the 80 minutes provides true patient comfort using only the battery system when necessary.  Standard treatment practice should be to use the AC adaptor at all times and only use battery system when can not access outlet.


The video on How To Use An Infrex Unit shows how the portable unit operates including using it with a rechargeable battery system.

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