IFC vs TENS: Electrical Stimulation for Pain and Swelling

In this article we’re looking at the difference between Inferential Current versus Transcutaneous Electric Nerve Stimulation (IFC vs TENS).

Transcutaneous Electric Nerve Stimulation (TENS)

TENS
variations are often described by their technical characteristics: high
frequency, low intensity (conventional TENS) or low frequency, high intensity
(acupuncture-like TENS, AL-TENS) (Walsh et al.,
2009).

How TENS Addresses
Pain:

  • Gate control theory, established in
    1965, proposes a gate consisting of excitatory and inhibitory synapses that
    exist in the dorsal horn of the spinal cord (Walsh et
    al., 2009). This gate can
    regulate the amount of nociceptive traffic (painful stimuli) transmitted to the
    brain. This gate could be closed by non-noxious stimuli (e.g. touch, pressure
    and electrical currents), and block potential nociceptive stimuli.
  • Increased release of endorphins through
    heat transmission, possibly more localized to the area of the pain
  • Physiologically, conventional TENS
    selectively activates non-noxious low threshold afferent nerve fibers in the
    skin (Aβ-fibers). When administering TENS, Aβ nerve fiber activity is reported
    by the client to feel like a strong electrical paresthesia (pins and needles)
    beneath the electrodes (Walsh et al., 2009). AL-TENS is intended to generate a
    muscle twitch to activate small diameter afferent nerve fibers in muscles (Aδ)
    and descending pain inhibitory pathways. AL-TENS is administered at low
    frequency and high intensity currents over muscles, without pain.

Placement for
TENS (Borst, n.d.)

  • Can either be placed directly over the
    area of pain, or pads can “sandwich” the pain
  • Pad placement effects the depth of the
    current

    • Close placement=superficial current
    • Further placement= deep current

Inferential current (IFC)

Developed in
the 1950s, IFC is most commonly used for pain relief (Kitchen, 2001). IFC is also claimed to reduce inflammation, and
assist tissue repair (including bone fractures), and reeducate muscle
(especially with incontinence).

How IFC
Addresses Pain:

  • IFC delivers current to deep-seated
    structures through an amplitude-modulated interference wave typically with the
    use of four electrodes (Kitchen, 2001).
  • The wave is created by two out of
    phase currents that collide with each other to generate an interference with a
    frequency that can penetrate through the skin to deeper structures and even
    excite neurons.
  • Use of IFC should generate a strong
    but comfortable electrical paranesthesia at the site of the pain, to generate
    Aβ activity (Kitchen, 2001).

Image 1.
Interference Wave (Kitchen, 2001)

Evidence to Support Use of Electrical Stimulation (TENS vs IFC) for Pain

  • A Cochrane systematic review found
    preliminary evidence that TENS reduces pain intensity over and above that seen
    with no treatment for acute pain (Walsh et
    al., 2009). Definitive
    conclusions were limited by the high risk of bias, inadequate sample sizes, and
    unsuccessful blinding of treatment interventions. Although the use of TENS as a
    potential treatment option for managing acute pain is debatable based on these
    results, it can be self-administered, is safe, and can be inexpensive (Walsh et al., 2009).
  • Current
    evidence suggests that overall TENS and IFC have similar effects on pain and
    improvements in functional outcome measures (de
    Almeida et al., 2018). There is a need for larger, well-designed and
    standardized studies to establish the best parameters for pain management due
    to limitations in current literature.

General Contraindications for Using
Electric Stimulation:
cardiac pacemakers (in areas close to
device), near the carotid sinus, near, central venous and peripheral
intravenous central catheter lines, metal implants, pregnancy, severe obesity,
active bleeding, cancer, over the spine (Borst, n.d.)

General Precautions for Using Electric
Stimulation:
muscle fatigue, peripheral nerve
pathology, cognitive impairment, allergic reactions, decreased sensation, open
wounds, tendon or nerve repair surgery (need to wait 4-6 weeks typically to not
displace tendon or nerve repair) (Borst, n.d.)

References

Borst, M. (n.d.). Test prep for the CHT exam (3rd
ed.). American Society of Hand Therapist.

de Almeida, C. C., da
Silva, V. Z. M., Júnior, G. C., Liebano, R. E., & Durigan, J. L. Q. (2018).
Transcutaneous electrical nerve stimulation and interferential current
demonstrate similar effects in relieving acute and chronic pain: a systematic
review with meta-analysis. Brazilian journal of physical therapy22(5),
347-354.

Kitchen, S. (Ed.).
(2001). Electrotherapy E-Book: evidence-based practice (11th
ed.). Elsevier Health Sciences.

Snyder, A. R.,
Perotti, A. L., Lam, K. C., & Bay, R. C. (2010). The influence of
high-voltage electrical stimulation on edema formation after acute injury: a
systematic review. Journal of sport rehabilitation19(4),
436-451.

Walsh, D. M., Howe,
T. E., Johnson, M. I., Moran, F., & Sluka, K. A. (2009). Transcutaneous
electrical nerve stimulation for acute pain. Cochrane Database of
Systematic Reviews
, (2).

6 Comments

  1. Collins on November 9, 2021 at 11:46 am

    Any pictures on how to position the inferential probes

    • Mia on December 11, 2021 at 2:39 am

      You cross cross the electrodes. Requires four leads, leads are likely color coded with one set red and one set black or something similar. Place the first set of leads (red) across the area of desired treatment area so that it is diagonal like this / with one lead at each end point. Then place the other set (black) perpendicular to it like this \ again with one lead at each end. When your done you should basically have an X shape or your four leads dotted out like the corners of a box with alternating colors, red, black, red, black. This will make the current cross paths, reminds me of GhostBusters movie from the 80’s haha. Place the leads so that the current will flow across/through the area being treated. If the leads are too far apart the current may not connect to the other lead, if this occurs then place the leads closer until there is a current noted. Hope this was helpful. 🤗

  2. Scott Roth on April 11, 2022 at 1:17 pm

    Can you use just 2 electrodes for a small localized area (groin strain). Which method is recommended, IFC or TENS? My device also has the NMES option too.

    • Miranda Materi on May 1, 2022 at 7:27 am

      I prefer IFC

    • Krishnaa Ananth on October 23, 2022 at 2:23 am

      it is suggested Not to use in Groin/sensitive & private areas.
      hey, Scott if you have already tried it do let others know if there were any adverse effects or on the contrary any improvements. Cheers!

    • DC on October 31, 2022 at 11:24 am

      TENS should be used when only using one channel/color. You can also use both channels/colors if needed. With TENS you do not need to criss-cross the colors.

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