TENS
TENS (Transcutaneous electrical muscle stimulation)
TENS describes the application of electrical impulses transmitted through the skin to effect the nerves. TENS therapy has been a widely accepted pain therapy technique for the relief of acute and chronic pain for over 25 years.
The handy, battery-powered digital dual-channel devices, target and stimulate specific nerves by transmitting electrical impulses. Such stimulation will in many cases significantly reduce or even eliminate the patient's perception of pain.
The TENS method is a very convenient form of non-invasive electrical therapy using specific stimulation current, electrode and application criteria. Therapeutic electrical stimulation triggers nerve responses and neuro-modulatory regulations and belongs to the targeted reflex and stimulation therapies. The primary objectives of the therapy are the suppression of pain, the optimisation of blood flow, muscle relaxation, as well as the therapeutic effect on visceral organ systems and endocrine glands or reflex-therapeutic effects.
TENS therapy also helps to optimise central endogenous regulation and impulse control systems. TENS impulses block signal transmission to the brain and stimulate the natural release of endorphins, which can also reduce pain. The TENS treatment can be used to harmonise (or eutonize) the psychovegetative tone, to increase performance, as a prophylactic measure.
TENS principles of action
Gate Control Theory “Continuous Pulse Sequence”
The stimulated nerves inhibit the transmission of nociceptive information at the dorsal horns of the spinal cord, such that pain is no longer perceived.
The continuous pulse sequence or conventional stimulation uses constant frequencies and pulses. The fixed frequency can be set at up to 150 Hz and the pulse duration up to 300 µs. The intensity is adjusted so that the stimulation causes strong but pleasant paraesthesia (tingling) in the painful area. This form of treatment is recommended for most initial applications, particularly for acute pain.
Endorphin-Theory “Burst”
Stimulation of the posterior fibres or certain subcortical brain structures can lead to serotonin and norepinephrine inhibition, and the release of endorphins.
This burst mode stimulates with 2–4 pulse bursts per second at a frequency of 0.5 to 5 Hz and a pulse duration of 100 to 300 µs. The intensity is adjusted so that the stimulation causes visible but painless muscle contractions. This form of systemic treatment releases β endorphins.
| Theory | Gate control effect (continuous pulse sequence) | Endorphin release (burst) |
| Mode of action | via motor neurons | via sensory neurons |
| Intensitsy | Low, slight tingling sensation | High, only just bearable |
| Duration of pulse (pulse bandpass) | short (30–300 µs) | long (150–300 µs) |
| Frequency of pulse | 50 – 150 Hz | 0,5 – 5 Hz |
| Muscle contraction | no | yes |
| Onset of pain relief | quickly | slowly (20–60 Min.) |
| Duration of pain relief | short (5–15 Min.) | long (20 Min.–12 Std.) |
| Length of treatment | start with 3 x 20–30 min. (increase later if required) | 30 Min. 2–3 x per day |
Frequency and pulse modulation
Modulated stimulation uses regularly fluctuating frequencies. The settings correspond to conventional stimulation (default values 100 Hz/200 µs), with the frequency (Hz) or pulse duration (µs) continuously changing between 40–70%. This form of therapy prevents accommodation or counteracts the tendency of nerves and muscles to become accustomed to stronger stimulation and is particularly indicated in cases of prolonged therapy and chronic pain.
Impulse parameter
Different analgesic and motor effects can be achieved by varying the carrier pulse duration, the pulse frequency and impulse modulation. innoTENS devices provide ample variations of pulse parameters for triggering distinct effects for different indications.
TENS rule of thumb
Higher frequencies
- stimulate blood flow and strengthen muscles
- higher frequencies (50–150 Hz) mean lower intensity
- are more effective in conjunction with the Gate Control Effect (Wall, Gunnick, Devor)
- not by naloxone blockade
Low frequencies
- have analgesic, calming, vasodilatory, endorphin-stimulating effects
- low frequencies (1–5 Hz) yield high intensity (needle acupuncture)
- more humoral effects (endorphins)
- via partial naloxone blockade (Pommeranz, 1987)
- receptor, performance pain, central pain processing disorder
- stronger analgesic
- longer lasting effect
Historic overview
- approx. 2500 BC: “Electrical” treatment of various pain conditions with electric rays from the Nile in Egypt
- approx. 45 AD: Scribonius Largus describes this electrical therapy with live electric rays (torpedo marmorata) in the classical literature.
- 1646: The physicist Sir Thomas Brown coins the term "electricity".
- 1850: W.G. Oliver (USA) uses electricity as a local anaesthetic for surgical procedures.
- 1965: Melzack and Wall publish the gate control theory and thereby create the prerequisites for the neurophysiological understanding of stimulation analgesics.
- 1967: Wall and Sweet use high frequency TENS for the first time in its current form for pain therapy.
- 1979: Sjölund and Eriksson develop the acupuncture-like TENS "Endorphin Theory" (Burst).
- since 1980: Worldwide dissemination and application of TENS in acute and chronic pain.
- 1987: First approval as a statutory health insurance medical benefit (Number 30712).
