How TSE Works and its Effectiveness

How TSE Works and its Effectiveness 

It has been common practice to stimulate the spinal cord (dorsal column) through the neurosurgical implantation of electrodes. Although there have been no reported side-effects from this electrical device, infection associated with the surgical implantation of wires and the stimulator is a long-term risk factor that needs to be addressed. Dr Alexander Macdonald and Dr Tim Coates sought to find a non-invasive method of spinal cord stimulation via surface electrodes. To elicit a voltage gradient within the spinal cord, the electrodes need to provide a current of sufficient amplitude to penetrate the tissues that lie between the skin and spinal cord. Existing electrotherapeutic devices such as Transcutaneous Electrical Nerve Stimulation (TENS) apply relatively broad pulse durations (50-200 µsec) that aim to excite peripheral nerves at low amplitude. Macdonald and Coates (1995) examined the effects of brief duration pulses (≤10 µsec) to produce a painless current of sufficient amplitude to stimulate the spinal cord.

Sourced from Acticare Website

 In order to produce an action potential in peripheral nerves via electrical stimulation, the input current must have a low to moderate voltage input and a high pulse width (Sato & Perl, 1991). TSE works by reducing the pulse width from 20- 200 to 4 µsec and increasing the Voltage output, therefore increasing patients pain tolerance and producing little sensation (i.e tingling) (Macdonald and Coates, 1995). This produces widespread analgesia when electrodes are placed over the spinal cord. Thus, TSE works by stimulating the spinal cord with high voltage, low amplitude current directly to the spinal nerve root. 

Electrical pulses employed by TSE can be delivered at regular intervals in the range of 100 to 50kHz, however most clinical studies have used a 2-20kHz range (Acticare, 2012). TSE pulses are typically composed of a biphasic square wave of short duration (≤4ms). This pulse duration is suggested to be too brief to elicit action potentials in peripheral nerves at voltages below 150V (peak-to-peak). Furthermore, like TENS and interferential the short pulse durations of TSE penetrates deeper into the body resulting in a reduction of skin impedance.

Initially TSE was strictly set at a frequency of 100Hz, however studies shave shown that the extent of TSE’s analgesic effect is dependent on its frequency (Acticare, 2012). It has been found in clinical trails that higher TSE frequencies increased the time to analgesic onset and its overall affect. For example, at 100 Hz, 40 minutes of application may be needed to produce analgesia, requiring only 8 minutes at a frequency of 150 kHz (Li & Bak, 1976).

A study was conducted by the inventors of TSE sought to determine the effectiveness of TSE on chronic pain conditions. 100 patients with a variety of chronic pain causing conditions received TSE to the appropriate spinal nerve root at a frequency of 600Hz and a pulse width of 4 µsec (square wave), 30min/day for 2 weeks. The patient’s pain levels were assessed via a Visual Analogue Scale (VAS). Results showed that the TSE treatment reduced pain by 60% in patients whose pain was of relatively recent origins (2.6 years) (Macdonald and Coates, 1995). Although, this study’s results showed positive outcomes for its subjects, more clinical research should be conducted on TSE by independent researches to decrease bias towards TSE and to compare it to a placebo or other electrophysiological devices.

In another double blind, randomized control trial comparing the effects of TSE to a placebo found different results. Eight subjects with chronic critical limb ischemia received a placebo treatment for one week, followed by the actual TSE treatment at a frequency of 2500 Hz and a voltage of 150V to the spinal cord. McGill Pain Questionnaire measured patient’s pain perception. The results showed that daily use of TSE did not decrease the subject’s pain or improve their physical function (Simpson & Ward, 2004). Therefore, suggesting that TSE did not affect the quality of life for chronic pain patients.

Another double blind randomized controlled clinical trial which supports the research conducted by Simpson & Ward, compared TSE to a placebo in chronic low back pain patients. 58 patients with low back pain were randomly assigned to a placebo and a TSE receive group and patients were assessed for pain via the Visual Analogue Scale (VAS). Subjects received the TSE or placebo treatment twenty minutes per day for 2 weeks. The results showed no difference in mean pain scores between the TSE and placebo groups (Thompson et.al, 2008). Therefore, the more recent research conducted by Simpson & Ward and Thompson et.al suggests that TSE is not effective in treating chronic pain conditions.

Currently, the evidence on TSE is limited and the benefits and contraindication of TSE are still unknown. To gain a stronger understanding of TSE and the benefits it may have in clinical practice, further research must be conducted.

                                                                               

 References

Macdonald, A.J.R. & Coates, T.W. (1995). The Discovery of Transcutaneous Spinal Electroanalgesia and its Relief of Chronic Pain. Physiotherapy. 81 (11): pp. 653-61.

Sato, J. & Perl, E.R. (1991). Adrenergic excitation of cutaneous pain receptors induced by peripheral nerve injury. Science. 251 (5001): pp. 1608-10.


Simpson, K. H. & Ward, J. (2008). A Randomised, Double- Blind, Crossover Study of the use of Transcutaneous Spinal Electroanalgesia in Patients with Pain from Chronic Critical Limb Ischemia. Journal of Pain Symptom Management, 28 (5), 511- 519.


Thompson, J. W., Bower, S. & Tyrer, S. P. (2008). A double blind randomized controlled clinical trial on the effect of transcutaneous spinal electroanalgesia (TSE) on low back pain. European Journal of Pain, 12 (3), 371- 377.