Traditional TENS (Hi TENS, Normal TENS)
Usually uses stimulation at a relatively high frequency (90 - 130Hz)
and employ a relatively narrow (short duration) pulses (start at about
100ms) though as mentioned above, there is less support for
manipulation of the pulse width in the current research literature. The
stimulation is delivered at ‘normal’ intensity
- definitely there but not uncomfortable. 30 minutes is probably the
minimal effective time, but it can be delivered for as long as needed.
The main pain relief is achieved during the stimulation, with a limited
‘carry over’ effect – i.e. pain relief after the machine has been
switched off.
Acupuncture TENS (Lo TENS, AcuTENS)
Use a lower frequency stimulation (2-5Hz) with wider (longer) pulses (200-250ms). The intensity employed will usually need to be greater than with the traditional TENS - still not at the patients threshold, but quite a definite, strong sensation. As previously, something like 30 minutes will need to be delivered as a minimally effective dose. It takes some time for the opioid levels to build up with this type of TENS and hence the onset of pain relief may be slower than with the traditional mode. Once sufficient opioid has been released however, it will keep on working after cessation of the stimulation. Many patients find that stimulation at this low frequency at intervals throughout the day is an effective strategy. The ‘carry over’ effect may last for several hours, though the duration of this carry over will vary between patients.Brief Intense TENS :
This is a TENS mode that can be employed to achieve a rapid pain relief, but some patients may find the strength of the stimulation too intense and will not tolerate it for sufficient duration to make the treatment worthwhile. The pulse frequency applied is high (in the 90-130Hz band) and the pulse duration (width) is also high (200ms plus). The current is delivered at, or close to the tolerance level for the patient - such that they would not want the machine turned up any higher. In this way, the energy delivery to the patients is relatively high when compared with the other approaches. It is suggested that 15 - 30 minutes at this stimulation level is the most that would normally be used.Burst Mode TENS :
As described above, the machine is set to deliver traditional TENS, but the Burst mode is switched in, therefore interrupting the stimulation outflow at rate of 2 - 3 bursts / second. The stimulation intensity will need to be relatively high, though not as high as the brief intense TENS – more like the Lo TENS. It is proposed that the application of BURST mode TENS can effectively stimulate both the PAIN GATE and the OPIOID mechanisms simultaneously.Modulation Mode TENS :
In modulation mode, the machine delivers a less regular pattern of
TENS stimulation in an attempt to reduce or minimise the accommodation
effects of regular, patterned stimulation. Machines offer different
methods of varying the stimulation pattern – some vary the frequency,
some vary the intensity and some vary the pulse duration, and some
machines offer a choice between these methods, though the research
evidence to date does not favour one variation method over another.
This potentially most useful for patients who use TENS for hours a day,
if for no other reason than accommodation occurs at a slower rate and
therefore less intensity adjustment may be required.