Can the Stimulette Edition 5 work with denervated muscle?

For several years we have worked successfully with the Stimulette Den2x with many home based clients in the UK. The product was designed for simple use in a home environment and has proved itself to be very effective in restoring muscle tissue bulk and quality with clients who have an injury to the spine or peripheral nerves resulting in muscle denervation. The product is currently being revised and the new version is not available yet (edit 2021 - it has now been update with the RISE system) so we have been working with the new Stimulette Edition 5 S2X which has a broader application scope. Let’s examine the differences between the Stimulette Edition 5 S2X and the Stimulette Den2x for working with denervated muscle.

The type of FES we see used with any of the FES bikes on the market such as the RehaMove 2, will not work with denervated muscle. This is because the electrical energy delivered by these systems relies on the presence of intact motor nerves. If these nerves are compromised by a denervation producing injury no muscle contraction can be generated. The most commonly used waveforms for FES Cycling are so called bipolar, rectangular, pulses with a pulse width of perhaps a maximum of 500 microseconds and a maximum current of 130 mA. The Den2x can also generate rectangular bipolar pulses but with a typical pulse width of a 100 or more milliseconds and current levels of up to 300 mA. These waveforms work directly on the muscle fibres and do not rely on the motor nerves.

With the Den2x we were able to pre-programme a number of keys on the unit to automatically select a programme for the client to use. Over time the client would learn to select a new programme according to our training schedule. The idea was to encourage the regular use of stimulation that would, in the early stages, bring about a recovery of the structure of the nerves and muscle fibres. Over time, the waveforms were designed to strengthen these muscle fibres. Quite a number of clients who were initially believed to have complete denervation recovered the ability of their muscles to be excited by more conventional FES and then be able to use a RehaMove 2.

We always preferred to use rectangular, bipolar pulses with the Den2x for reasons beyond the scope of this note. However, the Den2x could be set with triangular and other waveforms that could be useful in particular situations. For example, when working with the upper limbs and we have muscles with preserved innervation very close to denervated muscle.

So what about the Edition 5? The one difference is that the Edition 5 unit is not capable of generating the 300 mA which could be generated by the Den2x. In practical terms this is not generally a problem. Unless working with clients decades post-injury you would be unlikely to require so much current.

The Edition 5 has some pre-programmed waveforms for denervated muscle and by using the unit’s ability to custom programme the unit we can typically generate the same types of forms we used with the Den2x.

The Edition 5 has some definite advantages for clients and clinics. It supports a wider portfolio of applications including ones for pain management and stimulation of innervated muscle. If you would like to know more you can contact us for information.

UPDATE 2021: The Den2X was replaced by the RISE Stimulator which is now available in the UK.