Electrotherapy with "mixed" paraplegia

We have recently had a couple of spinal cord injured clients with a "mixed" paraplegia.  I'll explain what this means in a second.  Let me explain a bit about one case in particular.  He has supposedly a T11/12 complete lesion following a spinal cord injury that he sustained in Nov 2008.

He is using an FES bike (RTI 300) which illicits good contractions in hamstrings and gluteals but he gets absolutely nothing from his quadriceps muscles.  It's really debatable whether he can benefit from a FES bike; probably I wouldn't have offered him our RehaMove FES bike system. 

We did use the Stimulette den2x (specifically designed for denervated muscles) to see if we could obtain a contraction from his quadriceps muscles.

I was able to get good twitch response from his quads using the den2x with some "spill over" into hamstrings and even gastrocnemius with less than 100 mA.  However, trying to illicit a tetanic contraction was less successful as the spill over (using large carbon electrodes/sponge bags) was quite large at even moderate levels of current.

Let's go back to the idea of "mixed paraplegia"

This means, that below the level of his injury there is some intact spinal cord left.  But - as his injury is located in an area in which the spinal nerves = 2nd motoneurons run parallel to the spinal cord for some centimetres - we also find lesions of the 2nd motoneurons of some segments. And because of anatomical reasons this results in denervation of quadriceps and the muscles of the front side of the lower leg and to a spastic paresis of the hamstrings and the calf.  This is a very challenging situation we find sometimes in patients with conus-cauda-lesions.

What we will attempt to do in that situation is stimulate the denervated muscles with the usual den2x programs and accept that there may be a co-contraction of the other muscles. The only thing is, that you have to take care, that the intensity of the stimulation is not too strong for the spastic muscles – their tendons also have to get used to the pulling of their (much stronger than the denervated) muscles!

Very often, after some time the denervated quadriceps gets strong enough for leg extension, but not always – sometimes the strength of the hamstrings stays higher than that of the quads and no leg extension becomes possible.

The “spill over” to the calf is the effect of the intact nerve of the spastic muscles, which “transports” the impulse to its muscles.

As the clients’ legs are very slim, we could try to use smaller electrodes, which should cover the whole quadriceps, but should not reach the dorsal half of the thighs. Sometimes we try to turn them through 90°, so that they lie on the leg longitudinally.