Hi,
Get the neurologists involved and ask what kind of damage there is. Think about it, if the brachial plexus is completely severed, e-stim is worthless. The impulse only travels to where the injury is. You can get a temporay muscle contraction...but nothing lasting. If this is the case, make ororder a subluxation sling or use the taping method to prevent subluxation/ prolonged stretching of those muscles. The subluxation sling provides more support but most of them are rather complicated to donn and pt's/ caregivers use them only temporarily. Make sure they understand how important this is, so they are compliant.
The reason why e-stim is sometimes effective in CVA patients is that the neurological pathway is still intact and what you are hoping for is to send messages one way to provoke a message to be sent the opposite way.
In a brachial plexus injury, if the injury is incomplete you need to wait it out. Nerve regeneration is very slow. You may have total recovery or partial recovery or no recovery depending upon how much damage is done.
If the damge is permanent (per neuro) spend your time on educating him on injury prevention (due to lack of sensation) and don't forget your psychosocial aspects of this condition. Especially if this is a man. Men are raised to be strong/ invincible in our society and a permanent flaccid limb very "manly". There will be a lot of emotional stuff that needs to be addressed, if he is not already on one, you may want to recommend a anti-depressant.
Hope this helps, let me know if I can elaborate on anything.
Tracey Palmer