this may or may not apply, I wouldn't know... but I always like to try the simple stuff first...
change the way you grip the bars? numb hands often come from centering the bars on the center of your palms - ulnar channel and letting the wrists collapse cuts down on circulation.
straighter wrists and having the meaty parts of the palm and thumb bear the burden (when you can't put the bar under the knuckles...)
... just a suggestion...
Ride On
Yuri