First of all, keep in mind that I am unable to diagnose you because I am unable to examine you, this forum is for educational purposes.
The symptoms you describe are not specific for a single condition, but there are several likely possibilites. The atrophy, weakness and numbness in your hands indicates a lesion of the nerves somewhere between the spinal cord and the hand itself. The nerves can be injured in the roots as they exit the spinal cord (radiulopathy) often due to disc disease. They can also be damaged in the brachial plexus from the proximal neck to the clavicle. Finally, the nerves can be disabled as single nerve branches, such as the median, ulnar and radial, etc.) Common injuries of the terminal nerves include carpal tunnel syndrome (median nerve entrapment at the wrist), damage of the ulnar nerve at the elbow and entrapment of the radial nerve at the spiral groove of the humerous. Less commonly the ulnar nerve can be entraped at the wrist.
I would recommend an EMG (including paraspinal muscles) with nerve conduction studies (including proximal sites such Erbs point) to determine where you trouble is coming from. Depending on the results, you will likely need an MRI of your cervical spine for further evaluation for possible radiculopathy. It is odd to have carpal tunnel syndrome without pain (not impossible) especially since your symptoms include more advanced findings such as weakness and atrophy. Most people with carpal tunnel complain of severe wrist pain, mostly at night.
I hope this has been helpful.
starting with your left hand which could sound like an entrapment of the Ulnar nerve at the Guyon canal (in the wrist) except for the
1- numbness of the middle finger which is from the median nerve (a completely dfferent path/root of the brachial plexus)
2- Atrophy of the thumb extensor muscle, which is from the radial nerve(a partially different path of the Plexus)
3- having no pain and even no parathesia (pins and needles)as they indicate irritation of the nerve while numbness and atrophy more with heridiary problems
So you are beyond the ulnar nerve only from your history, and as you have numbness, that will eliminate some serious diseases of the spinal cord.
What should be ruled out
1- Thoracic outlet syndrom (syndrome) by a routine chest xray
2-Any compression of the lower part of the brachial pleaus(the gathering of the nerves in the neck)by a proper c-xray and MRI
3-At the same time look for a syrinx in the spine
4- Its less likely to be a root problem (the nerve coming out of the spine) in the lower part of the neck
About the rt hand, what you mentioned is not enough to point at CTS. We need to know more as does it wake you up from asleep, do u have to shake the hand to relieve the pain, what other situation could bring up the pain ..ext
But putting the entire detailes together it could be a one disease with liability of involving several nerves (those at a compression site)
In brief, you should be seen by a neurologist who is specialized in peripheral nerves diseas to put all these peaces together for localizing to the best or highest anatomical site
Bob
Thanks, RSR