The use of the term trapped nerve is not commonly used by the medical establishment. They often will give you a diagnosis of compressed nerve, or even pinched nerve. Of course injury to your back, shoulder, wrist or neck can cause a trapped nerve, but such conditions as carpal tunnel syndrome mean that you have swelling of the joints found in your wrist, and thus you have numbness and pain in your hand because the swelling has trapped a nerve.
Trapped nerves are also caused by arthritis. This would present with the same symptoms but located elsewhere in your body. Prior to your receiving a diagnosis of your trapped nerve, your doctor may do quite a few tests. For instance, X-rays are frequently helpful, MRI scans may reveal soft tissue abnormalities in your anatomy, dye tests may be called for, and finally Electromyography (EMG) may be used to confirm nerve dysfunction due to a trapped nerve.
Depending on where the nerve is trapped you may feel numbness, and weakness of wherever the nerve leads, such as your feet, legs, arms, or hands. For example when your vertebrae become misaligned you may have a sciatica nerve being trapped. This type of trapped nerve is extremely common.
When this happens, sometimes visits to your chiropractor may clear the problem up eventually. By adjusting the alignment of your back, the chiropractor may finally release the trapped nerve, thereby obliterating the debilitating pain for you. When dealing with any back pain thought to be a trapped nerve, the chiropractic formula is greatly preferred to drug interventions or even worse, surgery. You will find that the pain goes away very gradually and thus it will take ample visits to your chiropractor.
Sciatica treatment sometimes goes further than needing adjustments by your chiropractor. For instance often a combination of treatments is called for. Thus you may receive not only chiropractic help, but muscle relaxers and anti-inflammatories as well. In addition to the anti-inflammatories, inflammation cause by swelling, arthritis or other back problems will also be treated with the application of ice. Once all these measures have been tried, if the trapped nerve is not helped, then surgery will be recommended, as a last resort.
Suffering some kind of injury to your body sometimes traps nerves. For example if you break a bone, during the healing process it sometimes happens that a nerve will become trapped between the healing bone structures. This may occasion additional surgery unfortunately if no other means work.
Occasionally, you may receive a diagnosis that due to enlarged tissues such as a tumor or a lymph node has compressed a nearby nerve and thus caused you your symptoms as well. In this case removal of the problem will require surgery of course, and so will you need to perform follow up treatments as well. This would be a rare case though.
Arm and shoulder trapped nerves may include circulation changes in your arm, such as blotchiness, blueness, or excessive sweating. Or you may feel weakness, numbness or pins and needles in addition to perhaps feeling pain.
If you're interested in more info you can read about trapped nerves here.