A pinched nerve is the result of external pressure on the nerve; the nerve is structurally intact, but the pressure interferes with the conduction of signals through the nerve fibers. The pressure on the nerve can come from surrounding anatomical structures, or it can be postural (leaning on your elbow can pinch the nerves there and cause temporary hand numbness). Treatment for pinched nerves consists of relieving the pressure on the nerve through postural changes, anti-inflammatory medication to reduce soft-tissue swelling, and/or surgery to remove compressing structures such as bone overgrowths. Recovery can take weeks or months but is usually complete unless the pressure has resulted in permanent damage to the nerve cells.

In severed nerves, the nerve fibers have been completely disrupted. No signals can pass through a severed nerve, and until fairly recently it was thought that severed nerves could not be repaired. However, it turns out that much of this difficulty is the result of scar tissue bridging the gap in the nerve fibers and preventing healing of the nerve. Severed peripheral nerves are now commonly reconnected using microsurgical techniques (as with amputated limbs). Severed spinal cords have been treated in animals with varying degrees of success, possibly leading to successful treatment of severed spinal cords in humans in the next few years.

A pinched nerve is caused when a nerve is somehow damaged or injured by direct pressure or compression and is unable to properly conduct its signal.

Severed nerves on the other hand are nerves that are unable to conduct signal totally due to a cut or total occlusion.