Ulnar tunnel syndrome is caused by pressure on the ulnar nerve at the wrist. This nerve is found on the pinkie-finger side of the wrist.
Overuse or repetitive use of your hands or wrist may cause swelling or thickening of the tissues close to the ulnar nerve. Swelling from a ganglion can also affect the ulnar nerve. Bicycle riders may develop ulnar tunnel syndrome from holding on to the handlebars.