Guyon's canal syndrome refers to irritation or injury of the ulnar nerve as it courses through a tunnel called Guyon's canal in the wrist. This canal is located on the small finger side of the wrist. It is comprised of bone and ligament and is therefore rigid. The ulnar artery and ulnar nerve pass through Guyon's canal. The ulnar nerve provides feeling to the small finger and the side of the ring finger that faces the small finger. It also supplies many of the muscles of the hand.
The ulnar nerve may be injured by the transmission of external pressure or vibration to the nerve. Pressure may occur from placing the hand against a desktop while operating a computer mouse. Vibration may occur from operating power garden tools. A sudden impact may traumatize the nerve while catching a baseball.
Ulnar nerve irritation or injury may present with pain, numbness, or tingling involving the small finger side of the palm and the small finger and the side of the ring finger facing the small fingers. More serious ulnar nerve compression may be associated with hand grip weakness. Some of the muscles may shrink in size (atrophy) due to ulnar neuropathy. The most noticeable muscle atrophy involves the small finger side of the palm and the area of the hand between the thumb and index fingers.
Some simple physical exam tests can be done to help determine if a person has Guyon's canal syndrome. Tinel's sign is performed by tapping a finger tip over Guyon's canal. The Guyon's canal compression test is performed by placing finger pressure over Guyon's canal with the wrist slightly flexed (bent). Phalen's sign is performed by flexing (bending downwards) the wrist. These tests are considered positive for Guyon's canal syndrome if they result in precipitation or aggravation of pain and numbness radiating into the small finger and the side of the ring finger facing the small finger.
More specialized tests to confirm the diagnosis of Guyon's canal syndrome include injection of steroid and a local anesthetic (xylocaine) into Guyon's canal. Symptom relief after a Guyon's canal steroid injection supports a diagnosis of Guyon's canal syndrome.
Nerve conduction tests are a diagnostic test where an electrical stimulus is administered to the forearm above Guyon's canal. An electrode is placed around a finger of the hand, usually the small finger. The nerve conduction instrument measures the time it takes for the electrical stimulus to travel from the stimulating electrode in the forearm to the recording electrode attached to the finger. The electrical stimulus travels very fast through a normal nerve. However, the electrical stimulus travels more slowly though injured segments of nerve tissue. The magnitude and location of the conduction slowing allows determination of the severity and site of nerve injury.
Initial treatment includes avoiding pressure to the small finger side of the palm (ie, the ulnar side). NSAIDs (nonsteroidal anti-inflammatory drugs) such as ibuprofen can be used if there is no medical contraindication such as ulcer disease or concurrent use of blood thinning medications. A wrist splint with a rigid metal piece in the palm may be used to place the wrist in a "neutral" position and avoid repetitive wrist flexion/extension. A steroid injection into Guyon's canal is often effective in relieving pain and numbness.
Surgery can be done when symptoms persist despite nonsurgical treatment. Surgery consists an incision on the ulnar palm (small finger side of the palm). The ligament located over the ulnar nerve is cut to remove pressure on the underlying nerve. A wrist splint is worn for one week. Skin stitches are removed and the splint is discontinued one week after surgery. The hand should not be used for any strenuous activities for six weeks after surgery.
Surgery eliminates intrinsic pressure (ie, pressure inside the hand) on the ulnar nerve caused by the overlying ligament since the ligament is cut at surgery. But, surgery does not prevent injury to the ulnar nerve from extrinsic (ie, pressure on the outside of the hand) pressure caused by activities such as gripping. QwiTM Nerve Protection Gloves can help to prevent extrinsic pressure and vibration injury to the ulnar nerve.
It is important to distinguish between Guyon's canal syndrome (ulnar nerve irritation at the wrist) and cubital tunnel syndrome (ulnar irritation at the elbow since treatment is different for these two conditions.
QwiTM Gloves and the QwiTM Solution are effective for Guyon's canal syndrome, but will have no effect on cubital tunnel syndrome.
