Guyon’s Canal Syndrome

Guyon’s Canal Syndrome

Guyon’s canal syndrome is a combination of symptoms that result from the compression of the ulnar nerve within the canal. Guyon’s canal syndrome is an example of ulnar nerve entrapment (pinched ulnar nerve) and ulnar neuropathy. Other names:

• Guyon’s tunnel syndrome
• Ulnar tunnel syndrome (not to be confused with cubital tunnel syndrome)
• Cyclist palsy
• Handlebar palsy

Symptoms

In Guyon’s canal syndrome either only sensitivity or only muscle strength or both can be affected ^8,9:

• Burning pain in the wrist, which can radiate up into the elbow, shoulder or neck; the pain is often worse in the morning (due to sleeping with bent wrists) and during moving the wrist
• Paresthesia: tingling (pins and needles) followed by numbness on the little finger’s side of the palm, in the little finger and the adjacent half of the ring finger
• Cold intolerance in the little and ring finger
• Clumsiness of hand, difficulty spreading fingers
• Early fatigue of the hand during repetitive hand work

Picture 1. Guyon’s canal syndrome — impaired sensitivity
NOTE: When tingling and numbness additionally extend toward the wrist or into the forearm,
the ulnar nerve is more likely affected in the elbow than in the wrist.

Signs

References: ^5,6,9,10

• Swelling and tenderness in the pinky side of the wrist
• Decreased sensitivity on the pinky side of the hand, in the pinky finger and adjacent half of the ring finger (only on the palmar, not on the back side of the hand)
• Positive Tinel’s sign in the ulnar nerve entrapment or injury — tapping over the ulnar nerve triggers pain or tingling in the wrist or the pinky side of the palm or in the pinky finger ^12,13,14.
• Positive Phalen’s sign: maximal bending (flexion) of the wrist (hands with their back sides put together, hands hanging down) for more than one minute results in paresthesia in the 4th and 5th finger ¹⁴.
• In case of ganglion cyst or tumor, there can be visible or palpable mass in the wrist.

An entrapment of the motor branch of the ulnar nerve may result in the following signs:

• Froment’s sign. Weak pinch strength because the muscle that moves the thumb toward the palm (musculus adductor pollicis) is affected. A doctor can ask a person to hold a piece of paper or a card between his or her thumb and index finger; when the doctor pulls the paper, the affected person is not able to hold it ^6,9.
• Wartenberg’s sign. A person fully extends all fingers with the palm facing down. Then he or she spreads all fingers and then he or she puts them together again. The inability to move the pinky finger close to other fingers speak for ulnar nerve palsy, but not specifically for the Guyon’s canal syndrome (so the site of nerve damage cannot be determined solely from this sign) ^4,15.
• Ulnar claw or bishop’s hand (clawing of the little and ring finger)
• Hypothenar atrophy (wasting of the muscles on the pinky side of the palm)
• Weak grip strength

Picture 2. Froment’s sign — impaired muscle strength
When a person with a damaged motor branch of the ulnar nerve tries to make a pinch,
he or she cannot move the thumb toward the palm, so he or she bends the last thumb joint instead.
NOTE: Individuals who have only the sensory branch of the ulnar nerve damaged will be able to make a normal pinch (no Froment’s sign).

Picture 3. Ulnar claw or bishop’s hand — impaired muscle strength
When a person with Guyon’s canal syndrome and a damaged motor branch of the ulnar nerve holds the hand passively, his or her 5th and 4th finger are in the “ulnar claw” position.

Complications of Guyon’s canal Syndrome

• Long-term pressure on the ulnar nerve may result in:
  • Permanent numbness of the ulnar side of the hand
  • Wasting of the hypothenar muscles in the hand and weakness of the grasp and pinch.

Causes

Common causes ^3,5,7:

• Idiopathic (no known cause), often associated with carpal tunnel syndrome
• Soft tissue tumors: lipoma, ganglion cyst, schwannoma
• Congenital anatomical anomalies: accessory muscles, congenital bands, bone abnormalities in the wrist and hand
• Overuse of the wrist:
  • Repetitive wrist movements (twisting): working with the hands bent downwards and outwards (assembly work, guitar playing, computer mouse use)
  • Pressure of gripping: cycling or weight lifting
• Repetitive trauma: using vibration power tools, such as a jackhammer

Other causes:

• Using crutches
• Fracture of the wrist bones (a golfer hits the ground; injury during baseball batting) or the end part of the radius bone
• Rheumatoid arthritis, systemic lupus erythematosus (SLE), systemic sclerosis and other causes of the inflammation of synovial sheet in the wrist
• Swelling after surgery ³
• Diabetes, hypothyroidism and alcoholism, which can cause peripheral neuropathy
• Thrombosis or aneurysm of the ulnar artery

Picture 4. Cyclist or handlebar palsy.
The handlebar pressing upon the ulnar nerve in the wrist
can cause pain in the wrist and numbness in the 4th and 5th finger.

Associated Disorders

The following disorders may be present together with Guyon’s canal syndrome:

• Carpal tunnel syndrome (tingling and numbness in the thumb, index and middle finger)
• Hypothenar hand syndrome (sudden swelling, pain and white discoloration of the pinky side of the hand after prolonged use of hand as a hammer)
• Cubital tunnel syndrome (tenderness in the elbow; paresthesia in the pinky side of the forearm and hand and in the pinky finger on both palmar and back side)
• Wartenberg’s syndrome ⁷

Differential Diagnosis

The following disorders need to be distinguished from Guyon’s canal syndrome ⁸:

• Cubital tunnel syndrome (tender elbow and forearm, numbness on the palmar and back side of the pinky finger)
• Thoracic outlet syndrome (pain in the shoulder, paresthesia in the arm, hand and fingers)
• Cervical disc disease (pain in the neck, paresthesia in the arm, hand and fingers; symptoms aggravated by moving the neck)
• Pancoast tumor in the lung
• Atherosclerosis or vasculitis (numb, white or blue fingers)
• Ulnar collateral ligament injury
• Guillain-Barre syndrome (numbness progressing from the fingertips to arms)
• Amyotrophic lateral sclerosis
• Primary bone tumors
• Peripheral polyneuropathy (stocking-gloves pattern)

Diagnosis

When the cause is obvious (bicycling, crutches) the diagnosis of Guyon’s canal syndrome can be made from symptoms and signs ⁵.

Investigations may include:

• X-ray or CT scan can show the wrist fracture.
• CT or MRI of the wrist can show soft tumors and ganglion cyst.
• Doppler ultrasonography or arteriography can reveal ulnar artery aneurysm or thrombosis.
• Electromyography (EMG) and nerve conduction tests can help determine the exact point of nerve entrapment.

Treatment

Conservative Treatment

• Wrist rest
• Wearing wrist splint (brace) in a neutral position at night or also during the day
• Physical therapy: massage and special exercises as instructed by a chiropractor or physiotherapist
• Over-the-counter (OTC) Non-Steroidal Antirheumatic Drugs (NSAIDs), such as aspirin and ibuprofen
• Oral vitamin B6 supplements for 6-12 weeks
• Steroid injections

The affected person can expect improvement of symptoms in four to six weeks after the onset of the conservative therapy ⁸.

Guyon’s Canal Release Surgery

The surgical procedure involves ⁹:

• Local anesthesia (the anesthetic injected around the surgical area), regional anesthesia (axillary block or wrist block) or general anesthesia
• Decompression surgery to release the ulnar nerve: cutting the ligament that covers the ulnar nerve (Picture 5), removing the cyst or tumor or correcting other abnormality in the wrist.

Surgical treatment of Guyon’s canal syndrome is effective in 60-95% cases. Possible complications of surgery: palmar hypersensitivity, persistent numbness, surgical wound infection, wound dehiscence.

Picture 5. Guyon’s canal release surgery
A surgeon cuts the skin on the palmar side of the wrist,
moves the underlying tissues to the side and cuts the palmar carpal ligament
and thus releases the underlying ulnar nerve.

Prevention

• Soft, padded gloves for cyclists are available
• Splints at night may prevent symptoms in people who sleep with bent wrists

• References

  1. Relevant Surgical Exposures, y.2008, p.11  (Anatomy)
  2. NIH.gov  (Ganglion cyst)
  3. PubMed  (Causes of ulnar tunnel syndrome)
  4. Wheelessonline  (Interosseous muscles in the hand)
  5. Orthobullets  (Ulnar tunnel syndrome)
  6. Inkling.com  (Decompression of the ulnar nerve)
  7. Orthofracs.com  (Examination of the hand)
  8. Physio-pedia.com  (Signs of ulnar nerve entrapment)
  9. Eorthopod  (Treatment)
  10. ICD9data.com  (Ulnar nerve lesion ICD codes)
  11. ICD9data.com  (Ulnar nerve injury ICD codes)
  12. Wustl.edu  (Tinel’s sign)
  13. PubMed Central  (Positive Tinel’s sign in computer users)
  14. FPnotebook.com  (Ulnar neuropathy at the wrist)
  15. Physio-pedia.com  (Wartenberg’s sign)