Ulnar tunnel syndrome, also known as Guyon's canal syndrome or Handlebar palsy, is caused by entrapment of the ulnar nerve in the Guyon canal as it passes through the wrist. Symptoms usually begin with a feeling of

pins and needles ''Pins and Needles'' (1937) is a musical revue with a book by Arthur Arent, Marc Blitzstein, Emmanuel Eisenberg, Charles Friedman, David Gregory, Joseph Schrank, Arnold B. Horwitt, John Latouche, and Harold Rome, and music and lyrics by Rome. ...

in the ring and little fingers before progressing to a loss of sensation and/or impaired motor function of the intrinsic muscles of the hand which are innervated by the

ulnar nerve In human anatomy, the ulnar nerve is a nerve that runs near the ulna bone. The ulnar collateral ligament of elbow joint is in relation with the ulnar nerve. The nerve is the largest in the human body unprotected by muscle or bone, so injury is ...

. Ulnar tunnel syndrome is commonly seen in regular cyclists due to prolonged pressure of the Guyon's canal against bicycle handlebars. Another very common cause of sensory loss in the ring and pink finger is due to ulnar nerve entrapment at the

cubital tunnel The cubital tunnel is a space of the dorsal medial elbow which allows passage of the ulnar nerve around the elbow. It is bordered medially by the medial epicondyle of the humerus, laterally by the olecranon process of the ulna and the tendinous arc ...

near the elbow, which is known as

cubital tunnel syndrome Ulnar nerve entrapment is a condition where the ulnar nerve becomes physically trapped or pinched, resulting in pain, numbness, or weakness, primarily affecting the little finger and ring finger of the hand. Entrapment may occur at any point from ...

Causes

While being idiopathic in some cases, causative factors of the ulnar tunnel syndrome include tumors, ganglion cysts, repetitive use, anatomical variations, and diseases of the neighboring blood vessels (thrombosis or aneurysm of the ulnar artery).

Diagnosis

Classification

Ulnar tunnel syndrome may be characterized by the location or zone within the Guyon's canal at which the ulnar nerve is compressed. The nerve divides into a superficial sensory branch and a deeper motor branch in this area. Thus, Guyon's canal can be separated into three zones based on which portion of the ulnar nerve are involved. The resulting syndrome results in either muscle weakness or impaired sensation in the ulnar distribution. Zone 2 type syndromes are most common, while Zone 3 are least common.

Treatment

Initial line of treatment is with anti-inflammatory drugs or cortisone injections. There have been trials with gloves which help protect the ulnar nerve from compression. The most radical treatment option is surgery to relieve tension in the volar carpal ligament which forms the roof of Guyon's canal, thereby reducing compression on the ulnar nerve.

Causes

Diagnosis

Classification

Treatment

See also

References

Further reading