Ulnar Neuropathy of the Wrist and Elbow

Understanding Cubital Tunnel and Ulnar Tunnel Syndrome

Ulnar neuropathy
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Most people are probably familiar with carpal tunnel syndrome where impingement of the wrist (carpal tunnel) causes pain, tingling, and numbness primarily in the thumb, two adjacent fingers, and part of the palm.

A similar condition can take place on the other side of the wrist where impingement of the ulnar nerve causes a radiating pain or numbness in the pinky finger, ring finger, and edge of the hand.

This is called ulnar neuropathy which can be caused by two different conditions known as cubital tunnel syndrome and ulnar tunnel syndrome.

Understanding the Nerves of the Hand and Wrist

To understand why these syndromes occur requires a basic understanding of hand anatomy. The hand is made up of a complex network of nerves comprised of three main types: the radial, median, and ulnar nerves. Each of these nerves has a different function in the hand:

  • The radial nerve is responsible for sensation to most of the back of the hand as well as the straightening of the fingers.
  • The median nerve gives sensation to most of the thumb and first two fingers as well as providing flexion to the first two fingers and thumb.
  • The ulnar nerve is responsible for sensation to the pinky finger and part of the ring finger. It also flexes those fingers and allows you to fan your fingers apart.

The medical term "ulnar neuropathy" simply means that something is wrong with the ulnar nerve.

When this happens, it is usually the result of something pressing on the nerve (like when somehow hits your elbow and you feel that jarring pain down your arm).

As nerves travel from the spinal down the arm to the hand, they sometimes pass through tight spaces where they are more vulnerable to damage and compression.

The two most common places for ulnar nerve compression are the elbow and the wrist.

Cubital Tunnel Syndrome

The ulnar nerve (a.k.a. the "funny bone" nerve) originates from the spine and runs down the length of your arm. Cubital tunnel syndrome occurs specifically when the ulnar nerve is compressed at the elbow. 

Whenever the nerve is compressed at this level, any pain in the fingers and hand can be further aggravated by repeated flexion of the elbow (such as talking on the phone). These symptoms can sometimes be so profound as to wake you at night. It's not uncommon, in fact, for people to sleep with their elbows flexed to avoid the pain.

Cubital tunnel syndrome can also cause a radiating pain in the forearm and weakness in muscles of the hand. In severe cases, muscle atrophy and clawing of the hand can occur.

Ulnar Tunnel Syndrome

 Ulnar tunnel syndrome is caused by compression of the nerve at the wrist but at a different location than carpal tunnel syndrome, specifically, a narrow space called the Guyon's canal. Ulnar tunnel syndrome can be caused by repetitive jarring movements, such as hammering, or persistent pressure on the wrist, such as occurs when cyclists lean on their handlebars for prolonged periods of time.

In later stages, cubital tunnel syndrome can cause hand weakness due to atrophy or shrinkage of the hypothenar and interosseous muscles (muscles situated deep in your hand). In the most severe cases, atrophy can lead to clawing of the hand.

Diagnosis and Treatment

A physical examination is usually all that is needed to confirm a diagnosis of ulnar neuropathy. If the symptoms are severe and require more aggressive treatment, your doctor may order an electromyogram or nerve conduction studies.

Treatment for cubital tunnel syndrome and ulnar tunnel treatment are similar. The first aim is to relieve any inflammation that might be compressing the nerve.

This involves a combination of rest, proper mechanics, and supportive splinting. A pain reliever like ibuprofen may also be prescribed.

With that being said, there are several differences in how treatment is carried out:

  • With cubital tunnel syndrome, supportive splinting would involve maintaining flexion of the elbow at 45 degrees. The splint would either be worn continuously or only at night depending on the severity of symptoms. If conservative treatment fails, surgery may be used to decompress the nerve at the elbow level 
  • With ulnar tunnel syndrome, Supportive splinting would be similar to that for carpal tunnel syndrome, employing the use of a splint to keep the wrist from flexing. If conservative treatment fails, surgery may be used to decompress the nerve around the Guyon's canal. It might also involve the release of the transverse carpal tunnel ligament, which forms the roof of both the carpal tunnel and part of the ulnar tunnel.

If surgery is performed, a structured course of physical therapy would follow to regain strength and flexion of the elbow or wrist. Recovery can take up to 12 weeks.

Source

  • Bednar, M.; Light, T.; and Bindra, R. "Chapter 9. Hand Surgery". Current Diagnosis and Treatment in Orthopedics (5th edition). In: Skinner, H. and McMahon, P. eds. New York, NY: McGraw-Hill; 2014.

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