Optimal Treatment for Cubital Tunnel Syndrome

In the case of cubital tunnel syndrome, one treatment does not fit all. So say surgeons from the Hand and Upper Extremity Surgery at the University of Pittsburgh after reviewing recent studies on the topic. They found that there are a number of different surgical approaches that all have good results.

Cubital tunnel syndrome is a condition that affects the ulnar nerve where it crosses the inside edge of the elbow. The symptoms are very similar to the pain that comes from hitting your funny bone. When you hit your funny bone, you are actually hitting the ulnar nerve on the inside of the elbow. That's where the nerve runs through a passage called the cubital tunnel. When this area becomes irritated from injury or pressure, it can lead to cubital tunnel syndrome.

Pressure on the nerve over time can also lead to muscle weakness and loss of forearm function. Imagine not being able to make a fist to hold a spoon or pick up a simple object like a cup of coffee. That can happen when cubital tunnel syndrome causes pain, numbness, and weakness.

Pressure or traction on the nerve can come from a variety of places. Part of the problem may lie in the way the elbow works. The ulnar nerve actually stretches several millimeters when the elbow is bent. Sometimes the nerve will shift or even snap over the bony medial epicondyle. (The medial epicondyle is the bony point on the inside edge of the elbow). Over time, this can cause irritation of the nerve.

Bending the elbow over and over, such as pulling levers, reaching, or lifting can lead to cubital tunnel syndrome. Constant direct pressure on the elbow over time may also contribute to the problem. For example, the nerve can be irritated from leaning on the elbow while you sit at a desk or from using the elbow rest during a long drive.

The ulnar nerve can also be damaged from a blow to the cubital tunnel. Other possible causes include an extra slip of muscle that crosses the nerve, a ganglion cyst, or a bone spur. Any of these extra anatomical structures can cause enough pressure to compress the neural tissue. Sometimes it's not even possible to tell what's causing the problem. These cases are called idiopathic, which means unknown.

A careful history and evaluation of the patient's symptoms can help the surgeon make an accurate diagnosis. A loss of sensation can be measured using special wires called monofilaments. The monofilaments are pressed against the skin with a certain amount of pressure. The patient reports whether or not the pinpoints of pressure are felt.

Muscle and nerve testing are also done. Tapping over the nerve can reproduce the symptoms. This is called the Tinel's sign. But a more accurate test is the elbow flexion test. The elbow is held in a position of elbow flexion for 60 seconds. This position compresses and irritates the nerve and sets off the symptoms. Applying pressure to the bent elbow increases the sensitivity of this test. Studies show that not pressing long enough or applying pressure for too long can result in false negative or false positive tests.

Imaging studies such as ultrasound or MRIs have their place in the diagnostic process. Ultrasound pictures can show the presence of tumors, extra muscle tissue, or nerve subluxation (nerve slips out of its tunnel). MRIs can show when the nerve (or a section of the nerve) is enlarged. Tumors, cysts, infection, or other lesions are also clearly seen on MRIs.

Once the diagnosis has been made, then the task of determining the best treatment approach begins. Nonoperative care may include antiinflammatory drugs, activity modification, and rest. It is important to stop doing whatever is causing the pain in the first place. Limiting elbow flexion is a key factor.

If the symptoms are worse at night, a lightweight plastic arm splint or athletic elbow pad may be worn while sleeping. This will help limit movement and prolonged periods of time with the elbow bent, thus easing nerve irritation. The elbow pad can be worn during the day to protect the nerve from the direct pressure of leaning.

Doctors commonly have their patients with cubital tunnel syndrome work with a physical or occupational therapist. Therapist gives patients tips on how to rest the elbow and perform activities without putting extra strain on the elbow. Nerve gliding exercises can be done to keep the nerve moving smoothly and reduce pressure from adhesions or soft tissue obstructions. Exercises are used to gradually stretch and strengthen the forearm muscles.

When conservative treatment fails to give patients the relief needed, then surgery may be considered. Almost 100 years of research on this topic has yielded the following results:

  • There are many different surgical procedures that work well for patients with minimal nerve compression. Moving the nerve and overlying muscle apart from each other (called submuscular transposition) is successful for moderate nerve compression. The jury is still out on the best way to approach a severe compression. There just isn't enough data to support one treatment over another.

  • Transposition helps relieve symptoms both from traction and from compression on the nerve.

  • Many studies have been done trying to find the best method of transposition. In the end, surgeons have concluded that it might be better to leave the nerve in its track and just release any adhesions or soft tissue strictures from around it. This procedure is called decompression in situ. There are fewer complications after a simple decompression, less scar tissue, and equal results in terms of symptom resolution.

  • Nerve transposition can be helpful when the nerve subluxes (pops out of its groove) or when previous surgery has failed and a revision (second) surgery is needed.

    The results of many studies show that there's no reason to do a nerve dissection and transposition if the outcomes are just as good with simple decompression. Doing a medial epicondylectomy (shaving off the bump of bone along the inside elbow) has just as good of results as transposition and is recommended instead. The surgeon uses caution to take just the right amount of bone off to avoid elbow instability.

    Besides changing their thinking on when and how often to do transposition, researchers have also helped surgeons move from open incision to minimally invasive endoscopic procedures. With a much smaller incision and the use of a scope to see inside the elbow area, surgical techniques are continually refined and improved.

    Future studies are needed to assess the long-term effects of minimally invasive in-situ decompression for cubital tunnel syndrome. Differences between treatment methods may be easier to see when the results are compared over a longer period of time.

    References: Sohail N. Husain and Robert A. Kaufmann. The Diagnosis and Treatment of Cubital Tunnel Syndrome. In Current Orthopaedic Practice. September/October 2008. Vol. 19. No. 5. Pp. 470-474.