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Cubital Tunnel Syndrome
Cubital tunnel syndrome
is a condition brought on by increased pressure on the ulnar nerve
at the elbow. There is a bump of bone on the inner portion of the elbow
(medial epicondyle) under which the ulnar nerve passes. This site is
commonly called the “funny bone” (see
Figure 1). At this site, the ulnar nerve lies directly next to the
bone and is susceptible to pressure. When the pressure on the nerve
becomes great enough to disturb the way the nerve works, then numbness,
tingling, and pain may be felt in the elbow, forearm, hand, and/or
fingers.
Pressure on the ulnar nerve at the
elbow can develop in several ways. The nerve is positioned right next to
the bone and has very little padding over it, so pressure on this can put
pressure on the nerve. For example, if you lean your arm against a table
on the inner part of the elbow, your arm may fall asleep and be painful
from sustained pressure on the ulnar nerve. If this occurs repetitively,
the numbness and pain may be more persistent. In some patients, the ulnar
nerve at the elbow clicks back and forth over the bony bump (medial epicondyle)
as the elbow is bent and straightened. If this occurs repetitively,
the nerve may be significantly irritated. Additionally, pressure on
the ulnar nerve can occur from holding the elbow in a bent position
for a long time, which stretches the nerve across the medial epicondyle.
Such sustained bending of the elbow may tend to occur during sleep.
Sometimes the connective tissue over the nerve becomes thicker, or
there may be variations of the muscle structure over the nerve at the
elbow that cause pressure on the nerve. Cubital tunnel syndrome occurs
when the pressure on the nerve is significant enough, and sustained
enough, to disturb the way the ulnar nerve works.
Cubital tunnel syndrome symptoms
usually include pain, numbness, and/or tingling. The numbness or tingling
most often occurs in the ring and little fingers. The symptoms are usually
felt when there is pressure on the nerve, such as sitting with the elbow
on an arm rest, or with repetitive elbow bending and straightening. Often
symptoms will be felt when the elbow is held in a bent position for a period
of time, such as when holding the phone, or while sleeping. Some patients
may notice weakness while pinching, occasional clumsiness, and/or a tendency
to drop things. In severe cases, sensation may be lost and the muscles
in the hand may lose bulk and strength.
Your physician will assess the pattern
and distribution of your symptoms, and examine for muscle weakness, irritability
of the nerve to tapping and/or bending of the elbow, and changes in sensation.
Other medical conditions may need to be evaluated such as thyroid disease
or diabetes. A test called electromyography (EMG) and/or nerve conduction
study (NCS) may be done to confirm the diagnosis of cubital tunnel syndrome
and stage its severity. This test also checks for other possible nerve
problems, such as a pinched nerve in the neck, which may cause similar
symptoms.
Symptoms may sometimes be relieved
without surgery, particularly if the EMG/NCS testing shows that the pressure
on the nerve is minimal. Changing the patterns of elbow use may significantly
reduce the pressure on the nerve. Avoiding putting your elbow on
hard surfaces may help, or wearing an elbow pad over the ulnar nerve
and “funny bone” may
help. Keeping the elbow straight at night with a splint also may help.
A session with a therapist to learn ways to avoid pressure on the nerve
may be needed.
When symptoms are severe or do not improve, surgery may be needed
to relieve the pressure on the nerve. Many surgeons will recommend
shifting the nerve to the front of the elbow, which relieves pressure
and tension on the nerve. The nerve may be placed under a layer of
fat, under the muscle, or within the muscle. Some surgeons may recommend
trimming the bony bump (medial epicondyle). Following surgery, the
recovery will depend on the type of surgery that was performed. Restrictions
on lifting and/or elbow movement may be recommended. Therapy may be
necessary. The numbness and tingling may improve quickly or slowly,
and it may take several months for the strength in the hand and wrist
to improve. Cubital tunnel symptoms may not completely resolve after
surgery, especially in severe cases.
Ulnar Nerve at
elbow joint (inner side of elbow)
© 2007 American Society for Surgery of the Hand
Developed by the ASSH Public Education Committee
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National Institutes of Health
cubital, tunnel, syndrome, hand
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