Sane Treatment of a Crazy Bone
Gary E Cordingley, MD, PhD
The "funny bone" can be decidedly unfunny when the ulnar nerve is pinched or
injured at the elbow.
Do you remember what it felt like when you banged your elbow on a hard surface and it sent shocks through your
forearm and into your little finger? Not too pleasant, to be sure. But on the plus side, the unpleasantness was
merely temporary and, for the time being, you remembered not to do that again.
The part of the nervous system responsible for this annoying symptom is the ulnar nerve, a peripheral
nerve-bundle whose individual nerve-fibers originate in the spinal cord where it passes through the neck. The
nerve-fibers run most of the length of the arm, including through the "ulnar groove" which you may know as the
"funny bone" or "crazy bone."
Some people experience a more persisting impairment of the ulnar nerve called ulnar neuropathy. With "-pathy"
as the medical suffix meaning illness or impairment, an "ulnar neuropathy" means an illness or impairment of the
ulnar nerve. The ulnar nerve is vulnerable to injury or pinch in the ulnar groove for more than one reason. First,
instead of being surrounded by soft, cushioning muscles and tendons, it is sandwiched between a layer of skin on
its exterior surface and nothing but hard bone on its interior surface. Second, when the elbow bends, the ulnar
nerve stretches because it has to take the long way around the elbow.
Like a telephone cable containing numerous wires, the ulnar nerve-bundle contains many individual nerve-fibers,
some of which tell the muscles what to do and others of which carry messages back to the spinal cord and brain
about sensations experienced by the skin and other tissues. So when the ulnar nerve is injured, both motor and
sensory symptoms are possible. Most of the muscles of the hand receive their marching orders via the ulnar
nerve, so when the ulnar nerve is out of whack, there can be weakness in hand muscles. The muscles that
spread the fingers and those that straighten the middle joints of the ring and little fingers are often affected.
Damage to the ulnar nerve also causes changes in sensation. The ring and little fingers can become numb, and
so can the heel of the hand.
The ulnar nerve can come to harm in more than one way. For some people the problem might result from leaning
on their elbows too much. This can compress the ulnar nerve within the ulnar groove. Granted, many people lean
on their elbows without damaging their ulnar nerves, but like most things in medicine, an ulnar neuropathy is
usually caused by a combination of factors, and it is likely that some people are more vulnerable than others
based on their particular anatomies. Of course, rearranging one's anatomy, as for example from a preceding
elbow fracture, may also put one at risk for an ulnar neuropathy.
Another way to injure the ulnar nerve is by over-stretching it. In the author's clinical practice a thin, young lady
with loose elbow-joints who worked as an emergency medical technician injured her ulnar nerves repeatedly while
lifting heavy patients. For her, it was a problem that wouldn't go away, and she eventually changed professions.
Although, as discussed, the ulnar nerve at the elbow is especially vulnerable to injuries, it can also come to harm
by getting compressed or pinched by nearby abnormal tissues. The usual culprits are tendons, ligaments, blood
vessels, cysts and scars.
Sometimes, an ulnar neuropathy is the leading symptom of a "polyneuropathy," meaning that all the peripheral
nerves in the body are somewhat impaired, but the ulnar nerve is the first one to cause symptoms noticeable to
the affected individual. Polyneuropathy is not the result of injury, but can be seen in a variety of illnesses,
including diabetes, alcoholism and also on an inherited basis.
Diagnosing an ulnar neuropathy starts with the story of the symptoms and a physician's examination. The
physician might subsequently order nerve conduction testing which looks at the nerve and muscle electricity, and
can determine the degree of impairment. Moreover, nerve conduction studies can also evaluate other nerves to
see if the ulnar nerve is the only one impaired, or merely one of many.
What if a simple injury to the ulnar nerve at the elbow is diagnosed? What can be expected? Fortunately, the
peripheral nerves have some capacity to heal themselves. So if the degree of nerve impairment is not too severe,
conservative treatment is called for. Unfortunately, there are no conservative treatments that have been studied
by good, randomized, controlled trials, a form of evaluation in which the outcome of a treated group of patients is
compared to that of an untreated group. Randomized, controlled trials are the gold standard for deciding whether
or not a treatment is effective, so in this case all we have to go on is "clinical judgment" and observation.
A typical conservative treatment consists of putting a sport-pad (not a medical brace) on the elbow with the foam
covering the ulnar groove. This accomplishes two things. First, if the elbow gets leaned on, then the nerve is still
protected. Second, a well-fitting pad also prevents excessive elbow-bending (including during sleep) that
overstretches the nerve and re-injures it. In addition, eating nutritious, well-rounded meals, together with vitamins,
gives the ulnar nerve the building-blocks it needs in order to make the best possible recovery.
If the nerve injury is severe, or fails to respond to conservative treatment, then surgery might be beneficial. When
the nerve is tied up in scar tissue or compressed by nearby abnormal tissues, a simple release operation might
suffice in which the nerve is freed up. Otherwise, in a procedure called "anterior transposition" the nerve is
transferred out of the ulnar groove so it is out of harm's way from leaning on the elbow, and also gets to take to
the short way around when the elbow is flexed.
Neurosurgical researchers at Radboud University Nijmegen in The Netherlands conducted a randomized,
controlled trial of patients with ulnar neuropathy at the elbow in which half the patients received simple release
surgery and the other half received anterior transposition. In this study there was no difference in outcomes
between the two surgeries. About two-thirds of the patients in each group obtained an outcome that was
considered either excellent or good. However, there were more complications in the patients receiving the
anterior transposition procedure, so the results of this study favored the simple release approach.
(C) 2005 by Gary Cordingley