Pain, numbness, and tingling in the wrist and hand are common features of compression neuropathies like carpal tunnel syndrome (CTS) and radial tunnel syndrome. These are problems that develop when nerves in the wrist or forearm get pinched or pressed.
Carpal tunnel syndrome is often diagnosed quickly and easily because there are well-known tests that reliably and accurately point to compression of the median nerve as it passes through the bones of the wrist that form what is called the carpal tunnel.
But with radial nerve syndrome, there are no definite tests that prove the patient has radial nerve compression. The surgeon must rely on patient report and clinical findings to make the diagnosis.
For example, elbow pain along the outside of the elbow is typical with radial tunnel syndrome. There is often tenderness with palpation of the common extensor muscles just below the bump on the outside of the elbow. That bump is called the lateral epicondyle. But patients with pain at this place don’t always have radial tunnel syndrome. And people with radial tunnel syndrome don’t always have pain or tenderness there.
Surgeons rely on several other tests to help identify radial tunnel syndrome as the problem. The first is the forearm and finger extension test. The patient attempts to turn the palm up with the elbow extended (straight), a motion called supination. At the same time, the examiner resists the movement. The test is considered positive if there is pain with resistance. Another resistive test involves asking the patient to extend the middle finger. Pain with resistance to this movement is another sign that the radial nerve is entrapped somehow.
With carpal tunnel syndrome, the orthopedic surgeon can order electrophysiologic tests to confirm the diagnosis. A delay in the speed or signal along the nerve to the muscles suggests the median nerve is compromised. But with the radial nerve, electrophysiologic tests are almost always normal even when there’s a problem.
Imaging studies such as X-rays or magnetic resonance imaging (MRIs) have not proven helpful unless there is an obvious bone spur or abnormal anatomy causing nerve compression. The number of those cases is small compared to the total number of patients with radial tunnel syndrome.
Like electrophysiologic testing, imaging studies just don’t clearly verify this disease process in the majority of patients. And that’s probably why your diagnosis was difficult and delayed.