When I wake up in the morning, the inside of my elbow hurts. It doesn’t bother me during the day but it’s sure sore for the first hour or so. What could be causing this?

It could be the way you are sleeping at night. Bending the elbow while sleeping on your side can put a compressive force on the ulnar nerve as it passes through the elbow. Wearing a slip-on elbow support with the pad along the inside of the elbow may help.

If your symptoms are better in the morning, this could mean you have a mild nerve compression. Continuing to wear the elbow protection may be all that’s needed.

If your symptoms are unchanged, then there may be something else going on. If you develop more serious symptoms such as pain, numbness, or weakness, you may be experiencing a condition called cubital tunnel syndrome (CTS).

Cubital tunnel syndrome is the name of the condition that affects the ulnar nerve where it crosses the inside edge of the elbow. If it’s not caused by prolonged elbow flexion while sleeping, it may be caused by 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 your symptoms can help your physician 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, your physician can advise you as to the best treatment approach.