Labs and Diagnostic Tests for Chronic Pain

X-rays, MRIs, CT Scans, Blood Tests, and Nerve Tests

The medical community is full of tests to try to find the cause of pain or disease.  However, the real cause of your chronic, severe pain may be difficult to diagnose using labs and diagnostic tests.  It’s important to keep that in mind:  that even though there are many tools available to doctors today, there most likely won’t be a quick diagnosis of your pain.

Often, people who have undeniable pain don’t have anything “abnormal” show up on x-rays or in blood tests.  This doesn’t mean that their pain isn’t real.  Think of it this way:  for some people who have chronic pain, there is something wrong with how their nerves are transmitting messages.  We have yet to come up with a diagnostic test that can show these nerve problems.

Further complicating the chronic pain diagnostic process is that pain is a multi-faceted issue.  It’s the interaction of the nervous and your brain.  It can have a physical cause, but there are also emotional components to pain.  The body’s chemicals play a role, too.  With such a complex challenge, it’s understandable that there wouldn’t be one test that can accurately diagnose pain.

Therefore, the chronic pain diagnosis process can be long—and it can feel frustrating.  Try to stay patient with the diagnostic process, and as always, ask your doctor questions about the tests he or she is ordering.  You want to understand what tests you’re having done, why they’re being recommended, and what the results mean.

To help you navigate the chronic pain diagnostic process, we’ve put together basic explanations of the most common labs and diagnostic tests your doctor may order.

Imaging Tests
Imaging tests are also called radiological tests.  With these tests, the doctor uses different technologies to get a better picture of what’s going on in the body—with the bones, soft tissues, and organs.

Here are the most common imaging tests:

  • X-ray:  These show the doctor your bony structures so that he or she can look for any abnormalities.  For example, if the doctor suspects you have osteoarthritis in the knee, he or she may use x-ray to take a closer look at your joint.
  • CT scan:  A CT scan (which stands for computed tomography scan) is used to look at the soft tissues, as well as the bones.  On a CT scan, the doctor can see ligaments, for example.  For example, a CT scan can show a spinal herniated disc, which is a soft tissue.  Looking the CT, the doctor can see if the herniated disc is pushing on a spinal nerve or the spinal cord.
  • MRI:  Similar to a CT scan, an MRI (which stands for magnetic resonance imaging) shows the relationship between soft tissues and the bones.  Unlike CT scans, it doesn’t use radiation (x-rays) to do this; instead an MRI uses magnetic fields and computers to produce high-resolution images of your bones and soft tissues.

Other imaging tests are myelograms, bone scans, and ultrasounds.

Remember, the doctor may not be able to see anything as a cause of your pain on imaging tests.  Your structures may look completely normal—but that doesn’t mean you aren’t experiencing pain.

Nerve Tests
Nerve tests, which are part of the neurological exam process, can help your doctor see how well your nerves are working.  Especially in neuropathic pain—such as diabetic peripheral neuropathy—nerve tests can provide important information about your nerves.

Here are the most common nerve tests:

  • Electromyography test:  This test, frequently abbreviated as EMG, tests how well your muscles respond to signals from the nerves, helping your doctor understand if those nerves going to the muscles are damaged.  If they are damaged, then they won’t send clear messages to the muscles, and the muscles won’t respond well.
  • Nerve conduction velocity test:  This is abbreviated to NCV, and as suggested by the word velocity in the name, this nerve test measure how fast messages travel along the nerves.  Since damaged nerves don’t send signals as quickly, the doctor will be looking for messages that are slowed down.
  • Quantitative sensory testing:  That’s a very big phrase for a few very basic tests.  You have different nerves that transmit different messages—some transmit temperature messages and some send touch messages, for example.  The doctor may assess how well you can feel temperature changes; if you can’t feel the change from warm to cold, you may have a problem with your smaller peripheral nerves.

    Another test determines how much pressure you can feel, which tells the doctor how well your touch nerves are working.

    Also, the doctor may test your ability to feel vibrations.  The nerves that send the vibration message are larger peripheral nerves, and they are especially important for balance.

Blood Tests
In some cases, the doctor may want to have blood tests run on you.  For example, if he or she suspects that you have rheumatoid arthritis (RA), you may have blood work done to see if you have the rheumatoid factor in your blood.  That’s an antibody often produced in people who have RA, so a doctor may order a blood test to check for it as part of the diagnostic process.

Blood tests can also be used to check for levels of inflammation in the body—important if the doctor thinks you may have some type of arthritis.

Labs and Diagnostic Tests Conclusion
The two most important things to keep in mind as you have tests done are that most likely, no one test will be able to diagnose the exact cause of your pain, and that you should fully understand the labs and diagnostic tests you’re having.  Ask questions, especially about the results of the tests so that you understand how it impacts your care.

Updated on: 02/24/11