How Is Chronic Inflammatory Demyelinating Polyneuropathy (CIDP) Diagnosed?

Medically Reviewed by Christopher Melinosky, MD on May 12, 2023
Written by WebMD Editorial Contributors
2 min read

There’s no test to tell you if you have chronic inflammatory demyelinating polyneuropathy (CIDP). Its symptoms are similar to Guillain-Barre syndrome, but unlike GBS, those symptoms. If you’ve had symptoms including numbness, tingling, and weakness in your arms or legs for at least 2 months, it’s time to make an appointment with your doctor.

Your doctor will ask you about your health history, and they’ll want to know your symptoms, how long you’ve had them, and if you’ve had other problems like exhaustion. During the physical exam, they may check:

  • Your muscles for weakness
  • Your balance
  • Your reflexes
  • Your ability to feel sensations in your hands, feet, arms, and legs

Doctors use several different ones to help with diagnosis. They include:

Electromyography (EMG). This test examines how your muscles respond when your nerves are stimulated. With a needle EMG, a doctor will insert a very thin needle into your muscle, and a machine will record the muscle's activity. Another part of an EMG is a nerve conduction study. Nerve conduction studies use sensors called electrodes taped to the skin. These sensors measure how fast and strong signals travel between nerves. 

Spinal fluid testing (also known as a lumbar puncture). With this procedure, a doctor uses medicine to numb your back. Then they’ll insert a thin needle into your spine. The needle will take a small amount of spinal fluid, which is tested in a lab. If the test shows you have a lot of white blood cells, it could mean your symptoms are caused by an infection or disease that isn’t CIDP. However, it may suggest CIDP if protein levels are high and there is a normal cell count.

Nerve biopsy. This involves removing a small section of nerve in an outpatient surgery. Experts will examine it for inflammation, fiber changes, and other signs of CIDP. Nerve biopsy is often considered an important part of CIDP diagnosis. 

Blood tests. There’s no blood test for CIDP. Even so, your doctor may take your blood to check for other conditions and diseases that can cause nerve damage and similar symptoms. Type 2 diabetes, lupus, and Lyme disease can trigger numbness and weakness. 

Sometimes a doctor may not be sure you have CIDP, but they may start treatment. If it stops or improves your symptoms, that’s strong evidence to support a CIDP diagnosis.