Why Aren't My CIDP Treatments Working? Could It Be CMT?

If you were diagnosed with Chronic Inflammatory Demyelinating Polyneuropathy (CIDP) but treatments like IVIG or steroids aren’t working after a few months, it is possible that you actually have Charcot-Marie-Tooth (CMT) disease ^[1][2]. CIDP is an autoimmune condition that typically improves with immune-suppressing therapies, while CMT is a genetic condition that does not ^[3][4].

It is important to note that a lack of response might simply mean you need a different type of CIDP medication. However, because the two conditions can look nearly identical on initial nerve tests, it is not uncommon for CMT to be mistakenly diagnosed as CIDP ^[5][6]. If your current immunotherapy is not providing objective improvement, it is a major red flag that should prompt your medical team to review the diagnosis and consider genetic testing ^[1][6].

Why Are CIDP and CMT Easily Confused?

Both CIDP and certain types of CMT (specifically demyelinating CMT or CMT1) damage the protective coating around your nerves, called myelin ^[5]. When myelin is damaged, nerves cannot send electrical signals efficiently. Because both conditions affect myelin, they share several overlapping features that can confuse even experienced neurologists:

• Similar Nerve Tests: Standard nerve conduction studies (NCS) will show slowed electrical signals in both diseases ^[5].
• Spinal Fluid Proteins: A common test for CIDP looks for high protein levels in the cerebrospinal fluid (CSF). While high protein is a hallmark of CIDP, certain types of CMT can also cause elevated CSF protein, making it an imperfect way to tell the conditions apart ^[7].
• Similar Symptoms: Both cause weakness and numbness in the hands and feet.

Key Differences Between CIDP and CMT

While they look similar at first glance, important differences emerge when doctors look closer:

• Treatment Response: CIDP is an acquired autoimmune disease that usually improves with treatments like intravenous immunoglobulin (IVIG), corticosteroids, or plasma exchange, often within weeks to a few months ^[1]. CMT is a genetic disease that does not respond to these immune therapies ^[3][8].
• Nerve Damage Patterns: On nerve conduction tests, the nerve damage in CMT is typically uniform and symmetrical, meaning signals are slowed down evenly across all nerves ^[9][10]. In contrast, CIDP usually causes patchy or multifocal damage, with irregular slowing and “conduction blocks” (areas where the signal stops completely) ^[11][12].
• Physical Signs: CMT often causes physical changes that develop over many years, such as very high arches (pes cavus) or curled toes (hammertoes), which are rarely seen in CIDP ^[5][13].
• Onset and Timeline: CMT usually begins insidiously in childhood or adolescence and progresses very slowly ^[3]. CIDP typically appears more suddenly in adulthood and progresses over at least 8 weeks ^[5].

Steps to Take if Treatments Are Failing

If you have been diagnosed with CIDP and are not improving on standard therapies, you have the right to ask for a diagnostic review.

• Ask for Genetic Testing: Identifying a specific genetic mutation is the most definitive way to confirm CMT. This can save you from the side effects of unnecessary immune treatments ^[6][14]. Keep in mind that a negative genetic test does not 100% rule out CMT, as some rare genetic causes have not yet been discovered.
• Request Advanced Imaging: Specialized tests like nerve ultrasounds or MRI can help. In CIDP, nerves often look unevenly swollen, while in CMT, nerve thickening tends to be even and widespread ^[15][16].
• Review Your Family History: Tell your doctor if anyone in your family has high arches, “clumsiness,” or undiagnosed nerve issues, as CMT is inherited ^[17]. However, some cases of CMT are new mutations, so a lack of family history does not rule it out ^[18].
• Seek a Specialist: If your current doctor is dismissive of genetic testing or re-evaluating your diagnosis, consider getting a second opinion from a neuromuscular specialist.

While realizing you might have a genetic condition rather than an autoimmune one can be daunting, a correct CMT diagnosis is not a dead end. Instead of immune therapies, management focuses on targeted physical therapy, specialized orthotics (like leg braces), and connecting with a multidisciplinary care team to protect your mobility and independence.