5 Things to Know About Chronic Inflammatory Demyelinating Polyneuropathy

Ariel Harsinay

Disclosures

September 20, 2019

Chronic inflammatory demyelinating polyneuropathy (CIDP) may be a rare disease, but it is one of the most common forms of neuropathy and the most common form of chronic autoimmune neuropathy. Roughly 30,000 Americans are currently diagnosed with CIDP. Unlike many other neuropathies, CIDP is treatable, but its similarities with other nerve disorders often make it extremely difficult to diagnose. Here are five things to know about CIDP.

1. CIDP is an autoimmune disorder that attacks the peripheral nervous system.

CIDP is an autoimmune, neurologic condition in which the myelin sheath surrounding the axons of neurons is attacked by the immune system, causing demyelination. Myelin normally serves as axonal insulation, allowing neurons to rapidly transmit action potentials and communicate with neighboring neurons. The demyelination seen in CIDP impairs this process, resulting in motor impairment, numbness, difficulty walking, and general weakness and fatigue.

The immune response causing CIDP involves the activation of T cells as well as the expression of cytokines, tumor necrosis factor, interferons, and interleukins. Immunoglobulin and complement are also implicated in CIDP pathogenesis.

2. CIDP presentation can vary considerably.

Fifty to sixty percent of CIDP cases are so-called "typical," presenting with symmetric symptoms of both proximal and distal limbs in which motor impairment is more prominent than sensory symptoms. A diagnosis requires that a patient's symptoms have progressed gradually for at least 8 weeks, although some patients present with either acute or relapsing-remitting forms of the disease. While CIDP symptoms can usually be managed throughout life, long-term disability is not uncommon.

Some 20%-30% of CIDP cases are idiopathic, although it is frequently seen in conjunction with a variety of other illnesses,including HIV, diabetes, lupus, hepatitis, lymphatic cancer, and restless legs syndrome. It also may present as a comorbidity of infection or as a side effect of various cancer and HIV drugs.

CIDP can affect anyone but is most commonly diagnosed in individuals in their 50s and 60s and is twice as common in men. The global yearly incidence of the disorder is 1.5-3.6 million, with around 30,000 people affected in the United States at any given time. In patients with type 2 diabetes the incidence rises to over 26%.

3. A variety of tests can confirm a CIDP diagnosis.

Nerve conduction studies and electromyography are diagnostic standards in CIDP they; can reveal the demyelination and resulting slowed neuromuscular transmission characteristic of disease. Nerve biopsy can also be helpful, providing pathologic evidence of nerve damage and inflammation.

Often physicians will also order a lumbar puncture in suspected CIDP cases, looking for elevated spinal fluid protein without elevated white cells. In atypical cases, in which electrophysiologic tests may be inconclusive, MRI can help confirm a diagnosis. Blood tests may also be used to detect common comorbidities such as diabetes and lupus.

4. Distinguishing CIDP from other nerve-related disorders can be difficult.

CIDP is often conflated with other nerve disorders, most commonly Guillain-Barré syndrome (GBS). While CIDP and GBS are closely related, they have several clear distinctions. Unlike CIDP, GBS typically occurs after an infectious illness, disappearing soon after treatment of the infection. Therefore, GBS-associated morbidity tends to be shorter than that seen in CIDP. That said, those with untreated GBS may go on to develop CIDP.

CIDP can also look like other chronic demyelinating neuropathies—including diabetic polyneuropathy, multifocal motor neuropathy, and distal acquired demyelinating symmetric neuropathy—as well as a number of genetic disorders, like transthyretin familial amyloid polyneuropathy and Charcot-Marie-Tooth disease.

5. CIDP relies on treatment methods that are commonly used to treat other autoimmune disorders.

Early diagnosis and treatment of CIDP is critical in preventing severe nerve damage, with roughly 30% of those who do not receive treatment eventually requiring a wheelchair.

The gold standards in treating CIDP are plasma exchange, intravenous immune globulin (IVIG), and corticosteroids.

In the case of CIDP, plasma exchange lowers levels of antibodies and inflammatory factors that may be contributing to nerve damage. Studies suggest that the treatment is effective in up to 80% of patients.

IVIG is a blood product composed of concentrated antibodies from donors. It is used to mitigate an individual's immune response and works in over 60% of people with CIDP. While beneficial in both progressive and relapsing forms of the disease, IVIG has been shown most effective in those who have had symptoms for less than a year and in those presenting with acute symptoms.

Corticosteroids such as prednisone are commonly used as a treatment for CIDP, often in combination with IVIG, to impede the body's immune and inflammatory response. Steroid therapy leads to symptom improvement and remission in over 60% of patients.

As for non-drug treatments for CIDP, physical therapy, aerobic training, and resistance training are often recommended by physicians and can help combat fatigue and improve muscle strength. Both aerobic training and resistance training have been shown to improve strength and overall fitness in those with CIDP.

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