Chronic Inflammatory Demyelinating Polyradiculoneuropathy: symptoms, diagnosis and similarities with other diseases

What is chronic inflammatory demyelinating polyradiculoneuropathy?

CIDP is a rare autoimmune disease that affects the nerves and may lead to loss of feeling (numbness) and muscle weakness, causing absence or reduction of deep tendon reflexes.

The prevalence of the disease is estimated to be around 5-7 cases per 100,000 individuals. It is a predominantly male disease. The average age of onset is about 50 years old, but the disease can also develop as early as at 8 or as late as at 80 years old.  

The symptoms are caused by an unexplained reaction of the immune system which attacks the body and targets the myelin, a protective coating, or sheath, around the nerves that allows the proper transmission of messages carried by the nerves to the muscles.

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How is chronic inflammatory demyelinating polyradiculoneuropathy diagnosed?

The diagnosis of CIDP is made after various examinations, including:

• clinical examination, during which the doctor can identify the symptoms that suggest the disease: sensory impairments, numbness, abnormal sensations such as tingling or pain in the body, loss of reflexes and muscle weakness (which worsens continuously over a period of 8 weeks and more), as well as difficulty walking or a foot drop (difficulty or inability to lift the front part of the foot);
• electroneuromyogram (ENMG), to look for signs of demyelination (breakdown of the myelin sheath);
• cerebrospinal fluid (CSF) analysis, which shows the presence of abnormal cells and an abnormal increase in protein levels;
• MRI scan, which provides a detailed image of the nerve structure and reveals myelin abnormalities;
• nerve biopsy may be useful to look for signs of demyelination and inflammation;
• blood tests, which can show the presence of different types of autoantibodies (molecules produced by the immune system that attack the body).

To establish the diagnosis, the doctor usually performs a differential diagnosis. It is a method of differentiating a disease from other conditions that have similar symptoms or characteristics.

What are the conditions that should be differentiated from chronic inflammatory demyelinating polyradiculoneuropathy?

There are two main types of cases to consider when diagnosing CIDP: acute inflammatory demyelinating polyradiculoneuropathy and other types of neuropathy.

Acute inflammatory demyelinating polyradiculoneuropathy

Acute inflammatory demyelinating polyradiculoneuropathy is otherwise known as Guillain-Barré syndrome (GBS).

The symptoms of Guillain-Barré syndrome are quite similar to those of CIDP: muscle weakness, numbness, etc.

This is because in the case of GBS myelin sheath is also destroyed by the immune system.

The main difference that allows to rule out GBS when diagnosing CIDP, is the delay of symptoms development. The symptoms of CIDP gradually worsen over a period of more than 8 weeks, whereas the weakness caused by Guillain-Barré syndrome worsens over a period of 3 to 4 weeks and then stabilises or begins to return to normal.

Other types of neuropathy

CIDP must be differentiated from the following diseases:

• POEMS (polyneuropathy, organomegaly, endocrinopathy, monoclonal gammopathy and skin abnormalities) syndrome: a syndrome that inconsistently combines demyelinating neuropathy, organ involvement, the presence of a particular immunoglobulin (immune system molecule) in serum and/or urine, and a single tumour (often located on a bone). The location of the demyelination is different in these two diseases, and tests can highlight these differences.
• Hereditary transthyretin amyloidosis: a genetic disease linked to the TTR gene in which toxic deposits occur in various organs including the nerves. The differential diagnosis is made because the symptoms are more intense than in CIDP and because of the sequencing of the gene involved. 
• Anti-MAG peripheral neuropathy: a demyelinating neuropathy like CIDP which has similar characteristics: increased protein levels on CSF analysis, MRI abnormalities. However, it is characterised by certain abnormalities on electroneuromyogram.
• Neurolymphomatosis: a disease in which there is an infiltration of lymphoma cells into the nervous system, which may have similarities with CIDP. CSF analysis will help identify the abnormal cells.
• Amyotrophic lateral sclerosis (ALS): it presents symptoms similar to those of CIDP: muscle weakness, difficulty walking, cramps, spasms, etc. Damage to the first motor neuron (neuron linking the brain to the spinal cord), damage to the limbs and trunk or significant respiratory impairments are elements in favour of the diagnosis of ALS.
• Multifocal motor neuropathy (MMN) with conduction block: it is important to differentiate between these two diseases because treatment of CIDP can be harmful in case of MMN. MMN can be characterised by its highly asymmetric nature (in CIDP, it is symmetric), the presence of anti-GM1 antibodies in the serum, and a normal or low level of protein in the cerebrospinal fluid (in contrast with CIDP, which has a very high level of protein in the CSF).
• Diabetes: Diabetes can cause demyelinating electroneuromyogram abnormalities that may be mistaken for CIDP.
• Charcot-Marie-Tooth disease (CMT): a hereditary neuropathy with which CIDP can be confused, but the absence of certain factors should rule out this diagnosis: family history, absence of mutations in the genes involved in this disease, etc.
• Metabolic diseases: MNGIE (mitochondrial neurogastrointestinal encephalomyopathy) and Refsum's disease are two diseases that can provoke neuropathy, but they are characterised by different symptoms than CIDP.

The diagnosis of chronic inflammatory demyelinating polyradiculoneuropathy requires specialist’s advice, either from a neurologist or a specialised clinic.

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