Chronic inflammatory demyelinating polyneuropathy
CIDP is a rare autoimmune disease that affects the nerves. It causes sensory disturbances and muscle weakness, leading to absent or diminished deep tendon reflexes (in particular in the elbow, wrist, knee and Achilles’ tendon), which is called polyneuropathy (simultaneous malfunction of a large number of nerves throughout the body).
The symptoms progress:
- gradually, in 60% of cases (the condition becomes chronic);
- by exacerbations/relapses, in 30% of cases;
- in a single phase, followed by a permanent recovery, without relapse, in the remaining 10% of cases. This means that the disease appears only once and the patient recovers all his or her muscular capacities. The disease never reappears.
Symptoms usually develop over a period 8 weeks or more.
The main symptom is muscle weakness. The patient may complain of balance and coordination problems, difficulty walking, climbing stairs, or making more precise movements, such as putting a key in a lock, for example. The disease may also be accompanied by certain abnormal sensations, such as numbness in the limbs or tingling sensations. Reflex contractions (automatic contraction of certain muscles, to restore balance, for example) are no longer active.
These symptoms resemble those of Guillain-Barré syndrome (GBS) but develop over a longer period of time.
Causes and risk factors
CIDP is caused by the immune system malfunction: it mistakes myelin for a foreign body. Myelin is a component that surrounds the nerves and enables the nerve impulse that carries information to the muscles, to achieve its goal.
When myelin is damaged, the message carried by the nerve slows down or gets lost. The muscle may therefore never receive the signal.
The cause of this disorder is yet unknown. It could be linked to the presence of other diseases, such as inflammatory bowel disease, lymphoma, HIV, hepatitis C, melanoma, other connective tissue diseases, or even to organ transplantation.
CIDP can occur at any age but the onset is most common between ages 40 and 60.
The diagnosis is based first of all on the physical examination: loss of sensation, numbness, abnormal sensations, such as tingling, or pain, loss of reflexes, muscle weakness, difficulty walking, or foot drop (difficulty lifting the front part of the foot).
The diagnosis is confirmed by muscle examination (electromyogram (EMG)), which shows myelin degradation. For even greater precision, an electroneuromyogram (ENMG) can be used to study the slowdown of the nerve-to-muscle signal transmission.
In some cases, nerve biopsy or cerebrospinal fluid analysis may be carried out. Blood and urine tests can rule out other illnesses.
The differential diagnosis of CIDP includes ruling out the possibility of Guillain-Barré syndrome (GBS), the symptoms of which develop over a much shorter period of time, compared to those of CIDP.
There are three first-line treatments for CIDP.
Corticosteroids help reduce inflammation caused by the destruction of myelin by the immune system, and therefore rebuild muscle strength.
Immunoglobulins are natural antibodies obtained from healthy people. They can be injected intravenously (via infusion) or subcutaneously (using a pre-filled syringe with a short needle to prick under the skin). Immunoglobulins make it possible to modulate the immune system in the event of other treatments’ failure.
Plasma exchange, also called plasmapheresis, consists of removing some of the patient's blood and then reinjecting the blood cells without the plasma. This helps extract harmful antibodies from the blood.
In case of resistance to treatment, immunosuppressants may be considered, as they also help reduce inflammation.
Living with the disease
The disease prognosis is good. However, residual symptoms may persist after treatment, and affect the quality of life.
The follow-up care plan depends on the symptoms and the condition of the patient. The frequency of doctor's appointments may range from one appointment every three months to one appointment a year.
Healthcare professionals involved in the patient’s follow-up care are the patient’s GP, a neurologist and a physiatrist.