CIDP is a rare autoimmune condition of the peripheral nervous system. As many as 650 people are diagnosed with CIDP each year in the UK.
- It has several different forms which vary in
- It is not hereditary or infectious.
- It is not a ‘nervous’ or psychiatric condition.
- It can start at any age and is slightly more common in men than women.
CIDP is closely related to Guillain-Barré syndrome (GBS), and is only distinguished from GBS by its pattern of progression. In GBS the low point is reached within four to six weeks whereas in CIDP the initial progressive phase lasts longer, usually much longer.
Some patients with CIDP develop weakness acutely in much the same way as patients with GBS but instead of stabilising and then improving they go on to get worse for several months. This slowly progressive course points to the real diagnosis of CIDP.
Paraproteinaemic demyelinating neuropathy (PDN) is sometimes described as:
- chronic demyelinating neuropathy associated with a benign paraprotein;
- CIDP associated with paraprotein;
- CIDP with paraproteinaemia
Antibody-producing bone marrow cells go out of control and produce large numbers of the same antibody. The antibody (or immunoglobulin) sometimes damages nerve fibres causing peripheral neuropathy. Some doctors regard the clinical, electrophysiological and pathological features of the demyelinating paraproteinaemic neuropathies and of CIDP as closely similar and almost indistinguishable.
These neuropathies are usually late-onset in terms of age and are mixed motor and sensory, although the severity of sensory loss tends to be greater compared with CIDP. So there is usually more pain but less severe weakness and impairment.
Most patients respond to corticosteroids, cytotoxic drugs, or plasma exchange.
Multifocal motor neuropathy (MMN) or MMN with conduction block (MMNCB) is sometimes thought of as a rare variant of CIDP. However, there are differences that are more prominent than the similarities. MMN patients commonly have asymmetric weakness of the distal (far) muscles, while in CIDP, proximal (near) symmetric weakness is more common. The remitting and relapsing course that may occur in CIDP is uncommon in MMN. Patients with MMN rarely have significant sensory symptoms, unlike CIDP. Increased protein level in the cerebrospinal fluid of MMN patients is rare. Treatment with IVIg or cyclophosphamide is usually effective.
Lewis-Sumner syndrome is also known as MADSAM — multifocal acquired demyelinating sensory and motor neuropathy. It is a chronic condition with similarities to multifocal motor neuropathy but with enough differences, especially in treatment, to have acquired its own definition. Some report it to be an assymetrical variant of CIDP. MMN and MADSAM respond to IVIg. Some MADSAM sufferers respond to prednisolone whilst most MMN sufferers do not.
Chronic axonal neuropathies are common, particularly as a result of diabetes or alcoholism. However, the medical literature does report cases of immune-mediated chronic axonal neuropathy though there are suggestions that this is a secondary result of myelin damage that ultimately appears to be the primary cause of the condition.
Sub-acute inflammatory demyelinating polyradiculoneuropathy (SIDP)
GBS is defined when the nadir (worst point) occurs within four weeks of first symptoms. Usually it is much less. CIDP is defined when the nadir comes after eight weeks. Usually it takes much longer. An illness peaking after four weeks but before eight weeks may be called subacute and will be treated as CIDP or GBS depending on which it best resembles.