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Intravenous immune globulin (IVIG) has also been found to be beneficial. IVIG is usually given in divided doses over 4 or 5 consecutive days. Maintenance doses are often needed at variable intervals to maintain clinical response. Serious side effects of IVIG treatment are rare (fatal anaphylaxis in IgA-deficient patients; potential nephrotoxicity, especially in patients with pre-existing renal disease).

Those patients who do not respond to IVIG can be tried on Plasmapheresis. Other treatments that a doctor can prescribe are Cytotoxic eg (Imuran, Cyclosporin). Steroids can also be used .

The clinical diagnosis is based on a criteria which was set out by an American committee in 1991. It is a progressive or relapsing neuropathy and the progressive phase lasts for more than two months. There is no clear antibody test to prove the diagnosis, and it is reached by the following methods:-

• Nerve conduction tests
• Blood tests (to exclude things like diabetes, B12    level, which may mimic or even cause it)
• X-rays to ensure there is no underlying inflammatory reason, or even cancer
• Spinal fluid testing because the protein is usually raised in CIDP
• Careful family histories, as hereditary neuropathy can mimic CIDP

Nerve biopsies are not usually necessary.

There are many different types of GBS and 3% of patients have recurrent attacks. There is also a form where onset develops over a period of four weeks or so and a sub-acute type that develops over 4-8 weeks. CIDP is only named if it progresses very chronically. It is usually symmetrical and affects both the motor and sensory nerves, but there are many different sorts of CIDP and a type known as MADSAM (multifocal acquired demyelinating sensory and motor neuropathy) is very asymmetrical and involves different nerves. CIDP is usually motor, but is sometimes just sensory. A purely motor form, known as MMN (multifocal motor neuropathy) is a separate condition where conduction is not slow, but actually blocked at multiple sites.

The cause of CIDP is that its a autoimmune disease triggered by infections, toxins, vaccination, injury.  Antibodies to gangliosides have been found in only a small number of patients. It is believed to be an auto-immune condition as it has been found to resemble an experimental chronic auto-immune neuritis, but also because it responds to immuno suppression.

A study involving 40 patients with CIDP was looked at, with the following results:-

• More men than women were affected (as in GBS)
• Mainly middle age and elderly people were affected, and it was rare in children
• Preceding infections were only documented in 25% of patients (much more common in GBS)
• There were no examples of it being triggered by immunisations
• There were no examples of it being triggered by cytomegalovirus

Antibodies to various different myelin proteins have been looked at and Carolyn Gabriel produced a test for antibodies to a protein known as "PMP22", showing it to be positive in 41% of patients with CIDP. This is so far the closest they have got to finding antibodies consistently to any particular antigen and could be part of the story. More recently, the Sydney Group has shown antibodies to another protein, known as "PO", in 28% of patients. This is yet to be confirmed, but it is now possible to look for cell responses to those two proteins, though the jury is still out as to whether they are really responsible.

CIDP is usually treatable the first line of treatment is IVIG if a patient does not benefit from IVIG then the physician should consider other treatments like plasmaphersis or steroids, cyclosporon, avonex, enbral.

For those with multi-focal neuropathy with conduction block the rules for treatment are different. Those patients get worse with steroids and do not do very well with plasma exchange, but do respond well to IVIg.

Some patients with CIDP have a para-protein in the blood, which is an abnormal protein produced by the bone marrow. These patients may respond to CIDP treatments, but may also require treatment for the para-protein.

To conclude, CIDP is a very variable condition. It is almost certainly auto-immune and is treatable. It is exceptional for CIDP not to respond to at least one of the available drugs. The first choice of treatment is either prednisolone or IVIg. The diagnosis is difficult, much less so than GBS, depending critically on the nerve conduction studies and neuro-physiologies. Trials for immuno-suppression are badly needed to find out which of these drugs really work and which are the best to use. The research is exciting and funding is badly needed for it. ..........

 

Brain. 1996 Aug;119 ( Pt 4):1067-77.

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Intravenous immunoglobulin treatment in chronic inflammatory demyelinating polyneuropathy. A double-blind, placebo-controlled, cross-over study.

Hahn AF, Bolton CF, Zochodne D, Feasby TE.

University of Western Ontario, London, Canada.

Thirty patients with definite or probable chronic inflammatory demyelinating polyradiculoneuropathy (CIDP) of chronic progressive (16 patients) or relapsing (14 patients) course were randomly assigned to receive intravenous immunoglobulin (IvIg) 0.4 g per kg body weight or a placebo treatment on 5 consecutive days in a double-blind, cross-over trial. Neurological function was monitored by serial quantitative assessments [neurological disability score (NDS); clinical grade (CG) and grip strength (GS) measurements] and by electrophysiological studies before and after each treatment period. Twenty-five patients completed both treatment periods. A comparison of the observed changes in clinical outcome measures revealed statistically significant differences in favour of IvIg, with (mean +/- SD) improvements in NDS by 24.4 +/- 5.4 points (P < 0.002) in CG by 1 +/- 0.3 points (P < 0.001) in GS by +6.3 +/- 1.7 kg (P < 0.005), whereas scores were unchanged or worse with placebo. A secondary two-groups analysis of the first trial period included all 30 patients; 16 patients had been randomly assigned to IvIg and 14 to placebo treatments. Again significant differences in favour of IvIg were observed in all the clinical end-points: improvement in NDS was 35.6 +/- 25 points (P < 0.0001), in CG it was 1.3 +/- 1.9 points (P < 0.002) and in GS +9.8 +/- 7.7 kg (P < 0.001), whereas all scores worsened with placebo. Of the 30 patients, 19 (63%) improved with IvIg treatments; nine out of 16 patients (56%) with chronic progressive CIDP, and 10 out of 14 patients (71%) with relapsing CIDP (differences were not statistically significant). A placebo response was seen in five patients. Comparison of paired electrophysiological measurements before and 4 weeks after IvIg treatments revealed statistically significant improvements in the summed motor conduction velocities (sigma MCV; P < -0.0001) and in the summed compound muscle action potentials (CMAP) evoked with proximal stimulation (sigma proximal CMAP, P < 0.03) of median, ulnar, peroneal and tibial nerves. Eight of nine IvIg responders with chronic progressive CIDP improved gradually to normal function with a single 5 day course of IvIg; in five of these, small doses of prednisone were prescribed during follow-up. In 10 IvIg responders with relapsing CIDP, improvements lasted a median 6 weeks (range 3-22 weeks) and was reproducible with open label treatments. All 10 patients have been maintained and stabilized with IvIg pulse therapy of 1 g per kg body weight or less, given as a single infusion prior to the expected relapse. A beneficial response to IvIg was found to be most likely in patients with acute relapse or with disease of one year or less. Patients with predominantly sensory signs did not improve.

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