The Cochrane Neuromuscular Disease Group has featured in this publication before (Spring 2000 and 2001) and readers will remember that the group is part of the international Cochrane Collaboration set up in 1992 to assemble the evidence for the effects of healthcare interventions for all diseases.

The Neuromuscular Disease Group is responsible for assembling the evidence from randomized controlled trials for treatments for Guillain-Barré Syndrome, chronic inflammatory demyelinating polyradiculoneuropathy (CIDP), multifocal motor neuropathy and paraproteinaemic neuropathy.

Each review is developed in the same way: publishing a review protocol in advance, outlining the methods and objectives for the review, a comprehensive search for both published and unpublished randomized controlled trials in all languages, assessment of the quality of relevant trials, and if possible combining the results from several studies in a meta-analysis, a single numerical estimate of the efficacy of a treatment. All protocols and reviews are rigorously peer reviewed, revised and edited before publication. Cochrane reviews, unlike reviews published in print journals, are revisited regularly and updated at least every two years if new data become available.
Our previous articles addressed treatment for Guillain-Barré Syndrome which formed the basis of a Practice Parameter published by the Quality Standards Subcommittee of the American Academy of Neurology (Hughes et al. Neurology 2003; 61: 736-40).

We are making good progress in publishing systematic reviews on CIDP and now have 4 full reviews on treatments looking at plasma exchange, intravenous immunoglobulin, my cotoxic drugs and interferers and corticosteroid treatment. The results of the reviews on CIDP are as follows:

Corticosteroids for chronic inflammable demyelinating polyradiculoneuropathy
This review identified one randomized controlled trial, an open study in which 19 corticosteroids treated patients showed more improvement in impairment than 16 untreated controls after 12 weeks but when analyzed using an intention to treat analysis, this improvement was not significant. This small trial provided only weak evidence to support the conclusion from several large non-randomized studies that oral corticosteroids reduce impairment in chronic inflammatory demyelinating polyradiculoneuropathy. Nevertheless, observational studies suggest that corticosteroids are beneficial and many specialists recommend them as first line treatment. Corticosteroids are known to have serious long-term side embeds. The long-term risk and benefits have not been adequately compared with alternative regimens.

Plasma exchange for chronic inflammatory demyelinating polyradiculoneuropathy
Evidence from two small trials showed that plasma exchange provided significant short-term benefit in about two-thirds of patients with chronic inflammatory demyelinating polyradiculoneuropathy in measures of disability, impairment and nerve conduction but rapid deterioration may occur afterwards. Plasma exchange causes side effects in about 10% of patients and these are sometimes serious. The review concluded that more research is needed to identify agents which will prolong the beneficial action of plasma exchange. Some authorities consider plasma exchange the most effective treatment for CIDP but its inconvenience and limited availability render it a third line treatment.

Intravenous immunoglobulin for chronic inflamed Demyelinating Polyradiculoneuropathy
This review found four small randomized controlled trials which when combined in a meta-analysis showed that intravenous immunoglobulin (IVIg) improved disability for at least two to six weeks compared with patients treated with placebo. Two other small trials showed no significant difference between IVIg and plasma exchange in one, and corticosteroids in another. The review concluded that since IVIg, plasma exchange and prednisolone seem to be equally effective, it is currently uncertain which of these treatments should be the first choice. Cost, side effects, duration of treatment, dependency on regular hospital visits and ease of administration should all be considered before such a decision can be made. It was felt that further research was needed to draw conclusions about the long-term benefits of intravenous immunoglobulin compared with other treatments. Despite the evidence from the trials and observational studies, the FDA have not yet approved IVIg for use in the USA. Nevertheless, it is still widely used in North America and European ongoing trial seeks to register the use of IVIg for CIDP

Cytotoxic drugs and interferon’s for chronic inflammatory Demyelinating Polyradiculoneuropathy
This review found one open randomized trial of azathioprine for nine months involving 27 participants and another of interferon beta involving 10 participants in a double-blind crossover trial with each treatment period lasting 12 weeks. The trial of azathioprine showed no significant beneficial effect on impairment, or nerve conduction measures. The trial of beta interferon showed no benefit on a measure of disability. The review concluded that current evidence from thermo randomized trials was inadequate to decide whether azathioprine, interferon beta or any other immunosuppressive drug or interferon was effective in CIDP. There is a major need for more research in this area and a large trial of interferon beta is in progress.

Published reviews on CIDP
Mehndiratta MM, Hughes RAC. Corticosteroids for
chronic inflammatory Demyelinating Polyradiculoneuropathy (Cochrane review). In: The Cochrane Library, Issue 2, 2004. Chichester, UK: John Wiley and Sons, Ltd.

Hughes RAC, Swan AV, van Doom PA. Cytotoxic drugs and interferers for chronic inflammatory Demyelinating Polyradiculoneuropathy (Cochrane Review).
In: Cochrane Library, Issue 2, 2004. Chichester, UK: John Wiley & Sons, Ltd.
Van Schaik IN, Winer JB, de Haan R, Vermeulen M.
Intravenous immunoglobulin for chronic inflammatory demyelinating polyradiculoneuropathy (Cochrane Review). In: The Cochrane Library, Issue 2, 2004. Chichester, UK: John Wiley and Sons, Ltd.
Mehndiratta MM, Hughes RAC, Agarwal P. Plasma exchange for chronic inflammatory Demyelinating Polyradiculoneuropathy. (Cochrane Review). In: The Cochrane Library, Issue 3, 2004. Chichester, UK: John Wiley and Sons, Ltd.