Glucocorticoids were formerly the mainstay of therapy, but many patients become dependent on the medication and correspondingly suffer side effects. Our approach has been to use corticosteroids as an adjunct to one of the previously mentioned treatments, but other centers use them first. The usual regimen begins with 60 to 80 mg of prednisone daily that is tapered over months to the lowest effective dose, typically 25 to 40 mg. Without substantiation by a controlled trial, we have found that corticosteroids can be withdrawn without relapse in some patients by slow tapering over many months or a year. Attempts to withdraw the steroids more quickly have led to further cycles of relapse.
A number of patients will have no response to glucocorticoids within the first 1 or 2 months but will improve if treatment is continued. Barohn and colleagues (1989) have found that the earliest improvement occurs only after 2 months of treatment and is maximal at approximately 6 months. In addition to all the well-known side effects, the drug may produce tremor or exaggerate the tremor caused by the neuropathy. Long remissions lasting several years have been reported with the use of pulses of orally administered high-dose or daily corticosteroids, for example, by Eftimov and colleagues, who used dexamethasone 40 mg per day for 4 days, repeated for 6 cycles, or daily prednisolone, 60 mg for 6 weeks. Should a sustained trial of prednisone therapy prove unsuccessful, a course of azathioprine (for at least 3 months), 3 mg/kg in a single daily dose, has been recommended (Dalakas and Engel, 1981a), but a controlled trial has failed to show benefit from this combination and we have had little success with it.
When the preceding measures prove unsatisfactory, cyclophosphamide, mycophenolate, rituximab, or another similar immunosuppressive medication can be added, but we have been unable to draw any firm conclusions as to the effectiveness of these combined regimens.
High-dose cyclophosphamide has proven helpful in several cases under our care, although it has often failed (see Brannagan et al and the review by Brannagan that lists the applicable clinical trials). The usual regimen is 50 mg/kg IV daily for 4 days followed by granulocyte-stimulating factor beginning on the tenth day until the absolute neutrophil count recovers. Individual reports of successful treatment by autologous stem cell transplantation after high-dose chemotherapy have appeared but 1 patient relapsed after 5 years (Vermuelen and van Oers). This may become an option in severe and treatment-resistant cases. We have no explanation for the remarkable improvement and continued good health of a few of our patients after a severe toxic bacterial infection (Ropper, 1996).
It has been stated that patients with discrete relapses have a better prognosis than those with a progressive course. In McCombe’s series (1987b), 73 percent were said to have eventually recovered, but the long-term outcome has generally been poor. In fewer than 10 percent of patients has the disease finally remitted; additionally, unexplained remission occurs occasionally. The 5-year followup of 38 patients by Kuwabara and colleagues gives a figure of 49 percent with full or partial remission, far higher than in our series.
Several polyneuropathies that share many of the features of CIDP have been delineated on the basis of unique clinical, immune, or electrophysiologic attributes. These include particularly multifocal motor neuropathy (MMN) and multifocal conduction block (also called MADSAM, as mentioned earlier). The latter has as its main feature a block of mixed nerve conduction at focal sites in a limited number of nerves as described earlier. In multifocal motor neuropathy, only blocks in motor nerve conduction are evident.