Correspondence

Correction

Case 40-2007: A Man with Weakness in the Hands

N Engl J Med 2008; 358:1869-1870April 24, 2008

Article

To the Editor:

In the Case Record involving a 38-year-old man with multifocal motor neuropathy, discussed by Triggs and Cros (Dec. 27 issue),1 Triggs emphasizes that it is important to distinguish multifocal motor neuropathy from amyotrophic lateral sclerosis or other motor neuron diseases because it responds favorably to immunotherapy. He mentions that plasma exchange, cyclophosphamide, and intravenous immune globulin are all beneficial. However, only treatment with intravenous immune globulins has been shown to be beneficial in randomized, controlled trials.2 Cyclophosphamide has been reported to be effective but only anecdotally, and its toxicity precludes long-term use, which is usually necessary in patients with multifocal motor neuropathy. Plasma exchange is a well-established therapy in other immune-mediated neuropathies, such as chronic inflammatory demyelinating neuropathy, but has not been shown to be effective in patients with multifocal motor neuropathy and may lead to deterioration with respect to symptoms.3-5

Elisabeth A. Cats, M.D.
W-Ludo van der Pol, M.D., Ph.D.
Leonard H. van den Berg, M.D., Ph.D.
University Medical Center Utrecht, 3584 CX Utrecht, the Netherlands
e.cats@umcutrecht.nl

5 References

1. 1

   Case Records of the Massachusetts General Hospital (Case 40-2007). N Engl J Med 2007;357:2707-2715
   Full Text | Web of Science | Medline

2. 2

   van Schaik IN, van den Berg LH, de Haan R, Vermeulen M. Intravenous immunoglobulin for multifocal motor neuropathy. Cochrane Database Syst Rev 2005;2:CD004429-CD004429
   Medline

3. 3

   Carpo M, Cappellari A, Mora G, et al. Deterioration of multifocal motor neuropathy after plasma exchange. Neurology 1998;50:1480-1482
   Web of Science | Medline

4. 4

   Claus D, Specht S, Zieschang M. Plasmapheresis in multifocal motor neuropathy: a case report. J Neurol Neurosurg Psychiatry 2000;68:533-535
   CrossRef | Web of Science | Medline

5. 5

   Feldman EL, Bromberg MB, Albers JW, Pestronk A. Immunosuppressive treatment in multifocal motor neuropathy. Ann Neurol 1991;30:397-401
   CrossRef | Web of Science | Medline

Author/Editor Response

I agree with Cats and colleagues that plasma exchange has not been shown to be effective in multifocal motor neuropathy. In describing therapy for multifocal motor neuropathy, the published article states, “Plasma exchange, cyclophosphamide, and intravenous immune globulin are all beneficial. . . .” However, in my original discussion of this case, I mentioned treatment with plasma exchange only in reference to early reports describing treatment of multifocal motor neuropathy with plasma exchange and cyclophosphamide in combination. My original statement was as follows: “Initial treatment studies described beneficial effects of plasma exchange and cyclophosphamide. Prednisone, in contrast, is ineffective and may worsen the disease. Subsequent studies have demonstrated the beneficial effects of intravenous immunoglobulin in multifocal motor neuropathy and the favorable risk-to-benefit ratio of this therapy relative to that of cytotoxic therapy has made IVIg the initial treatment of choice in these patients.” This statement was changed during the editorial process, and the change erroneously implied that treatment of multifocal motor neuropathy with plasma exchange is beneficial.

William J. Triggs, M.D.
McKnight Brain Institute, Gainesville, FL 32611