Neurology -- Correspondence for Richman and Agius, 61 (12) 1652-1661

Correspondence published:

Treatment of autoimmune myasthenia gravis: Andrew C. Bragdon (30 March 2004)

Reply to Bragdon: David P. Richman, Mark A. Agius (30 March 2004)

Treatment of autoimmune myasthenia gravis 30 March 2004

Andrew C. Bragdon,
Upstate Medical University and VA Medical Center
VA Medical Center, 800 Irving Avenue, Syracuse, NY 13210
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Re: Treatment of autoimmune myasthenia gravis

andrew.bragdon{at}med.va.gov Andrew C. Bragdon

The article by Richman et al describes both the rationale for and the practical aspects of treating autoimmune myasthenia gravis. Perhaps the authors could provide further information on two additional aspects of the disease.
First, in generalized myasthenia, the authors base adjustments in treatment (e.g., responses to exacerbations) on clinical indicators of disease activity. Are there any other biological markers that might reliably indicate effectiveness (earlier, greater sensitivity) of treatment? These indicators could be used to monitor treatment and establish more efficient long-term remission.
In addition, are the approaches modified with regard to treatment in AChR-Ab-negative patients or primarily ocular myasthenia cases?

Reply to Bragdon 30 March 2004

David P. Richman,
Univ of Calif., Davis
Department of Neurology, Davis, CA 95616,
Mark A. Agius
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Re: Reply to Bragdon

dprichman{at}ucdavis.edu David P. Richman, et al.

We thank Dr. Bragdon for his comments and questions. In terms of the usefulness of biological markers of disease activity to guide treatment decisions, we are not aware of any that are more sensitive and useful than the clinical signs and symptoms. The availability of such markers would be helpful.
The approach to cases of ocular myasthenia or acetylcholine receptor (AChR) antibody-negative myasthenia is even more challenging. The treatment of ocular myasthenia is difficult with respect to both the risk/ benefit ratio and in terms of the potential usefulness of various treatments in these patients (e.g., thymectomy) [1,2]. Our impression [3] is that these patients do respond to these treatments and that the issue is solely one of risk/benefit that should be assessed for each individual patient (with patient�s input). The issue of epitope spreading leads us towards the early use of immune-directed treatment [4], including thymectomy. For the muscle specific kinase (MuSK) antibody-positive subset of AChR antibody-negative myasthenia gravis patients, insufficient data are available to determine if the treatment approach should differ from what we have presented for AChR antibody- positive patients [5]. Before the discovery of MuSK antibodies, some uncontrolled studies showed that when the entire group of AChR antibody-negative patients is considered, their response to immune-directed treatment appears to be similar to the responses of anti-AChR-positive patients [6].
As Dr. Bragdon�s questions highlight, not all the issues in the treatment of autoimmune myasthenia have been settled.
References
1. Lanska DJ. Indications for thymectomy in myasthenia gravis. Neurology 1990; 40(12):1828-1829.
2. Masaoka A, Yamakawa Y, Niwa H, Fukai I, Kondo S, Kobayashi M et al. Extended thymectomy for myasthenia gravis patients: a 20-year review. Ann Thorac Surg 1996; 62(3):853-859.
3. Roberts PF, Venuta F, Rendina E, De Giacomo T, Coloni GF, Follette DM et al. Thymectomy in the treatment of ocular myasthenia gravis. J Thorac Cardiovasc Surg 2001; 122(3):562-568.
4. Agius MA. Treatment of ocular myasthenia with corticosteroids: yes. Arch Neurol 2000; 57(5):750-751.
5. Sanders DB, El Salem K, Massey JM, McConville J, Vincent A. Clinical aspects of MuSK antibody positive seronegative MG. Neurology 2003; 60(12):1978-1980.
6. Evoli A, Batocchi AP, Lo MM, Servidei S, Padua L, Majolini L et al. Clinical heterogeneity of seronegative myasthenia gravis. Neuromuscul Disord 1996; 6(3):155-161.