Immunosuppression aids ocular myasthenia gravis.
The eye muscles are affected first in about 40% of patients who develop myasthenia gravis. The goal of any treatment for ocular myasthenia gravis is to halt the disease's progression to other muscles while controlling ocular symptoms. Immunosuppressive therapy promises to accomplish both goals in a significant number of patients.
Several recent studies have indicated that patients treated with prednisone or other immunomodulating drugs experience a significantly decreased incidence of disease progression, said Dr. Kaminski of Case Western Reserve University, and Veterans Affairs Medical Center, Cleveland. These studies are retrospective, and more research is needed to confirm the results.
About half of affected patients experience restrictive ocular motility, and half experience ptosis, often with hyperretraction of the contralateral lid. Most patients with advanced ocular myasthenia have double vision; some also complain of dizziness that may impair walking. Within 1 year of developing symptoms, up to 80% of patents with ocular disease will progress to generalized disease.
Prescribing acetylcholinesterase inhibitors has long been the first step in pharmacologic treatment. A typical dose is up to 90 mg every 3 hours. Unfortunately, only about 50% of patients have adequate symptom relief. In fact, the drug can make visual symptoms worse by strengthening the extraocular muscles, Dr. Kaminski said.
Corticosteroids are often necessary for those who don't respond to acetylcholinesterase inhibitors or who have disabling visual symptoms, he said. Typically, regimens start at 10-20 mg/day with gradual upward titration until symptoms are controlled.
A 2003 study showed a significant decrease in the incidence of disease generalization among patients treated with prednisone, Dr. Kaminski said. In that study, Mark Kupersmith, M.D., of Beth Israel Medical Center, New York, reviewed 147 patients with ocular myasthenia who received either prednisone, pyridostigmine bromide, or no pharmacotherapy. At 2 years, the incidence of generalized disease among the treated group was 7%, compared with 36% in patients who did not receive prednisone (Arch. Neurol. 2003; 60:243-8).
A second review, published in 2004, had a similar finding. N.T. Monsul, M.D., of Yale University, New Haven, reviewed 56 ocular myasthenia patients, 27 of whom had received prednisone therapy and 29 not. At 2 years, only three of the treated patients progressed to generalized myasthenia, compared with 10 of the 29 untreated patients (J. Neurol. Sci. 2004;217:131-3).
Research is also focusing on steroid-sparing immunosuppressive agents, including mycophenolate mofetil, Dr. Kaminski said. A poster presented at the meeting examined the use of that agent in the disorder.
Jane Chan, M.D., of the University of Nevada, Las Vegas, prospectively analyzed mycophenolate mofetil treatment in 31 ocular myasthenia patients over 38 months. Patients were started on 40-60 mg/day prednisone while mycophenolate mofetil was titrated up to the target dose of 1 g/day. After symptoms stabilized, the prednisone was tapered.
Three patients discontinued the drug due to an adverse event; one discontinued due to lack of efficacy; and one discontinued due to cost. No cases of cytopenias or infections were observed.
Of the patients who continued therapy, all remained at stage I of the disease. Symptom relapse, including ptosis or diplopia, occurred in 12 patients.
MICHELE G. SULLIVAN
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|Title Annotation:||Clinical Rounds|
|Author:||Sullivan, Michele G.|
|Publication:||Family Practice News|
|Date:||Jun 15, 2005|
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