False positive acetylcholine receptor antibodies in a case of unilateral chronic progressive external ophthalmoplegia: case report and review of literature.

METHODS: We present a rare case with atypical presenting features of unilateral CPEO with a false positive Acetylcholine Receptor Antibody (AchRA) test resulting in diagnostic delay. We illustrate the unilateral nature of this case and demonstrate the caveats of performing myogenic ptosis correction in such patients. We also discuss the differential diagnosis of false positive AchRA, a test commonly performed in the investigation of ptosis. RESULTS: A 34-year old female presented with a more than 3-year history of slowly-progressive, unilateral, right-sided restriction in eye movements and ptosis. Clinical examination showed EOM were grossly restricted in the right eye with a ptosis and normal in the left eye. Serum AchRA was positive on serum enzyme-linked immunosorbent assay (ELISA) however, following two months of oral pyridostigmine therapy there were no signs of clinical improvement. The initial serum sample sent was retested for AchRA by radio-immunoassay (RIA) which came back negative. Subsequently a muscle biopsy was requested which showed the presence of ragged red fibres. CONCLUSION: Unilateral ptosis and ophthalmoplegia is an unusual presentation for CPEO which characteristically produces bilateral symmetrical motility defects. In addition to Myasthenia Gravis elevated AchRA levels have been reported in other autoimmune conditions such as Primary biliary cirrhosis, Eaton Lambert syndrome and Graves's ophthalmopathy. We also highlight the superiority of RIA versus ELISA in the detection of AchRA and illustrate the diagnostic challenge of investigating and managing myogenic ptosis in this complex cohort of patients.

Mitochondrial ophthalmoplegia with fatigable weakness and elevated acetylcholine receptor antibody.

A 25-year-old man with chronically progressive ptosis and bilateral ophthalmoplegia displayed fatigability and fluctuation of ptosis, an abnormal single-fiber electromyogram, and a markedly elevated acetylcholine receptor antibody level. Yet a muscle biopsy showed clear evidence of a mitochondrial cytopathy, and the clinical features did not improve after treatment with prednisone. This case emphasizes the difficulty in differentiating mitochondrial cytopathy from myasthenia gravis and points out that elevated acetylcholine receptor antibody levels may occur in nonmyasthenic conditions.

Chronic progressive external ophthalmoplegia: a report of 6 cases and a review of the literature.

INTRODUCTION: Chronic progressive external ophthalmoplegia is a common mitochondrial disease that shares clinical, enzymatic, and genetic features with other mitochondrial disorders. Effective treatment does not exist, and corrective surgery of the ptosis as a palliative measure is a treatment option. PATIENTS AND METHODS: This was a retrospective study of 10 years' duration gathering patients with the diagnosis. Information related to clinical features, ancillary tests, and genetic data was obtained from our patients. RESULTS: Six patients were identified with this disease, 5 of them women, aged 44 to 72 years. All patients presented with ptosis, and in 50% of the patients it was asymmetric. Half of the patients noted mild dysphagia for liquids. The CPK and acetylcholine receptor antibody levels were normal. Jitter was increased in half of the patients and ragged-red fibers were present in 5 of them. The most common enzyme alteration was the combined deficit of complexes I and IV. Familial forms were not found among our patients. The most common genetic anomaly was a single deletion in the mitochondrial DNA. CONCLUSION: Knowledge of this disorder enables us to avoid the use of drugs with significant side effects in cases of ptosis and ophthalmoplegia that do not respond to anticholinesterases.

External ophthalmoplegia with ragged-red fibres and acetylcholine receptor antibodies.

The cases of two elderly women with external ophthalmoplegia, generalized muscle weakness and serum anti-acetylcholine receptor antibodies, are presented. The electophysiological studies showed a myopathic pattern but no indications of myasthenia after repetitive stimulation. The edrophonium test was negative and there was no response to anticholinesterase medication. In addition, elevated serum lactic acid levels and ragged-red muscle fibres in the muscle biopsy, were observed in both patients. These findings are discussed in relation to the fact that anti-acetylcholine receptor antibodies are diagnostic of myasthenia gravis, whereas ragged-red fibres and elevated lactic acid are correlated with mitochondrial myopathies.