Clinical Utility of Acetylcholine Receptor Antibody Testing in Ocular Myasthenia Gravis.

IMPORTANCE: The sensitivity of acetylcholine receptor (AChR) antibody testing is thought to be lower in ocular myasthenia gravis (OMG) compared with generalized disease, although estimates in small-scale studies vary. There is little information in the literature about the implications of AChR antibody levels and progression from OMG to generalized myasthenia gravis. OBJECTIVES: To test the hypothesis that serum AChR antibody testing is more sensitive in OMG than previously reported and to examine the association between AChR antibody levels and progression from OMG to generalized myasthenia gravis. DESIGN, SETTING, AND PARTICIPANTS: A retrospective, observational cohort study was conducted of 223 patients (mean [SD] age, 59.2 [16.4] years; 139 [62.3%] male) diagnosed with OMG between July 1, 1986, and May 31, 2013, at 2 large, academic medical centers. MAIN OUTCOMES AND MEASURES: Baseline characteristics, OMG symptoms, results of AChR antibody testing, and progression time to generalized myasthenia gravis (if this occurred) were recorded for each patient. Multiple logistic regression was used to measure the association between all clinical variables and antibody result. Kaplan-Meier survival analysis was performed to examine time to generalization. RESULTS: Among the 223 participants, AChR antibody testing results were positive in 158 participants (70.9%). In an adjusted model, increased age at diagnosis (odds ratio [OR], 1.03; 95% CI, 1.01-1.04; P = .007) and progression to generalized myasthenia gravis (OR, 2.92; 95% CI, 1.18-7.26; P = .02) were significantly associated with positive antibody test results. Women were less likely to have a positive antibody test result (OR, 0.36; 95% CI, 0.19-0.68; P = .002). Patients who developed symptoms of generalized myasthenia gravis had a significantly higher mean (SD) antibody level than those who did not develop symptoms of generalized myasthenia gravis (12.7 [16.5] nmol/L vs 4.2 [7.9] nmol/L; P = .002). CONCLUSIONS AND RELEVANCE: We demonstrate a higher sensitivity of AChR antibody testing than previously reported in the largest cohort of patients with OMG available to date. Older age, male sex, and progression to generalized myasthenia gravis were significantly associated with a positive antibody test result. In addition, to our knowledge, this is the first report of an association between high AChR antibody levels and progression from OMG to generalized disease.

Second chances.

An 81-year-old woman presented with light perception vision in her left eye and had pallid swelling of the left optic disk. Temporal artery biopsy was normal. Magnetic resonance imaging revealed enlargement and enhancement of the left orbital optic nerve. There were vitreous cells, but a vitrectomy specimen showed only a benign lymphocytic population. Her vision deteriorated to no light perception in the left eye, and an optic nerve biopsy revealed a diffuse astrocytoma of World Health Organization grade II.

Prognosis of Ocular Myasthenia Gravis: Retrospective Multicenter Analysis.

PURPOSE: To calculate the rate and timing of conversion from ocular myasthenia gravis to generalized myasthenia gravis. DESIGN: Retrospective multicenter analysis. SUBJECTS: Patients included in the study were diagnosed with ocular myasthenia gravis without the presence of generalized disease at onset. METHODS: We conducted a retrospective multicenter analysis. We reviewed charts of 158 patients who met diagnostic criteria for ocular myasthenia gravis. Patients were divided into 2 subgroups: an immunosuppressant treatment group and a nonimmunosuppressant treatment group. Timing of conversion to generalized disease and duration of follow-up also was evaluated. Additional data such as clinical symptoms at presentation, laboratory test results, and chest imaging results also were recorded. MAIN OUTCOME MEASURES: Conversion rates to generalized myasthenia at 2 years, effect of immunosuppression on conversion, and timing of conversion. RESULTS: The 158-patient cohort included 76 patients who received immunosuppressant therapy; the remaining 82 patients did not. The overall conversion rate to generalized disease was 20.9%. At 2 years, generalized myasthenia developed in 8 of 76 patients in the treated group and in 15 of 82 patients in the nonimmunotherapy group (odds ratio, 0.52; 95% confidence interval, 0.20-1.32). Median time for conversion to generalized disease was 20 months in the nonimmunosuppressant group and 24 months in the immunosuppressant group. Conversion occurred after 2 years of symptom onset in 30% of patients. CONCLUSIONS: Conversion rates from ocular to generalized myasthenia gravis may be lower than previously reported both in immunosuppressed and nonimmunosuppressed patients. A subset of patients may continue to convert to generalized disease beyond 2 years from onset of symptoms, and close monitoring should be continued.