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Chronic limb-girdle myasthenia gravis
1Department of Neurology, University of Alabama, Birmingham 35294.
Abstract:
The existence of chronic "limb-girdle" form of myasthenia gravis (MG) has been questioned. We report here 12 such patients (10 women and two men) who constituted 3.8% of 314 MG patients in our study. The duration of disease ranged from 4 months to 7 years before the diagnosis. In almost all cases, the initial diagnosis was other than MG. None of the patients had any oculobulbar weakness. Acetylcholine receptor antibody was positive in five cases, although not all in the first assay. Repetitive nerve stimulation test was positive in all cases, although not necessarily the first time. Single-fiber EMG was positive in 11 cases. All patients responded to acetylcholinesterase inhibitors, and two thirds underwent immunotherapy. Diagnosis of limb-girdle MG requires a strong index of suspicion.
Insights
The chronic limb-girdle form of myasthenia gravis (MG) is real, affecting 3.8% of patients. Early diagnosis requires a high index of suspicion, as symptoms can be mistaken for other conditions.
Area of Science:
- Neurology
- Clinical Medicine
Background:
- The existence of a chronic limb-girdle form of myasthenia gravis (MG) has been debated.
- This specific subtype of MG often presents with diagnostic challenges, leading to delayed recognition.
Purpose of the Study:
- To investigate the characteristics and diagnostic criteria of the limb-girdle form of myasthenia gravis.
- To highlight the importance of recognizing this subtype in clinical practice.
Main Methods:
- Retrospective analysis of 12 patients diagnosed with limb-girdle MG.
- Review of clinical presentation, diagnostic test results (acetylcholine receptor antibody, repetitive nerve stimulation, single-fiber EMG), and treatment response.
Main Results:
- Limb-girdle MG constituted 3.8% of the studied MG population (12 out of 314 patients).
- Patients presented with limb-girdle weakness, lacking oculobulbar symptoms, and disease duration varied significantly before diagnosis.
- Diagnostic tests showed positive results: acetylcholine receptor antibody in 5/12, repetitive nerve stimulation in all, and single-fiber EMG in 11/12.
- All patients responded to acetylcholinesterase inhibitors, with two-thirds receiving immunotherapy.
Conclusions:
- The limb-girdle form of myasthenia gravis is a distinct clinical entity that warrants recognition.
- A high index of suspicion is crucial for diagnosing limb-girdle MG, especially when initial symptoms are atypical or mimic other neuromuscular disorders.