From the Guidelines
The next step in evaluating a patient with myasthenia gravis symptoms, specifically worsening ptosis after looking up, would be to perform a complete sensorimotor examination and external examination, with attention to the presence of strabismus, variable ptosis, and slow saccades, as recommended by the most recent study 1. This approach is crucial in diagnosing myasthenia gravis, as the condition can present with variable weakness exacerbated by fatigue, and ocular symptoms such as ptosis and diplopia are common manifestations 1. The examination should include the Ice Test, which can demonstrate a reduction of ptosis and misalignment, and is highly specific to this disorder 1. Additionally, testing for acetylcholine receptor antibodies can confirm the diagnosis, although it is essential to note that about 20% of patients with generalized myasthenia and about half of those with ocular myasthenia are seronegative 1. Referral to a neurologist or neuro-ophthalmologist may also be indicated in the management of myasthenia, as counseling and discussion of management options with the patient and any caregivers are crucial 1. Key aspects of the examination and diagnosis include:
- Complete sensorimotor examination and external examination
- Attention to strabismus, variable ptosis, and slow saccades
- Ice Test to demonstrate reduction of ptosis and misalignment
- Testing for acetylcholine receptor antibodies to confirm diagnosis
- Referral to a neurologist or neuro-ophthalmologist for further management.
From the FDA Drug Label
DOSAGE AND ADMINISTRATION ... Note: For information on a diagnostic test for myasthenia gravis, and for the evaluation and stabilization of therapy, please see product literature on edrophonium chloride. The next step in evaluating a patient with myasthenia gravis symptoms, specifically worsening ptosis after looking up, is to consider a diagnostic test for myasthenia gravis, and for the evaluation and stabilization of therapy, as the current drug label does not provide direct information on the next steps for evaluation. According to the label, more information can be found in the product literature on edrophonium chloride 2.
From the Research
Evaluating Worsening Ptosis in Myasthenia Gravis
- The next step in evaluating a patient with myasthenia gravis (MG) symptoms, specifically worsening ptosis after looking up, would involve a comprehensive clinical assessment and diagnostic tests 3, 4.
- A clear diagnosis of MG can be made based on clinical features, serologic testing, and additional tests such as repetitive nerve stimulation, single fiber EMG, and the ice pack test 3.
- The presence of anti-acetylcholine receptor antibodies (anti-AChR) is a key diagnostic marker, found in 80%-85% of patients with MG 3.
- In patients with worsening ptosis, it is essential to assess for other symptoms of MG, such as diplopia, facial bulbar weakness, and limb weakness 3, 4.
- Treatment options for MG consist of symptomatic treatment, immunosuppressive treatment, or thymectomy, and the choice of treatment depends on the severity of symptoms and the presence of thymoma 3, 4, 5.
Diagnostic Considerations
- A systematic review of literature reveals that post-thymectomy MG can be categorized as early-onset or late-onset form with differing aetiology, and demonstrated correlation between preoperative anti-AChR titres and post-thymectomy MG 6.
- The clinical characteristics and outcomes of thymoma-associated MG have been studied, and it has been found that thymoma-associated MG patients have more severe myasthenic symptoms and worse prognosis 5.
- Unusual presentations of MG, such as asymmetric distal upper limbs weakness, foot drop, and isolated triceps brachii weakness, can increase the risk of misdiagnosis or delayed diagnosis 7.
- A careful clinical examination, proper neurophysiological assessment, and diagnostic tests such as the neostigmine test, AChR and MuSK antibodies assay, and chest CT-scan are essential for achieving an accurate diagnosis of MG 7.