- Can mimic an isolated or combined neuropathy of CN III (except pupil involvement), IV, or VI, but often presents with diplopia or ptosis that is not easily categorized.
- Ocular involvement is seen early and may be the only system affected in some patients, with an inability to forcefully close their eyes against resistance.
- Patients frequently report worsening symptoms as the day progresses and relief after a nap or rest.
- Investigation
- The diagnosis is sometimes difficult to make because the results of edrophonium chloride (Tensilon) testing, serum acetylcholine receptor antibody assay, repetitive electromyographic nerve stimulation, or trials of pyridostigmine bromide (Mestinon) may be equivocal.
- The ice test is also a useful screen.
- Single-fiber electromyography has the greatest sensitivity and specificity but is technically difficult.
- CT of the thorax is performed to exclude a thymoma.
Made with Bullet