Signs of fatiguable muscle weakness in myasthenia gravis, how to elicit them and sensitivities and specificities from the published literature47–51
| Sign | How to elicit | Sensitivity | Specificity |
| Fatiguable ptosis on upgaze (Simpson’s test) | Measure the marginal reflex distance (see figure 3) before and after 30 s of looking up. Photography of the examination may help | 73% (when combined with ice-pack test) | 97% (when combined with ice-pack test) |
| Peek sign | Ask the patient to close the eyes gently. Separation of the eyelid margins and visibility of the sclera within 30 s is a positive finding | 4%–12% | 98%–99% |
| Curtain sign and enhanced ptosis | Passive elevation of the ptotic eyelid unmasks ptosis on the other side (curtain sign); passive elevation of the non-ptotic eyelid results in worsening ptosis on the affected side (enhanced ptosis). These phenomena occur due to Hering’s law of equal innervation and are not specific to myasthenia gravis | Unknown | Unknown |
| Cogan’s lid twitch | Ask the patient to look down for 30 s followed by quick movement into primary gaze. Transient improvement in ptosis with brief lid retraction is a positive finding | 50%–99% | 75%–99% |
| Quiver movements and glissades | Cogan also described characteristic high-velocity short-amplitude eye movements (quivers), often followed by slow corrective drifts to a target (glissades) | Unknown | Unknown |
| Lid-hopping sign | Ask the patient to perform alternating horizontal saccades (ie, look left, look right). Bilateral transient lid twitch is a positive finding | Unknown | Unknown |
| Ice-pack test | Measure ptosis before and after application of ice over the eyelid for 2 min, ideally also with a warm pack control to eliminate the effect of rest. Improvement of ptosis ≥2 mm is a positive finding | 20%–90% | 30%–100% |
| Bienfang’s test | Measure ptosis in primary gaze before and after 30 s of asking the patient to squeeze the eyelids tightly. Transient improvement in ptosis is a positive finding | 94% | 91% |
| Fatiguable limb weakness | Assess muscle strength (eg, shoulder abduction) before and after 30 s of repetitive exercise. Blind the examiner to the side exercised | Unknown | Unknown |