Objective: Cogan's lid twitch is thought to suggest myasthenia gravis in patients with unexplained ptosis. The validity of this clinical test has not been established. We conducted a prospective study to ascertain the sensitivity and specificity of this finding.
Methods: 35 patients with isolated, symptomatic ptosis, referred to a neuro-ophthalmologist or oculoplastics specialist were enrolled. The presence or absence of Cogan's lid twitch was noted, according to standard technique. Further testing was performed, and the final diagnosis for each patient was recorded.
Results: Four patients were found to have a Cogan's lid twitch. Two patients had ocular myasthenia gravis as the final diagnosis, and of those, only one had a twitch.
Conclusions: The sensitivity and specificity of Cogan's lid twitch is relatively low. Other conditions may cause a lid twitch as well. The presence of a Cogan's lid twitch may increase suspicion of myasthenia, but is not diagnostic, and does not exclude alternate etiologies of ptosis.