Cogan’s (Lid Twitch) Sign
Cogan’s sign is a twitching of the upper eyelid seen a moment after the eyes are moved from downgaze to the primary position. Twitches may also be seen with eye closure after sustained upgaze. These phenomena are said to be characteristic signs of ocular myasthenia gravis, and were found in 60% of myasthenics in one study. They may also occur occasionally in other oculomotor brainstem disorders, such as Miller Fisher syndrome, but are not seen in normals.
Cogan’s sign should not be confused with either Cogan’s syndrome, an autoimmune disorder of episodic vertigo, tinnitus, hearing loss and interstitial keratitis; or the oculomotor apraxia of Cogan, a congenital lack of lateral gaze.
Cogan DG. Myasthenia gravis: a review of the disease and a description of lid twitch as a characteristic sign. Archives of Ophthalmology1965; 74: 217-221
Whye Onn H, Cleary M, Metcalfe R. Cogan’s lid twitch revisited. Journal of Neurology, Neurosurgery and Psychiatry 2004; 75: 805 (abstract 082)