Three months after the onset, there was bilateral lid retraction, slow elevation and depression of both eyes, and limited elevation and depression of the left eye. His pupils were unremarkable. Two days later, the patient reported that he had developed about 30 episodes daily of vertical diplopia, each heralded by transient right periorbital tingling. His right eye would deviate down and in for up to 3 minutes. Tingling would recur, and the eye would return to a normal position. There was no oscillopsia. Observation of several episodes during re-examination several days later confirmed his description. Carbamazepine abolished the episodes. Three months later, he had full ductions, but elevation and depression of both eyes were slow. On all refixations, both eyes would make a slow, conjugate, small-amplitude clockwise rotation and then a corrective movement before stabilizing. At present, he is still receiving carbamazepine.