Transient visual loss, lower extremity monoparesis, and sudden sharp headaches precipitated by long car trips.

CLINICAL HISTORY This is a 53-year-old white male who has had about 12 spells in the last year. The episodes are almost all the same and only occur if he is either driving or a passenger in a car for over 1 hour. When he gets out of the car and starts walking with a latency of about 30 seconds, he develops blurred vision where the entire field of vision is almost gray. The right lower extremity becomes weak and he drags it. In the last two episodes, the right leg was so weak that he went down to his knee. His head drops and he has to lift it up but then it drops again. The visual and right lower extremity symptoms have been lasting 10 to 15 seconds, but the last two episodes have lasted a couple of minutes. These initial symptoms are immediately followed by a sudden sharp pain on the top of the head with an intensity of 10/10 lasting 5 minutes like his head is going to explode. There is no associated nausea, light or noise sensitivity. There is no speech disturbance or paresthesias associated with the episode. With the one recent spell, he sat down at the onset, and the symptoms were better but then he stood up and he had a