Walking to work at St Mary's Hospital, Rochester, Minnesota, USA, as a visiting internal medicine resident in February 2010, I noticed some strange grey spots dancing in my visual field and thought them rather odd. I had never experienced this before and put it down to the glare from all the surrounding snow. Little did I know at the time that this was the beginning of my encounter with acephalgic migraine, or migraine aura without the headache. Thankfully my visual symptoms vanished after 3 or 4 min and I continued on my way to work. Later that week, while driving my car, I began to notice a subtle difference in my left arm and hand, almost a weakening or deadening; this lasted for about 10 min and then resolved gradually. At first these episodes occurred separately but as time went on the arm symptoms were sometimes followed by visual aura. The right arm, hand and leg have never been involved. These rather strange phenomena were new and puzzling to me.

The symptoms affecting my left hand and arm occurred thereafter intermittently but began to increase in frequency as the summer months approached. As these symptoms became more troublesome, I …